Reproduction

Q2. What is the role of seminal vesicles and the prostate gland? 

Ans. Seminal vesicles and prostate gland help in the nutrition and mobility of sperms. 

Q4. Why does menstruation occur? 

Ans. Menstruation is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina.
It starts between puberty and lasts till menopause.
During this period, the body prepares itself for pregnancy.
Every month one of the ovaries releases an egg for fertilization.
When fertilization does not take place, the inner lining of the uterus gets ruptured and released through the vagina along with blood vessels and mucus. 

Q6. What could be the reasons for adopting contraceptive methods? 

Ans.
To prevent -
Unwanted pregnancy, and STDs (sexually transmitted diseases)