Evolution — BIOLOGY STD 12 Science — Question

Explain giving three reasons why tropics show, greatest level of species diversity.

Why do we experience shivering during winters when the temperature is very low?

Give two examples of biogeographical evidence in favour of evolution.

A, B, D are three independently assorting genes with their recessive alleles a, b, d, respectively. A cross was made between individuals of Aa bb DD genotype with aa bb dd. Find out the type of genotypes of the offspring produced.

Define the following and give one example of each (a) False fruit, (b) True fruit, (c) Parthenocarpic fruit, (d) Polyembryony.

Two independent monohybrid crosses were carried out involving a tall pea plant with a dwarf pea plant. In the first cross, the offspring population had equal number of tall and dwarf plants, whereas in the second cross it was different. Work out the crosses, and explain giving reasons for the difference in the offspring populations.

OR

Work out a cross to find the genotype of a tall pea plant. Name the type of cross.

The microscopic pollen grains of the past are obtained as fossils. Which compound makes this possible?

Why is a person with cuts and bruises following an accident administered tetanus antitoxin? Give reasons.

OR

Why does a doctor administer tetanus antitoxoid and not a tetanus vaccine to a child injured in a roadside accident with a bleeding wound? Explain.

Described the two-two functions of testis and ovary.

Give information about cocaine drug.