Every Cell Biology (Cellular Organization) question CSIR-NET Life Sciences has set in its last 11 papers, sorted by topic, with 16 of them solved step by step. Answers follow NTA’s final answer keys.
Unit 2 of the CSIR-NET Life Sciences syllabus, Cellular Organization, covers membranes and transport, organelles, protein sorting and vesicular traffic, the cytoskeleton and motors, cell junctions and the extracellular matrix, chromatin organisation, the cell cycle and cell division. A few questions on cell death and stem cells are also tagged here. We went through all 11 papers from February 2022 to June 2025 and pulled out every question from this unit.
How much of the paper is Cell Biology?
Across the 11 papers, 99 of the 1,375 Part B and Part C questions (7.2%) came from Unit 2. That ranks it ninth of the 13 units. 59 of the 99 were 4-mark Part C questions.
| Paper | Part B | Part C | Total |
|---|---|---|---|
| June 2025 | 5 | 4 | 9 |
| December 2024, Shift 1 | 6 | 8 | 14 |
| December 2024, Shift 2 | 5 | 6 | 11 |
| June 2024, Shift 1 | 3 | 5 | 8 |
| June 2024, Shift 2 | 2 | 5 | 7 |
| December 2023, Shift 1 | 4 | 7 | 11 |
| December 2023, Shift 2 | 3 | 4 | 7 |
| June 2023, Shift 1 | 5 | 5 | 10 |
| June 2023, Shift 2 | 1 | 5 | 6 |
| February 2022, Shift 1 | 3 | 8 | 11 |
| February 2022, Shift 2 | 3 | 2 | 5 |
| All 11 papers | 40 | 59 | 99 |
Which Cell Biology topics come up most
Protein Sorting & Vesicular Trafficking and Cell Division & Cell Cycle together account for 49% of the unit’s questions.
16 solved Cell Biology PYQs
One or two from each major subtopic, from different papers. Try each one before you open the solution.
Which cell cycle phase is typically the shortest in mammalian cells?
- 1G0 phase
- 2G1 phase
- 3G2 phase
- 4Mitosis
Show answer and solution
In a typical 24-hour mammalian cycle, G1 takes about 11 hours, S about 8, G2 about 4 and M phase only about 1 hour. Mitosis is the shortest phase. G0 is not a phase of the cycle at all: it is a resting state outside it, and it can last indefinitely.
Porins, which are normally present on the outer mitochondrial membrane, reach their destination by
- 1direct synthesis of porins on mitochondria membrane by the mitochondrial protein synthesis machinery.
- 2synthesis on the ER and transport via vesicles to the mitochondria.
- 3synthesis in the cytosol, import by TOM complex and insertion from the inter-mitochondrial membrane space.
- 4synthesis in the cytosol, import by TIM complex and insertion in the membrane.
Show answer and solution
Porin (VDAC) is a nuclear-encoded β-barrel protein made on cytosolic ribosomes. It enters through the TOM complex into the intermembrane space, where small TIM chaperones carry it to the SAM complex, which inserts it into the outer membrane from the inside. TIM23 and TIM22 handle inner-membrane and matrix proteins.
Which one of the following is involved in the pinching-off of the neck of invaginating coated pit to form endocytotic vesicle at the pre-synaptic terminal?
- 1Synaptojanin
- 2AP2
- 3Clathrin
- 4Dynamin
Show answer and solution
Answer: (4) Dynamin
Clathrin and the adaptor AP2 build the coat and bend the membrane into a pit. The GTPase dynamin then forms a collar around the neck and, by hydrolysing GTP, constricts it and cuts the vesicle free. At synapses this keeps vesicles recycling. Synaptojanin removes clathrin afterwards by dephosphorylating PIP2.
In the context of protein import in the nucleus, which molecule is responsible for releasing the cargo from the importing receptor?
- 1Ras
- 2RhoA
- 3Ran
- 4Rock
Show answer and solution
Answer: (3) Ran
An importin carries its cargo through the nuclear pore. In the nucleus, Ran-GTP (kept high there by the chromatin-bound GEF RCC1) binds importin-β and makes it release the cargo. The importin–Ran-GTP complex returns to the cytosol, where RanGAP makes Ran hydrolyse its GTP and the importin is freed. That gradient gives transport its direction.
Which one of the following describes an amphisome?
- 1It is an intermediate/hybrid organelle produced through the fusion of endosomes with autophagosomes within cells.
- 2It is a double-membrane sequestering vesicle that is the hallmark of the intracellular catabolic process called macroautophagy.
- 3It is a compartment formed when autophagosome fuses with a lysosome.
- 4It is a vacuole that arises when membranes of the ER sequester parts of the cytoplasm.
Show answer and solution
Answer: (1) It is an intermediate/hybrid organelle produced through the fusion of endosomes with autophagosomes within cells.
In macroautophagy an autophagosome can first fuse with a late endosome or multivesicular body. The hybrid compartment is the amphisome, which later fuses with a lysosome to form an autolysosome. Option 2 describes the autophagosome, and option 3 the autolysosome.
In cell membranes, the lipid molecules are arranged as a continuous double layer, with an approximate thickness of
- 120 nm
- 250 nm
- 35 nm
- 41 nm
Show answer and solution
Answer: (3) 5 nm
The hydrophobic core of a phospholipid bilayer is about 3 nm across. With the head groups the bilayer is about 5 nm thick (4–5 nm in most texts). This is the “unit membrane” seen in electron micrographs as two dark lines with a light band between.
Progression across G1/S boundary followed by entry into S-phase is promoted by the activation of which one of the following protein complexes?
- 1Cdk4/Cyclin D
- 2Cdk2/Cyclin E
- 3Cdk4,6/Cyclin
- 4Cdk4,6/Cyclin D, E
Show answer and solution
Answer: (2) Cdk2/Cyclin E
Cyclin E–Cdk2 peaks at the G1/S boundary. It finishes Rb hyperphosphorylation and helps fire origins, committing the cell to S phase. Cyclin D–Cdk4/6 acts earlier, in G1, responding to growth factors and starting Rb phosphorylation. Cyclin A–Cdk2 then drives S phase itself.
Signal sequences direct proteins to the correct intracellular locations. Which one of the following sequences is typically used to import proteins into the nucleus?
- 1-Pro-Pro-Lys-Lys-Arg-Lys-Val-
- 2-Leu-Ala-Leu-Lys-Leu-Ala-Gly-Leu-Asp-Ile-
- 3-Ser-Lys-Leu-COO−
- 4-Lys-Asp-Glu-Leu-COO−
Show answer and solution
Answer: (1) -Pro-Pro-Lys-Lys-Arg-Lys-Val-
The classic nuclear localisation signal is a short basic stretch, PKKKRKV from the SV40 large T antigen, recognised by importin-α. A hydrophobic stretch like option 2 is an ER signal peptide. C-terminal SKL targets peroxisomes (PTS1), and C-terminal KDEL keeps proteins in the ER.
Which one of the following is likely to enter a pure phospholipid bilayer?
- 1CO2 and Diethyl urea
- 2Water and Glucose
- 3Lysine and Ethanol
- 4Urea and Chloride ions
Show answer and solution
Answer: (1) CO2 and Diethyl urea
A pure lipid bilayer lets small, uncharged, fairly hydrophobic molecules diffuse through. CO2 passes freely, and diethylurea, more hydrophobic than urea, crosses far faster than urea itself. Glucose and lysine are too polar or charged, and Cl− is an ion. All of these need transporters or channels.
During the most common form of protein glycosylation in the ER, a preformed precursor oligosaccharide which is transferred as a complete unit to the asparagine residue in a protein is:
- 13 N-acetylglucosamines, 10 mannoses and 4 glucoses
- 22 N-acetylglucosamines, 9 mannoses and 3 glucoses
- 33 N-acetylglucosamines, 9 mannoses and 3 glucoses
- 42 N-acetylglucosamines, 8 mannoses and 3 glucoses
Show answer and solution
Answer: (2) 2 N-acetylglucosamines, 9 mannoses and 3 glucoses
N-linked glycosylation starts with the precursor Glc3Man9GlcNAc2, assembled on dolichol pyrophosphate. Oligosaccharyltransferase moves it in one piece onto asparagine in an Asn–X–Ser/Thr sequence. Its three glucoses are trimmed later, in the calnexin/calreticulin folding cycle.
Mammalian cells that have just crossed the Restriction Point of the cell cycle are likely to have:
- 1high levels of unphosphorylated retinoblastoma protein.
- 2an active anaphase promoting complex.
- 3low levels of mitotic cyclin B.
- 4condensed chromosomes.
Show answer and solution
Answer: (3) low levels of mitotic cyclin B.
Just past the restriction point a cell is in late G1. Rb is already hyperphosphorylated (so option 1 is wrong), chromosomes are decondensed, and mitotic cyclin B is still low, because APC/C–Cdh1 kept destroying it through G1. Cyclin B builds up only in S and G2. Option 2 is ruled out because APC/C–Cdh1 is switched off at the G1/S transition.
Among the organelles listed below, which one does NOT obtain proteins via vesicular transport?
- 1Endosomes
- 2Lysosome
- 3Mitochondria
- 4Golgi
Show answer and solution
Answer: (3) Mitochondria
Endosomes, lysosomes and the Golgi belong to the secretory and endocytic system and receive proteins in vesicles. Mitochondria are outside that system. Their nuclear-encoded proteins are made in the cytosol and imported after translation through the TOM and TIM translocases. Chloroplasts, peroxisomes and the nucleus also import without vesicles.
Mitotic cyclin increases gradually through the G2 phase of the cell cycle but the activity of mitotic CDK1 increases suddenly at the onset of M phase. This is because
- 1active CDK1 subunit is synthesized in M phase.
- 2mitotic cyclin is sequestered in the cytosol.
- 3activation of CDK1 requires post-translational modifications.
- 4the inhibitor of CDK1 is degraded in the M phase.
Show answer and solution
Answer: (3) activation of CDK1 requires post-translational modifications.
Cyclin B–CDK1 builds up through G2 but is kept off by inhibitory phosphorylation of CDK1 (Thr14/Tyr15, by Wee1 and Myt1), even though the activating Thr161 is already phosphorylated by CAK. At the G2/M transition Cdc25 removes the inhibitory phosphates. Active CDK1 then switches on more Cdc25 and switches off Wee1, so activity jumps suddenly.
Ribosomes attach to the endoplasmic reticulum via
- 1differing surface ribosomal protein composition that allow it to interact with polar headgroups on the ER lipid bilayer.
- 25′UTR of mRNA being translated that directs the localization of the ribosomes to the ER.
- 3the translated nascent chain which carries a signal allowing interaction with SRP-receptor on the ER.
- 4tethered mRNAs that interact with rRNA.
Show answer and solution
Answer: (3) the translated nascent chain which carries a signal allowing interaction with SRP-receptor on the ER.
A ribosome is targeted to the ER by what it is making. As the signal sequence of the nascent chain emerges, SRP binds it and pauses translation. SRP then docks on the SRP receptor in the ER membrane, which passes the ribosome to the Sec61 translocon. Free and ER-bound ribosomes are identical.
Membrane-enclosed organelles often have a characteristic position in the cytosol. In animal cells, for example, the Golgi apparatus is located close to the nucleus. Which component is directly involved in ensuring correct Golgi localization in animal cells?
- 1Actin cytoskeleton
- 2Microtubules
- 3Nucleolus
- 4Peroxisomes
Show answer and solution
Answer: (2) Microtubules
The Golgi gathers next to the nucleus, around the centrosome, because it is attached to microtubules. Golgi membranes and ER-to-Golgi carriers are moved towards the minus ends by dynein. Depolymerising microtubules with nocodazole scatters the Golgi into ministacks throughout the cytoplasm.
In eukaryotic cells, DNA replication is restricted to the S phase of the cell cycle because
- 1DNA polymerase is present only in the S phase of the cell cycle.
- 2Origin recognition complex (ORC) recognizes origin only in the S phase.
- 3MCM helicases get activated in the S phase of the cell cycle.
- 4MCM helicases get activated in the G1 phase of the cell cycle.
Show answer and solution
Answer: (3) MCM helicases get activated in the S phase of the cell cycle.
Replication is confined to S phase by two-step origin control. In G1, ORC, Cdc6 and Cdt1 load inactive MCM2–7 onto origins (licensing). Only in S phase do S-CDK and DDK activate the MCM helicase, with Cdc45 and GINS forming the CMG complex. High CDK activity then blocks any new licensing until the next G1. ORC binds origins throughout the cycle.
All 99 Cell Biology questions, by subtopic
Each link opens the question on its full paper page. Press Show answer and solution there to see NTA’s final key and a worked solution.
Protein Sorting & Vesicular Trafficking (28 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q67 | B | Ribosomes attach to the endoplasmic reticulum via |
| Jun 2025, Q75 | C | The following statements are made regarding vesicle formation, transport, and fusion in cells expressing a mutant Arf protein. This mutant… |
| Jun 2025, Q104 | C | Proteins possess a sorting signal known as a nuclear localization signal (NLS) for their import into the nucleus. A few statements are… |
| Dec 2024 S1, Q74 | C | Given below are a few statements about intracellular protein transport. Choose the option that has all correct statements. |
| Dec 2024 S2, Q35 | B | Which one of the following statements best describes the functions of the SNARE protein complex in vesicular transport? |
| Dec 2024 S2, Q46 | B | During the most common form of protein glycosylation in the ER, a preformed precursor oligosaccharide which is transferred as a complete… |
| Dec 2024 S2, Q78 | C | A putative mitochondrial signal peptide was attached to the N-terminus of the DHFR protein and expressed in mammalian cells. Mitochondria… |
| Dec 2024 S2, Q109 | C | Adding mRNA that encodes a eukaryotic secretory protein to a cell-free translation system initiates protein translation. Signal recognition… |
| Dec 2024 S2, Q110 | C | Given below are a few statements about vesicular transport. Which one of the following options has all correct statements about endocytosis? |
| Jun 2024 S1, Q73 | C | The Ran GTPase imposes directionality on transport through nuclear pore complexes (NPCs). Like other GTPases, Ran is a molecular switch… |
| Jun 2024 S1, Q89 | C | In vivo interaction between FLAG-tagged protein P and chaperone H was examined by co-immunoprecipitation (co-IP). Co-chaperone A was… |
| Jun 2024 S1, Q126 | C | A KDEL sequence is added at the C-terminus of a secreted glycoprotein X (500 amino acid residues) having no site for N-linked glycosylation… |
| Jun 2024 S2, Q66 | B | Among the organelles listed below, which one does NOT obtain proteins via vesicular transport? |
| Jun 2024 S2, Q123 | C | Isolated mitochondria were either treated with protease or first briefly incubated in hypotonic solution prior to treatment with protease… |
| Dec 2023 S1, Q28 | B | Porins, which are normally present on the outer mitochondrial membrane, reach their destination by |
| Dec 2023 S1, Q46 | B | Which one of the following is involved in the pinching-off of the neck of invaginating coated pit to form endocytotic vesicle at the… |
| Dec 2023 S1, Q78 | C | Iron (Fe) is taken up by cells via receptor-mediated endocytosis utilizing transferrin and transferrin receptor. In a cell line with a… |
| Dec 2023 S1, Q82 | C | Researcher plans to study protein trafficking into the endoplasmic reticulum (ER). For this purpose, they plan different experimental… |
| Dec 2023 S2, Q81 | C | Protein transport into the ER is co-translational and proteins are inserted via an aqueous channel into the ER. This can be studied using… |
| Jun 2023 S1, Q28 | B | In the context of protein import in the nucleus, which molecule is responsible for releasing the cargo from the importing receptor? |
| Jun 2023 S1, Q38 | B | Which one of the following describes an amphisome? |
| Jun 2023 S2, Q80 | C | An investigator identified a nuclear localization signal (NLS; Pro-Lys-Lys-Lys-Arg-Lys) at the C-terminus of the protein X (50 kDa). To… |
| Jun 2023 S2, Q82 | C | A researcher isolated a mutant of an ER resident protein-folding enzyme (PFE) that has lost its KDEL sequence (ER retention sequence)… |
| Feb 2022 S1, Q27 | B | The movement of proteins bigger than 50 kDa across the nuclear envelope requires: |
| Feb 2022 S1, Q79 | C | Given below are a few statements about nuclear transport. Which one of the following combination contains all correct statments? |
| Feb 2022 S1, Q82 | C | To delineate the steps in endoplasmic reticulum (ER) transport, a PhD student homogenized pancreatic acinar cells to isolate microsomes… |
| Feb 2022 S2, Q27 | B | Signal sequences direct proteins to the correct intracellular locations. Which one of the following sequences is typically used to import… |
| Feb 2022 S2, Q82 | C | Following statements were made about protein trafficking in cells: Which one of the following represents the correct combination of above statements? |
Cell Division & Cell Cycle (21 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q39 | B | The activation of Cdk2 in vertebrates is dependent on |
| Jun 2025, Q73 | C | Spindle assembly requires the formation of numerous new microtubules. To meet this demand, the spindle contains a large number of… |
| Dec 2024 S1, Q136 | C | Spindle assembly in animal cells requires nuclear envelope breakdown (NEBD). NEBD is a multistep process, which begins when Cdk1/cyclinB… |
| Dec 2024 S2, Q92 | C | After synchronizing mammalian cells in culture with a double thymidine block (cell cycle duration of 24h), cells are released into fresh… |
| Jun 2024 S1, Q54 | B | In eukaryotic cells, DNA replication is restricted to the S phase of the cell cycle because |
| Jun 2024 S1, Q93 | C | Some features mentioned below are important for the segregation of homologous chromosomes in meiosis I. Which one of the following options… |
| Jun 2024 S2, Q59 | B | Mitotic cyclin increases gradually through the G2 phase of the cell cycle but the activity of mitotic CDK1 increases suddenly at the onset… |
| Jun 2024 S2, Q94 | C | Protein phosphatase 2A (PP2A) is a critical regulator of Cdk1 substrates during the cell cycle. The B55 subunit of PP2A influences the… |
| Jun 2024 S2, Q137 | C | Match the major cell cycle regulatory proteins in Column (X) and their typical function in Column (Y) Which one of the following options… |
| Dec 2023 S1, Q27 | B | Which cell cycle phase is typically the shortest in mammalian cells? |
| Dec 2023 S1, Q79 | C | In yeast, temperature-sensitive mutants of cell cycle regulators, cdc2 (the key cyclin-dependent kinase), cdc13 (required for telomeric DNA… |
| Dec 2023 S1, Q92 | C | Synchronous cultures of MCF7 breast cancer cells were grown and treated with the following: (i) buffer (plate was named MCF7), (ii) an… |
| Dec 2023 S2, Q26 | B | Mammalian cells that have just crossed the Restriction Point of the cell cycle are likely to have: |
| Dec 2023 S2, Q79 | C | During metaphase to anaphase transition, complete removal of cohesin allows sister chromatids to separate and move to opposite poles of the… |
| Jun 2023 S1, Q27 | B | A temperature sensitive S. pombe mutant exhibits cell cycle arrest both, at the G1 to S, as well as at the G2 to M transition phases. This… |
| Jun 2023 S1, Q79 | C | The following statements were made about cell cycle regulation in fission yeast: Which one of the following options represents the… |
| Feb 2022 S1, Q25 | B | Progression across G1/S boundary followed by entry into S-phase is promoted by the activation of which one of the following protein complexes? |
| Feb 2022 S1, Q77 | C | Following statements were made about chromosome cohesion during mitosis and meiosis. Which one of the following combination contains all… |
| Feb 2022 S1, Q80 | C | During cytokinesis, a small GTPase, RhoA, localizes to the equatorial membrane above the spindle midzone. The localization/activity of RhoA… |
| Feb 2022 S1, Q88 | C | DNA replication occurs in S phase. The entry of cells into S phase is regulated by the tumor suppressor protein Rb. The statements below… |
| Feb 2022 S2, Q81 | C | Following statements were made about cell cycle regulation: Which one of the following represents the combination of the correct statements? |
Membrane Structure & Transport (16 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q50 | B | Which one of the following options best represents cholesterol distribution as a percentage of total membrane lipid in a typical animal cell? |
| Jun 2025, Q142 | C | Human lymphocytes were incubated with increasing concentrations of NaCl. Which one of the following options represents the correct response… |
| Dec 2024 S1, Q26 | B | A transmembrane receptor protein (X) and a transmembrane protein bound to the actin cytoskeleton (Y) with fluorescent tags were expressed… |
| Dec 2024 S1, Q43 | B | Which one of the following is NOT a major phospholipid in mammalian plasma membrane? |
| Dec 2024 S1, Q55 | B | Which one of the following is likely to enter a pure phospholipid bilayer? |
| Dec 2024 S1, Q76 | C | Given below are components that facilitate transfer of molecules across phospholipid bilayers (Column X) and the properties of these… |
| Dec 2024 S1, Q110 | C | A researcher placed plant cells in a hypertonic solution to cause the cells to shrink. The following statements are made regarding the… |
| Dec 2024 S1, Q121 | C | Protein X can be extracted from disrupted erythrocyte plasma membranes with high salt concentrations. Treatment of intact erythrocytes with… |
| Dec 2024 S2, Q21 | B | Which one of the following properties is NOT responsible for the self-sealing nature of ruptured biological membranes? |
| Dec 2024 S2, Q129 | C | The lipid composition of the two monolayers of the plasma membrane is quite different. This lipid asymmetry is functionally relevant… |
| Jun 2024 S1, Q112 | C | Given below are some components that could potentially influence membrane fluidity. i. Monomeric G-proteins ii. Peripheral membrane… |
| Dec 2023 S2, Q28 | B | Which one of the following statements about biological membranes is INCORRECT? |
| Dec 2023 S2, Q75 | C | Newly identified proteins X, Y, and Z are associated with endoplasmic reticulum (ER) membrane fraction. The above ER membrane fraction is… |
| Jun 2023 S1, Q26 | B | Which one of the following changes is energetically favorable and occurs spontaneously in an aqueous solution? |
| Jun 2023 S2, Q26 | B | In cell membranes, the lipid molecules are arranged as a continuous double layer, with an approximate thickness of |
| Feb 2022 S1, Q26 | B | In eukaryotic cells, covalently attached lipids help to anchor some water soluble proteins to the plasma membrane. One group of cytosolic… |
Cytoskeleton & Motor Proteins (9 questions)
| Paper and question | Part | Question |
|---|---|---|
| Dec 2024 S1, Q27 | B | Dynein is a microtubule-dependent motor protein essential for cellular processes. Which one of the following statements related to dynein… |
| Dec 2024 S1, Q30 | B | Which one of the following statements regarding cytoskeleton proteins is INCORRECT? |
| Dec 2024 S1, Q117 | C | Actin dynamics in cells is dependent on several actin-binding proteins. Given below are actin-binding proteins in Column X and their… |
| Jun 2024 S2, Q109 | C | To test the lever-arm model of myosin movement, an investigator utilizes recombinant DNA technology to attach myosin head to various length… |
| Dec 2023 S2, Q78 | C | Microtubule cytoskeleton utilizes some accessory proteins to regulate microtubule dynamics. Accessory proteins are given in column X and… |
| Jun 2023 S1, Q82 | C | In eukaryotes, microtubules and actin-binding proteins influence the dynamics and organization of the cytoskeleton. Match the… |
| Jun 2023 S2, Q79 | C | Cytoskeleton-dependent motor proteins are critical for the movement of cellular organelles in animal cells. In the fertilized egg of C… |
| Feb 2022 S1, Q81 | C | Cellular actin levels can be as high as 100-400 µM. Of this, unpolymerized actin concentration can be as much as 50-200 µM. However, the… |
| Feb 2022 S2, Q26 | B | Membrane-enclosed organelles often have a characteristic position in the cytosol. In animal cells, for example, the Golgi apparatus is… |
Cell Junctions & Extracellular Matrix (8 questions)
| Paper and question | Part | Question |
|---|---|---|
| Dec 2024 S1, Q75 | C | The following statements are made regarding the role of cadherins in cell junctions. Which one of the following options represents all… |
| Dec 2024 S2, Q32 | B | Which one of the following statements regarding the cadherin superfamily proteins is correct? |
| Jun 2024 S1, Q35 | B | Which one of the following statements regarding plasmodesmata in a plant cell is INCORRECT? |
| Dec 2023 S1, Q91 | C | Extracellular matrix comprises of various proteins and polysaccharides that assemble into an organized meshwork. This associates with the… |
| Dec 2023 S2, Q35 | B | Which one of the following statements about different cellular junctions is INCORRECT? |
| Jun 2023 S1, Q34 | B | Which one of the following is the communicating junction linking adjacent cells in plants, which permits small molecules to pass from cell… |
| Jun 2023 S2, Q91 | C | In a tissue, cells are bound together by physical attachment between cell to cell or between cell to the extracellular matrix. The… |
| Feb 2022 S1, Q92 | C | Some cellular and extracellular proteins are enlisted in List I and their typical characteristics are enlisted in List II Which one of the… |
Cell Death, Ageing & Stem Cells (7 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q46 | B | Which one of the following does NOT promote aging in humans? |
| Dec 2024 S1, Q85 | C | The following statements are made regarding apoptosis in the nematode, C. elegans: Which one of the following options represents all… |
| Dec 2024 S2, Q47 | B | Which one of the following statements is true about cellular senescence? |
| Dec 2024 S2, Q82 | C | In an experiment, while screening for loss-of-function mutants, a student found a mutation in the gene encoding caspase-9 in the intrinsic… |
| Dec 2023 S1, Q93 | C | Apoptosis refers to programmed cell death that is triggered by specialized intracellular proteases called caspases. The intrinsic pathway… |
| Feb 2022 S1, Q93 | C | Following statements have been proposed for cancer cells and cancer stem cells: Which one of the following combination of statements is correct? |
| Feb 2022 S2, Q28 | B | Which one of the following statements about stem cells is correct? |
Structure & Function of Organelles (5 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q61 | B | All of the following are covered by lipid monolayers, EXCEPT |
| Jun 2024 S1, Q65 | B | Which one of the following activities is associated with Mitochondria-associated ER membranes (MAM)? |
| Jun 2024 S2, Q90 | C | Given below are a list of sub-cellular compartments (Column X) and markers (Column Y). Which one of the following options correctly matches… |
| Dec 2023 S1, Q142 | C | Following are marker enzymes that would be used to identify correct sub-cellular fractions. Which one of the following options correctly… |
| Jun 2023 S1, Q81 | C | Match the eukaryotic cellular organelles listed in Column X with their typical function from among those listed in Column Y. Which one of… |
Organization of Genes & Chromosomes (4 questions)
| Paper and question | Part | Question |
|---|---|---|
| Dec 2024 S1, Q58 | B | Which one of the following statements regarding mutations in the mitochondria during aging is INCORRECT? |
| Dec 2023 S1, Q26 | B | Which one of the following statements about distribution of chromosomes within the interphase nucleus of a mammalian cell is correct? |
| Jun 2023 S1, Q77 | C | A researcher isolated chromatin from mammalian cells and digested with micrococcal nuclease in different tubes for 1 h, 3 h, 6 h, and 12 h… |
| Jun 2023 S1, Q78 | C | The following statements were made about the structure of the 30-nm chromatin fiber: Which one of the following options represents the… |
Microbial Physiology (1 question)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2023 S2, Q81 | C | When budding yeast (a facultative anaerobe) is grown for a few days in medium containing high glucose it shows a growth pattern with two… |
PYQs for every CSIR-NET unit
How to revise Cell Biology with these questions
- Start with the two biggest subtopicsProtein Sorting & Vesicular Trafficking and Cell Division & Cell Cycle are where most of the marks have been. Revise them first.
- Attempt before you readWork through a subtopic’s questions on paper, then check them against the answer keys.
- Find the repeatsThe same ideas keep coming back in new wording. When you get one wrong, look for its earlier version in the list above.
- Finish with a full paperTake a whole paper in live exam mode to practise choosing which Part C questions to attempt.
Keep going
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p class=”lbq-src”>Source: CSIR-NET Life Sciences question papers and final answer keys, National Testing Agency, February 2022 to June 2025. Subtopic tags, difficulty ratings and solutions: Lesson Basket.
