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← Theoretical 1

Q7 — Apoptosis — p53/Bax/Bcl-2 Pathway Under Hypoxia

Theoretical 1 Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license
Cell Junctions, Extracellular Matrix & Cell Death

Hypoxia is a hallmark of solid tumors and plays a critical role in different steps of tumor progression. To develop an effective treatment against malignant tumors, it is important to understand how cancer cells that develop under hypoxic conditions avoid apoptosis. The figure shows the mechanism of apoptosis.

Pathway diagram: Hypoxia inhibits p53, p53 promotes Bax (opposed by Bcl-2), Bax triggers mitochondrial cytochrome c release, activating Apaf-1/Caspase 9, then Caspase 3/7, leading to apoptosis. Mechanism of apoptosis. p53 protein promotes the expression of Bax and its translocation from cytosol to mitochondria, which leads to mitochondrial protein cytochrome C release to the cytoplasm, activating the caspase cascade.

Using the information and figure, determine whether the following statements are true or false:

A. Hypoxia in cancer cells suppresses apoptosis.
B. Upon Bcl-2 overexpression, the integrity of the mitochondrial membranes is preserved, which in return prevents apoptosis.
C. It is necessary to suppress p53 to ensure the apoptosis of cancer cells.
D. Deficiency of Bax protein promotes apoptosis.
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Question reproduced from IBO 2022, Theoretical Paper 1, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)