Blood and immunity: platelet dense granules: practice question

A Physiology 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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Physiology · Blood and immunity: platelet dense granules

Sample item

A child with easy bruising and nosebleeds has a normal platelet count and a prolonged bleeding time. Aggregometry shows absent second-wave aggregation with epinephrine, and electron microscopy shows platelets lacking dense bodies. Which released substance is deficient?

AADP, which normally amplifies aggregationBFibrinogen stored in alpha granulesCVon Willebrand factor stored in alpha granulesDPlatelet-derived growth factor stored in alpha granules

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

The answer and the reasoning

A. ADP, which normally amplifies aggregation

Dense granules store ADP, ATP, calcium and serotonin. Release of ADP recruits more platelets and produces the second wave of aggregation, so storage pool deficiency gives a prolonged bleeding time with a normal count. Fibrinogen, von Willebrand factor and growth factors are held in alpha granules.

Option by option

A. ADP, which normally amplifies aggregation (correct)
Correct. Dense granule ADP release amplifies aggregation and its absence removes the second wave.
B. Fibrinogen stored in alpha granules
Fibrinogen is an alpha granule product, and these platelets lack dense bodies.
C. Von Willebrand factor stored in alpha granules
Von Willebrand factor is stored in alpha granules, not dense bodies.
D. Platelet-derived growth factor stored in alpha granules
Platelet-derived growth factor is an alpha granule product.

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.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is A, ADP, which normally amplifies aggregation. Dense granules store ADP, ATP, calcium and serotonin.

Why is "Fibrinogen stored in alpha granules" not the answer?

Fibrinogen is an alpha granule product, and these platelets lack dense bodies.

Why is "Von Willebrand factor stored in alpha granules" not the answer?

Von Willebrand factor is stored in alpha granules, not dense bodies.

Why is "Platelet-derived growth factor stored in alpha granules" not the answer?

Platelet-derived growth factor is an alpha granule product.

What concept does this question test?

It tests Blood and immunity: platelet dense granules in Physiology. Release of ADP recruits more platelets and produces the second wave of aggregation, so storage pool deficiency gives a prolonged bleeding time with a normal count. Fibrinogen, von Willebrand factor and growth factors are held in alpha granules.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Blood and immunity: platelet dense granules?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.