A textbook describes the events of a typical 28-day human menstrual cycle in a woman who does not become pregnant that month. Which statement correctly describes the sequence of events in this cycle?

IGCSE Biology 0610: The Sequence of Events in the Menstrual Cycle

Step 1: Recall the general pattern of the menstrual cycle

Across a typical 28-day cycle, the lining of the uterus and the release of an egg cell from an ovary follow a repeating pattern, even without naming the specific hormones involved.

Step 2: Place the key events in order

After menstrual bleeding ends, the lining of the uterus begins to thicken again, building up a blood-supplied lining. Roughly midway through the cycle, an egg cell is released from an ovary. This event is called ovulation. If this egg cell is not fertilised, there is no embryo to support, so the thickened lining is no longer maintained: it breaks down and is shed from the body as menstrual bleeding, and the whole cycle then begins again.

Step 3: Match this sequence to the options

Option A places these events in the correct order: lining thickens, ovulation occurs midway through the cycle, and (since the egg cell is not fertilised) the lining is later shed as menstruation, with the cycle then repeating.

Why the other options are wrong

B: ovulation does not happen at the same time as menstrual bleeding; it occurs roughly midway through the cycle, well after bleeding has stopped and the lining has begun to thicken.
C: the lining does thicken during the cycle before it is later shed; it is not shed “before it has thickened at all.”
D: ovulation is a single event occurring roughly once each cycle, not a continuous daily process, and menstrual bleeding is the shedding of the uterus lining, not the release of egg cells.

Final answer

Lining thickens after menstruation, an egg cell is released around the middle of the cycle, and (if unfertilised) the lining is later shed as the next period, option A.