COMPETITIVE EXAM MCQs SERIES of LIFE SCIENCES for CSIR-UGC NET/JRF, SLET, GATE, and other entrance tests: CELL COMMUNICATION AND CELL SIGNALING – Host-Parasite Interactions and Signalling.
Syllabus Outline
- Recognition and entry processes of different pathogens, like bacteria and viruses, into animal and plant host cells.
- Alteration of host cell behaviour by pathogens.
- Virus-induced cell transformation.
- Pathogen-induced diseases in animals and plants.
- Cell-cell fusion in normal and abnormal cells.
This quiz contains concept-based, most frequently asked 25 MCQs of “CELL COMMUNICATION AND CELL SIGNALING – Host-Parasite Interactions and Signalling”. Each question has a single correct/most appropriate answer.
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1. Parasite-induced modulation of cytokine signalling often results in:
A) Enhanced host immune clearance
B) Inhibition of DNA repair mechanisms
C) Decrease host metabolism
D) Suppression of host immune responses
2. Which of the following best describes changes in cells undergoing oncogenic transformation in vitro?
A) Increased contact inhibition and higher serum requirement
B) Elongated morphology with reduced nutrient uptake
C) Loss of contact inhibition and expression of tumour antigens
D) Permanent G0 arrest with cytoplasmic enlargement
3. What happens when mouse L cells are treated with interferon before infection with vesicular stomatitis virus?
A) Productive infection with cell death
B) Abortive infection due to inhibition of protein synthesis
C) Persistent infection without cytopathic effects
D) Viral genome integrates into host DNA
4. Which viral families can transform cells while maintaining their DNA in an episomal (non-integrated) state?
A) Retroviridae and Flaviviridae
B) Adenoviridae and Parvoviridae
C) Poxviridae and Picornaviridae
D) Papillomaviridae and Herpesviridae
5. In studies comparing myoblast and macrophage fusion, which mechanism is conserved across both cell types?
A) Both rely only on Brag2-mediated ARF6 activation
B) Dock180 is required for fusion in both cell types
C) Macrophages use Myomaker, while myoblasts use Syncytin-2
D) ARF6 inhibition stabilizes paxillin–β1-integrin interaction
6. Comparing viral entry and mammalian cell fusion, which statement is correct?
A) Viral fusion is heterotypic, while myoblast fusion requires fusogens on both cells
B) Both processes are strictly homotypic
C) Mammalian fusion mainly depends on extracellular matrix degradation
D) Viral fusion uses host SNARE proteins instead of viral proteins
7. Which group of proteins forms a conserved superfamily of eukaryotic fusogens across species?
A) Internalins
B) Syncytins
C) Fusexins
D) Integrins
8. After entry into epithelial cells, what happens to Listeria monocytogenes?
A) It remains inside endosomes permanently
B) It escapes the endosome and replicates in the cytoplasm
C) It induces apoptosis from within the endosome
D) It is transported across the cell and releases Listeriolysin O into the bloodstream
9. Which structure helps Salmonella Typhi evade immune detection and resist macrophage killing?
A) Vi antigen capsule
B) T3SS translocon
C) Outer membrane vesicles
D) Flagellin
10. How does the Dengue virus type-2 NS1 protein contribute to lung damage?
A) It inhibits protein synthesis in lung epithelial cells
B) It induces apoptosis in lung epithelial cells
C) It silences p53 expression in lung epithelial cells
D) It integrates into the DNA of lung epithelial cells
11. Which mechanism allows intracellular pathogens to evade host immunity?
A) Integration of virulence genes into host DNA
B) Inducing syncytia using viral proteins
C) Manipulating autophagy and macrophage polarisation
D) Using host nuclear transport systems
12. Why can some pathogens (e.g., Pseudomonas aeruginosa) infect both plants and animals?
A) Both have identical MHC systems
B) Both have identical cell walls
C) Pathogens target conserved cellular processes
D) Rapid genome recombination with eukaryotic host DNA
13. Agrobacterium tumefaciens begins infection by activating its virulence (vir) genes. Which condition and interaction correctly describe this initial step?
A) Indole acetic acid activates VirG in alkaline conditions
B) ChvE enhances VirA sensitivity to acetosyringone under acidic conditions
C) VirC proteins bind double-stranded T-DNA for direct transfer
D) Ros protein degrades the ChvG/ChvI system to activate vir genes
14. How do plants biochemically defend against early Agrobacterium infection?
A) Degrade the VirB2 pilus using proteases
B) Produce high levels of IAA that inhibit VirA activation
C) Secrete VIP1 to bind acetosyringone outside the cell
D) Reduce microRNAs to degrade bacterial proteins
15. Which mechanism is commonly used by parasites to manipulate host cell signalling pathways?
A) DNA mutation in the host nucleus
B) Blocking ATP synthesis in host cells
C) Destruction of host receptors
D) Secretion of effector proteins
16. Which epigenetic mechanism restricts T-DNA integration in plants?
A) Accumulation of H3K27me3 leading to condensed chromatin
B) Genome-wide DNA hypomethylation
C) Degradation of histone H2A
D) Telomere hyperacetylation
17. What is the natural function of the plant protein VIP1?
A) Regulates stomatal closure
B) Functions in stress and defence signalling
C) Forms part of the chloroplast membrane
D) Acts as an RNA silencing molecule
18. Where does gamete fusion occur in the Plasmodium life cycle?
A) Human red blood cells
B) Human liver cells
C) Mosquito midgut
D) Mosquito salivary glands
19. What enables infected red blood cells to adhere to blood vessel walls in Plasmodium falciparum infection?
A) Syncytin-mediated fusion
B) Export of parasite proteins to the RBC surface
C) Type III secretion system
D) E-cadherin expression by RBCs
20. How does Plasmodium falciparum survive inside red blood cells?
A) Lives freely in the cytoplasm and uses the host mitochondria
B) Resides in a parasitophorous vacuole
C) Causes immediate RBC rupture
D) Forms syncytia with other RBCs
21. How do viroids replicate and cause disease?
A) Use reverse transcription and integrate into host DNA
B) Replicate using their own RNA polymerase
C) Use host RNA polymerase and disrupt host processes
D) Use reverse transcription and inhibit host translation by blocking ribosomes
22. How do fungal pathogens use small RNAs to manipulate plant cells?
A) Integrate into chloroplast DNA
B) Alter splicing of all Nucleotide-binding Leucine-rich Repeat (NLR) genes
C) Enter host cells and silence immunity-related genes
D) Activate immune receptors directly
23. What role do host small RNAs play in regulating plant genes that encode proteins responsible for recognising pathogen attack and activating defence responses (R gene) expression?
A) Block pathogen secretion systems
B) Replace the plant genome
C) Through negative feedback
D) Act as membrane receptors
24. Which of the following statements about cytocidal viruses and host DNA is correct?
I – Poxviruses degrade host DNA to support cytoplasmic replication.
II – Herpesviruses cause chromatin to move toward the nuclear periphery.
III – Rhabdoviruses stimulate host DNA synthesis for RNA transcription.
A) I and II only
B) I and III only
C) II and III only
D) I, II and III
25. Assertion (A): Transformation by DNA viruses usually occurs in nonpermissive cells or during abortive infection.
Reason (R): DNA viruses typically kill host cells during productive replication, making long-term cell survival incompatible with viral production.
A) Both A and R are true, and R correctly explains A
B) Both A and R are true, but R does not explain A
C) A is true, but R is false
D) A is false, but R is true
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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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