Cell death signaling MCQs With Answer
Introduction: This question set is designed for M.Pharm students studying Advanced Pharmaceutical Biotechnology to deepen their understanding of regulated cell death mechanisms. The 20 multiple-choice questions focus on molecular pathways and regulatory checkpoints of apoptosis, necroptosis, pyroptosis and autophagy-related death, highlighting key proteins such as caspases, Bcl-2 family members, IAPs, RIP kinases, inflammasomes and gasdermins. Clinical and experimental implications — including small-molecule modulators, biochemical assays and therapeutic targets — are integrated to bridge basic signaling knowledge with translational pharmacology. Use these MCQs to assess comprehension and prepare for higher-level discussion and exam questions.
Q1. In the intrinsic (mitochondrial) apoptosis pathway, which event directly leads to apoptosome assembly?
- Release of Smac/DIABLO into the cytosol
- Translocation of Bax/Bak to the nucleus
- Release of cytochrome c from mitochondria into the cytosol
- Closure of the mitochondrial permeability transition pore (mPTP)
Correct Answer: Release of cytochrome c from mitochondria into the cytosol
Q2. Which Bcl-2 family proteins are primarily responsible for inducing mitochondrial outer membrane permeabilization (MOMP)?
- Anti‑apoptotic proteins such as Bcl-2 and Bcl-xL
- BH3-only sensitizers like Bad only
- Multidomain pro-apoptotic effectors Bax and Bak
- Inhibitor of apoptosis proteins (IAPs) such as XIAP
Correct Answer: Multidomain pro-apoptotic effectors Bax and Bak
Q3. Activation of which caspase is the key initiator in the extrinsic death receptor pathway leading to apoptotic execution?
- Caspase-3
- Caspase-8
- Caspase-9
- Caspase-1
Correct Answer: Caspase-8
Q4. Which molecular event explains how caspase-8 controls the choice between apoptosis and necroptosis?
- Caspase-8 phosphorylates MLKL to activate necroptosis
- Caspase-8 ubiquitinates RIPK1 to prevent signaling
- Caspase-8 cleaves and inactivates RIPK1 and RIPK3
- Caspase-8 directly activates gasdermin D
Correct Answer: Caspase-8 cleaves and inactivates RIPK1 and RIPK3
Q5. Which protein is the executioner that forms plasma membrane pores during pyroptosis following canonical inflammasome activation?
- MLKL
- AIF (Apoptosis-inducing factor)
- Gasdermin D (GSDMD)
- Cytochrome c
Correct Answer: Gasdermin D (GSDMD)
Q6. Which inflammasome sensor is most commonly associated with sensing diverse stress signals and activating caspase-1 in many inflammatory contexts?
- RIPK3
- NLRP3
- Fas (CD95)
- Atg5
Correct Answer: NLRP3
Q7. SMAC/DIABLO promotes apoptosis primarily by which mechanism?
- Direct activation of Bax and Bak oligomerization
- Neutralizing inhibitor of apoptosis proteins (IAPs) to permit caspase activation
- Blocking cytochrome c release from mitochondria
- Inhibiting caspase-8 activation at the DISC
Correct Answer: Neutralizing inhibitor of apoptosis proteins (IAPs) to permit caspase activation
Q8. Which assay combination best distinguishes early apoptosis from late apoptosis/necrosis in cultured cells?
- TUNEL assay alone
- Annexin V positive / Propidium iodide negative vs Annexin V positive / Propidium iodide positive
- Measuring ATP levels only
- Western blot for LC3-II only
Correct Answer: Annexin V positive / Propidium iodide negative vs Annexin V positive / Propidium iodide positive
Q9. Which small molecule is a selective inhibitor of RIPK1 kinase activity used to block necroptosis in experimental systems?
- zVAD-fmk
- Necrostatin-1
- MCC950
- Venetoclax
Correct Answer: Necrostatin-1
Q10. Which transcriptional target of p53 directly promotes mitochondrial apoptosis by antagonizing anti-apoptotic Bcl-2 proteins?
- Mdm2
- PUMA (p53 upregulated modulator of apoptosis)
- FLIP
- XIAP
Correct Answer: PUMA (p53 upregulated modulator of apoptosis)
Q11. Caspase-3 cleaves Poly (ADP-ribose) polymerase (PARP) during apoptosis. What is the functional consequence of PARP cleavage?
- Enhanced DNA repair and cell survival
- Loss of PARP enzymatic activity contributing to DNA fragmentation and energy preservation
- Activation of necroptotic signaling via RIPK3
- Direct inhibition of apoptosome formation
Correct Answer: Loss of PARP enzymatic activity contributing to DNA fragmentation and energy preservation
Q12. Which statement best describes the role of cFLIP within death receptor signaling?
- cFLIP is a mitochondrial pore-forming protein causing cytochrome c release
- cFLIP mimics caspase-8 structure and inhibits its activation at the DISC
- cFLIP ubiquitinates TNF receptor to enhance signaling
- cFLIP phosphorylates RIPK1 to induce necroptosis
Correct Answer: cFLIP mimics caspase-8 structure and inhibits its activation at the DISC
Q13. Which of the following best distinguishes regulated necrosis (necroptosis) from accidental necrosis?
- Necroptosis requires mitochondrial cytochrome c release.
- Necroptosis is an ATP-independent passive process.
- Necroptosis is a programmed process mediated by defined signaling molecules such as RIPK1, RIPK3 and MLKL.
- Necroptosis is inhibited by activation of gasdermin D.
Correct Answer: Necroptosis is a programmed process mediated by defined signaling molecules such as RIPK1, RIPK3 and MLKL.
Q14. Which molecular event is essential for MLKL to execute plasma membrane disruption during necroptosis?
- Ubiquitination of MLKL by cIAPs
- Phosphorylation of MLKL by RIPK3 leading to MLKL oligomerization and membrane translocation
- Cleavage of MLKL by caspase-3
- Binding of MLKL to mitochondrial cardiolipin
Correct Answer: Phosphorylation of MLKL by RIPK3 leading to MLKL oligomerization and membrane translocation
Q15. In the context of endoplasmic reticulum (ER) stress, which UPR branch primarily mediates CHOP induction and pro-apoptotic signaling?
- IRE1α → XBP1s splicing only
- PERK → eIF2α phosphorylation leading to ATF4 and CHOP induction
- ATG7-dependent autophagy activation
- ATF6 cleavage leading exclusively to autophagy
Correct Answer: PERK → eIF2α phosphorylation leading to ATF4 and CHOP induction
Q16. Which therapeutic agent is a BH3-mimetic used clinically to antagonize Bcl-2 and induce apoptosis in certain hematological malignancies?
- MCC950
- Venetoclax
- Necrostatin-1
- zVAD-fmk
Correct Answer: Venetoclax
Q17. Which caspase is primarily involved in canonical inflammatory cytokine maturation (IL-1β and IL-18) downstream of inflammasome activation?
- Caspase-3
- Caspase-8
- Caspase-1
- Caspase-9
Correct Answer: Caspase-1
Q18. Which experimental readout specifically measures mitochondrial outer membrane permeabilization (MOMP) rather than downstream caspase activation?
- Cleavage of PARP detected by Western blot
- Release of cytochrome c from mitochondria to cytosol detected by subcellular fractionation
- Annexin V staining only
- Measurement of caspase-3 activity with fluorogenic substrate
Correct Answer: Release of cytochrome c from mitochondria to cytosol detected by subcellular fractionation
Q19. Which post-translational modification of RIPK1 is critical for suppressing its pro-death signaling in the TNF receptor complex I?
- Phosphorylation by caspase-8
- K63-linked ubiquitination by cIAPs
- Sumoylation by SUMO1 exclusively
- Acetylation at the BH3 domain
Correct Answer: K63-linked ubiquitination by cIAPs
Q20. Which mechanism explains how SMAC mimetics can sensitize cancer cells to TNFα-induced cell death?
- SMAC mimetics increase Bcl-2 expression to promote apoptosis
- SMAC mimetics stabilize XIAP to block caspases
- SMAC mimetics promote degradation of cIAPs, altering TNF signaling to favor cell death
- SMAC mimetics directly inhibit MLKL phosphorylation
Correct Answer: SMAC mimetics promote degradation of cIAPs, altering TNF signaling to favor cell death
