(a) Name the three types of methods usually used for birth control. Describe each method briefly.
(b) What is meant by sexually transmitted diseases? Name any two sexually transmitted diseases and their causative organisms.
​(c) Which method of contraception can prevent sexually transmitted diseases?

(a) Three types of methods for birth control are -

• Barrier method: In this method, the fertilisation of the ovum and the sperm is prevented with the help of barriers such as a condom.
• Oral contraceptive method: In this method, tablets or drugs are taken orally to prevent fertilisation.
• Implants and surgical methods: Contraceptive devices, such as a loop and a copper-T rod, are placed in the uterus to prevent pregnancy. However, they can cause side effects to the uterus.

(b) Diseases that get transferred from one individual to another through sexual contact are called sexually-transmitted diseases.
Gonorrhoea - Neisseria gonorrhoeae
AIDS - Human immuno virus (HIV)

(c) The spread of sexually transmitted diseases can be prevented by using condoms and avoiding multiple partners.