Reproduction: combined oral contraceptive: 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 · Reproduction: combined oral contraceptive

Sample item

A combined oral contraceptive pill prevents pregnancy chiefly by which mechanism?

ABlocking the acrosome reaction so that sperm cannot penetrate the zonaBProvoking an early LH surge so the follicle luteinises before the egg maturesCNegative feedback by oestrogen and progestin suppressing GnRH, FSH and the LH surge, so ovulation does not occurDRaising FSH to cause multiple follicles to ovulate at once

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

The answer and the reasoning

C. Negative feedback by oestrogen and progestin suppressing GnRH, FSH and the LH surge, so ovulation does not occur

The steady exogenous oestrogen and progestin lower GnRH pulsatility and pituitary gonadotrophin output. Follicular development stalls and no mid-cycle LH surge occurs, so ovulation is prevented. Thickened cervical mucus and a thin endometrium add to the contraceptive effect.

Option by option

A. Blocking the acrosome reaction so that sperm cannot penetrate the zona
The pill acts through the female hormonal axis and does not block the acrosome reaction.
B. Provoking an early LH surge so the follicle luteinises before the egg matures
The pill suppresses rather than provokes the LH surge.
C. Negative feedback by oestrogen and progestin suppressing GnRH, FSH and the LH surge, so ovulation does not occur (correct)
Suppression of gonadotrophins and the LH surge is the principal action.
D. Raising FSH to cause multiple follicles to ovulate at once
FSH is suppressed, not raised; stimulating FSH is the effect of ovulation-induction drugs.

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 C, Negative feedback by oestrogen and progestin suppressing GnRH, FSH and the LH surge, so ovulation does not occur. The steady exogenous oestrogen and progestin lower GnRH pulsatility and pituitary gonadotrophin output.

Why is "Blocking the acrosome reaction so that sperm cannot penetrate the zona" not the answer?

The pill acts through the female hormonal axis and does not block the acrosome reaction.

Why is "Provoking an early LH surge so the follicle luteinises before the egg…" not the answer?

The pill suppresses rather than provokes the LH surge.

Why is "Raising FSH to cause multiple follicles to ovulate at once" not the answer?

FSH is suppressed, not raised; stimulating FSH is the effect of ovulation-induction drugs.

What concept does this question test?

It tests Reproduction: combined oral contraceptive in Physiology. Follicular development stalls and no mid-cycle LH surge occurs, so ovulation is prevented. Thickened cervical mucus and a thin endometrium add to the contraceptive effect.

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 Reproduction: combined oral contraceptive?

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.