Feedback inhibition at the committed step
In the pathway A → B → C → D, intermediate B also feeds a second pathway. The end product D most efficiently controls its own synthesis by inhibiting which step?
Answer D: explanation for every choice
A
Inhibiting A → B would also block the second pathway that needs B.
B
Inhibiting the last step would let intermediates such as C accumulate.
C
End products typically inhibit, not activate, their own synthesis.
D
Correct. B → C is the first committed step toward D. Inhibiting it stops D production without starving the other pathway of B.
TakeawayEnd products usually inhibit the first committed step of their own branch.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb32.