Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

Analogous organs do not have significant role in evolution.

Comment on the statement that "evolution and natural selection are end result or consequence of some other processes but themselves are not processes".

Name the two special types of lymphocytes in humans. How do they differ in their roles in immune response?

The tobacco smoking is associated with the rise in blood pressure and emphysema (oxygen deficiency in the body). Explain.

Sketch and label ecological pyramids of energy and pyramid of biomass

Name the category of codons, UGA belongs to. Mention another codon of the same category. Explain their role in protein synthesis.

Sketch and label – Structure of Antibody

Sometimes a gene which carries a major disadvantage in homozygous state confers an advantage in heterozygous condition. Explain by giving suitable example.

Enlist various types of barriers which prevent entry of foreign agents into the body.

Explain giving reasons why an alien piece of DNA needs to be integrated to a specific sequence of host DNA for its cloning.