Human Reproduction — BIOLOGY STD 12 Science — Question

What are the characteristics of DNA?

Discuss the following:Radioactive wastes.

Replication was allowed to take place in the presence of radioactive deoxynucleotides precursors in E.coli that was a mutant for DNA ligase. Newly synthesised radioactive DNA was purified and strands were separated by denaturation. These were centrifuged using density gradient centrifugation. Which of the following would be a correct result?

1. Work out a dihybrid cross upto F, generation between pea plants bearing violet-coloured axial flowers and white-coloured terminal flowers. Give their phenotypic ratio.
2. State the Mendel's law of inheritance that was derived from such a cross.

Explain any three preventive measures to control microbial infections.

A few statements are given below followed by a set of terms in a box. Pick the correct term and write it against the appropriate statement,

1. Mating of closely related individuals within the same breed.
2. Mating of animals of same breed but having no common ancestors on either side for 4-6 generations.
3. Mating of animals of two different species.
4. Breeding of animals belonging to different breeds.

1. Cross breeding.
2. Inter-specific hybridization.
3. Out breeding.
4. Out crossing.
5. Inbreeding.

Give reasons why:
Most zygotes in angiosperms divide only after certain amount of endosperm is formed.

Draw a diagrammatic sketch of biogas plant, and label its various components given below: Gas Holder, Sludge Chamber, Digester, Dung + water chamber.

Explain polygenic inheritance with the help of an example.

What is Hardy-Weinberg principle? Discuss with suitable example.