Quick revision note on reproduction.

1. REPRODUCTION IN ANIMALS
The production of new organisms from the existing organisms of the same species is known as
reproduction. There are two main methods of reproduction in living organisms -:
A. Asexual reproduction
B. Sexual reproduction
Asexual reproduction – In asexual reproduction new individual is produced from a
single parent. Sex organs or gametes are not involved.
Different types of asexual reproduction are - Fission, Fragmentation, Budding,
Regeneration, Spore formation and vegetative propagation.
B) Sexual reproduction – Sexual reproduction takes place by union of two types of sex
cells, i.e. male and female gametes. The male and female gametes unite to form a
‘zygote’. This zygote then develops into new organisms.
Sexual reproduction in plants- Flowers are the reproductive organs in higher plants.
Stamens are the male reproductive organs producing male gametes, while carpel is the
female reproductive part producing the female gamete or egg inside the ovule.
Reproduction in human being- The reproductive systems in humans develop and
function under the influence of certain chemicals called hormones. In males, sexual
maturity is attained at the age of 14- 16 years while in females, it is between 11-12
years. During this period certain changes takes place in both girls and boys.
Organs of male reproductive system are- A pair of testes, Epididymis, Vas deferens and
penis.
Organs of female reproductive system are - A pair of ovaries, Oviduct, uterus and
vegina.
 The male produces millions of sperms in is testes each day. The female produces
eggs in her ovaries.
 One egg cell is released from one of the ovary approximately every 28 days.
Fertilization in humans occurs in the oviducts. It is thus internal fertilization
Adolescence -:
Between the age of 11 and 14, the testes start to make sperms and the ovaries
start to make eggs. This time of development in life is called puberty.
Adolescence in humans is due to hormones secreted in the body. The pituitary
gland starts to make hormones. The rapid growth in adolescence is due to the
hormones secreted by the body. The two main types of hormones – sex
hormones and growth hormones – influence adolescent age in boys and girls.