Rohan studies in class 8.He experiences certain physical and emotional changes in himself. He is very confused. His father observes the changes in Rohan and guides him on the natural changes common to all adolecents.

Que1. What type of changes do you think Rohan is experiencing?
Que2. What happens to the ovum when it is (a) fertilised (b) not fertilised in the fallopian tube?



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 .  
rohan will be about 12 to 14 years old and this age is called puberty.rohan was experiencing those changes which a male usually face during his ages of grows on the pubic region , perspiration increases, muscle developes etc.

ques 2=a)the formation of zygote takes place.

b)the lining of the uterus breaks down.