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

DNA is unzipped twice in a cell. Mention the two events and the enzymes responsible for it.

Sometimes due to biotic/ abiotic factor the climax remain in a particular seral stage (preclimax) without reaching the climax. Do you agree with this statement. If yes, give a suitable example.

Given alongside is an enlarged view of one microsporangium of a mature anther.
Name ‘a’, ‘b’ and ‘c’ wall layers.

Why the plants that inhabit a desert are not found in a mangrove? Give reasons.

What does ICSI stand for? Describe the technique.

(a) Write scientific names of causal organism and vector organism of malaria and write symptoms of this disease.
(b) Write names of two diseases spread by Aedes mosquito.

 Describe sexually transmitted diseases. Name some important STDs and their causative agents.

Certain attributes of innate immunity are given in the table below. Identify A, B, C, D, E and Frespectively in it.

S.No.	Type of barrier	Example of the barrier	Function
(і)	А	B	Prevent microbial growth
(ii)	C	Polymorpho nuclear leucocytes	D
(iii)	Cytokine	E	F

What roles do enzymes play in detergents that we use for washing clothes? Are these enzymes produced from some unique microorganisms?