Cell injury and adaptation: extrinsic apoptosis: practice question

A Pathology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pathology · Cell injury and adaptation: extrinsic apoptosis

Sample item

Cytotoxic T cells induce apoptosis in a virus-infected hepatocyte by binding Fas on its surface. Which adaptor protein recruited to the receptor's death domain directly activates caspase-8?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. FADD

Fas ligand binding trimerises Fas, which recruits the adaptor FADD through death domains. FADD then binds procaspase-8, whose activation starts the caspase cascade of the extrinsic pathway. Apaf-1 and cytochrome c belong to the intrinsic mitochondrial route.

Option by option

  • A. FADD (correct)

    Correct. FADD links the death receptor to procaspase-8.

  • B. Apaf-1

    Apaf-1 forms the apoptosome with cytochrome c and activates caspase-9 in the intrinsic pathway.

  • C. Cytochrome c

    Cytochrome c is released from mitochondria in the intrinsic pathway.

  • D. Bcl-xL

    Bcl-xL is an anti-apoptotic protein that guards the mitochondrial membrane.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More Pathology questions

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is A, FADD. Fas ligand binding trimerises Fas, which recruits the adaptor FADD through death domains.

Why is "Apaf-1" not the answer?

Apaf-1 forms the apoptosome with cytochrome c and activates caspase-9 in the intrinsic pathway.

Why is "Cytochrome c" not the answer?

Cytochrome c is released from mitochondria in the intrinsic pathway.

Why is "Bcl-xL" not the answer?

Bcl-xL is an anti-apoptotic protein that guards the mitochondrial membrane.

What concept does this question test?

It tests Cell injury and adaptation: extrinsic apoptosis in Pathology. FADD then binds procaspase-8, whose activation starts the caspase cascade of the extrinsic pathway. Apaf-1 and cytochrome c belong to the intrinsic mitochondrial route.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Cell injury and adaptation: extrinsic apoptosis?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.