Apoptosis and Cell Death Questions and Answers

Answer: B

Subtracting 131 from 1,090 leaves 959, which is the number of somatic cells in the adult hermaphrodite. The constancy of that figure is what made the lineage mappable at all. Every individual worm follows the same developmental script.

Answer: C

Correct answer: True

The pathway was worked out in Caenorhabditis elegans, where the genes ced-3, ced-4 and ced-9 control the death of exactly 131 cells during development, and each has a human counterpart - the caspases, Apaf-1 and Bcl-2 respectively. The conservation is what made a millimetre-long worm the route to understanding human apoptosis, and it earned the 2002 Nobel Prize.

Answer: D

Cells that detach from their proper place normally die, which helps keep them where they belong. Resisting it is one of the things a cancer cell must manage before it can metastasise. Detachment is normally a death sentence for an anchorage-dependent cell.

Answer: A

Both are true and the reason gives the obstacle: a tumour cell cannot travel and colonise a distant site while the ordinary response to detachment remains intact. Anoikis is one of several barriers a metastasising cell has to overcome.

Answer: B

Correct answer: can allow a starving cell to survive

Autophagy digests the cell’s own components in lysosomes and recycles the products, so under starvation it is a survival mechanism rather than a death programme - the cell consumes its least essential parts to keep going. It can contribute to death if it runs unchecked, but that is the exception; apoptosis, by contrast, always ends in the death of the cell.

Answer: C

It is chiefly a survival mechanism, recycling worn-out organelles and providing nutrients during starvation. Only in extreme or sustained form does it contribute to a cell's death. Whether it saves or kills depends on how far and how long it proceeds.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 describe the intrinsic pathway: mitochondria release cytochrome c into the cytosol, where it assembles the apoptosome and activates the caspases, and the Bcl-2 family - pro-apoptotic Bax and Bak against anti-apoptotic Bcl-2 and Bcl-xL - governs whether that release happens. Statement 3 belongs to the extrinsic pathway, in which a death ligand such as Fas binds a surface receptor. The two converge on the same executioner caspases.

Answer: A

Cutting a protein is a permanent change, unlike phosphorylation, so the cell cannot change its mind once the executioner caspases are active. That irreversibility is exactly why activation is so tightly controlled. Everything upstream of the caspases is a decision; everything downstream is execution.

Answer: B

Both are true and the reason gives the necessity: all the decision-making must happen before the point of no return, since nothing downstream of it can be recalled or corrected. The design places all the deliberation before the commitment.

Answer: C

Losing cells that cannot be replaced explains the progressive nature of these conditions. Cancer is the opposite failure, with cells surviving that should have died. The same process, misregulated in either direction, produces very different diseases.