Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

Identify a, b, c and d in the following table with reference to birth control?

Method	Example
a	Diaphragm
Female sterilisation	b
c	Saheli
d	Cut

Explain the relationship between CFC's and Ozone in the stratosphere.

How has the bacterium Bacillus thuringiensis helped us in controlling caterpillars of insect pests?

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.

Draw a labelled diagram of the lac operon system.

Why is the structure of an antibody molecule represented as H₂L₂. Name any two types of antibodies produced in a human body.

Write a note on fossil evidence. State the method by which age of fossils is calculated.

If the Tropical rainforest would have been from the present 6% areas of earth to 12% areas how would the biodiversity be affected by it? Explain with reason.

What is the significance of adding proteases at the time of isolation of genetic material (DNA).

When do the oogenesis and the spermatogenesis initiate in human females and males respectively?