Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Is the use of contraceptives justified? Give reasons.

Mention the reasons for difference in ploidy of zygote and primary endosperm nucleus in an angiosperm.

OR

In angiosperms, zygote is diploid while primary endosperm cell is triploid. Explain.

Sun is the only source of energy for all ecosystems on Earth. Explain.

Which part of the plant is best suited for making virus-free plants and why ?

Explain the Rivet popper hypothesis.

Study the schematic representation of evolutionary history of plant forms given below and mention

1. The plant forms ferns and conifers are most related to.
2. The nearest ancestors of flowering plants.
3. The most primitive group of plants.
4. Common ancestry of Psilophyton provides to.
5. The common ancestor of Psilophyton and seed ferns.
6. The common ancestors of mosses and tracheophytes.

What is sterilization ? Write two reason for sterilization.###What do you understand by sterilization ? Name any two methods.

Explain - Phenylketonuria.

Differentiate between DNA and RNA.

What is splicing? Why is splicing necessary in eukaryotic genes?