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| 3. | STATIC GENERAL KNOWLEDGE |
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| 4. | CHALLENGING SYLLOGISM |
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| 5. | STRAIT OF HORMUZ: STRATEGIC & ECONOMIC ROLE |
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| 6. | BIHAR TEACHER ELIGIBILITY TEST (BIHAR TET) : COMPLETE GUIDE |
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| 7. | SSC ENGLISH PREVIOUS YEAR MCQ |
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| 8. | BANKING KNOWLEDGE QUESTIONS AND ANSWERS MCQ |
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| 9. | BIHAR ANM, GNM & PHARMACIST EXAM: PAST MCQ QUESTIONS & ANSWERS – |
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| 10. | ARAVALLI MOUNTAIN RANGE: THE ANCIENT SPINE OF INDIA |
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| 11. | GK SSC TIER I PREVIOUS YEAR MCQ |
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| 12. | REITs AND InvITs IN INDIA: COMPLETE GUIDE (SCOPE, RISKS & FUTURE) |
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| 13. | भारतीय संसद का सत्र: प्रक्रिया, नियमऔर एस ओ पी ; पी एस यू परीक्षा के लिए संपूर्ण मार्ग दर्शिका |
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| 17. | PETROLEUM REFINERY PROCESS: WITH 200 MCQ |
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| 18. | SET THEORY: A COMPLETE GUIDE WITH 400 MCQ |
| https://play.google.com/books/publish/u/0/a/12574378860292240754#book/GGKEY:83LKH7QHRQH/review | |
| 19. | WORLD’S SMALLEST, LONGEST, THINNEST, THICKEST AND TALLEST |
| https://play.google.com/books/publish/u/0/a/12574378860292240754#book/GGKEY:9LE49HEDZJE/review | |
| 20. | HIGH TIDE AND LOW TIDE: A COMPLETE GUIDE |
| https://play.google.com/books/publish/u/0/a/12574378860292240754#book/GGKEY:TKR79QBDE7R/review | |
| 21. | 1000 HISTORY QESTIONS & ANSWERS FOR PSU |
| https://play.google.com/books/publish/u/0/a/12574378860292240754#book/GGKEY:1SGWQKT7BDF/review | |
| 22. | नालंदा विश्वविद्यालय : सम्पूर्ण अध्ययन |
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| 23. | भगवान शिव के 12 ज्योतिर्लिंग: इतिहास, महत्व और दर्शन क्रम |
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| 24. | NISM-SERIES-V-A MUTUAL FUND DISTRIBUTOR: COMPLETE STUDY GUIDE & EXAM PREPARATION |
| https://play.google.com/books/publish/u/0/a/12574378860292240754#book/GGKEY:YP1PQ8RQY07/review | |
| 25. | WORKSHOP TECHNOLOGY & MANUFACTURING PROCESSES COMPLETE EXAM GUIDE |
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DISCLAIMER
This educational material is intended for examination preparation only. Questions presented as PYQs should be checked against official examination papers wherever available. Some questions may be paraphrased to improve clarity. GK GALAXY does not claim ownership of official examination papers and is not responsible for errors in unofficial or memory-based question compilations. Students should consult the official NEET-UG/NTA website and the prescribed NCERT textbook for verification.
PART 1: COMPLETE THEORY OF CELL ORGANELLES
1. INTRODUCTION TO CELL ORGANELLES
Cell organelles are specialized structures inside cells that perform particular functions necessary for cellular survival, growth, energy production, synthesis, transport and waste removal.
The cell is the basic structural and functional unit of life. Different organelles work together to maintain cellular activities.
Cell organelles are broadly classified into:
Membrane-bound organelles: Endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, plastids and peroxisomes.
Non-membranous structures: Ribosomes, nucleolus, centrioles and cytoskeletal elements.
Genetic control centre: Nucleus, which is surrounded by a double membrane in eukaryotic cells.
Prokaryotic cells lack a true membrane-bound nucleus and most membrane-bound organelles. Eukaryotic cells possess a well-organized nucleus and various specialized organelles.
2. Cell Membrane
The plasma membrane, also called the cell membrane, forms the outer boundary of the cell and regulates the movement of substances into and out of it.
STRUCTURE
It is mainly composed of lipids and proteins.
Phospholipids form a bilayer.
Hydrophilic heads face the aqueous environment.
Hydrophobic tails face inward, away from water.
Proteins may be integral or peripheral.
Cholesterol helps regulate membrane fluidity in animal cells.
Carbohydrates associated with lipids and proteins participate in cell recognition.
The accepted model is the fluid mosaic model, proposed by S. J. Singer and G. L. Nicolson in 1972.
FUNCTIONS
- Controls the entry and exit of substances.
- Maintains cellular integrity.
- Facilitates cell signalling and recognition.
- Supports passive and active transport.
- Participates in endocytosis and exocytosis.
NEET HIGH-YIELD FACTS
Simple diffusion occurs down a concentration gradient without direct energy expenditure.
Facilitated diffusion uses membrane proteins but does not directly require ATP.
Active transport can move substances against their concentration or electrochemical gradient and requires energy.
Osmosis is the movement of water across a selectively permeable membrane in response to a difference in water potential.
3. CELL WALL
The cell wall is a rigid outer covering present in plant cells, fungi and most bacteria, but absent in animal cells.
| Organism | Major cell-wall component |
| Plants | Cellulose |
| Fungi | Chitin |
| Most bacteria | Peptidoglycan |
| Archaea | No true bacterial peptidoglycan; composition varies |
Functions
Provides shape and mechanical support.
Protects the cell against physical damage.
Helps prevent excessive swelling under suitable conditions.
Allows communication between adjacent plant cells through plasmodesmata.
In plants, the middle lamella is rich in calcium pectate and helps cement neighbouring cells together.
4. NUCLEUS
The nucleus contains most of the genetic material in a eukaryotic cell and regulates gene expression and cellular activities.
STRUCTURE
NUCLEAR ENVELOPE: A double membrane surrounding the nucleus. The two membranes enclose a perinuclear space.
NUCLEAR PORES: Permit regulated exchange of RNA, proteins and other molecules between the nucleus and cytoplasm.
NUCLEOPLASM: The internal fluid-like matrix of the nucleus.
CHROMATIN: DNA associated with proteins, particularly histones. It condenses into visible chromosomes during cell division.
NUCLEOLUS: A dense region involved in ribosomal RNA synthesis and ribosomal subunit assembly.
Functions
Stores and protects genetic information.
Controls gene expression.
Supports DNA replication before cell division.
Produces RNA through transcription.
Participates in ribosome biogenesis through the nucleolus.
Important exception: Mature mammalian red blood cells lack a nucleus. Prokaryotes do not possess a membrane-bound nucleus; their genetic material is located in the nucleoid region.
5. Mitochondria
Mitochondria are double-membrane-bound organelles primarily involved in aerobic cellular respiration and ATP production.
They are often called the powerhouses of the cell.
STRUCTURE
Outer membrane: Forms the external boundary.
Intermembrane space: Space between the two membranes.
Inner membrane: Contains components of the electron transport chain and ATP synthase.
Cristae: Folds of the inner membrane that increase its surface area.
Matrix: Contains enzymes, mitochondrial DNA, RNA and ribosomes.
FUNCTIONS
- Produces ATP through oxidative phosphorylation.
- Participates in the citric acid cycle, also called the Krebs cycle.
- Supports oxidation of pyruvate-derived acetyl-CoA.
- Participates in the regulation of programmed cell death.
- Helps regulate cellular calcium and metabolic processes.
Why are mitochondria called semiautonomous organelles?
Mitochondria possess their own DNA and ribosomes and can produce some of their own proteins. However, most mitochondrial proteins are encoded by nuclear genes and imported into the organelle.
NEET FACTS
The electron transport chain and ATP synthase are located in the inner mitochondrial membrane.
The Krebs cycle occurs in the mitochondrial matrix in eukaryotic cells.
Mitochondrial DNA is generally circular.
Mitochondria are associated with the endosymbiotic origin of eukaryotic cells.
6. PLASTIDS
Plastids are found in plants and many algae. They are double-membrane-bound organelles that include chloroplasts, chromoplasts and leucoplasts.
A. CHLOROPLASTS
Chloroplasts are the principal sites of photosynthesis in plants.
STRUCTURE
Outer and inner membranes
Stroma
Thylakoids
Grana, which are stacks of thylakoids
Stroma lamellae connecting grana
Chlorophyll and other photosynthetic pigments in thylakoid membranes
Chloroplast DNA and ribosomes
FUNCTIONS
Light-dependent reactions occur in the thylakoid membranes.
The Calvin cycle occurs in the stroma.
Produces carbohydrates through photosynthesis using energy derived from light.
B. CHROMOPLASTS
Chromoplasts contain carotenoid pigments and contribute yellow, orange and red colours to many flowers and fruits. These colours can assist in attracting pollinators and seed dispersers.
C. LEUCOPLASTS
Leucoplasts are generally colourless plastids involved mainly in storage.
| Type | Main stored substance |
| Amyloplast | Starch |
| Elaioplast | Oils and fats |
| Proteinoplast (aleuroplast) | Proteins |
Plastids can change their developmental state in some plant tissues. Like mitochondria, they contain their own genetic material and ribosomes.
7. ENDOPLASMIC RETICULUM (ER)
The endoplasmic reticulum is a network of membrane-bound tubules, vesicles and flattened sacs called cisternae. It is involved in the synthesis, processing and transport of cellular materials.
A. Rough Endoplasmic Reticulum (RER)
RER has ribosomes attached to its cytoplasmic surface, giving it a rough appearance.
Functions:
Synthesis of many secretory proteins.
Synthesis of membrane proteins.
Initial folding and processing of newly synthesized proteins.
Transport of proteins towards the Golgi apparatus.
B. Smooth Endoplasmic Reticulum (SER)
SER lacks attached ribosomes.
Functions:
Synthesis of lipids and phospholipids.
Synthesis of steroid hormones in steroid-producing cells.
Detoxification of drugs and harmful substances, particularly in liver cells.
Calcium storage and release in specialized muscle-cell SER, called the sarcoplasmic reticulum.
NEET distinction: RER is primarily associated with protein synthesis, whereas SER is associated with lipid synthesis and several metabolic functions.
8. Golgi Apparatus
The Golgi apparatus consists of stacks of flattened membrane-bound sacs called cisternae. It was discovered and described by Camillo Golgi in 1898.
Structure
Cis face: Generally receives transport vesicles from the endoplasmic reticulum.
Medial region: Participates in the modification and processing of molecules.
Trans face: Generally sorts and dispatches materials to their destinations.
Functions
- Modifies proteins and lipids received from the ER.
- Participates in the formation of glycoproteins and glycolipids.
- Sorts and packages materials into vesicles.
- Produces secretory vesicles.
- Contributes to lysosome formation by processing and sorting lysosomal enzymes.
- Helps synthesize certain complex carbohydrates.
Important fact: The Golgi apparatus is a central processing and distribution centre of the endomembrane system.
9. Lysosomes
Lysosomes are single-membrane-bound organelles containing hydrolytic enzymes that digest biological materials.
They are formed through the coordinated activities of the endoplasmic reticulum and Golgi apparatus.
Functions
Intracellular digestion of macromolecules.
Breakdown of materials taken up by endocytosis.
Recycling of damaged cellular components through autophagy.
Destruction of certain invading microorganisms.
Removal and recycling of cellular waste.
Lysosomal enzymes work best in an acidic environment, typically around pH 4.5–5, maintained partly by proton pumps in the lysosomal membrane.
Why are lysosomes called suicidal bags?
This traditional term refers to the possibility that the release of lysosomal enzymes into the cytoplasm under certain circumstances can contribute to cellular damage. It does not mean that lysosomes normally destroy healthy cells.
10. Vacuoles
Vacuoles are membrane-bound compartments involved in storage, regulation and waste management. In plant cells, a large central vacuole may occupy much of the cell’s volume.
Important components
Cell sap: Fluid containing water, ions, sugars, pigments and other dissolved substances.
Tonoplast: The membrane surrounding a vacuole.
Functions
- Stores water, ions, nutrients and waste products.
- Maintains turgor pressure in plant cells.
- Helps regulate cellular osmotic balance.
- Stores pigments, including anthocyanins in some plant cells.
- Supports digestion in certain protists.
Contractile vacuoles help remove excess water from many freshwater protists.
11. Ribosomes
Ribosomes are non-membranous structures responsible for protein synthesis. They consist of ribosomal RNA (rRNA) and proteins.
Types
| Ribosome type | Typical location |
| 70S | Prokaryotic cytoplasm; mitochondria and plastids |
| 80S | Eukaryotic cytoplasm and the surface of rough ER |
The 70S ribosome contains a 50S large subunit and a 30S small subunit. The 80S ribosome contains a 60S large subunit and a 40S small subunit.
The Svedberg (S) unit represents sedimentation behaviour; it is not an additive measure of mass, which explains why the subunits’ S values do not simply add to the value of the complete ribosome.
Polysomes
When multiple ribosomes translate a single mRNA molecule simultaneously, they form a polysome or polyribosome.
NEET facts
Ribosomes are not surrounded by a membrane.
Free ribosomes commonly synthesize proteins used in the cytosol and certain organelles.
Ribosomes attached to RER synthesize many proteins destined for secretion, membranes or the endomembrane system.
12. Peroxisomes and Glyoxysomes
Peroxisomes are single-membrane-bound microbodies containing enzymes involved in oxidation reactions.
Functions of peroxisomes
Break down certain fatty acids.
Produce hydrogen peroxide during some oxidation reactions.
Use catalase to convert hydrogen peroxide into water and oxygen.
Participate in photorespiration in plant cells.
Glyoxysomes
Glyoxysomes are specialized microbodies found particularly in oil-rich seeds during germination.
They contain enzymes of the glyoxylate cycle, which helps convert stored lipids into carbohydrate precursors needed by the developing seedling.
Distinction: Peroxisomes and glyoxysomes are not considered part of the endomembrane system in the standard NCERT classification.
13. Cytoskeleton
The cytoskeleton is a network of protein filaments that provides structural organization and supports movement inside cells.
It consists of three major components.
| Component | Main protein | Major functions |
| Microtubules | Tubulin | Intracellular transport, spindle formation, cilia and flagella |
| Microfilaments | Actin | Cell movement, contraction and cytokinesis |
| Intermediate filaments | Various proteins | Mechanical strength and structural stability |
Functions
Maintains cell shape.
Supports intracellular transport.
Helps position organelles.
Participates in cell division.
Enables movement and changes in cell shape.
14. Centrosome and Centrioles
The centrosome is an important microtubule-organizing centre in animal cells. It typically contains a pair of centrioles surrounded by pericentriolar material.
Each centriole has a characteristic arrangement of nine peripheral microtubule triplets, often described as a cartwheel-like organization in cross-section.
Functions
Organizes microtubules.
Helps organize the mitotic spindle in animal cells.
Centrioles can form basal bodies from which cilia and flagella develop.
A centriole is not the same structure as a basal body, although they share a similar microtubule arrangement.
15. Cilia and Flagella
Cilia and flagella are cell-surface projections involved in movement or moving fluid across a cell surface.
Structure
Many motile eukaryotic cilia and flagella possess an axoneme with a 9 + 2 arrangement:
Nine peripheral microtubule doublets.
Two central microtubules.
The axoneme is surrounded by the plasma membrane. Dynein motor proteins help produce bending movements.
Basal bodies generally possess nine peripheral microtubule triplets and lack the central pair characteristic of the typical motile axoneme.
Examples:
Cilia move mucus in the human respiratory tract.
Flagella help sperm cells move.
Not all cilia are motile; primary cilia often perform sensory functions.
16. Other Important Cell Structures
A. Nucleolus
The nucleolus is a region inside the nucleus where ribosomal RNA is synthesized and ribosomal subunits are assembled. It is not surrounded by a membrane.
B. Chromatin and Chromosomes
Chromatin consists of DNA and associated proteins. During cell division, chromatin becomes more condensed and forms visible chromosomes.
Histones help package DNA into chromatin.
C. Plasmodesmata
Plasmodesmata are cytoplasmic channels connecting neighbouring plant cells through their cell walls. They enable communication and transport of certain substances between cells.
D. Mesosomes — an important historical caution
Older biology texts described mesosomes as infoldings of the bacterial plasma membrane and attributed several functions to them. However, mesosomes are now generally considered artifacts of chemical fixation in electron microscopy, not accepted normal structures of living bacterial cells. Be careful when interpreting older examination questions that repeat the historical description.
17. Endomembrane System
The endomembrane system consists of organelles that work together in the synthesis, modification, packaging, transport and digestion of cellular materials.
The standard NCERT grouping includes:
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Not included in this grouping: Mitochondria, chloroplasts, peroxisomes and ribosomes.
This is a particularly important NEET distinction because an organelle can be membrane-bound without belonging to the endomembrane system.
18. Rapid Revision Table
| Organelle or structure | Most important function or identifying feature |
| Nucleus | Genetic control and DNA storage |
| Nucleolus | rRNA synthesis and ribosomal subunit assembly |
| Mitochondria | Aerobic respiration and ATP production |
| Chloroplast | Photosynthesis |
| RER | Synthesis of many secretory and membrane proteins |
| SER | Lipid synthesis and detoxification |
| Golgi apparatus | Modification, sorting and packaging |
| Lysosomes | Intracellular digestion |
| Vacuoles | Storage and osmotic regulation |
| Ribosomes | Protein synthesis |
| Peroxisomes | Oxidation and hydrogen peroxide metabolism |
| Glyoxysomes | Glyoxylate cycle in germinating oil-rich seeds |
| Cytoskeleton | Cell shape, organization and movement |
| Centrioles | Microtubule organization and basal-body formation |
| Cilia and flagella | Movement or sensory functions |
| Plasmodesmata | Communication between plant cells |
PART 2: NEET PREVIOUS-YEAR QUESTIONS (PYQS) : CELL ORGANELLES
Question 1. Match the cell organelles and their functions.
Exam: NEET-UG 2024 Re-Examination
| Column I | Column II |
| A. Nucleolus | I. Storage of nutrients |
| B. Centriole | II. Site of active rRNA synthesis |
| C. Leucoplast | III. Cartwheel-like organization |
| D. Golgi apparatus | IV. Formation of glycolipids |
Choose the correct matching:
A. A–II, B–III, C–I, D–IV
B. A–I, B–II, C–IV, D–III
C. A–III, B–IV, C–II, D–I
D. A–IV, B–I, C–III, D–II
Correct answer: A
Explanation: The nucleolus is a major site of rRNA synthesis. Centrioles have nine peripheral microtubule triplets in a characteristic arrangement. Leucoplasts store substances such as starch, oils and proteins. The Golgi apparatus participates in glycolipid formation and processing.
Question 2. Which of the following are NOT parts of the endomembrane system?
Exam: NEET-UG 2023 (All India)
A. Mitochondria, chloroplasts and peroxisomes
B. Endoplasmic reticulum and Golgi apparatus
C. Lysosomes and vacuoles
D. Endoplasmic reticulum, Golgi apparatus and lysosomes
Correct answer: A
Explanation: The standard NCERT endomembrane system includes the endoplasmic reticulum, Golgi apparatus, lysosomes and vacuoles. Mitochondria, chloroplasts and peroxisomes are excluded because their functions are not coordinated with this system in the same way.
Question 3. Which statement about the Golgi apparatus is correct?
Exam: NEET-UG 2023 (Manipur)
A. It is the primary site of aerobic respiration.
B. It participates in the formation of glycoproteins and glycolipids.
C. It contains the cell’s principal genetic material.
D. It is the site of translation on free ribosomes.
Correct answer: B
Explanation: The Golgi apparatus modifies, sorts and packages proteins and lipids. It also participates in the formation of glycoproteins and glycolipids. Aerobic respiration occurs mainly in mitochondria in eukaryotic cells, while translation occurs on ribosomes.
Question 4. What is the expected effect of raising lysosomal pH to an alkaline level?
Exam: NEET-UG 2022, Phase 2
A. Lysosomal hydrolytic enzymes become more active.
B. Lysosomal hydrolytic enzyme activity generally decreases.
C. Lysosomes begin photosynthesis.
D. Lysosomes produce ribosomes.
Correct answer: B
Explanation: Lysosomal acid hydrolases function optimally in an acidic environment. Raising the pH towards alkaline conditions reduces the activity of many of these enzymes and interferes with intracellular digestion.
Question 5. Which statement about mitochondria and chloroplasts is correct?
Exam: NEET-UG 2024
A. Both are single-membrane-bound organelles.
B. Both possess a double membrane and their own genetic material.
C. Neither contains ribosomes.
D. Both are components of the endomembrane system.
Correct answer: B
Explanation: Mitochondria and chloroplasts are double-membrane-bound organelles that contain their own DNA and ribosomes. They are considered semiautonomous because they can synthesize some proteins but depend on nuclear genes for many others. Neither is classified as part of the endomembrane system.
Question 6. Which structure is correctly associated with mitochondria?
Exam: NEET-UG 2024 Re-Examination
A. F₁ particles
B. Histones
C. Axoneme
D. Plasmodesmata
Correct answer: A
Explanation: F₁ particles are associated with ATP synthase complexes on the inner mitochondrial membrane and project towards the matrix. Histones are associated with chromatin, axonemes form the internal structure of cilia and flagella, and plasmodesmata connect adjacent plant cells.
Question 7. Which organelle is primarily responsible for lipid synthesis and drug detoxification?
Exam: NEET-UG 2024
A. Rough endoplasmic reticulum
B. Smooth endoplasmic reticulum
C. Nucleolus
D. Lysosome
Correct answer: B
Explanation: Smooth endoplasmic reticulum is involved in lipid synthesis and detoxification of drugs and other substances, particularly in liver cells. Rough ER is associated with the synthesis of many proteins.
Question 8. Which organelle is enclosed by a single membrane?
Exam: NEET-UG 2024
A. Chloroplast
B. Lysosome
C. Nucleus
D. Mitochondrion
Correct answer: B
Explanation: Lysosomes are surrounded by a single membrane. The nucleus, mitochondria and chloroplasts have double-membrane boundaries.
Question 9. Which organelle contains enzymes involved in the glyoxylate cycle in germinating oil-rich seeds?
Exam: NEET-UG 2024
A. Lysosome
B. Glyoxysome
C. Golgi apparatus
D. Nucleolus
Correct answer: B
Explanation: Glyoxysomes are specialized microbodies that contain enzymes of the glyoxylate cycle. This pathway helps developing seedlings use stored lipids as a source of carbon for carbohydrate production.
Question 10. Which structure is directly responsible for protein synthesis?
Exam: NEET-UG 2023, ribosome-related PYQ topic
A. Ribosome
B. Lysosome
C. Peroxisome
D. Vacuole
Correct answer: A
Explanation: Ribosomes translate the information carried by mRNA into a polypeptide chain. They consist of rRNA and proteins and are not surrounded by a membrane.
Question 11. Where does the Krebs cycle occur in a eukaryotic cell?
Exam: NEET-UG Practice Set, 2026
A. Mitochondrial matrix
B. Inner nuclear membrane
C. Golgi cisternae
D. Chloroplast outer membrane
Correct answer: A
Explanation: In eukaryotic cells, the enzymes of the Krebs cycle are located primarily in the mitochondrial matrix, with succinate dehydrogenase associated with the inner mitochondrial membrane.
Question 12. Which part of a chloroplast contains the enzymes of the Calvin cycle?
Exam: NEET-UG Practice Set, 2026
A. Thylakoid lumen
B. Stroma
C. Outer membrane
D. Intermembrane space
Correct answer: B
Explanation: The Calvin cycle takes place in the chloroplast stroma. The light-dependent reactions take place in the thylakoid membranes.
Question 13. Which component of a typical motile eukaryotic cilium shows a 9 + 2 arrangement?
Exam: NEET-UG Practice Set, 2026
A. Axoneme
B. Nucleolus
C. Centrosome matrix
D. Tonoplast
Correct answer: A
Explanation: The axoneme of a typical motile eukaryotic cilium or flagellum contains nine peripheral microtubule doublets and two central microtubules.
Question 14. What is the main function of the tonoplast?
Exam: NEET-UG Practice Set, 2026
A. Surrounds the plant-cell vacuole
B. Forms the mitochondrial cristae
C. Produces ribosomes
D. Forms the nuclear pores
Correct answer: A
Explanation: The tonoplast is the membrane surrounding the vacuole. It regulates the movement of substances into and out of the vacuolar compartment.
Question 15. Which organelle is most directly associated with the modification, sorting and packaging of proteins?
Exam: NEET-UG Practice Set, 2026
A. Golgi apparatus
B. Centriole
C. Nucleolus
D. Peroxisome
Correct answer: A
Explanation: The Golgi apparatus receives materials from the ER, modifies them, sorts them and dispatches them in vesicles to their destinations.
SECTION A: ENDOPLASMIC RETICULUM AND GOLGI APPARATUS
Question 16. Which part of the endoplasmic reticulum is directly associated with the synthesis of many secretory proteins?
Exam: NEET-UG Practice Set, 2026
A. Smooth endoplasmic reticulum
B. Rough endoplasmic reticulum
C. Tonoplast
D. Nuclear lamina
Correct answer: B. Rough endoplasmic reticulum
Explanation: Ribosomes attached to the cytoplasmic surface of rough ER synthesize many proteins destined for secretion, insertion into membranes or delivery to the endomembrane system.
Question 17. The smooth endoplasmic reticulum is particularly well developed in cells that synthesize:
Exam: NEET-UG Practice Set, 2026
A. Steroid hormones
B. Ribosomal RNA exclusively
C. Cellulose microfibrils exclusively
D. Lysosomal DNA
Correct answer: A. Steroid hormones
Explanation: Smooth ER participates in lipid metabolism and steroid synthesis. It is prominent in many steroid-producing cells and also contributes to detoxification in certain tissues.
Question 18. The cis face of the Golgi apparatus is generally associated with:
Exam: NEET-UG Practice Set, 2026
A. Receiving transport vesicles from the ER
B. DNA replication
C. ATP synthesis by oxidative phosphorylation
D. Chromosome separation
Correct answer: A. Receiving transport vesicles from the ER
Explanation: The cis face is generally the receiving side of the Golgi apparatus. The trans face is associated with sorting and dispatching processed materials.
Question 19. Which sequence best represents the usual pathway of a protein destined for secretion?
Exam: NEET-UG Practice Set, 2026
A. Ribosome on RER → ER lumen → Golgi apparatus → secretory vesicle → plasma membrane
B. Lysosome → nucleolus → mitochondrion → plasma membrane
C. Golgi apparatus → nucleus → chloroplast → plasma membrane
D. Peroxisome → centriole → vacuole → plasma membrane
Correct answer: A
Explanation: Many secretory proteins enter the ER during synthesis, undergo processing and transport to the Golgi apparatus, and are then packaged into vesicles that deliver them to the plasma membrane for secretion.
Question 20. Which organelle is most directly involved in the packaging of hydrolytic enzymes for delivery to lysosomes?
Exam: NEET-UG Practice Set, 2026
A. Golgi apparatus
B. Centriole
C. Mitochondrial matrix
D. Nucleolus
Correct answer: A. Golgi apparatus
Explanation: Lysosomal enzymes are synthesized on ribosomes associated with the rough ER and processed and sorted through the endomembrane system. The Golgi apparatus plays an important role in their sorting and delivery.
Question 21. Which organelle is an important site for the formation of glycoproteins and glycolipids in eukaryotic cells?
Exam: NEET-UG 2020
A. Golgi apparatus
B. Polysomes
C. Peroxisomes
D. Centrioles
Correct answer: A. Golgi apparatus
Explanation: The Golgi apparatus modifies and processes proteins and lipids and participates in the formation of glycoproteins and glycolipids. Polysomes synthesize proteins, peroxisomes perform oxidative reactions, and centrioles organize microtubules.
Question 22. Which statement about the endoplasmic reticulum is incorrect?
Exam: NEET-UG 2022
A. Rough ER has ribosomes attached to its surface.
B. Smooth ER lacks attached ribosomes.
C. Prokaryotic cells possess rough and smooth endoplasmic reticulum.
D. Smooth ER is involved in lipid synthesis.
Correct answer: C
Explanation: Prokaryotic cells lack a membrane-bound endoplasmic reticulum. Rough ER has attached ribosomes, while smooth ER is involved in lipid synthesis and other metabolic activities.
SECTION B: MITOCHONDRIA AND PLASTIDS
Question 23. What are the infoldings of the inner mitochondrial membrane called?
Exam: NEET-UG Practice Set, 2026
A. Grana
B. Cristae
C. Cisternae
D. Thylakoids
Correct answer: B. Cristae
Explanation: Cristae increase the surface area of the inner mitochondrial membrane and accommodate components of the electron transport chain and ATP synthase.
Question 24. Which statement best describes the semiautonomous nature of mitochondria?
Exam: NEET-UG Practice Set, 2026
A. They are completely independent of the nucleus.
B. They contain their own DNA and ribosomes but depend on nuclear genes for many proteins.
C. They contain no genetic material.
D. They synthesize every protein required for their functioning.
Correct answer: B
Explanation: Mitochondria contain their own genetic material and ribosomes, but most mitochondrial proteins are encoded by nuclear genes and imported into the organelle.
Question 25. Which chloroplast structure consists of a stack of thylakoids?
Exam: NEET-UG Practice Set, 2026
A. Granum
B. Stroma
C. Crista
D. Matrix
Correct answer: A. Granum
Explanation: A granum is a stack of thylakoids. Multiple grana are connected by stroma lamellae. The stroma is the fluid matrix surrounding the thylakoid system.
Question 26. Which pair is correctly matched?
Exam: NEET-UG Practice Set, 2026
A. Cristae — Chloroplast
B. Thylakoids — Mitochondria
C. Stroma — Chloroplast
D. Matrix — Golgi apparatus
Correct answer: C. Stroma — Chloroplast
Explanation: The chloroplast stroma contains enzymes required for the Calvin cycle, as well as DNA and ribosomes. Cristae are mitochondrial inner-membrane folds, and the mitochondrial matrix is enclosed by the inner mitochondrial membrane.
SECTION C: RIBOSOMES AND LYSOSOMES
Question 27. Which organelle is responsible for intracellular digestion using hydrolytic enzymes?
Exam: NEET-UG Practice Set, 2026
A. Lysosome
B. Ribosome
C. Centriole
D. Nucleolus
Correct answer: A. Lysosome
Explanation: Lysosomes contain acid hydrolases that break down macromolecules, ingested materials and damaged cellular components.
Question 28. Which statement about ribosomes is correct?
Exam: NEET-UG Practice Set, 2026
A. They are surrounded by a double membrane.
B. They contain only DNA.
C. They are composed of rRNA and proteins.
D. They are responsible for lipid synthesis.
Correct answer: C
Explanation: Ribosomes are non-membranous complexes made of rRNA and proteins. Their primary role is translation, during which the information in mRNA is used to synthesize proteins.
Question 29. What is a polysome?
Exam: NEET-UG Practice Set, 2026
A. A group of lysosomes enclosed by one membrane
B. Multiple ribosomes translating the same mRNA molecule
C. A stack of Golgi cisternae
D. A group of mitochondria sharing one matrix
Correct answer: B
Explanation: A polysome or polyribosome consists of multiple ribosomes simultaneously translating a single mRNA molecule. This arrangement allows efficient production of multiple copies of a polypeptide.
Question 30. Which feature distinguishes lysosomes from ribosomes?
Exam: NEET-UG Practice Set, 2026
A. Lysosomes are membrane-bound, whereas ribosomes are non-membranous.
B. Ribosomes contain digestive enzymes, whereas lysosomes synthesize proteins. C. Both are surrounded by double membranes.
D. Both are the primary sites of photosynthesis.
Correct answer: A
Explanation: Lysosomes are single-membrane-bound digestive organelles. Ribosomes lack a surrounding membrane and carry out protein synthesis.
SECTION D: VACUOLES
Question 31. Which membrane surrounds the central vacuole of a plant cell?
Exam: NEET-UG Practice Set, 2026
A. Tonoplast
B. Crista
C. Axoneme
D. Nuclear envelope
Correct answer: A. Tonoplast
Explanation: The tonoplast surrounds the vacuole and regulates the movement of ions and other substances between the vacuole and cytoplasm.
Question 32. The large central vacuole of a mature plant cell primarily helps maintain:
Exam: NEET-UG Practice Set, 2026
A. Turgor pressure
B. Ribosomal subunit assembly
C. Chromosome replication
D. Oxidative phosphorylation
Correct answer: A. Turgor pressure
Explanation: Water entering the vacuole generates turgor pressure, helping maintain the firmness of plant tissues. Loss of water can reduce turgor and cause wilting.
Question 33. Which substance may be stored in the cell sap of a plant vacuole?
Exam: NEET-UG Practice Set, 2026
A. Anthocyanin pigments
B. Only mitochondrial DNA
C. Only ribosomal proteins
D. Only cellulose microfibrils
Correct answer: A. Anthocyanin pigments
Explanation: Plant vacuoles may contain water-soluble pigments such as anthocyanins, along with ions, sugars, organic acids and waste products.
Question 34. What is the principal function of a contractile vacuole in many freshwater protists?
Exam: NEET-UG Practice Set, 2026
A. Osmoregulation and removal of excess water
B. Synthesis of steroid hormones
C. Production of ribosomes
D. Photosynthesis
Correct answer: A
Explanation: Water tends to enter many freshwater protists by osmosis. Contractile vacuoles collect and expel excess water, helping maintain osmotic balance.
SECTION E: PEROXISOMES AND GLYOXYSOMES
Question 35. Which enzyme breaks down hydrogen peroxide in peroxisomes?
Exam: NEET-UG Practice Set, 2026
A. Catalase
B. Pepsin
C. DNA polymerase
D. RuBisCO exclusively
Correct answer: A. Catalase
Explanation: Catalase converts hydrogen peroxide into water and oxygen. Hydrogen peroxide is produced during several oxidative reactions and can damage cellular components if it accumulates.
Question 36. Glyoxysomes are particularly important during the germination of:
Exam: NEET-UG Practice Set, 2026
A. Oil-rich seeds
B. Mature animal red blood cells
C. Bacterial spores exclusively
D. Human nerve cells
Correct answer: A. Oil-rich seeds
Explanation: Glyoxysomes contain enzymes of the glyoxylate cycle. This pathway enables germinating oil-rich seeds to convert carbon from stored fats into intermediates used for carbohydrate production.
Question 37. Which statement correctly distinguishes peroxisomes from lysosomes?
Exam: NEET-UG Practice Set, 2026
A. Peroxisomes are associated with oxidative reactions, whereas lysosomes contain digestive hydrolases.
B. Peroxisomes are the main sites of translation, whereas lysosomes synthesize DNA.
C. Both are non-membranous organelles.
D. Both are the principal sites of photosynthesis.
Correct answer: A
Explanation: Peroxisomes contain enzymes for oxidation and hydrogen peroxide metabolism. Lysosomes contain hydrolytic enzymes that digest biological materials in an acidic environment.
Section F: Cytoskeleton
Question 38. Which of the following functions is carried out by the cytoskeleton in a cell?
Exam: NEET-UG 2023
A. Transportation, nuclear division and motility
B. Protein synthesis only
C. Photosynthesis only
D. Formation of cell-wall cellulose only
Correct answer: A
Explanation: The cytoskeleton is a network of proteinaceous filaments that helps maintain cell shape, supports intracellular transport, participates in cell division and enables movement. Ribosomes perform protein synthesis, while photosynthesis occurs in chloroplasts.
Question 39. Microtubules are constituents of which structures?
Exam: NEET-UG 2016
A. Spindle fibres, centrioles and cilia
B. Chromatin, nucleosomes and lysosomes
C. Peroxisomes, vacuoles and Golgi cisternae
D. Ribosomes, chromosomes and lysosomes
Correct answer: A
Explanation: Microtubules are made of tubulin and are major components of spindle fibres, centrioles, cilia and flagella. Chromatin contains DNA and proteins, whereas lysosomes and peroxisomes are membrane-bound organelles.
Question 40. An elaborate network of filamentous proteinaceous structures in the cytoplasm that helps maintain cell shape is called:
Exam: AIPMT 2010
A. Endoplasmic reticulum
B. Plasmalemma
C. Cytoskeleton
D. Thylakoid
Correct answer: C. Cytoskeleton
Explanation: The cytoskeleton provides internal structural support. Its three major components are microtubules, microfilaments and intermediate filaments.
Question 41. The cytoskeleton is primarily made up of:
Exam: AIPMT 2009
A. Calcium carbonate granules
B. Callose deposits
C. Cellulosic microfibrils
D. Proteinaceous filaments
Correct answer: D. Proteinaceous filaments
Explanation: Microtubules consist of tubulin, microfilaments mainly consist of actin, and intermediate filaments are composed of different structural proteins. Together, they form the cytoskeletal network.
SECTION G: CENTRIOLES AND CENTROSOMES
Question 42. What is the characteristic microtubule arrangement in a typical centriole?
Exam: NEET-UG Practice Set, 2026
A. Nine peripheral microtubule triplets
B. Nine peripheral doublets and two central microtubules
C. Eight peripheral triplets
D. Two central triplets only
Correct answer: A
Explanation: A typical centriole contains nine peripheral microtubule triplets arranged in a cylindrical structure. The 9 + 2 arrangement is characteristic of many motile eukaryotic cilia and flagella, not centrioles.
Question 43. In animal cells, which structure is an important microtubule-organizing centre?
Exam: NEET-UG Practice Set, 2026
A. Centrosome
B. Lysosome
C. Tonoplast
D. Nucleolus
Correct answer: A. Centrosome
Explanation: The centrosome is an important microtubule-organizing centre in animal cells. It generally contains a pair of centrioles surrounded by pericentriolar material and helps organize the mitotic spindle.
Question 44. Centrioles can give rise to which structures?
Exam: NEET-UG Practice Set, 2026
A. Basal bodies of cilia and flagella
B. Cristae of mitochondria
C. Grana of chloroplasts
D. Cisternae of the Golgi apparatus
Correct answer: A
Explanation: Centrioles can serve as precursors of basal bodies, which organize the microtubules of cilia and flagella. Cristae, grana and Golgi cisternae are distinct membrane structures.
SECTION H: CILIA AND FLAGELLA
Question 45. What does the 9 + 2 arrangement refer to in a typical motile eukaryotic cilium?
Exam: NEET-UG Practice Set, 2026
A. Nine microtubule triplets surrounding two nuclei
B. Nine peripheral microtubule doublets surrounding two central microtubules
C. Nine actin filaments surrounding two ribosomes
D. Nine membranes surrounding two centrioles
Correct answer: B
Explanation: The typical motile eukaryotic axoneme contains nine peripheral microtubule doublets and two central microtubules. This arrangement supports ciliary and flagellar movement.
Question 46. Which motor protein is directly involved in the bending movement of many eukaryotic cilia and flagella?
Exam: NEET-UG Practice Set, 2026
A. Dynein
B. Histone
C. Collagen
D. RuBisCO
Correct answer: A. Dynein
Explanation: Axonemal dynein uses ATP to generate sliding forces between adjacent microtubule doublets. Structural connections convert this sliding into bending movements.
Question 47. Which statement correctly distinguishes a typical motile cilium from a basal body?
Exam: NEET-UG Practice Set, 2026
A. The ciliary axoneme typically has a 9 + 2 arrangement, while the basal body has nine microtubule triplets.
B. Both always have identical 9 + 2 arrangements.
C. The basal body is made entirely of cellulose.
D. The cilium lacks microtubules.
Correct answer: A
Explanation: A typical motile ciliary axoneme contains nine peripheral doublets and two central microtubules. A basal body generally has nine peripheral triplets and lacks the central pair.
SECTION I: MATCH-THE-COLUMN REVISION
Question 48. Match each organelle or structure with its principal feature.
Exam: NEET-UG Practice Set, 2026
| Column I | Column II |
| A. Tonoplast | I. Hydrogen peroxide metabolism |
| B. Glyoxysome | II. Vacuolar membrane |
| C. Peroxisome | III. Glyoxylate cycle |
| D. Centriole | IV. Nine microtubule triplets |
Options:
A. A–II, B–III, C–I, D–IV
B. A–I, B–II, C–IV, D–III
C. A–III, B–IV, C–II, D–I
D. A–IV, B–I, C–III, D–II
Correct answer: A
Explanation: The tonoplast surrounds the vacuole; glyoxysomes participate in the glyoxylate cycle; peroxisomes metabolize hydrogen peroxide; and centrioles have nine peripheral microtubule triplets.
Question 49. Which set contains only non-membranous structures?
Exam: NEET-UG Practice Set, 2026
A. Ribosomes, centrioles and nucleolus
B. Lysosomes, ribosomes and vacuoles
C. Mitochondria, centrioles and peroxisomes
D. Golgi apparatus, ribosomes and lysosomes
Correct answer: A
Explanation: Ribosomes, centrioles and the nucleolus are not surrounded by membranes. Lysosomes, vacuoles, mitochondria, peroxisomes and the Golgi apparatus are membrane-bound.
Question 50. Which of the following pairs is incorrectly matched?
Exam: NEET-UG Practice Set, 2026
A. Microtubules — Tubulin
B. Microfilaments — Actin
C. Intermediate filaments — Structural proteins
D. Axoneme — Cellulose microfibrils
Correct answer: D
Explanation: An axoneme is a microtubule-based structure found in cilia and flagella. Cellulose microfibrils are components of plant cell walls, not axonemes.
SECTION J: ADVANCED NCERT-BASED MCQS
Question 51. Which statement about the mitochondrial inner membrane is correct?
Exam: NEET-UG Practice Set, 2026
A. It contains components of the electron transport chain and ATP synthase.
B. It contains the enzymes responsible for all nuclear DNA replication.
C. It is the principal site of ribosome assembly in the cell.
D. It is continuous with the Golgi apparatus.
Correct answer: A
Explanation: The inner mitochondrial membrane contains electron transport chain complexes and ATP synthase, which participate in oxidative phosphorylation. Ribosomal subunit assembly occurs mainly in the nucleolus, and the mitochondrial inner membrane is not continuous with the Golgi apparatus.
Question 52. Which statement correctly describes the chloroplast stroma?
Exam: NEET-UG Practice Set, 2026
A. It is the space enclosed within the thylakoid membrane.
B. It contains enzymes of the Calvin cycle, along with chloroplast DNA and ribosomes.
C. It is the principal site of lysosomal digestion.
D. It is a fold of the inner mitochondrial membrane.
Correct answer: B
Explanation: The stroma is the fluid matrix surrounding the thylakoid system. It contains enzymes for carbon fixation and also contains chloroplast DNA and ribosomes.
Question 53. Which organelle is most directly involved in the initial folding and processing of many newly synthesized secretory proteins?
Exam: NEET-UG Practice Set, 2026
A. Rough endoplasmic reticulum
B. Centriole
C. Peroxisome
D. Contractile vacuole
Correct answer: A
Explanation: Many secretory proteins enter the rough ER during synthesis. There, they undergo folding and initial processing before transport through the endomembrane system.
Question 54. Which feature is shared by mitochondria and chloroplasts but not by lysosomes?
Exam: NEET-UG Practice Set, 2026
A. Their primary role is intracellular digestion.
B. They possess their own DNA and ribosomes.
C. They are both components of the endomembrane system.
D. They contain no membrane.
Correct answer: B
Explanation: Mitochondria and chloroplasts contain their own DNA and ribosomes. Lysosomes are digestive organelles and are not characterized by their own genetic systems.
Question 55. Which organelle–function combination is incorrect?
Exam: NEET-UG Practice Set, 2026
A. Golgi apparatus — sorting and packaging
B. Lysosome — intracellular digestion
C. Peroxisome — hydrogen peroxide metabolism
D. Ribosome — synthesis of phospholipid bilayers
Correct answer: D
Explanation: Ribosomes synthesize proteins. Phospholipids are synthesized primarily through membrane-associated lipid metabolic pathways, including those associated with the smooth ER.
Question 56. A cell produces large amounts of a protein that will be secreted outside the cell. Which combination of structures is most directly involved in its production and export?
Exam: NEET-UG Practice Set, 2026
A. Ribosomes on rough ER, Golgi apparatus and secretory vesicles
B. Centrioles, lysosomes and nuclear pores only
C. Peroxisomes, centrioles and contractile vacuoles only
D. Chloroplast grana and mitochondrial cristae only
Correct answer: A
Explanation: Secretory proteins are synthesized on ribosomes associated with the rough ER, processed through the ER and Golgi apparatus, and delivered in secretory vesicles to the plasma membrane.
SECTION K: ORGANELLE STRUCTURE AND IDENTIFICATION
Question 57. Which of the following structures is directly associated with the detoxification of hydrogen peroxide?
Exam: NEET-UG Practice Set, 2026
A. Peroxisome
B. Golgi apparatus
C. Nucleolus
D. Ribosome
Correct answer: A. Peroxisome
Explanation: Peroxisomes contain oxidative enzymes and catalase. Catalase decomposes hydrogen peroxide into water and oxygen, helping protect the cell from oxidative damage.
Question 58. Which of the following correctly describes the Golgi apparatus?
Exam: NEET-UG Practice Set, 2026
A. It consists of stacks of flattened membrane-bound cisternae.
B. It consists exclusively of non-membranous protein filaments.
C. It contains the principal chromosomes of the cell.
D. It is the primary site of mitochondrial ATP synthesis.
Correct answer: A
Explanation: The Golgi apparatus consists of flattened membrane-bound sacs called cisternae, arranged in stacks. It modifies, sorts and packages cellular products.
Question 59. Which structure is associated with calcium storage in many muscle cells?
Exam: NEET-UG Practice Set, 2026
A. Sarcoplasmic reticulum
B. Nucleolus
C. Golgi apparatus
D. Chromoplast
Correct answer: A. Sarcoplasmic reticulum
Explanation: The sarcoplasmic reticulum is a specialized form of smooth endoplasmic reticulum in muscle cells. It stores and releases calcium ions involved in muscle contraction.
Question 60. Which statement about the nucleolus is correct?
Exam: NEET-UG Practice Set, 2026
A. It is surrounded by a double membrane.
B. It is involved in ribosomal RNA synthesis and ribosomal subunit assembly.
C. It performs oxidative phosphorylation.
D. It contains the enzymes of the glyoxylate cycle.
Correct answer: B
Explanation: The nucleolus is a dense, non-membranous region inside the nucleus. It is involved in rRNA synthesis and the assembly of ribosomal subunits.
Question 61. Which structure connects the cytoplasm of adjacent plant cells through their cell walls?
Exam: NEET-UG Practice Set, 2026
A. Plasmodesmata
B. Cristae
C. Grana
D. Nuclear pores
Correct answer: A. Plasmodesmata
Explanation: Plasmodesmata are channels that connect neighbouring plant cells and facilitate intercellular communication and transport.
Question 62. Which statement about plastids is correct?
Exam: NEET-UG Practice Set, 2026
A. All plastids contain abundant chlorophyll.
B. Leucoplasts are generally colourless and participate in storage.
C. Chromoplasts are the principal sites of aerobic respiration.
D. Plastids are found in all animal cells.
Correct answer: B
Explanation: Leucoplasts are generally colourless plastids that store starch, oils or proteins. Chloroplasts contain photosynthetic pigments, while chromoplasts contain pigments such as carotenoids. Plastids are characteristic of plants and many algae, not animal cells.
SECTION L: ASSERTION–REASON QUESTIONS
For Questions 63–66, choose the correct option:
A. Both Assertion and Reason are true, and Reason correctly explains Assertion.
B. Both Assertion and Reason are true, but Reason does not correctly explain Assertion.
C. Assertion is true, but Reason is false.
D. Assertion is false, but Reason is true.
Question 63. Mitochondria are described as semiautonomous organelles.
Exam: NEET-UG Practice Set, 2026
Assertion: Mitochondria possess their own DNA and ribosomes.
Reason: Mitochondria can synthesize all the proteins required for their functioning independently of the nucleus.
Correct answer: C
Explanation: The assertion is true, but the reason is false. Mitochondria can synthesize some proteins using their own genetic machinery, but most mitochondrial proteins are encoded by nuclear genes.
Question 64. Lysosomal enzymes function most effectively in an acidic environment.
Exam: NEET-UG Practice Set, 2026
Assertion: Lysosomes maintain an acidic internal environment.
Reason: Many lysosomal hydrolytic enzymes have optimal activity at acidic pH.
Correct answer: A
Explanation: Proton pumps in the lysosomal membrane help maintain an acidic lumen. This environment supports the activity of lysosomal acid hydrolases.
Question 65. Rough endoplasmic reticulum appears rough under an electron microscope.
Exam: NEET-UG Practice Set, 2026
Assertion: Rough ER has a rough appearance on its cytoplasmic surface.
Reason: Ribosomes are attached to its cytoplasmic surface.
Correct answer: A
Explanation: The attached ribosomes give rough ER its characteristic appearance and are involved in the synthesis of many secretory and membrane proteins.
Question 66. Chloroplasts are the sites of the light-dependent reactions of photosynthesis.
Exam: NEET-UG Practice Set, 2026
Assertion: Light-dependent reactions occur in the thylakoid membranes.
Reason: The thylakoid membranes contain photosystems, electron transport components and ATP synthase.
Correct answer: A
Explanation: The thylakoid membranes contain the molecular machinery required for light capture, electron transport and ATP formation during the light-dependent reactions.
SECTION M: FINAL HIGH-YIELD MCQS
Question 67. Which organelle is most directly associated with the glyoxylate cycle in germinating oil-rich seeds?
Exam: NEET-UG Practice Set, 2026
A. Glyoxysome
B. Lysosome
C. Nucleolus
D. Centrosome
Correct answer: A. Glyoxysome
Explanation: Glyoxysomes contain enzymes of the glyoxylate cycle, which supports the conversion of stored lipid-derived carbon into carbohydrate precursors during seed germination.
Question 68. Which combination is correctly matched?
Exam: NEET-UG Practice Set, 2026
A. Amyloplast — starch storage
B. Elaioplast — DNA replication exclusively
C. Chromoplast — ATP production by oxidative phosphorylation
D. Chloroplast — intracellular digestion by acid hydrolases
Correct answer: A. Amyloplast — starch storage
Explanation: Amyloplasts store starch. Elaioplasts are associated with oil storage, chromoplasts contain carotenoid pigments, and chloroplasts carry out photosynthesis.
Question 69. Which statement correctly distinguishes microfilaments from microtubules?
Exam: NEET-UG Practice Set, 2026
A. Microfilaments are mainly made of actin, while microtubules are made of tubulin. B. Microfilaments are made of DNA, while microtubules are made of RNA.
C. Both consist exclusively of cellulose.
D. Microtubules are found only in plant cell walls.
Correct answer: A
Explanation: Actin forms microfilaments, which are important in cell movement, contraction and cytokinesis. Tubulin forms microtubules, which participate in intracellular transport, spindle formation and the structure of cilia and flagella.
Question 70. Which statement about eukaryotic cilia and flagella is correct?
Exam: NEET-UG Practice Set, 2026
A. All cilia and flagella are made of cellulose.
B. Many motile forms contain a microtubule-based axoneme.
C. Their principal function is the synthesis of ribosomal RNA.
D. They are always enclosed by a double membrane.
Correct answer: B
Explanation: Many motile eukaryotic cilia and flagella contain a microtubule-based axoneme surrounded by the plasma membrane. Their functions include cell movement and movement of fluid over cell surfaces. Some cilia are non-motile and serve sensory functions.
SECTION N: MEMBRANES AND ORGANELLE TRANSPORT
Question 71. Which statement about biological membranes is correct?
Exam: NEET-UG Practice Set, 2026
A. All biological membranes have exactly the same protein composition.
B. Membrane composition varies according to the organelle and its function.
C. Biological membranes consist entirely of phospholipids.
D. Membrane proteins cannot participate in transport.
Correct answer: B
Explanation: Biological membranes contain lipids and proteins, with composition varying according to their function. Membrane proteins participate in transport, signalling, enzymatic reactions and cell recognition.
Question 72. Which process allows a cell to release substances contained in secretory vesicles to the extracellular environment?
Exam: NEET-UG Practice Set, 2026
A. Exocytosis
B. Endocytosis
C. Osmosis
D. Simple diffusion through the lipid bilayer only
Correct answer: A. Exocytosis
Explanation: During exocytosis, a vesicle fuses with the plasma membrane and releases its contents outside the cell. Endocytosis involves the uptake of material into the cell through membrane-associated processes.
Question 73. A protein intended for secretion enters the endoplasmic reticulum during its synthesis. Which organelle generally receives it next through transport vesicles?
Exam: NEET-UG Practice Set, 2026
A. Golgi apparatus
B. Centriole
C. Peroxisome
D. Nucleolus
Correct answer: A. Golgi apparatus
Explanation: Many secretory proteins move from the ER to the Golgi apparatus for further processing, sorting and packaging.
Question 74. What is the main significance of membrane-bound compartments in eukaryotic cells?
Exam: NEET-UG Practice Set, 2026
A. They prevent all chemical reactions from occurring in the cytoplasm.
B. They allow different cellular processes to occur in specialized environments.
C. They eliminate the need for enzymes.
D. They ensure that every organelle performs the same function.
Correct answer: B
Explanation: Compartmentalization enables cells to maintain distinct chemical environments and organize specialized metabolic processes. For example, lysosomes maintain an acidic lumen, while the mitochondrial matrix supports enzymes of the Krebs cycle.
SECTION O: MITOCHONDRIAL AND PLASTID DETAILS
Question 75. Where is mitochondrial ATP synthase located?
Exam: NEET-UG Practice Set, 2026
A. Outer mitochondrial membrane
B. Inner mitochondrial membrane
C. Nuclear envelope
D. Golgi cisternae
Correct answer: B. Inner mitochondrial membrane
Explanation: ATP synthase is embedded in the inner mitochondrial membrane. During oxidative phosphorylation, it uses the proton gradient across this membrane to produce ATP.
Question 76. Which statement about mitochondrial DNA is correct?
Exam: NEET-UG Practice Set, 2026
A. Mitochondria contain no DNA.
B. Mitochondrial DNA generally forms a circular molecule in many eukaryotes.
C. Mitochondrial DNA is located exclusively inside the nucleus.
D. Mitochondrial DNA is identical in organization to the entire nuclear genome.
Correct answer: B
Explanation: Mitochondria possess their own genetic material, which is generally circular in many eukaryotes. Mitochondrial genomes differ in size and organization among organisms.
Question 77. Which plastid is primarily associated with the storage of oils?
Exam: NEET-UG Practice Set, 2026
A. Elaioplast
B. Chloroplast
C. Chromoplast
D. Amyloplast
Correct answer: A. Elaioplast
Explanation: Elaioplasts are leucoplasts specialized in oil and fat storage. Amyloplasts store starch, while chromoplasts contain carotenoid pigments and chloroplasts perform photosynthesis.
Question 78. Which statement about chloroplast thylakoids is correct?
Exam: NEET-UG Practice Set, 2026
A. They are membrane-bound compartments involved in the light-dependent reactions of photosynthesis.
B. They are folds of the mitochondrial inner membrane.
C. They are the principal storage sites of lysosomal enzymes.
D. They form the nuclear pores.
Correct answer: A
Explanation: Thylakoids are flattened membrane-bound compartments within chloroplasts. Their membranes contain photosystems, electron transport components and ATP synthase.
Question 79. Which pair of organelles is associated with endosymbiotic origin?
Exam: NEET-UG Practice Set, 2026
A. Mitochondria and chloroplasts
B. Golgi apparatus and lysosomes
C. Ribosomes and nucleolus
D. Vacuoles and centrioles
Correct answer: A. Mitochondria and chloroplasts
Explanation: The endosymbiotic theory proposes that mitochondria and chloroplasts evolved from ancestral bacteria that entered into a stable relationship with ancestral eukaryotic cells. Their own DNA, ribosomes and double membranes support this theory.
SECTION P: LYSOSOMES, VACUOLES AND MICROBODIES
Question 80. The recycling of damaged cellular components through lysosomal degradation is called:
Exam: NEET-UG Practice Set, 2026
A. Autophagy
B. Transcription
C. Photolysis
D. Translation
Correct answer: A. Autophagy
Explanation: Autophagy involves the delivery of cellular components to lysosomes for degradation and recycling. It helps cells remove damaged structures and recover useful building blocks.
Question 81. Which statement about plant-cell vacuoles is correct?
Exam: NEET-UG Practice Set, 2026
A. They may store ions, sugars, pigments and waste products.
B. They always contain only pure water.
C. They are surrounded by the nuclear envelope.
D. They are the principal sites of protein translation.
Correct answer: A
Explanation: Plant vacuoles contain cell sap, which may include water, inorganic ions, sugars, organic acids, pigments and waste substances. Their composition varies with cell type and physiological condition.
Question 82. Which statement correctly describes the relationship between peroxisomes and hydrogen peroxide?
Exam: NEET-UG Practice Set, 2026
A. Peroxisomes can generate hydrogen peroxide during oxidation reactions and contain enzymes that help break it down.
B. Peroxisomes use hydrogen peroxide exclusively to synthesize DNA.
C. Peroxisomes lack enzymes.
D. Hydrogen peroxide is never formed during cellular metabolism.
Correct answer: A
Explanation: Some peroxisomal oxidation reactions produce hydrogen peroxide. Catalase and other protective mechanisms help control its concentration and reduce oxidative damage.
Question 83. Which statement best describes the relationship between glyoxysomes and lipid metabolism in germinating seeds?
Exam: NEET-UG Practice Set, 2026
A. They help convert stored lipid-derived carbon into intermediates used for carbohydrate production.
B. They directly perform all stages of photosynthesis.
C. They synthesize cellulose for the entire plant cell wall.
D. They replace the nucleus during germination.
Correct answer: A
Explanation: Glyoxysomes contain enzymes of fatty-acid metabolism and the glyoxylate cycle. These activities support the conversion of stored lipids into carbon compounds that can contribute to carbohydrate synthesis during germination.
Section Q: Protein Targeting and Organelle Comparisons
Question 84. Which organelle is the main site of synthesis of many proteins destined to be secreted from a eukaryotic cell?
Exam: NEET-UG Practice Set, 2026
A. Ribosomes associated with rough ER
B. Lysosomes
C. Centrioles
D. Contractile vacuoles
Correct answer: A
Explanation: Ribosomes associated with rough ER synthesize many secretory proteins. These proteins enter the ER and are subsequently processed and transported through the endomembrane system.
Question 85. Which of the following is NOT a function of the Golgi apparatus?
Exam: NEET-UG Practice Set, 2026
A. Modification of certain proteins
B. Sorting and packaging cellular products
C. Formation of transport and secretory vesicles
D. Oxidative phosphorylation to generate mitochondrial ATP
Correct answer: D
Explanation: Oxidative phosphorylation occurs at the inner mitochondrial membrane. The Golgi apparatus processes, sorts and packages proteins and lipids.
Question 86. Which structure is directly responsible for the synthesis of polypeptide chains during translation?
Exam: NEET-UG Practice Set, 2026
A. Ribosome
B. Golgi apparatus
C. Lysosome
D. Tonoplast
Correct answer: A. Ribosome
Explanation: Ribosomes translate the nucleotide sequence of mRNA into a polypeptide chain. They perform this function whether free in the cytoplasm or associated with the rough ER.
Question 87. Which pair is correctly matched?
Exam: NEET-UG Practice Set, 2026
A. Mitochondrial matrix — Krebs cycle
B. Chloroplast stroma — Lysosomal digestion
C. Golgi apparatus — DNA replication
D. Nucleolus — Oxidative phosphorylation
Correct answer: A. Mitochondrial matrix — Krebs cycle
Explanation: Most enzymes of the Krebs cycle in eukaryotic cells are located in the mitochondrial matrix. The chloroplast stroma contains Calvin-cycle enzymes, while the nucleolus is associated with ribosome biogenesis.
Question 88. Which of the following structures is a component of the endomembrane system according to the standard NCERT classification?
Exam: NEET-UG Practice Set, 2026
A. Golgi apparatus
B. Mitochondrion
C. Chloroplast
D. Peroxisome
Correct answer: A. Golgi apparatus
Explanation: The standard NCERT endomembrane system comprises the ER, Golgi apparatus, lysosomes and vacuoles. Mitochondria, chloroplasts and peroxisomes are excluded from this grouping.
SECTION R: FINAL LEFTOVER MICRO-TOPIC TEST
Question 89. Which structure is responsible for the characteristic mechanical support provided by intermediate filaments?
Exam: NEET-UG Practice Set, 2026
A. Structural stability and resistance to mechanical stress
B. Photosynthesis
C. Synthesis of lysosomal enzymes
D. Oxidative phosphorylation
Correct answer: A
Explanation: Intermediate filaments contribute to the structural stability of cells and help them withstand mechanical stress. They differ from actin microfilaments and tubulin microtubules in composition and function.
Question 90. Which statement about cilia is correct?
Exam: NEET-UG Practice Set, 2026
A. Every cilium is motile.
B. Some cilia have sensory functions and are not primarily involved in movement.
C. Cilia are composed entirely of cellulose.
D. Cilia are present only in plant cell walls.
Correct answer: B
Explanation: Although many cilia are motile, primary cilia often perform sensory and signalling functions. Cilia are membrane-covered cellular projections containing a microtubule-based internal structure.
Question 91. Which structure is most directly involved in organizing the microtubules of the mitotic spindle in typical animal cells?
Exam: NEET-UG Practice Set, 2026
A. Centrosome
B. Lysosome
C. Tonoplast
D. Elaioplast
Correct answer: A. Centrosome
Explanation: The centrosome acts as a major microtubule-organizing centre in typical animal cells. Its duplicated centrosomes help organize the spindle poles during mitosis.
Question 92. Which structure separates the mitochondrial matrix from the intermembrane space?
Exam: NEET-UG Practice Set, 2026
A. Inner mitochondrial membrane
B. Outer mitochondrial membrane
C. Plasma membrane
D. Nuclear envelope
Correct answer: A
Explanation: The inner mitochondrial membrane encloses the matrix and separates it from the intermembrane space. Its selective permeability is essential for maintaining the proton gradient used in ATP synthesis.
Question 93. Which statement about the nuclear envelope is correct?
Exam: NEET-UG Practice Set, 2026
A. It consists of a double membrane containing nuclear pores.
B. It is the membrane surrounding the central vacuole.
C. It is the same structure as the tonoplast.
D. It is made exclusively of ribosomal RNA.
Correct answer: A
Explanation: The nuclear envelope consists of inner and outer membranes and contains nuclear pores that regulate molecular exchange between the nucleus and cytoplasm. It is distinct from the tonoplast.
Question 94. Which organelle–function pair is incorrectly matched?
Exam: NEET-UG Practice Set, 2026
A. Chloroplast — Photosynthesis
B. Mitochondrion — Oxidative phosphorylation
C. Lysosome — Intracellular digestion
D. Centriole — Synthesis of secretory proteins
Correct answer: D
Explanation: Centrioles participate in microtubule organization and can form basal bodies. Secretory proteins are synthesized by ribosomes associated with the rough ER and processed through the endomembrane system.
PART 6: OVERLOOKED CELL ORGANELLES MCQS
Q95. Which organelle is continuous with the outer membrane of the nuclear envelope?
A. Golgi apparatus
B. Endoplasmic reticulum
C. Lysosome
D. Peroxisome
Correct Answer: B. Endoplasmic reticulum
Explanation: The outer membrane of the nuclear envelope is continuous with the endoplasmic reticulum. Ribosomes may be attached to the outer nuclear membrane, as they are on rough ER.
Exam tag: Original NEET-UG practice question, 2026
Q96. In eukaryotic cells, which structure is especially associated with the formation and assembly of ribosomal subunits?
A. Nucleolus
B. Centrosome
C. Tonoplast
D. Smooth endoplasmic reticulum
Correct Answer: A. Nucleolus
Explanation: The nucleolus is a non-membrane-bound region inside the nucleus where ribosomal RNA is produced and ribosomal subunits are assembled with proteins before their export to the cytoplasm.
Exam tag: Original NEET-UG practice question, 2026
Q97. The acrosome of a mammalian sperm is derived primarily from which organelle?
A. Mitochondrion
B. Golgi apparatus
C. Smooth endoplasmic reticulum
D. Peroxisome
Correct Answer: B. Golgi apparatus
Explanation: The acrosome develops from the Golgi apparatus and contains enzymes that help sperm penetrate the coverings of the ovum. This is an important example of a specialised structure derived from an organelle.
Exam tag: Original NEET-UG practice question, 2026
Q98. In plant cells, the Golgi apparatus contributes directly to the formation of which structure during cell division?
A. Cell plate
B. Mitotic spindle fibres
C. Mitochondrial cristae
D. Nuclear pores
Correct Answer: A. Cell plate
Explanation: Golgi-derived vesicles accumulate at the division plane of a dividing plant cell and fuse to form the cell plate, which develops into the new separating cell wall.
Exam tag: Original NEET-UG practice question, 2026
Q99. Which part of a chloroplast contains the photosynthetic pigments associated with the light-harvesting machinery?
A. Chloroplast envelope
B. Thylakoid membrane
C. Stroma only
D. Outer membrane only
Correct Answer: B. Thylakoid membrane
Explanation: Chlorophyll and other photosynthetic pigments are located in the thylakoid membranes. The light-dependent reactions of photosynthesis take place in these membranes.
Exam tag: Original NEET-UG practice question, 2026
Q100. The connections between grana in a chloroplast are formed by:
A. Cristae
B. Stroma lamellae
C. Nuclear pores
D. Plasmodesmata
Correct Answer: B. Stroma lamellae
Explanation: Stroma lamellae connect the grana within a chloroplast. They are thylakoid membranes that extend through the stroma and help organise the internal photosynthetic membrane system.
Exam tag: Original NEET-UG practice question, 2026
Q101. Which statement about the mitochondrial outer membrane is correct?
A. It forms the cristae
B. It contains proteins that allow passage of certain small molecules
C. It contains the enzymes of the Calvin cycle
D. It is the site of ribosomal RNA synthesis in the nucleolus
Correct Answer: B. It contains proteins that allow passage of certain small molecules
Explanation: The mitochondrial outer membrane contains porin proteins that permit the passage of various small molecules and ions. The cristae are folds of the inner mitochondrial membrane, not the outer membrane.
Exam tag: Original NEET-UG practice question, 2026
Q102. Which organelle is particularly important in photorespiration in plant cells?
A. Peroxisome
B. Golgi apparatus
C. Lysosome
D. Centrosome
Correct Answer: A. Peroxisome
Explanation: Peroxisomes participate in photorespiration alongside chloroplasts and mitochondria. They contain oxidative enzymes, including catalase, which helps break down hydrogen peroxide.
Exam tag: Original NEET-UG practice question, 2026
Q103. Which organelle is most directly involved in producing and modifying many of the membrane lipids used by eukaryotic cells?
A. Smooth endoplasmic reticulum
B. Nucleolus
C. Centrosome
D. Lysosome
Correct Answer: A. Smooth endoplasmic reticulum
Explanation: Smooth ER participates in lipid synthesis, including the production of phospholipids and, in particular cell types, steroid-related lipids. Lipid metabolism is one of its major functions.
Exam tag: Original NEET-UG practice question, 2026
Q104. Which of the following is a non-membrane-bound cellular structure?
A. Lysosome
B. Golgi apparatus
C. Ribosome
D. Peroxisome
Correct Answer: C. Ribosome
Explanation: Ribosomes are complexes of ribosomal RNA and proteins and are not surrounded by a membrane. Lysosomes, Golgi apparatus and peroxisomes are membrane-bound structures.
Exam tag: Original NEET-UG practice question, 2026
Q105. Which plastid is mainly responsible for storing oils and fats in plant cells?
A. Amyloplast
B. Elaioplast
C. Chloroplast .
D. Chromoplast
Correct Answer: B. Elaioplast
Explanation: Elaioplasts are a type of leucoplast specialised for storing oils and fats. Amyloplasts store starch, while chromoplasts contain pigments that contribute to yellow, orange or red coloration.
Exam tag: Original NEET-UG practice question, 2026
Q106. Which cellular structure is responsible for selective transport between the nucleus and cytoplasm?
A. Nuclear pore complex
B. Cristae
C. Tonoplast
D. Stroma lamellae
Correct Answer: A. Nuclear pore complex
Explanation: Nuclear pore complexes are located in the nuclear envelope and regulate the movement of molecules, including RNA and proteins, between the nucleus and cytoplasm.
Exam tag: Original NEET-UG practice question, 2026
Q107. Which organelle contains enzymes that can digest worn-out cellular components during autophagy?
A. Lysosome
B. Centrosome
C. Chloroplast
D. Nucleolus
Correct Answer: A. Lysosome
Explanation: Lysosomes contain hydrolytic enzymes that digest macromolecules and cellular material delivered to them. During autophagy, cellular components are broken down and their constituents may be recycled.
Exam tag: Original NEET-UG practice question, 2026
Q108. Which pairing is correctly matched?
A. Amyloplast — oil storage
B. Elaioplast — starch storage
C. Proteinoplast — protein storage
D. Chromoplast — ATP synthesis
Correct Answer: C. Proteinoplast — protein storage
Explanation: Proteinoplasts are leucoplasts associated with protein storage. Amyloplasts store starch, while elaioplasts store oils. Chromoplasts contain coloured pigments rather than serving as the main site of ATP synthesis.
Exam tag: Original NEET-UG practice question, 2026
Q109. Which feature best explains why mitochondria are described as semi-autonomous organelles?
A. They have no membranes
B. They possess their own DNA and ribosomes but depend on the cell for many proteins
C. They synthesise every protein required for their operation
D. They are independent of the nucleus and cytoplasm
Correct Answer: B. They possess their own DNA and ribosomes but depend on the cell for many proteins
Explanation: Mitochondria have their own genetic material and protein-synthesis machinery. However, many mitochondrial proteins are encoded by nuclear genes and imported into the organelle. Therefore, mitochondria are not fully independent.
Exam tag: Original NEET-UG practice question, 2026
Q110. Which statement correctly distinguishes the cell wall from the plasma membrane in a typical plant cell?
A. Both are made exclusively of phospholipids
B. The cell wall is a rigid external covering, whereas the plasma membrane is selectively permeable
C. The plasma membrane is outside the cell wall
D. The cell wall controls all molecular transport through membrane proteins
Correct Answer: B. The cell wall is a rigid external covering, whereas the plasma membrane is selectively permeable
Explanation: The plant cell wall provides support and protection, while the plasma membrane regulates the movement of substances into and out of the cell. The plasma membrane lies inside the cell wall.
Exam tag: Original NEET-UG practice question, 2026
Q111. Which statement about the middle lamella of adjacent plant cells is correct?
A. It is primarily associated with calcium pectate
B. It is composed entirely of mitochondrial DNA
C. It is the inner membrane of the chloroplast
D. It forms the spindle apparatus
Correct Answer: A. It is primarily associated with calcium pectate
Explanation: The middle lamella lies between adjacent plant cells and helps bind them together. It is rich in pectic substances, commonly described in school biology as calcium pectate.
Exam tag: Original NEET-UG practice question, 2026
Q112. Which statement about the endomembrane system is most accurate according to the standard NCERT classification?
A. It includes mitochondria, chloroplasts and ribosomes
B. It includes ER, Golgi apparatus, lysosomes and vacuoles
C. It includes only the plasma membrane
D. It includes all organelles with their own DNA
Correct Answer: B. It includes ER, Golgi apparatus, lysosomes and vacuoles
Explanation: In the standard NCERT classification, the endomembrane system comprises the endoplasmic reticulum, Golgi apparatus, lysosomes and vacuoles, whose functions are coordinated. Mitochondria, chloroplasts and peroxisomes are not included in this group.
Exam tag: Original NEET-UG practice question, 2026
Q113. Which organelle is responsible for modifying, sorting and packaging many proteins received from the endoplasmic reticulum?
A. Golgi apparatus
B. Centrosome
C. Nucleolus
D. Glyoxysome
Correct Answer: A. Golgi apparatus
Explanation: The Golgi apparatus receives material from the ER, modifies and sorts it, and packages it into vesicles for delivery to different destinations, including the plasma membrane and lysosomes.
Exam tag: Original NEET-UG practice question, 2026
Q114. Which of the following is correctly associated with the sarcoplasmic reticulum of muscle cells?
A. Storage and release of calcium ions
B. Formation of ribosomal subunits
C. Digestion of foreign particles
D. Photosynthesis
Correct Answer: A. Storage and release of calcium ions
Explanation: The sarcoplasmic reticulum is a specialised form of smooth endoplasmic reticulum in muscle cells. It stores and releases calcium ions that help regulate muscle contraction.
Exam tag: Original NEET-UG practice question, 2026
Q115. Which statement about organelle membranes is correct?
A. Every organelle has a double membrane
B. Every organelle has a single membrane
C. Membrane organisation varies among organelles; some are membrane-bound and others are not
D. Ribosomes are enclosed by a phospholipid bilayer
Correct Answer: C. Membrane organisation varies among organelles; some are membrane-bound and others are not
Explanation: Mitochondria and chloroplasts have double membranes; lysosomes, peroxisomes, ER and Golgi compartments have single membranes; ribosomes and centrioles lack surrounding membranes. Avoid memorising a single membrane rule for all organelles.
Exam tag: Original NEET-UG practice question, 2026
PART 7: FINAL HIGH-YIELD MCQS
Q116. Which of the following structures is directly involved in the formation of the mitotic spindle in typical animal cells?
A. Centrosome
B. Lysosome
C. Golgi cisterna
D. Tonoplast
Correct Answer: A. Centrosome
Explanation: In typical animal cells, the centrosome acts as a major microtubule-organising centre and helps organise the mitotic spindle. Plant cells can organise spindle microtubules without the typical animal-cell centriole arrangement.
Exam tag: Original NEET-UG practice question, 2026
Q117. Which organelle is most directly associated with the breakdown of hydrogen peroxide into water and oxygen by catalase?
A. Peroxisome
B. Nucleolus
C. Golgi apparatus
D. Ribosome
Correct Answer: A. Peroxisome
Explanation: Peroxisomes contain oxidative enzymes that may generate hydrogen peroxide, along with catalase, which decomposes hydrogen peroxide and protects the cell from its harmful effects.
Exam tag: Original NEET-UG practice question, 2026
Q118. Which statement correctly describes the relationship between rough ER and free ribosomes?
A. Both can participate in protein synthesis
B. Rough ER synthesises DNA, while free ribosomes synthesise lipids
C. Free ribosomes are enclosed within lysosomes
D. Rough ER occurs only in prokaryotic cells
Correct Answer: A. Both can participate in protein synthesis
Explanation: Ribosomes attached to rough ER commonly synthesise proteins entering the secretory pathway, membrane proteins and many lysosomal proteins. Free ribosomes synthesise proteins that generally function in the cytosol or are directed to certain other destinations.
Exam tag: Original NEET-UG practice question, 2026
Q119. Which combination is correctly matched?
A. Mitochondrion — cristae
B. Chloroplast — tonoplast
C. Lysosome — stroma lamellae
D. Golgi apparatus — axoneme
Correct Answer: A. Mitochondrion — cristae
Explanation: Cristae are folds of the inner mitochondrial membrane. Tonoplast is the membrane surrounding a vacuole, stroma lamellae are found in chloroplasts, and an axoneme forms the core structure of cilia and eukaryotic flagella.
Exam tag: Original NEET-UG practice question, 2026
Q120. Which option lists only structures that are not surrounded by their own membrane?
A. Ribosome, centriole and nucleolus
B. Lysosome, ribosome and Golgi apparatus
C. Mitochondrion, centriole and peroxisome
D. Chloroplast, lysosome and ribosome
Correct Answer: A. Ribosome, centriole and nucleolus
Explanation: Ribosomes and centrioles are non-membranous structures. The nucleolus is a non-membrane-bound region inside the nucleus. Lysosomes, Golgi apparatus, mitochondria, chloroplasts and peroxisomes are membrane-bound.
Exam tag: Original NEET-UG practice question, 2026
Q121. Which component of the mitochondrial inner membrane is directly involved in ATP synthesis?
A. ATP synthase
B. DNA polymerase only
C. Cellulose synthase
D. Catalase only
Correct Answer: A. ATP synthase
Explanation: ATP synthase is embedded in the inner mitochondrial membrane. It uses the proton gradient generated during cellular respiration to synthesise ATP.
Q122. Which statement about the Golgi apparatus is correct?
A. Its cis face generally receives material from the ER
B. Its trans face is the principal receiving face from the ER
C. It is the site of the Krebs cycle
D. It contains the cell’s main genetic material
Correct Answer: A. Its cis face generally receives material from the ER
Explanation: The cis face is generally oriented towards the ER and receives transport vesicles. The trans face sorts and dispatches processed materials towards their destinations.
Q123. Which organelle is most closely associated with the conversion of stored fats into carbohydrates in germinating oil-rich seeds?
A. Glyoxysome
B. Lysosome
C. Centrosome
D. Nucleolus
Correct Answer: A. Glyoxysome
Explanation: Glyoxysomes are specialised peroxisomes found particularly in oil-rich seeds. They contain enzymes of the glyoxylate cycle, which helps convert products of fatty-acid breakdown into compounds that can contribute to carbohydrate production.
Q124. Which statement about ribosomes is correct?
A. They are composed of DNA and lipids
B. They are composed of ribosomal RNA and proteins
C. They are enclosed by a double membrane
D. They function primarily in lipid storage
Correct Answer: B. They are composed of ribosomal RNA and proteins
Explanation: Ribosomes are ribonucleoprotein complexes made of rRNA and proteins. Their primary function is translation of messenger RNA into polypeptides.
Q125. Which structure surrounds the central vacuole of a typical mature plant cell?
A. Tonoplast
B. Crista
C. Nuclear pore
D. Axoneme
Correct Answer: A. Tonoplast
Explanation: The tonoplast is the membrane surrounding the vacuole. It regulates the transport of substances between the cytoplasm and the vacuolar contents and helps maintain cellular water balance.
Q126. Which cellular structure contains microtubules arranged in the characteristic \(9+2\) pattern in a typical motile eukaryotic cilium?
A. Axoneme
B. Centriole
C. Nucleolus
D. Middle lamella
Correct Answer: A. Axoneme
Explanation: The axoneme of a typical motile eukaryotic cilium has nine peripheral microtubule doublets surrounding two central microtubules. A centriole or basal body instead typically has nine microtubule triplets.
Q127. Which organelle is involved in the detoxification of certain drugs and harmful compounds, particularly in liver cells?
A. Smooth endoplasmic reticulum
B. Nucleolus
C. Chloroplast
D. Ribosome alone
Correct Answer: A. Smooth endoplasmic reticulum
Explanation: Smooth ER contains enzymes involved in lipid metabolism and detoxification of various compounds. Its abundance can increase in cells exposed to certain drugs and chemicals.
Q128. A protein is synthesised on the rough ER and destined for secretion outside the cell. Which route best represents its usual pathway?
A. Rough ER → Golgi apparatus → secretory vesicle → plasma membrane
B. Golgi apparatus → nucleus → mitochondrion → plasma membrane
C. Lysosome → nucleolus → rough ER → nucleus
D. Peroxisome → chloroplast → centrosome → plasma membrane
Correct Answer: A. Rough ER → Golgi apparatus → secretory vesicle → plasma membrane
Explanation: Many secreted proteins enter the ER during synthesis, pass through the Golgi apparatus for processing and sorting, and are delivered in vesicles that fuse with the plasma membrane.
Q129. Which structure is most directly responsible for maintaining the organisation of microtubules in the cytoskeleton?
A. Microtubule-organising centres
B. Lysosomal enzymes
C. Tonoplast transporters alone
D. Chlorophyll molecules
Correct Answer: A. Microtubule-organising centres
Explanation: Microtubule-organising centres help initiate and organise microtubule formation. The centrosome is a major example in typical animal cells, although microtubule organisation differs among cell types and organisms.
Q130. Which statement about chloroplast DNA is correct?
A. Chloroplasts contain their own DNA
B. Chloroplasts contain no genetic material
C. Chloroplast DNA is stored only inside the nucleus
D. Chloroplasts contain DNA only during cell division
Correct Answer: A. Chloroplasts contain their own DNA
Explanation: Chloroplasts possess their own genetic material and ribosomes. However, many proteins needed for chloroplast function are encoded by nuclear genes, so chloroplasts are not fully independent.
Q131. Which pair consists of organelles that participate in the endomembrane system under standard NCERT classification?
A. Endoplasmic reticulum and Golgi apparatus
B. Mitochondria and chloroplasts
C. Ribosomes and centrioles
D. Peroxisomes and mitochondria
Correct Answer: A. Endoplasmic reticulum and Golgi apparatus
Explanation: The standard NCERT endomembrane system includes the ER, Golgi apparatus, lysosomes and vacuoles. Mitochondria, chloroplasts and peroxisomes are excluded from this classification.
Q132. Which of the following is a major function of intermediate filaments in animal cells?
A. Providing mechanical strength
B. Directly carrying out photosynthesis
C. Synthesising all cellular ATP
D. Storing starch in plastids
Correct Answer: A. Providing mechanical strength
Explanation: Intermediate filaments help cells withstand mechanical stress and maintain structural stability. They are one of the three major cytoskeletal filament systems, alongside microtubules and microfilaments.
Q133. Which structure helps regulate the movement of substances into and out of a eukaryotic nucleus?
A. Nuclear pore complex
B. Mitochondrial crista
C. Chloroplast granum
D. Lysosomal membrane only
Correct Answer: A. Nuclear pore complex
Explanation: Nuclear pore complexes regulate traffic across the nuclear envelope, including the export of many RNA molecules and the import of nuclear proteins.
Q134. Which organelle is most directly associated with the modification of proteins by adding carbohydrate groups to form many glycoproteins?
A. Golgi apparatus
B. Centrosome
C. Mitochondrial matrix only
D. Contractile vacuole only
Correct Answer: A. Golgi apparatus
Explanation: The Golgi apparatus performs several protein-processing steps, including the modification of carbohydrate groups on many proteins. Glycosylation can also begin in the ER, so not every glycosylation event occurs exclusively in the Golgi.
Q135. Which statement correctly distinguishes a lysosome from a peroxisome?
A. Lysosomes mainly contain digestive hydrolytic enzymes, whereas peroxisomes contain oxidative enzymes such as catalase
B. Lysosomes contain chlorophyll, whereas peroxisomes contain cellulose
C. Both are non-membranous structures
D. Peroxisomes are the main sites of ribosomal subunit assembly
Correct Answer: A. Lysosomes mainly contain digestive hydrolytic enzymes, whereas peroxisomes contain oxidative enzymes such as catalase
Explanation: Lysosomes digest macromolecules and cellular material using hydrolytic enzymes. Peroxisomes participate in oxidative reactions and detoxification of hydrogen peroxide. Both are single-membrane-bound organelles.
PART 9: QUESTIONS 136–150 — ASSERTION–REASON, MATCHING AND APPLICATION-BASED MCQS
Section A: Assertion–Reason Questions
For Questions 136–140, select the correct option:
A. Both Assertion and Reason are true, and Reason correctly explains Assertion.
B. Both Assertion and Reason are true, but Reason does not correctly explain Assertion.
C. Assertion is true, but Reason is false.
D. Assertion is false, but Reason is true.
Q136. Mitochondria are called semi-autonomous organelles.
Assertion: Mitochondria possess their own DNA and ribosomes.
Reason: Mitochondria can synthesise all the proteins required for their functioning independently of the nucleus.
Correct Answer: C. Assertion is true, but Reason is false.
Explanation: Mitochondria have their own DNA and ribosomes, but many mitochondrial proteins are encoded by nuclear genes and imported into mitochondria. They are therefore not fully independent.
Exam tag: Original NEET-UG practice question, 2026.
Q137. The Golgi apparatus is important in cellular secretion.
Assertion: The Golgi apparatus modifies, sorts and packages many proteins.
Reason: Golgi-derived vesicles can transport cellular products towards the plasma membrane for secretion.
Correct Answer: A. Both Assertion and Reason are true, and Reason correctly explains Assertion.
Explanation: Golgi processing and vesicular transport are important parts of the secretory pathway. Vesicles may fuse with the plasma membrane and release their contents by exocytosis.
Exam tag: Original NEET-UG practice question, 2026.
Q138. Lysosomes are involved in intracellular digestion.
Assertion: Lysosomes contain hydrolytic enzymes.
Reason: Lysosomal enzymes generally function best in an acidic environment.
Correct Answer: B. Both Assertion and Reason are true, but Reason does not correctly explain Assertion.
Explanation: Both statements are true. The presence of hydrolytic enzymes explains the digestive function, while their preference for acidic conditions helps these enzymes function effectively inside lysosomes. The Reason describes a favourable condition rather than directly explaining the presence of the enzymes.
Exam tag: Original NEET-UG practice question, 2026.
Q139. Smooth endoplasmic reticulum is important in lipid metabolism.
Assertion: Smooth ER participates in the synthesis of lipids.
Reason: Smooth ER is characteristically covered with ribosomes on its cytoplasmic surface.
Correct Answer: C. Assertion is true, but Reason is false.
Explanation: Smooth ER participates in lipid synthesis and other metabolic functions. Unlike rough ER, it does not characteristically have ribosomes attached to its cytoplasmic surface.
Exam tag: Original NEET-UG practice question, 2026.
Q140. Chloroplasts are semi-autonomous organelles.
Assertion: Chloroplasts contain their own DNA and ribosomes.
Reason: Every protein required for chloroplast function is encoded by chloroplast DNA.
Correct Answer: C. Assertion is true, but Reason is false.
Explanation: Chloroplasts have their own genetic material and ribosomes, but many chloroplast proteins are encoded by nuclear genes and imported into the organelle.
Exam tag: Original NEET-UG practice question, 2026.
SECTION B: MATCH THE FOLLOWING
Q141. Match each organelle or structure with its principal association.
| Column I | Column II |
| 1. Cristae | A. Storage of oils |
| 2. Elaioplast | B. Inner mitochondrial membrane folds |
| 3. Tonoplast | C. Ribosomal subunit assembly |
| 4. Nucleolus | D. Vacuolar membrane |
Options:
A. 1–B, 2–A, 3–D, 4–C
B. 1–A, 2–B, 3–C, 4–D
C. 1–C, 2–D, 3–A, 4–B
D. 1–D, 2–C, 3–B, 4–A
Correct Answer: A. 1–B, 2–A, 3–D, 4–C
Explanation: Cristae are folds of the inner mitochondrial membrane; elaioplasts store oils; the tonoplast surrounds the vacuole; and the nucleolus is involved in rRNA production and ribosomal subunit assembly.
Exam tag: Original NEET-UG practice question, 2026.
Q142. Match the structure with its characteristic organisation.
| Column I | Column II |
| 1. Typical motile ciliary axoneme | A. Nine microtubule triplets |
| 2. Typical centriole | B. Nine peripheral doublets and two central microtubules |
| 3. Ribosome | C. rRNA and proteins |
| 4. Plasma membrane | D. Phospholipid bilayer with associated proteins |
Options:
A. 1–B, 2–A, 3–C, 4–D
B. 1–A, 2–B, 3–D, 4–C
C. 1–C, 2–D, 3–A, 4–B
D. 1–D, 2–C, 3–B, 4–A
Correct Answer: A. 1–B, 2–A, 3–C, 4–D
Explanation: A typical motile ciliary axoneme has a 9+2 arrangement, while a typical centriole has nine microtubule triplets. Ribosomes contain rRNA and proteins, and the plasma membrane is organised around a lipid bilayer with associated proteins.
Exam tag: Original NEET-UG practice question, 2026.
SECTION C: APPLICATION-BASED QUESTIONS
Q143. A cell that secretes large amounts of protein is expected to have a particularly well-developed:
A. Rough endoplasmic reticulum
B. Tonoplast only
C. Chromoplast
D. Contractile vacuole only
Correct Answer: A. Rough endoplasmic reticulum
Explanation: Rough ER contains ribosomes that synthesise many proteins destined for secretion, membranes and certain organelles. Cells specialised for protein secretion commonly have an extensive rough ER and Golgi apparatus.
Exam tag: Original NEET-UG practice question, 2026.
Q144. A plant cell requires a large amount of stored starch. Which plastid is most directly associated with this function?
A. Elaioplast
B. Amyloplast
C. Chromoplast
D. Proteinoplast
Correct Answer: B. Amyloplast
Explanation: Amyloplasts are starch-storing leucoplasts. Elaioplasts are associated with oil storage, proteinoplasts with protein storage, and chromoplasts with coloured pigments.
Exam tag: Original NEET-UG practice question, 2026.
Q145. A defect prevents lysosomal enzymes from reaching their correct destination. Which cellular function would most directly be impaired?
A. Intracellular digestion
B. Light absorption by chlorophyll
C. Formation of mitochondrial cristae
D. Assembly of the ciliary 9+2 structure
Correct Answer: A. Intracellular digestion
Explanation: Lysosomal enzymes digest macromolecules and cellular material. If these enzymes fail to reach lysosomes properly, the breakdown and recycling of material can be impaired.
Exam tag: Original NEET-UG practice question, 2026.
Q146. A drug disrupts microtubule formation in a dividing animal cell. Which process is most likely to be affected directly?
A. Organisation of the mitotic spindle
B. Formation of starch inside amyloplasts only
C. Hydrogen peroxide breakdown by catalase only
D. Lipid synthesis in smooth ER only
Correct Answer: A. Organisation of the mitotic spindle
Explanation: Microtubules form the major structural components of the mitotic spindle, which organises chromosome movement during cell division. Disruption of microtubules can therefore interfere with normal chromosome segregation.
Exam tag: Original NEET-UG practice question, 2026.
Q147. A cell has abundant smooth ER and is specialised for steroid hormone production. Which function best explains this observation?
A. Lipid and steroid synthesis
B. Ribosomal subunit assembly
C. Starch storage
D. Intracellular digestion by hydrolytic enzymes
Correct Answer: A. Lipid and steroid synthesis
Explanation: Smooth ER participates in lipid metabolism and steroid synthesis in specialised cells. The nucleolus is associated with ribosomal subunit assembly, amyloplasts store starch, and lysosomes perform intracellular digestion.
Exam tag: Original NEET-UG practice question, 2026.
Q148. Which pair of organelles is most directly associated with the production of ATP during aerobic cellular respiration and photosynthesis, respectively?
A. Mitochondrion and chloroplast
B. Golgi apparatus and lysosome
C. Nucleolus and centriole
D. Peroxisome and tonoplast
Correct Answer: A. Mitochondrion and chloroplast
Explanation: Mitochondria produce ATP during cellular respiration, while chloroplasts produce ATP during the light-dependent reactions of photosynthesis. Chloroplast ATP is primarily used within the chloroplast for photosynthetic processes.
Exam tag: Original NEET-UG practice question, 2026.
Q149. Which organelle would be most directly affected if the cell lost the ability to maintain the proton gradient across the inner mitochondrial membrane?
A. Mitochondrion
B. Golgi apparatus
C. Nucleolus
D. Amyloplast
Correct Answer: A. Mitochondrion
Explanation: The proton gradient across the inner mitochondrial membrane drives ATP synthesis by ATP synthase during oxidative phosphorylation. Disrupting this gradient reduces the efficiency of this ATP-producing process.
Exam tag: Original NEET-UG practice question, 2026.
Q150. Which statement best summarises the functional coordination of the ER and Golgi apparatus?
A. The ER participates in synthesis and initial processing, while the Golgi modifies, sorts and packages many products
B. The ER performs all cellular functions, making the Golgi unnecessary
C. The Golgi synthesises all cellular DNA, while the ER stores chromosomes
D. Both organelles are non-membranous and function only during cell division
Correct Answer: A. The ER participates in synthesis and initial processing, while the Golgi modifies, sorts and packages many products
Explanation: The ER and Golgi apparatus work together in the secretory and membrane-trafficking pathways. The ER participates in protein and lipid synthesis, while the Golgi modifies, sorts and packages many materials for delivery to their destinations.
Exam tag: Original NEET-UG practice question, 2026.
SECTION A: CONCEPTUAL MCQS
Q151. Which organelle is primarily responsible for the synthesis of phospholipids used in the formation of many cellular membranes?
A. Smooth endoplasmic reticulum
B. Nucleolus
C. Lysosome
D. Centrosome
Correct Answer: A. Smooth endoplasmic reticulum
Explanation: Smooth ER plays an important role in lipid metabolism and the synthesis of many membrane lipids. The precise site of lipid synthesis can vary with the lipid type and cell.
Exam tag: Original NEET-UG practice question, 2026.
Q152. Which statement about the mitochondrial matrix is correct?
A. It contains enzymes involved in the Krebs cycle
B. It is the location of the Golgi cis face
C. It contains chlorophyll in animal cells
D. It is the space between the plasma membrane and cell wall
Correct Answer: A. It contains enzymes involved in the Krebs cycle
Explanation: The mitochondrial matrix contains enzymes for several reactions of cellular respiration, including the Krebs cycle. The electron transport chain and ATP synthase are associated with the inner mitochondrial membrane.
Exam tag: Original NEET-UG practice question, 2026.
Q153. Which organelle contains the enzymes responsible for many of the initial oxidative reactions in fatty-acid breakdown?
A. Peroxisome
B. Golgi apparatus
C. Nucleolus
D. Centriole
Correct Answer: A. Peroxisome
Explanation: Peroxisomes carry out oxidative reactions, including fatty-acid oxidation in many eukaryotic cells. They also contain catalase, which helps decompose hydrogen peroxide.
Exam tag: Original NEET-UG practice question, 2026.
Q154. Which structure is primarily associated with the selective movement of proteins and RNA across the nuclear envelope?
A. Nuclear pore complex
B. Cristae
C. Thylakoid
D. Middle lamella
Correct Answer: A. Nuclear pore complex
Explanation: Nuclear pore complexes regulate transport between the nucleus and cytoplasm. Many proteins enter the nucleus through these pores, while RNA and ribosomal subunits are exported through regulated pathways.
Exam tag: Original NEET-UG practice question, 2026.
Q155. Which of the following is a characteristic function of the plant cell vacuole?
A. Helping maintain turgor pressure
B. Carrying out all nuclear DNA replication
C. Forming the mitotic spindle in every plant cell
D. Producing all ribosomal RNA
Correct Answer: A. Helping maintain turgor pressure
Explanation: The large central vacuole stores water and dissolved substances and contributes to turgor pressure. This pressure helps support non-woody plant tissues.
Exam tag: Original NEET-UG practice question, 2026.
Q156. Which structure is directly associated with the attachment of microtubules during chromosome movement in mitosis?
A. Kinetochore
B. Tonoplast
C. Nucleolus
D. Golgi cisterna
Correct Answer: A. Kinetochore
Explanation: The kinetochore is a protein complex assembled at the centromere of each chromosome. Spindle microtubules attach to kinetochores and help move chromosomes during cell division. This is a chromosome-associated structure rather than a membrane-bound organelle.
Exam tag: Original NEET-UG practice question, 2026.
Q157. Which statement about the rough endoplasmic reticulum is correct?
A. Ribosomes attached to it synthesise many secretory and membrane proteins
B. It is the primary site of photosynthesis
C. It is surrounded by three membranes
D. It stores all the cell’s chromosomes
Correct Answer: A. Ribosomes attached to it synthesise many secretory and membrane proteins
Explanation: Ribosomes on rough ER synthesise proteins entering the secretory pathway, including many secreted proteins and membrane proteins. The ER also assists with protein folding and quality control.
Exam tag: Original NEET-UG practice question, 2026.
Q158. Which pair is correctly matched?
A. Lysosome — intracellular digestion
B. Nucleolus — lipid synthesis
C. Elaioplast — starch storage
D. Cristae — protein packaging
Correct Answer: A. Lysosome — intracellular digestion
Explanation: Lysosomes contain digestive hydrolytic enzymes. The nucleolus is associated with ribosome production, elaioplasts store oils, and cristae are folds of the inner mitochondrial membrane.
Exam tag: Original NEET-UG practice question, 2026.
SECTION B: HIGHER-LEVEL MCQS
Q159. A mutation disrupts the function of mitochondrial ATP synthase. Which process would be most directly impaired?
A. ATP production driven by the mitochondrial proton gradient
B. Protein modification by the Golgi apparatus
C. Starch storage in amyloplasts
D. Ribosomal RNA production in the nucleolus
Correct Answer: A. ATP production driven by the mitochondrial proton gradient
Explanation: ATP synthase uses the proton gradient across the inner mitochondrial membrane to synthesise ATP during oxidative phosphorylation. A defect in this enzyme directly impairs this process.
Exam tag: Original NEET-UG practice question, 2026.
Q160. Which option correctly identifies the site of the Calvin cycle in a chloroplast?
A. Stroma
B. Thylakoid lumen only
C. Outer chloroplast membrane
D. Intermembrane space of mitochondria
Correct Answer: A. Stroma
Explanation: The Calvin cycle occurs in the chloroplast stroma, where enzymes use carbon dioxide and products of the light-dependent reactions to support carbohydrate synthesis.
Exam tag: Original NEET-UG practice question, 2026.
Q161. Which of the following structures is directly involved in the intracellular transport of materials along cytoskeletal tracks?
A. Motor proteins moving along cytoskeletal filaments
B. Cellulose microfibrils alone
C. Middle lamella alone
D. Chlorophyll molecules alone
Correct Answer: A. Motor proteins moving along cytoskeletal filaments
Explanation: Motor proteins such as kinesins and dyneins move cargo along microtubules, while myosins move along actin filaments. These systems support intracellular transport and various types of cellular movement.
Exam tag: Original NEET-UG practice question, 2026.
Q162. Which organelle is directly associated with the formation of many transport vesicles involved in the secretory pathway?
A. Golgi apparatus
B. Nucleolus
C. Centrosome only
D. Chromoplast only
Correct Answer: A. Golgi apparatus
Explanation: The Golgi apparatus sorts and packages cellular products into vesicles for delivery to different destinations. Vesicle formation and trafficking also involve the ER and other cellular membrane compartments.
Exam tag: Original NEET-UG practice question, 2026.
Q163. Which statement about lysosomal enzymes is correct?
A. They are hydrolytic enzymes that digest biological macromolecules
B. They are photosynthetic pigments
C. They directly form the mitochondrial electron transport chain
D. They are structural proteins of the cell wall
Correct Answer: A. They are hydrolytic enzymes that digest biological macromolecules
Explanation: Lysosomal enzymes break down proteins, nucleic acids, lipids and carbohydrates. Their activity is adapted to the acidic environment inside lysosomes.
Exam tag: Original NEET-UG practice question, 2026.
Q164. Which feature distinguishes the chloroplast from a typical lysosome?
A. Chloroplasts have a double-membrane envelope and internal thylakoid membranes
B. Chloroplasts are non-membranous particles made entirely of RNA
C. Lysosomes contain grana and chlorophyll
D. Lysosomes possess the chloroplast stroma
Correct Answer: A. Chloroplasts have a double-membrane envelope and internal thylakoid membranes
Explanation: Chloroplasts contain a double-membrane envelope and an internal thylakoid membrane system organised into grana and stroma lamellae. Lysosomes are single-membrane-bound digestive organelles and do not contain this photosynthetic apparatus.
Exam tag: Original NEET-UG practice question, 2026.
Q165. Which statement best explains the importance of compartmentalisation by membrane-bound organelles?
A. It allows different cellular processes to occur in specialised environments
B. It makes every cellular reaction occur at the same pH
C. It eliminates the need for enzymes
D. It prevents all transport between organelles
Correct Answer: A. It allows different cellular processes to occur in specialised environments
Explanation: Membrane-bound organelles create distinct chemical environments that support specialised reactions. For example, lysosomes maintain an acidic interior, while mitochondria maintain a proton gradient across their inner membrane.
Exam tag: Original NEET-UG practice question, 2026.
PART 11: QUESTIONS 166–180 — DIAGRAM-BASED AND STRUCTURE-IDENTIFICATION MCQS
SECTION A: DIAGRAM-BASED IDENTIFICATION
Q166. In a diagram of a mitochondrion, label X points to the folds of the inner membrane. What is X?
A. Cristae
B. Grana
C. Cisternae of Golgi apparatus
D. Nuclear pores
Correct Answer: A. Cristae
Explanation: Cristae are folds of the inner mitochondrial membrane. They increase the membrane’s surface area and contain components involved in electron transport and ATP synthesis.
Exam tag: Original NEET-UG practice question, 2026.
Q167. In a chloroplast diagram, label X points to a stack of flattened, disc-shaped thylakoids. Identify X.
A. Granum
B. Stroma
C. Crista
D. Tonoplast
Correct Answer: A. Granum
Explanation: A granum is a stack of thylakoids. The surrounding fluid-filled region is the stroma, and the thylakoid membranes contain the photosynthetic pigments and machinery for light-dependent reactions.
Exam tag: Original NEET-UG practice question, 2026.
Q168. A diagram shows a network of membrane-bound tubules without ribosomes attached to their surface. Which structure is represented?
A. Smooth endoplasmic reticulum
B. Rough endoplasmic reticulum
C. Ribosome
D. Nuclear pore complex
Correct Answer: A. Smooth endoplasmic reticulum
Explanation: Smooth ER lacks ribosomes attached to its cytoplasmic surface. It participates in lipid metabolism, detoxification in certain cells and other specialised functions.
Exam tag: Original NEET-UG practice question, 2026.
Q169. In a Golgi apparatus diagram, label X marks the receiving side oriented towards the endoplasmic reticulum. Identify X.
A. Cis face
B. Trans face
C. Tonoplast
D. Crista
Correct Answer: A. Cis face
Explanation: The cis face generally receives transport vesicles from the ER. The trans face is associated with sorting and dispatching processed materials.
Exam tag: Original NEET-UG practice question, 2026.
Q170. A diagram shows a spherical, single-membrane-bound organelle containing hydrolytic enzymes. Which organelle is most likely represented?
A. Lysosome
B. Ribosome
C. Centriole
D. Nucleolus
Correct Answer: A. Lysosome
Explanation: Lysosomes contain hydrolytic enzymes that digest macromolecules and cellular material. Their acidic interior supports the activity of many of these enzymes.
Exam tag: Original NEET-UG practice question, 2026.
Section B: Structural Recognition
Q171. A micrograph shows an organelle with a double-membrane envelope, internal thylakoid membranes and chlorophyll-containing structures. Identify it.
A. Chloroplast
B. Lysosome
C. Golgi apparatus
D. Peroxisome
Correct Answer: A. Chloroplast
Explanation: Chloroplasts have a double-membrane envelope and an internal thylakoid membrane system. Their chlorophyll-containing membranes are central to photosynthesis.
Exam tag: Original NEET-UG practice question, 2026.
Q172. Which feature in an electron micrograph would most strongly indicate the presence of rough ER?
A. Ribosomes attached to the cytoplasmic surface of membrane cisternae
B. Stacks of thylakoids containing chlorophyll
C. Nine microtubule triplets arranged in a cylinder
D. A single membrane enclosing digestive enzymes
Correct Answer: A. Ribosomes attached to the cytoplasmic surface of membrane cisternae
Explanation: Ribosomes attached to the outer surface give rough ER its characteristic appearance. It is associated with the synthesis and processing of many secretory and membrane proteins.
Exam tag: Original NEET-UG practice question, 2026.
Q173. A diagram shows nine peripheral microtubule triplets arranged in a cylindrical structure, without a central pair. Which structure is most likely shown?
A. Centriole
B. Typical motile ciliary axoneme
C. Mitochondrial crista
D. Chloroplast granum
Correct Answer: A. Centriole
Explanation: A typical centriole has nine microtubule triplets arranged in a cylinder. A typical motile eukaryotic ciliary axoneme instead has nine peripheral doublets and a central pair of microtubules.
Exam tag: Original NEET-UG practice question, 2026.
Q174. A diagram shows a membrane-bound organelle with oxidative enzymes and catalase. Which organelle should be identified?
A. Peroxisome
B. Ribosome
C. Centrosome
D. Nucleolus
Correct Answer: A. Peroxisome
Explanation: Peroxisomes contain oxidative enzymes and catalase. They participate in several metabolic processes, including hydrogen peroxide breakdown and, in plants, aspects of photorespiration.
Exam tag: Original NEET-UG practice question, 2026.
Q175. In a cell diagram, label X points to the membrane surrounding the large central vacuole of a plant cell. Identify X.
A. Tonoplast
B. Plasma membrane
C. Nuclear envelope
D. Inner mitochondrial membrane
Correct Answer: A. Tonoplast
Explanation: The tonoplast surrounds the vacuole and regulates the exchange of substances between the vacuolar contents and cytoplasm.
Exam tag: Original NEET-UG practice question, 2026.
SECTION C: STRUCTURE–FUNCTION INTERPRETATION
Q176. A diagram of a mitochondrion shows a large number of cristae. Which conclusion is most appropriate?
A. The inner membrane has a large surface area for respiratory machinery
B. The mitochondrion is performing photosynthesis
C. The organelle has no inner membrane
D. The organelle is a type of plastid
Correct Answer: A. The inner membrane has a large surface area for respiratory machinery
Explanation: Cristae increase the surface area of the inner mitochondrial membrane, which houses the electron transport chain and ATP synthase.
Exam tag: Original NEET-UG practice question, 2026.
Q177. A cell image shows many flattened membrane-bound sacs arranged in stacks, with small vesicles budding from their edges. Which organelle is most likely represented?
A. Golgi apparatus
B. Centriole
C. Ribosome
D. Nuclear pore
Correct Answer: A. Golgi apparatus
Explanation: The Golgi apparatus consists of flattened membrane-bound cisternae and associated vesicles. It processes, sorts and packages many cellular products.
Exam tag: Original NEET-UG practice question, 2026.
Q178. Which observation most strongly supports identifying a structure as a ribosome rather than a membrane-bound organelle?
A. It consists of rRNA and proteins and lacks a surrounding membrane
B. It contains a double-membrane envelope
C. It has an internal proton gradient across a membrane
D. It contains a large acidic compartment enclosed by a membrane
Correct Answer: A. It consists of rRNA and proteins and lacks a surrounding membrane
Explanation: Ribosomes are non-membranous complexes responsible for protein synthesis. Double-membrane envelopes and membrane gradients are associated with other cellular structures.
Exam tag: Original NEET-UG practice question, 2026.
Q179. A diagram of a typical motile cilium shows nine peripheral microtubule doublets and two central microtubules. What is the arrangement called?
A. 9+2 arrangement
B. 9+0 arrangement
C. 9 triplets
D. 7+2 arrangement
Correct Answer: A. 9+2 arrangement
Explanation: The typical motile eukaryotic ciliary axoneme has nine peripheral doublets and two central microtubules. Some specialised or non-motile cilia have different arrangements, so the 9+2 pattern is not universal to every cilium.
Exam tag: Original NEET-UG practice question, 2026.
Q180. A cell diagram shows a membrane-bound organelle containing its own DNA, ribosomes and an internal membrane system used in photosynthesis. Which organelle is it?
A. Chloroplast
B. Lysosome
C. Golgi apparatus
D. Smooth endoplasmic reticulum
Correct Answer: A. Chloroplast
Explanation: Chloroplasts contain their own DNA and ribosomes and have an internal thylakoid membrane system for photosynthesis. They remain dependent on the rest of the cell for many proteins and other functions.
Exam tag: Original NEET-UG practice question, 2026.
PART 12: QUESTIONS 181–195 — CASE-BASED, MATCHING
AND HIGHER-ORDER MCQS
SECTION A: CASE-BASED QUESTIONS
Q181. A cell produces large quantities of digestive enzymes that must be released outside the cell. Which combination is most important for this process?
A. Rough ER and Golgi apparatus
B. Centriole and nucleolus
C. Chloroplast and amyloplast
D. Peroxisome and chromoplast
Correct Answer: A. Rough ER and Golgi apparatus
Explanation: Many secreted proteins are synthesised on ribosomes associated with rough ER. They then pass through the Golgi apparatus for processing, sorting and packaging before being released through vesicular transport.
Exam tag: Original NEET-UG practice question, 2026.
Q182. A plant cell is placed in conditions that cause its central vacuole to lose water. Which effect is most likely?
A. Reduced turgor pressure
B. Increased chlorophyll synthesis in the nucleus
C. Immediate conversion of all ribosomes into lysosomes
D. Formation of additional mitochondrial cristae as the direct result
Correct Answer: A. Reduced turgor pressure
Explanation: The central vacuole stores water and dissolved substances. When the cell loses water, vacuolar volume and turgor pressure can decrease, causing the plant cell to become less firm.
Exam tag: Original NEET-UG practice question, 2026.
Q183. A researcher observes an organelle that produces hydrogen peroxide during oxidative reactions and contains catalase. Which organelle is being studied?
A. Peroxisome
B. Golgi apparatus
C. Nucleolus
D. Ribosome
Correct Answer: A. Peroxisome
Explanation: Peroxisomes contain oxidative enzymes and catalase. Catalase decomposes hydrogen peroxide, helping limit oxidative damage to cellular components.
Exam tag: Original NEET-UG practice question, 2026.
Q184. A mutation interferes with the formation of functional ribosomes. Which cellular activity would be directly affected?
A. Translation of mRNA into polypeptides
B. Storage of oils in elaioplasts only
C. Formation of the cell wall’s middle lamella only
D. Breakdown of hydrogen peroxide by catalase only
Correct Answer: A. Translation of mRNA into polypeptides
Explanation: Ribosomes are the sites of protein synthesis. If functional ribosomes cannot form, translation and consequently many cellular functions that depend on newly synthesised proteins will be impaired.
Exam tag: Original NEET-UG practice question, 2026.
Q185. A plant cell has chloroplasts that contain normal thylakoid membranes but lack functional enzymes for the Calvin cycle. Which process would be most directly impaired?
A. Carbon fixation and carbohydrate production through the Calvin cycle
B. Formation of the mitochondrial outer membrane
C. Ribosomal subunit assembly in the nucleolus
D. Digestion of macromolecules by lysosomes
Correct Answer: A. Carbon fixation and carbohydrate production through the Calvin cycle
Explanation: The Calvin cycle occurs in the chloroplast stroma and uses carbon dioxide, ATP and reducing power to produce carbohydrate precursors. Functional thylakoid membranes alone cannot replace the enzymes required for carbon fixation.
Exam tag: Original NEET-UG practice question, 2026.
SECTION B: ORGANELLE COMPARISONS
Q186. Which pair consists of organelles with their own DNA and ribosomes?
A. Mitochondria and chloroplasts
B. Golgi apparatus and lysosomes
C. Peroxisomes and ribosomes
D. Vacuoles and centrioles
Correct Answer: A. Mitochondria and chloroplasts
Explanation: Mitochondria and chloroplasts possess their own genetic material and ribosomes. They are semi-autonomous because many proteins required for their operation are encoded by nuclear genes.
Exam tag: Original NEET-UG practice question, 2026.
Q187. Which option correctly matches each structure with its principal role?
A. Nucleolus — ribosomal subunit assembly
B. Tonoplast — ATP synthesis in mitochondria
C. Cristae — starch storage
D. Amyloplast — protein translation
Correct Answer: A. Nucleolus — ribosomal subunit assembly
Explanation: The nucleolus is involved in rRNA production and ribosomal subunit assembly. The tonoplast surrounds the vacuole, cristae are folds of the inner mitochondrial membrane, and amyloplasts store starch.
Exam tag: Original NEET-UG practice question, 2026.
Q188. Which of the following is not a membrane-bound organelle or cellular structure?
A. Ribosome
B. Lysosome
C. Peroxisome
D. Golgi apparatus
Correct Answer: A. Ribosome
Explanation: Ribosomes consist of rRNA and proteins and are not enclosed by a membrane. Lysosomes, peroxisomes and Golgi compartments are membrane-bound.
Exam tag: Original NEET-UG practice question, 2026.
Q189. Which statement correctly distinguishes the endoplasmic reticulum from the Golgi apparatus?
A. ER participates in synthesis and initial processing, while Golgi modifies, sorts and packages many products
B. ER stores all cellular DNA, while Golgi produces chromosomes
C. ER is always non-membranous, while Golgi is always double-membranous
D. Golgi is the primary site of the Krebs cycle, while ER performs photosynthesis
Correct Answer: A. ER participates in synthesis and initial processing, while Golgi modifies, sorts and packages many products
Explanation: ER and Golgi are membrane-bound components of the endomembrane system. They work together in protein and lipid processing, intracellular transport and secretion.
Exam tag: Original NEET-UG practice question, 2026.
Q190. Which organelle–function pair is incorrectly matched?
A. Lysosome — intracellular digestion
B. Peroxisome — oxidative reactions
C. Smooth ER — lipid metabolism
D. Golgi apparatus — Krebs cycle
Correct Answer: D. Golgi apparatus — Krebs cycle
Explanation: The Krebs cycle occurs mainly in the mitochondrial matrix in eukaryotic cells. The Golgi apparatus processes, sorts and packages cellular products.
Exam tag: Original NEET-UG practice question, 2026.
SECTION C: HIGHER-ORDER APPLICATION
Q191. A substance prevents the formation of the proton gradient across the inner mitochondrial membrane. Which function is most directly affected?
A. Oxidative phosphorylation
B. Assembly of ribosomal subunits in the nucleolus
C. Starch storage in amyloplasts
D. Golgi-mediated modification of proteins
Correct Answer: A. Oxidative phosphorylation
Explanation: The proton gradient across the inner mitochondrial membrane drives ATP synthesis by ATP synthase. Disruption of the gradient interferes with oxidative phosphorylation.
Exam tag: Original NEET-UG practice question, 2026.
Q192. Which organelle would be especially important in a cell specialised for extensive detoxification of certain drugs?
A. Smooth endoplasmic reticulum
B. Nucleolus
C. Centriole
D. Chloroplast
Correct Answer: A. Smooth endoplasmic reticulum
Explanation: Smooth ER contains enzymes involved in the metabolism and detoxification of certain drugs and chemicals, particularly in specialised cells such as liver cells.
Exam tag: Original NEET-UG practice question, 2026.
Q193. A defect prevents transport vesicles from delivering proteins from the ER to the Golgi apparatus. Which pathway is most directly disrupted?
A. Secretory-pathway transport
B. Chromosome replication
C. Direct ATP production by mitochondrial ATP synthase
D. Starch storage in leucoplasts
Correct Answer: A. Secretory-pathway transport
Explanation: Many proteins destined for secretion or certain cellular membranes travel from the ER to the Golgi in transport vesicles. Blocking this movement disrupts normal protein processing and delivery.
Exam tag: Original NEET-UG practice question, 2026.
Q194. Which structure provides a pathway for communication and transport between the cytoplasm of adjacent plant cells?
A. Plasmodesmata
B. Cristae
C. Centrioles
D. Nuclear pores
Correct Answer: A. Plasmodesmata
Explanation: Plasmodesmata are channels through plant cell walls that connect neighbouring cells. They allow regulated movement of certain substances and support intercellular communication.
Exam tag: Original NEET-UG practice question, 2026.
Q195. Which statement about organelle specialisation is correct?
A. Different organelles provide specialised environments for different cellular reactions
B. All organelles perform identical biochemical functions
C. Every organelle contains its own DNA
D. Every organelle is surrounded by a double membrane
Correct Answer: A. Different organelles provide specialised environments for different cellular reactions
Explanation: Cellular compartmentalisation allows different processes to operate under suitable conditions. For example, lysosomes maintain an acidic interior, mitochondria maintain a proton gradient, and chloroplasts contain specialised membranes for photosynthesis.
Exam tag: Original NEET-UG practice question, 2026.
Q196. Which organelle is directly involved in the breakdown of very-long-chain fatty acids in many eukaryotic cells?
A. Peroxisome
B. Golgi apparatus
C. Nucleolus
D. Centrosome
Correct Answer: A. Peroxisome
Explanation: Peroxisomes carry out fatty-acid oxidation, including the breakdown of very-long-chain fatty acids. Their metabolic activities vary among cell types and organisms.
Exam tag: Original NEET-UG practice question, 2026.
Q197. Which component of the chloroplast contains the enzymes responsible for carbon dioxide fixation during the Calvin cycle?
A. Stroma
B. Intermembrane space
C. Outer envelope membrane only
D. Thylakoid lumen only
Correct Answer: A. Stroma
Explanation: The Calvin cycle takes place in the chloroplast stroma. It uses enzymes, including RuBisCO, to incorporate carbon dioxide into organic molecules.
Exam tag: Original NEET-UG practice question, 2026.
Q198. Which organelle is most directly associated with the processing and sorting of proteins destined for lysosomes?
A. Golgi apparatus
B. Centrosome
C. Chloroplast
D. Contractile vacuole
Correct Answer: A. Golgi apparatus
Explanation: The Golgi apparatus modifies, sorts and packages many proteins. Lysosomal enzymes are directed towards lysosomes through specialised trafficking and sorting mechanisms.
Exam tag: Original NEET-UG practice question, 2026.
Q199. Which structure helps maintain the shape and mechanical stability of many animal cells by forming a network of protein filaments?
A. Cytoskeleton
B. Tonoplast
C. Thylakoid system
D. Golgi cisternae alone
Correct Answer: A. Cytoskeleton
Explanation: The cytoskeleton consists of microtubules, actin microfilaments and intermediate filaments. Together, these structures support cell shape, organisation, movement and intracellular transport.
Exam tag: Original NEET-UG practice question, 2026.
Q200. Which cellular structure is primarily responsible for the synthesis of proteins from an mRNA template?
A. Ribosome
B. Lysosome
C. Peroxisome
D. Tonoplast
Correct Answer: A. Ribosome
Explanation: Ribosomes carry out translation by reading the codons of messenger RNA and assembling amino acids into a polypeptide chain.
Exam tag: Original NEET-UG practice question, 2026.
SECTION B: STRUCTURE AND ORGANISATION
Q201. Which statement correctly describes the nuclear envelope?
A. It consists of two membranes and contains nuclear pore complexes
B. It is a single protein sheet without pores
C. It is identical to the cell wall
D. It is formed exclusively from cellulose
Correct Answer: A. It consists of two membranes and contains nuclear pore complexes
Explanation: The nuclear envelope has inner and outer membranes. Nuclear pore complexes regulate transport between the nucleus and cytoplasm, and the outer membrane is continuous with the ER.
Exam tag: Original NEET-UG practice question, 2026.
Q202. Which feature is characteristic of a typical mature mammalian red blood cell?
A. It lacks a nucleus and most conventional organelles
B. It contains numerous chloroplasts
C. It has an extensive Golgi apparatus
D. It contains a large central vacuole
Correct Answer: A. It lacks a nucleus and most conventional organelles
Explanation: Mature mammalian erythrocytes lose their nucleus and most organelles during development. This leaves more space for haemoglobin and supports their specialised role in oxygen transport.
Exam tag: Original NEET-UG practice question, 2026.
Q203. Which structure in a chloroplast is the immediate site of the light-dependent reactions of photosynthesis?
A. Thylakoid membrane
B. Chloroplast outer membrane
C. Stroma only
D. Intermembrane space of mitochondria
Correct Answer: A. Thylakoid membrane
Explanation: Photosystems, electron transport components and ATP synthase involved in the light-dependent reactions are located in the thylakoid membrane.
Exam tag: Original NEET-UG practice question, 2026.
Q204. Which structure is associated with the organisation of the contractile apparatus in many animal cells?
A. Actin microfilaments
B. Chloroplast grana
C. Lysosomal hydrolases
D. Nuclear pores
Correct Answer: A. Actin microfilaments
Explanation: Actin microfilaments interact with myosin in many forms of cellular contraction and movement. They also contribute to cell shape, cell migration and cytokinesis.
Exam tag: Original NEET-UG practice question, 2026.
Q205. Which statement about the Golgi apparatus is correct?
A. It consists of stacks of flattened membrane-bound cisternae
B. It is a non-membranous collection of ribosomes
C. It is the main site of mitochondrial DNA replication
D. It forms the central pair of a motile cilium
Correct Answer: A. It consists of stacks of flattened membrane-bound cisternae
Explanation: The Golgi apparatus consists of flattened membrane-bound sacs called cisternae, together with associated vesicles. It processes, sorts and packages many cellular products.
Exam tag: Original NEET-UG practice question, 2026.
SECTION C: APPLIED AND COMPARATIVE MCQS
Q206. Which combination is correctly matched?
A. Peroxisome — catalase
B. Nucleolus — lipid storage
C. Amyloplast — photosynthetic pigment production as its main role
D. Tonoplast — ribosomal subunit assembly
Correct Answer: A. Peroxisome — catalase
Explanation: Peroxisomes contain catalase, which breaks down hydrogen peroxide. The nucleolus participates in ribosomal subunit assembly, amyloplasts store starch, and the tonoplast surrounds the vacuole.
Exam tag: Original NEET-UG practice question, 2026.
Q207. Which organelle is particularly important for the production of steroid hormones in specialised endocrine cells?
A. Smooth endoplasmic reticulum
B. Lysosome
C. Nucleolus
D. Centriole
Correct Answer: A. Smooth endoplasmic reticulum
Explanation: Smooth ER participates in lipid and steroid synthesis. The relative contribution of the ER and mitochondria to steroid production depends on the cell type and the specific steps involved.
Exam tag: Original NEET-UG practice question, 2026.
Q208. Which structure is directly associated with the attachment of ribosomes during the synthesis of many secreted proteins?
A. Cytoplasmic surface of rough ER
B. Inner surface of the tonoplast only
C. Mitochondrial cristae only
D. Chloroplast stroma lamellae only
Correct Answer: A. Cytoplasmic surface of rough ER
Explanation: Ribosomes bind to the cytoplasmic surface of rough ER when synthesising many proteins that enter the secretory pathway. The nascent protein is directed into or across the ER membrane as appropriate.
Exam tag: Original NEET-UG practice question, 2026.
Q209. Which statement correctly describes the relationship between lysosomes and autophagy?
A. Lysosomes can digest cellular components delivered to them during autophagy
B. Lysosomes are the only organelles that contain DNA
C. Autophagy is the process by which chloroplasts synthesise chlorophyll
D. Lysosomes perform the Calvin cycle during starvation
Correct Answer: A. Lysosomes can digest cellular components delivered to them during autophagy
Explanation: Autophagy is a cellular recycling process in which components are enclosed and delivered to lysosomes, directly or through intermediate compartments, for degradation and recycling.
Exam tag: Original NEET-UG practice question, 2026.
Q210. Which statement best describes why mitochondria and chloroplasts are considered semi-autonomous?
A. They possess their own genetic material but depend on the cell for many functions and proteins
B. They can survive indefinitely without the rest of the cell
C. They lack ribosomes and DNA
D. They are both parts of the Golgi apparatus
Correct Answer: A. They possess their own genetic material but depend on the cell for many functions and proteins
Explanation: Mitochondria and chloroplasts contain their own DNA and ribosomes. However, many proteins and other components needed for their function are supplied through nuclear gene expression and cellular metabolism.
Exam tag: Original NEET-UG practice question, 2026.
Q211. Which part of a mitochondrion contains enzymes involved in the Krebs cycle?
A. Outer membrane
B. Intermembrane space
C. Matrix .
D. Cristae
Correct Answer: C. Matrix
Explanation: The mitochondrial matrix contains enzymes responsible for most reactions of the Krebs cycle. The inner mitochondrial membrane contains the electron transport chain and ATP synthase.
Q212. In chloroplasts, the space enclosed by the thylakoid membrane is called the:
A. Stroma
B. Thylakoid lumen
C. Intermembrane space
D. Cytosol
Correct Answer: B. Thylakoid lumen
Explanation: The thylakoid membrane encloses the thylakoid lumen. During light-dependent photosynthesis, protons accumulate in this lumen, helping establish the proton gradient used for ATP synthesis.
Q213. Which plastid is primarily associated with imparting yellow, orange or red colour to many flowers and fruits?
A. Leucoplast
B. Chromoplast
C. Amyloplast
D. Proplastid
Correct Answer: B. Chromoplast
Explanation: Chromoplasts contain carotenoid pigments that produce yellow, orange and red colours in many plant tissues. These colours can help attract pollinators and seed-dispersing animals.
Q214. Which statement about proplastids is correct?
A. They occur only in mature red blood cells.
B. They are undifferentiated plastids found in meristematic cells.
C. They are responsible exclusively for protein digestion.
D. They are the main sites of cellular respiration.
Correct Answer: B. They are undifferentiated plastids found in meristematic cells.
Explanation: Proplastids are small, relatively undifferentiated plastids found in plant meristematic cells. Depending on the tissue and developmental conditions, they can develop into chloroplasts, chromoplasts or leucoplasts.
Q215. Which organelle is most directly involved in the folding and initial processing of many proteins destined for secretion?
A. Rough endoplasmic reticulum
B. Smooth endoplasmic reticulum
C. Centriole
D. Peroxisome
Correct Answer: A. Rough endoplasmic reticulum
Explanation: Ribosomes attached to rough endoplasmic reticulum (RER) synthesise proteins entering the secretory pathway. The RER also provides an environment for protein folding and certain early modifications before proteins are transported onward, commonly to the Golgi apparatus.
Q216. Which organelle is especially important for storing anthocyanin pigments in many plant cells?
A. Mitochondrion
B. Central vacuole
C. Ribosome
D. Centrosome
Correct Answer: B. Central vacuole
Explanation: Anthocyanins are water-soluble pigments commonly stored in vacuoles. They contribute to red, purple and blue colours in many flowers, fruits and other plant tissues. Vacuoles also store ions, metabolites and waste products.
Q217. Which statement correctly distinguishes the mitochondrial matrix from the intermembrane space?
A. Both are located outside the outer mitochondrial membrane.
B. The matrix lies inside the inner membrane, while the intermembrane space lies between the two membranes.
C. The matrix contains no enzymes.
D. The intermembrane space contains the mitochondrial chromosomes exclusively.
Correct Answer: B. The matrix lies inside the inner membrane, while the intermembrane space lies between the two membranes.
Explanation: Mitochondria have an outer and an inner membrane. The matrix is enclosed by the inner membrane, whereas the intermembrane space separates the outer and inner membranes. These compartments have different roles in cellular respiration.
Q218. During photosynthesis, the accumulation of protons inside the thylakoid lumen contributes directly to:
A. DNA replication
B. ATP synthesis through chemiosmosis
C. Protein digestion by lysosomes
D. Formation of the plant cell wall
Correct Answer: B. ATP synthesis through chemiosmosis
Explanation: Light-dependent reactions establish a proton gradient across the thylakoid membrane. As protons flow through ATP synthase from the lumen towards the stroma, ATP is produced.
Q219. Which cellular process involves the uptake of extracellular material by the inward folding of the plasma membrane?
A. Exocytosis
B. Endocytosis
C. Translation
D. Transcription
Correct Answer: B. Endocytosis
Explanation: Endocytosis brings substances into a cell through the formation of membrane-bound vesicles. The material may subsequently pass through endosomes and, in certain pathways, reach lysosomes for digestion.
Q220. Which organelle is responsible for modifying, sorting and packaging many proteins received from the endoplasmic reticulum?
A. Golgi apparatus
B. Nucleolus
C. Centrosome
D. Mitochondrial matrix
Correct Answer: A. Golgi apparatus
Explanation: The Golgi apparatus receives proteins and lipids from the endoplasmic reticulum, modifies some of them, and sorts them for delivery to appropriate destinations, including the plasma membrane and lysosome-related pathways.
Q221. Which statement about the smooth endoplasmic reticulum is correct?
A. It is covered with numerous attached ribosomes.
B. It is involved in lipid synthesis and, in certain cells, detoxification.
C. It is the primary site of chromosome formation.
D. It contains the cell’s main store of genetic information.
Correct Answer: B. It is involved in lipid synthesis and, in certain cells, detoxification.
Explanation: Smooth endoplasmic reticulum (SER) lacks ribosomes on its cytoplasmic surface. It participates in lipid synthesis and detoxification reactions. In muscle cells, a specialised form called the sarcoplasmic reticulum stores and releases calcium ions.
Q222. Which structure helps maintain the shape of a cell and supports the organisation and movement of intracellular components?
A. Cytoskeleton
B. Nucleolus alone
C. Lysosomal lumen
D. Chromoplast pigments
Correct Answer: A. Cytoskeleton
Explanation: The cytoskeleton consists of protein filaments, including microtubules, actin microfilaments and intermediate filaments in many animal cells. It contributes to cell shape, intracellular organisation, movement and cell division.
Q223. Which statement about the Golgi apparatus in plant cells is correct?
A. It is absent from all plant cells.
B. Golgi-derived vesicles can contribute materials used in cell-wall formation.
C. It is the site of the Krebs cycle.
D. It produces all cellular ATP directly.
Correct Answer: B. Golgi-derived vesicles can contribute materials used in cell-wall formation.
Explanation: The Golgi apparatus produces and processes certain polysaccharides and other materials used in plant cell walls. These materials are transported in vesicles to appropriate locations in the cell.
Q224. Which of the following is a correct example of compartmentalisation in eukaryotic cells?
A. All metabolic reactions occur in one undivided space.
B. Different organelles provide specialised environments for particular cellular processes.
C. Membrane-bound organelles have no functional differences.
D. Every enzyme is restricted to the nucleus.
Correct Answer: B. Different organelles provide specialised environments for particular cellular processes.
Explanation: Compartmentalisation allows different cellular processes to occur in specialised environments. For example, lysosomes maintain an acidic interior for digestive enzymes, while mitochondria maintain membrane gradients important for ATP production.
Q225. Which statement correctly describes the relationship between plastid differentiation and plant development?
A. Every plastid remains a chloroplast throughout its life.
B. Plastids can differentiate into different forms depending on cell type and developmental conditions.
C. Plastids are present only in animal cells.
D. Plastids cannot contain pigments or store substances.
Correct Answer: B. Plastids can differentiate into different forms depending on cell type and developmental conditions.
Explanation: Plastids are a group of plant and algal organelles that includes chloroplasts, chromoplasts and leucoplasts. Their differentiation depends on developmental and environmental conditions. For example, chloroplasts carry out photosynthesis, chromoplasts accumulate certain pigments, and leucoplasts commonly participate in storage.
Q226. Which of the following is a major function of the mitochondrial inner membrane?
A. Storage of starch granules
B. Housing the electron transport chain and ATP synthase
C. Synthesis of ribosomal subunits in the nucleolus
D. Formation of the plant cell wall
Correct Answer: B. Housing the electron transport chain and ATP synthase
Explanation: The mitochondrial inner membrane contains components of the electron transport chain and ATP synthase. The proton gradient across this membrane drives ATP production during oxidative phosphorylation.
Q227. Which organelle is directly associated with the formation of the acrosome in developing sperm cells?
A. Golgi apparatus
B. Smooth endoplasmic reticulum
C. Peroxisome
D. Central vacuole
Correct Answer: A. Golgi apparatus
Explanation: The acrosome develops from Golgi-derived vesicles during sperm formation. It contains enzymes that help sperm penetrate the coverings surrounding the egg.
Q228. Which of the following correctly describes a leucoplast?
A. A plastid mainly associated with photosynthesis in green tissues
B. A colourless plastid commonly involved in the synthesis or storage of substances C. A membrane-bound digestive organelle in animal cells
D. A structure responsible for chromosome movement during mitosis
Correct Answer: B. A colourless plastid commonly involved in the synthesis or storage of substances
Explanation: Leucoplasts are generally colourless plastids found in non-photosynthetic tissues. Different forms are associated with storage: amyloplasts with starch, elaioplasts with oils, and proteinoplasts with proteins.
Q229. Which statement about the nucleolus is correct?
A. It is the main site of lipid synthesis.
B. It plays an important role in ribosomal RNA production and ribosomal subunit assembly.
C. It is surrounded by an independent double membrane.
D. It carries out the Krebs cycle.
Correct Answer: B. It plays an important role in ribosomal RNA production and ribosomal subunit assembly.
Explanation: The nucleolus is a dense region inside the nucleus. It is involved in the production of most ribosomal RNA and the assembly of ribosomal subunits. It is not surrounded by a membrane.
Q230. Which organelle contains enzymes that break down hydrogen peroxide using catalase?
A. Peroxisome
B. Ribosome
C. Nucleolus
D. Centrosome
Correct Answer: A. Peroxisome
Explanation: Peroxisomes contain oxidative enzymes and catalase. Catalase converts hydrogen peroxide into water and oxygen, helping protect the cell from potentially harmful accumulation of this reactive compound.
Q231. In a plant cell, which structure separates the vacuolar contents from the cytoplasm?
A. Tonoplast
B. Middle lamella
C. Nuclear envelope
D. Thylakoid membrane
Correct Answer: A. Tonoplast
Explanation: The tonoplast is the membrane surrounding the vacuole. It regulates the movement of ions and other substances between the vacuolar contents and the cytoplasm, contributing to storage and cellular water balance.
Q232. Which of the following best explains why mitochondria are described as semi-autonomous organelles?
A. They can survive indefinitely without the cell.
B. They contain their own DNA and ribosomes but still depend on nuclear genes for many proteins.
C. They produce every protein required for their own functioning.
D. They are not affected by the activities of the nucleus.
Correct Answer: B. They contain their own DNA and ribosomes but still depend on nuclear genes for many proteins.
Explanation: Mitochondria possess their own genetic material and protein-synthesis machinery. However, many mitochondrial proteins are encoded by nuclear DNA and imported into the organelle. Therefore, mitochondria are semi-autonomous rather than completely independent.
Q233. Which organelle is most directly involved in the synthesis of phospholipids for many cellular membranes?
A. Smooth endoplasmic reticulum
B. Lysosome
C. Nucleolus
D. Centriole
Correct Answer: A. Smooth endoplasmic reticulum
Explanation: The smooth endoplasmic reticulum is a major site of lipid synthesis, including the synthesis of many phospholipids used in cellular membranes. Lipid metabolism varies among cell types, and some lipids are synthesised at other cellular sites as well.
Q234. Which statement correctly describes the 9 + 2 arrangement in a typical motile eukaryotic cilium?
A. Nine pairs of microtubules surround two central microtubules.
B. Nine triplets surround two central triplets.
C. Two pairs surround nine central microtubules.
D. Nine actin filaments surround two intermediate filaments.
Correct Answer: A. Nine pairs of microtubules surround two central microtubules.
Explanation: A typical motile eukaryotic cilium has an axoneme with nine peripheral microtubule doublets surrounding two central microtubules. This arrangement is commonly described as 9 + 2. It should not be confused with the nine microtubule triplets of a typical centriole.
Q235. Which of the following is a principal function of lysosomal enzymes?
A. Replicating nuclear DNA
B. Digesting macromolecules within the cell
C. Producing chlorophyll
D. Synthesising all cellular ATP
Correct Answer: B. Digesting macromolecules within the cell
Explanation: Lysosomes contain hydrolytic enzymes that break down macromolecules and cellular material. They function in intracellular digestion and contribute to processes such as the recycling of damaged cellular components.
Q236. Which structure is primarily responsible for synthesising proteins during translation?
A. Ribosome
B. Golgi apparatus
C. Peroxisome
D. Vacuole
Correct Answer: A. Ribosome
Explanation: Ribosomes translate the information carried by messenger RNA into a polypeptide chain. Ribosomes may be free in the cytoplasm or attached to the rough endoplasmic reticulum. Their location often relates to the destination of the proteins being produced.
Q237. Which of the following correctly identifies the site of the Calvin cycle in a chloroplast?
A. Thylakoid lumen
B. Stroma
C. Intermembrane space
D. Outer membrane surface only
Correct Answer: B. Stroma
Explanation: The Calvin cycle occurs in the chloroplast stroma. It uses carbon dioxide, ATP and NADPH to produce carbohydrate intermediates. The ATP and NADPH are generated through the light-dependent reactions associated with the thylakoid membrane.
Q238. Which organelle is particularly abundant in many cells that actively synthesise and secrete proteins?
A. Rough endoplasmic reticulum
B. Leucoplast
C. Central vacuole
D. Centriole
Correct Answer: A. Rough endoplasmic reticulum
Explanation: Cells specialised for protein secretion often have extensive rough endoplasmic reticulum because ribosomes on its surface synthesise proteins entering the secretory pathway. These proteins may then be transported to the Golgi apparatus for further processing and sorting.
Q239. Which statement about the plant cell wall is correct?
A. It is the main location of protein translation.
B. It provides mechanical support and helps maintain cell shape.
C. It is identical to the plasma membrane in composition.
D. It contains the enzymes responsible for the Krebs cycle.
Correct Answer: B. It provides mechanical support and helps maintain cell shape.
Explanation: The plant cell wall provides structural support and protection. The primary cell wall contains cellulose, hemicellulose and pectin. The plasma membrane lies inside the cell wall and is chemically and functionally distinct from it.
Q240. Which pairing is correct?
A. Mitochondrion — intracellular digestion by hydrolytic enzymes
B. Golgi apparatus — modification and sorting of proteins
C. Ribosome — storage of cellular water
D. Tonoplast — synthesis of messenger RNA
Correct Answer: B. Golgi apparatus — modification and sorting of proteins
Explanation: The Golgi apparatus modifies, sorts and packages many proteins and lipids. Lysosomes are associated with intracellular digestion, vacuoles store water and other substances, and messenger RNA is synthesised by transcription from DNA.
Q241. A cell produces large quantities of proteins for export outside the cell. Which pathway best describes the movement of many of these proteins?
A. Golgi apparatus → nucleus → ribosome → plasma membrane
B. Rough endoplasmic reticulum → transport vesicles → Golgi apparatus → secretory vesicles
C. Lysosome → mitochondrion → Golgi apparatus → nucleus
D. Smooth endoplasmic reticulum → centriole → plasma membrane
Correct Answer: B. Rough endoplasmic reticulum → transport vesicles → Golgi apparatus → secretory vesicles
Explanation: Many secreted proteins are synthesised by ribosomes associated with the rough endoplasmic reticulum. They enter the ER, are transported to the Golgi apparatus for further processing and sorting, and may then be delivered to the plasma membrane in secretory vesicles.
Q242. Which structure is directly associated with the movement of chromosomes during mitosis?
A. Microtubules of the mitotic spindle
B. Thylakoid membranes
C. Tonoplast
D. Cristae of mitochondria
Correct Answer: A. Microtubules of the mitotic spindle
Explanation: Spindle microtubules interact with chromosomes at their kinetochores and help separate sister chromatids during cell division. Microtubules are an important component of the cytoskeleton.
Q243. Which of the following statements about chloroplasts is correct?
A. The Calvin cycle occurs inside the thylakoid lumen.
B. Chlorophyll is located in the thylakoid membrane.
C. Chloroplasts lack their own genetic material.
D. The outer membrane alone carries out all photosynthetic reactions.
Correct Answer: B. Chlorophyll is located in the thylakoid membrane.
Explanation: Chlorophyll and other components of the photosynthetic machinery are associated with thylakoid membranes. The Calvin cycle occurs in the stroma, while the thylakoid membrane supports the light-dependent reactions.
Q244. Assertion–Reason
Assertion (A): Lysosomal enzymes function effectively in an acidic environment.
Reason (R): Lysosomes maintain an internal pH lower than that of the surrounding cytosol.
A. Both A and R are true, and R correctly explains A.
B. Both A and R are true, but R does not correctly explain A.
C. A is true, but R is false.
D. A is false, but R is true.
Correct Answer: A. Both A and R are true, and R correctly explains A.
Explanation: Lysosomes maintain an acidic lumen using proton-transporting membrane proteins. Their acid hydrolases are adapted to function under these conditions, which supports intracellular digestion.
Q245. Which organelle is most closely associated with the detoxification of hydrogen peroxide produced during oxidative reactions?
A. Peroxisome
B. Ribosome
C. Nucleolus
D. Centriole
Correct Answer: A. Peroxisome
Explanation: Peroxisomes contain oxidases and catalase. Oxidases can generate hydrogen peroxide during certain reactions, and catalase helps convert hydrogen peroxide into water and oxygen.
Q246. Which of the following is a correct difference between a typical centriole and a motile ciliary axoneme?
A. A centriole typically has nine microtubule triplets, while a motile ciliary axoneme typically has nine peripheral doublets and two central microtubules.
B. A centriole has a 9 + 2 arrangement, while a ciliary axoneme has nine triplets without a central pair.
C. Both always have nine peripheral doublets and two central microtubules.
D. Neither structure contains microtubules.
Correct Answer: A. A centriole typically has nine microtubule triplets, while a motile ciliary axoneme typically has nine peripheral doublets and two central microtubules.
Explanation: A typical centriole has nine sets of microtubule triplets and lacks the central pair characteristic of the usual motile ciliary 9 + 2 axoneme. This distinction is important in cell-structure questions.
Q247. Which organelle is most directly associated with the storage of starch in many plant storage tissues?
A. Amyloplast
B. Chromoplast
C. Lysosome
D. Peroxisome
Correct Answer: A. Amyloplast
Explanation: Amyloplasts are colourless plastids specialised for starch synthesis and storage. They are common in storage tissues such as tubers and some seeds.
Q248. Which statement about ribosomes is correct?
A. They are surrounded by a double membrane.
B. They are the sites of protein synthesis.
C. They are responsible for lipid digestion.
D. They store most of the cell’s DNA.
Correct Answer: B. They are the sites of protein synthesis.
Explanation: Ribosomes translate messenger RNA into polypeptides. They are non-membranous structures composed of ribosomal RNA and proteins. They may occur freely in the cytoplasm or attach to the rough endoplasmic reticulum.
Q249. Assertion–Reason
Assertion (A): Mitochondria and chloroplasts are described as semi-autonomous organelles.
Reason (R): Both possess their own DNA and ribosomes but depend on the nucleus for many proteins.
A. Both A and R are true, and R correctly explains A.
B. Both A and R are true, but R does not correctly explain A.
C. A is true, but R is false.
D. A is false, but R is true.
Correct Answer: A. Both A and R are true, and R correctly explains A.
Explanation: Mitochondria and chloroplasts contain their own genetic material and protein-synthesis machinery. However, many proteins needed for their structure and functions are encoded by nuclear genes, so these organelles are not fully independent.
Q250. Which component of the endomembrane system is most directly involved in the formation and processing of many transport vesicles destined for the Golgi apparatus?
A. Endoplasmic reticulum
B. Nucleolus
C. Mitochondrial matrix
D. Centriole
Correct Answer: A. Endoplasmic reticulum
Explanation: Proteins and lipids produced or processed in the endoplasmic reticulum can be packaged into transport vesicles that move towards the Golgi apparatus. This movement is part of the secretory pathway.
Q251. Which statement correctly describes the plant central vacuole?
A. It is surrounded by the tonoplast and can help maintain turgor pressure.
B. It is surrounded by the nuclear envelope.
C. It contains the mitotic spindle.
D. It is the primary location of the electron transport chain in cellular respiration.
Correct Answer: A. It is surrounded by the tonoplast and can help maintain turgor pressure.
Explanation: The central vacuole stores water and dissolved substances. Water uptake can create turgor pressure, helping support non-woody plant tissues. The tonoplast regulates exchange between the vacuole and the cytoplasm.
Q252. Which organelle is the main site of aerobic cellular respiration in most eukaryotic cells?
A. Golgi apparatus
B. Mitochondrion
C. Lysosome
D. Chromoplast
Correct Answer: B. Mitochondrion
Explanation: Mitochondria carry out major stages of aerobic cellular respiration, including the Krebs cycle in the matrix and oxidative phosphorylation at the inner membrane. Glycolysis, however, occurs in the cytosol.
Q253. Which of the following correctly matches an organelle with its primary function?
A. Smooth endoplasmic reticulum — lipid synthesis
B. Nucleolus — ATP production by oxidative phosphorylation
C. Lysosome — photosynthesis
D. Chloroplast — intracellular digestion by acid hydrolases
Correct Answer: A. Smooth endoplasmic reticulum — lipid synthesis
Explanation: Smooth endoplasmic reticulum participates in lipid synthesis and other functions, including detoxification in certain cells. The nucleolus supports ribosome biogenesis, lysosomes perform intracellular digestion, and chloroplasts carry out photosynthesis.
Q254. Which structure in a plant cell allows direct cytoplasmic connections between neighbouring cells?
A. Plasmodesmata
B. Cristae
C. Centrioles
D. Lysosomal membranes
Correct Answer: A. Plasmodesmata
Explanation: Plasmodesmata are channels through plant cell walls that connect the cytoplasm of neighbouring cells. They facilitate intercellular transport and communication. They are distinct from the gaps between adjacent cells.
Q255. A researcher observes an organelle with a double membrane, its own DNA and ribosomes, and internal membrane folds called cristae. Which organelle is being examined?
A. Chloroplast
B. Mitochondrion
C. Lysosome
D. Golgi apparatus
Correct Answer: B. Mitochondrion
Explanation: Cristae are folds of the inner mitochondrial membrane. They increase the membrane area available for the electron transport chain and ATP synthesis. Mitochondria also possess their own DNA and ribosomes.
