COMPETITIVE EXAM MCQs SERIES of LIFE SCIENCES for CSIR-UGC NET/JRF, SLET, GATE, and other entrance tests: CELL COMMUNICATION AND CELL SIGNALLING – Cell Communication and Intercellular Interactions.
Syllabus Outline
- Regulation of hematopoiesis.
- Principles of cell communication.
- Cell adhesion and roles of different adhesion molecules.
- Gap junctions, extracellular matrix and integrins.
- Neurotransmission and its regulation.
This quiz contains concept-based, most frequently asked 25 MCQs of “CELL COMMUNICATION AND CELL SIGNALLING – Cell Communication and Intercellular Interactions”. Each question has a single correct/most appropriate answer.
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1. Erythropoietin and thrombopoietin regulate erythrocyte and platelet production, respectively. Which signalling pathway is directly activated by their receptors?
A) Intrinsic receptor tyrosine kinase → Ras/MAPK pathway
B) JAK2 activation → STAT5 phosphorylation
C) Proteolytic cleavage of the receptor, releasing the transcription factor
D) G-protein activation → cAMP → PKA
2. Which feature distinguishes fetal hematopoietic stem cells (HSCs) from adult HSCs?
A) Fetal HSCs lack self-renewal ability, whereas adult HSCs possess self-renewal ability.
B) Fetal HSCs reside primarily in the bone marrow before birth, whereas adult HSCs circulate in blood vessels.
C) Adult HSCs are predominantly quiescent, whereas fetal HSCs are highly proliferative.
D) Adult HSCs can support hematopoiesis under stress, whereas fetal HSCs cannot.
3. A leukemic cell population shows the phenotype: Lin⁻ CD34⁺ CD38⁺ CD45RA⁺. Which normal progenitor population corresponds to this profile?
A) Common lymphoid progenitor
B) Megakaryocyte-erythroid progenitor
C) Granulocyte-macrophage progenitor
D) Multipotent progenitor
4. After administration of recombinant erythropoietin, which intracellular marker indicates immediate receptor activation in erythroid cells?
A) Increase in intracellular calcium
B) Phosphorylation of STAT5
C) Nuclear translocation of β-catenin
D) Cleavage of Notch receptor
5. Which mechanism maintains stemness during asymmetric division of hematopoietic stem cells?
A) Unequal distribution of cytoplasmic components
B) Uneven loss of adhesion to the extracellular matrix
C) Chromatin acetylation in only one daughter cell
D) Local niche signals acting on only one daughter cell
6. Fluorescence Recovery After Photobleaching (FRAP) analysis shows that a receptor’s immobile fraction increases from 10% to 90% after drug treatment. What is the most likely effect of the drug?
A) Increased receptor internalisation
B) Inhibition of ligand binding
C) Increased membrane fluidity
D) Cross-linking of receptors to the cytoskeleton
7. Nitric oxide (NO) regulates vascular smooth muscle tone. Which pathway correctly describes its action?
A) NO → adenylate cyclase → cAMP → contraction
B) NO → guanylate cyclase → cGMP → Protein Kinase G → relaxation
C) NO → G-Protein–Coupled Receptor → phospholipase C → Ca²⁺ → relaxation
D) NO directly depolymerises actin
8. Which statement about receptor tyrosine kinases (RTKs) is incorrect?
A) Ligand binding induces dimerisation
B) Autophosphorylation creates docking sites
C) SH2/PTB proteins bind phosphorylated tyrosines
D) RTKs signal through trimeric G-proteins
9. An epithelial cell culture is treated with EDTA, a chelator of divalent cations. Cells lose cell–cell adhesion and dissociate. Which class of adhesion molecules is primarily affected?
A) N-CAM
B) Selectins
C) Integrins
D) Cadherins
10. Pemphigus vulgaris is an autoimmune disease characterised by loss of cell–cell adhesion in the epidermis. Autoantibodies are directed against:
A) Desmoglein 1 and Desmoglein 3
B) Integrin α6β4
C) E-cadherin and β-catenin
D) Connexin 43
11. Which interaction is essential for mammalian sperm–egg fusion?
A) E-cadherin–N-cadherin
B) Izumo1–Juno
C) Bindin–ZP3
D) Integrin–fibronectin
12. How are adherens junctions linked to the actin cytoskeleton?
A) Cadherins → β-catenin → α-catenin → actin
B) Cadherins → α-catenin → β-catenin → actin
C) Integrins connect to intermediate filaments
D) Connexins link to actin via ZO proteins
13. Cells expressing high vs. low levels of the same cadherin are mixed. What is the final arrangement?
A) Homogenised and maintained equal cadherin
B) High-cadherin cells at the centre, low-cadherin outside
C) Low-cadherin cells at the centre, high-cadherin outside
D) Separation into two clusters with high and low-cadherin
14. Which molecule is NOT a component of the extracellular matrix?
A) Fibronectin
B) Laminin
C) Cadherin
D) Collagen
15. Which statement about collagen structure and synthesis is correct?
A) Collagen fibres assemble inside the Golgi
B) Collagen contains α-helices and β-sheets
C) Proline hydroxylation enables tight double helix formation
D) Glycine occurs at every third position
16. Fibroblasts adhere to fibronectin-coated plates. Addition of excess soluble RGD (Arginine–Glycine–Aspartic acid) peptides leads to:
A) Increased adhesion
B) Differentiation into osteoblasts
C) Increased proliferation
D) Cell detachment and rounding
17. What triggers the closure of gap junctions in damaged cells?
A) Increased pH and decreased Ca²⁺
B) Decreased pH and protein influx
C) Decreased Ca²⁺ levels
D) Increased Ca²⁺ and decreased pH
18. Which molecules form the core structure of the basal lamina?
A) Type I collagen, elastin, hyaluronan
B) Type IV collagen, laminin, nidogen, perlecan
C) Fibronectin, type II collagen, decorin
D) Cadherin, β-catenin, actin
19. During focal adhesion maturation, which event occurs?
A) Talin unfolds under tension
B) Integrins are cleaved to increase adhesion
C) Actin filaments disassemble under tension
D) Cadherins change binding specificity
20. How does the clearance of acetylcholine differ from that of dopamine?
A) Acetylcholine is removed by reuptake, whereas dopamine is degraded enzymatically.
B) Acetylcholine is degraded enzymatically, whereas dopamine is removed by reuptake.
C) Acetylcholine is cleared by glial cells, whereas dopamine is not cleared by glial cells.
D) Acetylcholine diffuses away from the synapse, whereas dopamine is degraded postsynaptically.
21. Botulinum and tetanus toxins block neurotransmission by:
A) Blocking postsynaptic receptors
B) Activating acetylcholinesterase
C) Inhibiting Ca²⁺ channels
D) Cleaving SNARE proteins
22. Which protein acts as the primary Ca²⁺ sensor for fast neurotransmitter release?
A) Calmodulin
B) Synapsin
C) Synaptotagmin-1
D) Complexin
23. Which statements about integrins are correct?
I – Integrins are covalently linked α and β subunits
II – Integrins bind carbohydrates on Extracellular Matrix proteins
III – Ligand binding site is formed between α and β domains in αI-less integrins
IV – Integrins mediate both inside-out and outside-in signalling
A) I and II
B) II and IV
C) III, and IV
D) I, III and IV
24. Assertion (A): The bone marrow microenvironment regulates hematopoietic stem cell (HSC) quiescence and mobilisation.
Reason (R): Osteoblasts and perivascular stromal cells secrete factors such as CXCL12 that bind CXCR4 on HSCs to maintain quiescence.
A) Both A and R are correct, and R explains A
B) Both A and R are correct, but R does not explain A
C) A is correct, but R is incorrect
D) A is incorrect, but R is correct
25. Assertion (A): Tight junctions are essential for directional transport of glucose in epithelial cells.
Reason (R): Tight junctions prevent mixing of apical and basolateral membrane proteins.
A) Both A and R are correct, and R explains A
B) Both A and R are correct, but R does not explain A
C) A is correct, but R is incorrect
D) A is incorrect, but R is correct
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References
- Nelson, David L. & Cox, Michael M. (2021). Lehninger Principles of Biochemistry, W. H. Freeman, 8th Edition.
- Willey, J. M., Sandman, K. M., & Wood, D. H. (2022). Prescott’s Microbiology, McGraw-Hill, 12th Edition
- Kuby, J., Kindt, T. J., Osborne, B. A., & Goldsby, R. A. (2019). Kuby Immunology, W. H. Freeman, 8th Edition.
- Alberts, B., Johnson, A., Lewis, J., Morgan, D., Raff, M., Roberts, K., & Walter, P. (2014). Molecular Biology of the Cell, Garland Science, 4th Edition.
- Geoffrey Cooper and Kenneth Adams (2022). The Cell: A Molecular Approach, Oxford University Press, 9th Edition
- Robert A Weinberg, Robert A. Weinberg (2006). The Biology of Cancer, Taylor & Francis, 1st Edition.
- Gupta, P.K. (2022). Cell and Molecular Biology, Rastogi Publications, 5th Edition.
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