AIDS is caused by a virus named HIV. It can be transmitted from an infected person to a healthy person by following ways:
(i) Byinfected syringes
(ii) Byinfected mother to an infant.
(iii) By sexual contact with infected person.

During puberty, there is increase in the activity of sweat and sebaceous glands. This leads to increased sweating often resulting in body odour. The excess oil and sweat get collected in the tiny po~es of the skin, blocking them so that the bacteria can grow in it. This causes the formation of pimples and acne on the face of boys and girls at this time.

For personal hygiene an adolescent should have a bath at least once every day, because increased activity of sweat glands makes body smelly. If cleanliness is not maintained there can be bacterial infection. Girl should take special care of cleanliness during the time of menstrual flow.

Endocrine glands release hormones into the blood stream to reach a particular body part called target site.

During puberty, the secretion of sweat glands and sebaceous glands (Oil glands) increases. Many young people get acne and pimples on the face due to the increased activity of these glands in the skin.

Yes, animals also have hormones. In animals like frogs, thyroxine hormone has also role to play in reproduction as it controls metamorphosis i.e., conversion of larva into adult.

Sex of a baby is determined by the chromosomes which it receives from the male. Males have two types of gametes one with X-chromosome and other with Y-chromosome. If a sperm (gamete) with X-chromosome fertilizes the egg, the zygote would develop into female and if a sperm with Y-chromosome fertilizes the egg, the zygote would develop into male.

Adrenaline hormone maintains the correct balance of salts in the blood.

Some endocrine glands are thyroid pancreas and adrenals

XY

Adam's apple.

Insect hormones bring about metamorphosis in silk moth.

Y is the sex chromosome that determines the sex of baby.

No, this marriage is not legal as the marriageable age according to Indian law is 18 years for girls.

Oestrogen is the female hormone produced by ovaries that help in development of breasts/mammary glands.