Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

DNA being hydrophilic, cannot pass through the cell membrane of a host cell. Explain how the recombinant DNA gets introduced into the host cellto transform the latter.

1. Write the desirable characters a farmer looks for in his sugarcane crop.
2. How did plant breeding techniques help north Indian farmers to develop cane with desired characters?

In peas, tallness is dominant over dwarfness, and red colour of flowers is dominant over the white colour. When a tall plant bearing red flowers was pollinated with a dwarf plant bearing white flowers, the different phenotypic groups were obtained in the progeny in numbers mentioned against them:
Tall, Red = 138
Tall, White = 132
Dwarf, Red = 136
Dwarf, White = 128
Mention the genotypes of the two parents and of the four offspring types.

Why didn’t natural selection lead to the evolution of such totally harmless parasites?

By the end of 2002 the public transport of Delhi switched over to a new fuel. Name the fuel. Why is this fuel considered better? Explain.

It is commonly observed that parents feel embarrassed to discuss freely with their adolescent children about sexuality and reproduction. The result of this parental inhibition is that the children go astray sometimes.

1. Explain the reasons that you feel are behind such embarrassment amongst some parents to freely discuss such issues with their growing children.
2. By taking one example of a local plant and animal, how would you help these parents to overcome such inhibitions about reproduction and sexuality?

What is the main idea behind “Joint Forest Management Concept” introduced by the Government of India?

Sketch and label T. S. of angiospermic anther.

Medically it is advised to all young mothers that breastfeeding is the best for their newborn babies. Do you agree? Give reasons in support of your answer.

Give functions : Meninges and CSF.