CBSE Class 10 Science 2019 · Paper 31/3/1 · Question 18(b)

(a) Sexually transmitted diseases (STDs) are diseases that are transmitted from an infected person to a healthy person through sexual contact. Viral STDs: AIDS (caused by HIV) and warts. Bacterial STDs: gonorrhoea and syphilis. (b) Contraception is the deliberate prevention of pregnancy (of unwanted pregnancies) by using contraceptive methods. Reasons for adopting contraceptive methods: (1) to prevent unwanted pregnancies; (2) to keep a proper gap between successive births, for the better health of the mother; (3) to control the rise in population (birth rate). Preventing the transmission of STDs (by barrier methods) is also an accepted reason, as is any other correct one.