Science (English Medium) Class 12 - CBSE Question Bank Solutions

Using various resources such as your school library or the internet and discussions with your teacher, trace the evolutionary stages of any one animal say horse.

Discuss briefly the following:

Radioactive wastes

Write the function of RNA polymerase II.

Answer the following question.
Explain the process of splicing of hn-RNA in a eukaryotic cell.

From among the sets of terms given below, identify those that are associated with the gynoecium.

From the statements given below choose the option that are true for a typical female gametophyte of a flowering plant.

1. It is 8-nucleate and 7-celled at maturity
2. It is free-nuclear during the development
3. It is situated inside the integument but outside the nucellus
4. It has an egg apparatus situated at the chalazal end

The first genetic material could be ______.

Which of the following are the functions of RNA?

Segments of mRNA removed during splicing are called ______.

In eukaryotes, mRNA is synthesized with the aid of ______.

Read the following and answer from given below:

The translation is the process of polymerization of amino acids to form a polypeptide. The order and sequence of amino acids are defined by the sequence bases in the mRNA. The amino acids are joined by a bond called a peptide bond. The ribosome is the site of protein synthesis.

Which part of mRNA contains untranslated regions (UTR)?

In an embryo sac, the cells that degenerate after fertilisation are ______.

In a flower, if the megaspore mother cell forms megaspores without undergoing meiosis and if one of the megaspores develops into an embryo sac, its nuclei would be ______.

Name the component cells of the ‘egg apparatus’ in an embryo sac.

Draw the diagram of a mature embryo sac and show its 8-nucleate, 7-celled nature. Show the following parts: antipodals, synergids, egg, central cell, polar nuclei.

With a neat, labelled diagram, describe the parts of a mature angiosperm embryo sac. Mention the role of synergids.

Embryo sacs of some apomictic species appear normal but contain diploid cells. Suggest a suitable explanation for the condition.

Viviparity is considered to be more evolved because ______.

What is the most important pre-condition for adaptive radiation?

When we talk of functional macromolecules (e.g. proteins as enzymes, hormones, receptors, antibodies etc), towards what are they evolving?