Human Reproduction — BIOLOGY STD 12 Science — Question

Where is an 'operator' located in a prokaryote DNA? How does an operator regulate gene expression at transcriptional level in a prokaryote? Explain.

Name the hormone that maintains the functions of male accessory ducts and glands.

Match Column I with Column II.

S. No.	Column I	S. No.	Column II
A.	Cleavage	1.	Outer layer of the blastocyst that attaches to the endometrium during implantation.
B.	Implantation	2.	Mitotic divisions of the zygote in quick succession.
C.	Inner cell mass	3.	Embedding of the blastocyst in the endometrium of uterus.
D.	Trophoblast	4.	Release of secondary oocyte from the ovary.
E.		5.	Group of cells attached to one end of trophoblast that differentiate into embryo proper.

One of the twins born to parents having normal colour vision was colour blind whereas the other twin had normal vision. Work out the cross. Give two reasons how it is possible.

Explain the primary productivity of ecosystem.

Name and explain the surgical method advised to human males and females as a means of birth control. Mention its one advantage and one disadvantage.

A large number of married couples the world over are childless. It is shocking to know that in India the female partner is often blamed for the couple being childless.
Suggest a technique that can help the couple to have a child where the problem is with the male partner.

The blood group of a man is A and his wife has the blood group O. Which blood group will the children not have? Justify your answer also.

Generally, it is observed that human males suffer from hemophilia more than human females, who rarely suffer from it. Explain giving reasons.