Ans 1 . Rohan is a boy . So changes are
1. Physical changes = Height growing , growing up of Adam's apples ( heaviness in voice ) , beard and moustaches , Reddening of skin , growing hairs at pubic region , slight breast growth .
Ans 2 . (A - part) When ovum is fertilised ( in females ) zygote is formed .The zygote divides rapidly by mitosis as it move down slowly in the oviduct and forms a hollow balls of hundreds of cells . This hollow ball of cells , now called an embryo , sinks into the soft and thick lining of the uterus and get embedded in it .The embedding of embryo in the thick lining of uterus is called implantation . The Placenta provides all the necessary nutrients to the developing foetus . During the gestation period ( Period of Nine months ) the foetus grows to become a baby .
(B - Part ) If the fertilisation is not take place in the ovum , the thick and soft lining of the uterus breaks down .Since the thick and soft lining of the uterus contains a lot of blood vessels , so the breaking of the uterus lining alongwith other tissues . This blood and other tissues come out of vagina in the form of bleeding . This process is called menstrual flow or menstruation .