8 th Science: Chapter: Reproduction and Reaching of adolescence 1. How are human twins produced? Ans: There are two way twins are formed. (a) Twins occur when a single egg is fertilized to form one zygote which then divides into two separate embryos.(b) Twins occur when two separate eggs are fertilized by two separate sperm. 2. Whose sex chromosomes is responsible for sex of unborn baby, either father’s or mother’s sex hormones. Ans: The sex chromosomes of the father determine the sex of an unborn baby. 3. Why ace and pimple appear in adolescent age of human being? Ans: This is because during puberty the secretion of sweat glands and sebaceous glands (oil glands) increases in the skin. 4. What is Adam’s apple? At puberty, the voice box or the larynx begins to grow. The growing voice box in boys can be seen as bump in the throat called Adam’s apple. 5. Why does reproductive age of women starts from menarche and end at menopause? Women start producing...
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