Human Reproduction — BIOLOGY STD 12 Science — Question

A and B are two different cloning vectors in two different bacterial colonies cultured in chromogenic substrate. Bacterial colonies with cloning vector A were colourless, whereas those with B were blue coloured. Explain by giving reasons the cause of difference in colour that appeared.

Transgenic animals are the animals in which a foreign gene is expressed. Such animals can be used to study the fundamental biological process, phenomenon as well as for producing products useful for mankind. Give one example for each type.

Explain adaptive radiation. (Figure is not necessary)

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

Name two hormones that are constituents of contraceptive pills. Why do they have high and effective contraceptive value? Name a commonly prescribed non – steroidal oral pill.

Kanchan went to a garden and saw some flowers which were closed. She assumed that those flowers must be buds. But she was astonished to see that all the flowers of that plant were closed and none of them was open. She was confused and asked her queries to her teacher.

1. What do you think, are there any plants with closed flowers? Give an example.
2. Are such plants get pollinated? Explain.
3. What are such flowers/ plants called?
4. What values are shown by Kanchan?

Who propounded the Central Dogma principle and what is meant by it?

What are the functions of-

1. Methylated guanosine cap?
2. Poly-A 'tail' in a mature RNA?

What is a recombinant DNA? List its features. How do enzymes restriction endonuclease and DNA Ligase help its formation?

Name the important mammary gland secretions that help in resistance of the new born baby.