Question

what are periods class 10. biology​

Answer 1

Explanation:

Menstruation: menstruation is when the thickened lining of the uterus (endometrium) leaves the body through the vagina. The lining of the uterus supplies a fertilised egg with nutrients, so if the egg isn't fertilised, then the lining is no longer needed.

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Answer 2

A period is the part of the menstrual cycle when a woman bleeds from her vagina for a few days. For most women this happens every 28 days or so, but it's common for periods to be more or less frequent than this, ranging from day 21 to day 40 of their menstrual cycle.