When a fertilised egg E formed in the oviduct of a human female divides repeatedly to form an embryo, the embryo gets implanted in the thick and soft lining of the uterus. After this a disc-like special tissue T develops between the uterus wall and embryo through which all the requirements of the developing embryo (and foetus) are met from the mother's body. The embryo is connected to the tissue T through a string like structure S.

(a) What is the other name of fertilised egg cell E ?

(b) What is the name of tissue T ?

(c) Name the string-like structure S .

(d) Name two substances which pass from mother's blood to embryo through tissue T and, one type of substance which passes from embryo to mother's blood.

(e) What happens to S when the baby is born ? Why ?

When a human female reaches a certain age then vaginal bleeding occurs for a few days after regular time intervals.

(a) What is this process known as (i) in scientific terms, and (ii) in everyday language?

(b) At what approximate age this process starts in human females? What is the human female said to have attained at this stage ?

(c) After how much time is this process repeated? For how many days this process usually lasts?

(d) What does the onset of this process in human females signify?

(e) At which particular event in the life of a human female this process stops temporarily but starts again?

(f) At which approximate age of human female this process stops permanently ?

X and Y are two human beings. The organ A in the reproductive system of X releases a mature gamete B once a month which goes into a tube-like structure C through a funnel-like opening. The organ D in the reproductive system of Y makes and releases gametes E which pass through a duct F and are introduced by an organ of Y, into the body of X. B and E fuse together in C to form a new cell G. The cell G divides repeatedly to form a ball of cells H which gets embedded in the lining of organ I of reproductive system of X where it grows and develops into a baby.

(a) Name (i) organ A, and (ii) gamete B.

(b) Write two names of tube-like structure C.

(c) Name (i) organ D, and (ii) gamete E.

(d) Write two names of duct F.

(e) Name (i) cell G (ii) ball of cells H, and (iii) organ I.

(f) Out of X and Y, which one is (i) male, and (ii) female ?

When a female child is born, her ovaries already contain thousands of immature eggs (or ova) contained in immature structures A. On maturing, A bursts open and an egg shoots out of the ovary in a process called B. The process B starts in the females at puberty and occurs again and again after a time period x. Before every occurrence of process B, the inner lining of uterus becomes thick and soft with lots of blood vessels in it. When the egg cell gets fertilised by a sperm, then an event C occurs in the life of mature human female which lasts for time period y leading to the birth of baby. If, however, the egg cell released by the ova does not get a sperm to fuse with, then the thick and soft inner lining of uterus breaks down and comes out of the female's body in an event called D. The occurrence of event Dis controlled by chemical substances E

(a) What are A?

(b) What is process B?

(c) What is the time period x?

(d) Name the event C

(e) How much is the time period y?

(f) What is the name of process D?

(g) Name the chemical substances E

In the surgical method of birth control available for males, the structures A in the reproductive system are cut and ligated (tied up) at both ends. This prevents the reproductive cells B from coming out from the organs C where they are made in the male body. Since B cannot come out from the male body, they cannot fuse with cell D in the body of a female and hence pregnancy is prevented.

(a) What are structures A ?

(b) What are cells B?

(c) Name the organs C.

(d) What is cell D ?

(e) What is the name of this surgical procedure for birth control available to males?