Human Reproduction — BIOLOGY STD 12 Science — Question

Why does the 'insertional inactivation' method to detect recombinant DNA is preferred to 'antibiotic resistance' procedure?

Indiscriminate human activities such as alien species invasion, fragmentation and habitat loss have accelerated the loss of biodiversity. Justify by taking one example for each.

Taking the example of white-winged moths and dark-winged moths of England in pre and postindustrialised era, explain evolution by natural selection.

OR

How can evolution by natural selection be explained by melanised moths before and after industrialisation in England?

OR

How did industrialisation play a role in Natural Selection of light and dark-coloured moth in England?

OR

What do these pictures (a) and (b) illustrate with reference to evolution? Explain.

Why is predation important and required in a community with rich biodiversity? Explain with the help of suitable examples.

OR

What is 'predation"? Explain with the help of suitable examples, why it is required in a community with rich biodiversity.

i. Compare the mechanism of sex determination in humans with that of honey bees, with respect to chromosome number.
ii. How is the gamete formation comparable in the above two cases?

Depending upon the chemical nature of the template (DNA or RNA) and the nature of nucleic acids synthesized from it (DNA or RNA), list the types of nucleic acid polymerases.

Distinguish between embryo and endosperm found in Angiosperms.

When Morgan conducted dihybrid cross on Drosophila like Mendel did with pea plants, the F₂ ratio deviated significantly from that of Mendel's F, ratio. Write the explanation Morgan and his group gave to the observations they obtained from their experiment.

“In a food-chain, a trophic level represents a functional level, not a species.” Explain.