A student claims, “In humans, ovulation always happens on day 14 of the menstrual cycle”. Critically examine this claim and state whether the claim is correct or not. Give at least two reasons for your answer.
The claim is incorrect. Ovulation does not always happen on day 14 of the menstrual cycle.
First, the length of the menstrual cycle varies in humans. The cycle repeats typically every 21–35 days, meaning the day of ovulation will shift depending on the individual's cycle length rather than being fixed at day 14. Second, a 28-day cycle is only described as often or typical, not a universal rule. Since cycle lengths differ among individuals, assuming ovulation always occurs on day 14 is inaccurate.
Explanation
The textbook context explicitly states that the menstrual cycle repeats typically every 21–35 days and is often around 28 days. This variation in cycle length directly contradicts the student's claim that ovulation 'always' happens on day 14. If a cycle is 21 days or 35 days, ovulation would not be on day 14.