Question

Assertion: Melatonin influences the menstrual cycle, pigmentation and defense capability.
Reason: It plays an important role in the regulation of diurnal rhythm of our body.

Answer 1

The correct answer is (b) both Assertion and reason are true but reason is not the correct explanation of asssertion.
Melatonin concentration in the blood appears to follow a diurnal cycle as it rises in the evening and through the night and drops to a low around noon. Because of this light mediated response, the pineal gland may act as a kind of 'biological clock' which may produce circadian rhythms. In addition, melatonin also influences metabolism, pigmentation, the menstrual cycle as well as our defence capability.