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

How do microbes reduce the environmental degradation caused by chemicals?

Draw a labelled diagram of dicot embryo.

State the causes of cancer.

Put these statements in the proper order, by rearranging the letters, to describe Darwin's theory of natural selection-

1. The end result of organic evolution is many different species, each adapted to specific environments.
2. Many more individuals are produced each generation that can survive and reproduce.
3. Gradually, over long periods of time, a population can become well adapted to a particular environment.
4. There are inheritable variation among the members of a population.
5. Individuals with adaptive characteristics are more likely to be selected to reproduce by the environment.

Why is the frequency of red-green colour blindness is many times higher in males than that in the females?

Select two pairs from the following which exhibit divergent evolution. Give reasons for your answer.

1. Forelimbs of cheetah and mammals.
2. Flippers of dolphins and penguins.
3. Wings of butterflies and birds.
4. Forelimbs of whales and mammals.

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 by a dwarf plant bearing white flowers, the different phenotypic groups were obtained in the progeny.
Tall, Red = 138
Tall, White = 132
Dwarf, Red = 136
Dwarf, White= 128
Mention the genotypes of the two parents and of the types of four off springs. in numbers mentioned against them.

How LABs are useful to us explain.###Give a brief account on importance of lactobacillus bacteria in house hold products.

After a brief medical examination a healthy couple came to know that both of them are unable to produce functional gametes and should look for an 'ART' (Assisted Reproductive Technique). Name the 'ART' and the procedure involved that you can suggest to them to help them bear a child.

Mention two strategies evolved to prevent self-pollination in flowers.