Question 1 Name the male and female gamete in humans?
Question 2 What is a zygote?
Question 3 Define the term fertilisation?
Question 4 What is an embryo?
Question 5 What is an internal fertilisation?
Question 6 How does fertilisation take place in humans?
Question 7 What is the average duration of human pregnancy?
Reproduction in human beings
The male gamete or sex cell is called sperm (it has long tail, motile and can move independently).
The female gamete or sex cell is called ovum or egg (It contains water, stored food and nucleus).
Fusion of egg and sperm give rise to a single cell called ZYGOTE.
The fusion of male gamete with female gamete to form a zygote during sexual reproduction is called fertilisation.
The zygote grows and develops to form a new baby .The stage of development between zygote and newly formed baby is called embryo.
The fertilisation which occur inside the female body is called internal fertilisation.
During internal fertilisation, male put his sperm inside a women body through an organ called penis. These sperms then fertilise the egg inside the woman’s body.
The fertilisation which occur outside the female body is called external fertilisation.
For Example : Frogs, Toads, Fishes.
The male and female animal releases their sperm and egg in water where fertilisation take place by collision between them.
(1) Sperms made in testes are introduced into vagina of woman through penis during mating. Million of sperms are released into the vagina at one time. The sperms are highly active and mobile. The sperm move up through cervix into uterus. From uterus, sperms pass into oviduct.
(2) One of the oviduct contain egg released by the ovary during ovulation. Only one sperm fuses with the egg in oviduct to form Zygote. The fertilisation of egg take place in oviduct.
(3) The zygote divides rapidly by mitosis as it moves down slowly in oviduct and form a hollow ball of hundred of cells(embryo).The embryo sinks into soft and thick lining of uterus and get embedded in it. The embedding of embryo in the thick lining of uterus is called implantation.
(4) After implantation a disc like special tissue develops between uterus wall and embryo or foetus called placenta. The foetus is connected to placenta in mother body through umbilical cord.
The exchange of nutrients, oxygen, waste products between embryo and mother take place through the placenta. The time period from fertilisation up to birth of baby is called gestation(9 months)
The baby is born as a result of rhythmic contraction of muscles in uterus.