D.

formation of thick walled spores.

Bacteria, fungi and lower plants survive in adverse conditions through formation of thick walled spores. Algae form resting spore or akinetes which are thick walled spores and store food material. In fungi, thick walled perennating spores called chlamydospores are formed. Bacteria form endospores which is probably the most resistant living thing known. They may remain alive in boiling water for more than 2 hours.

C.

a botanist and a zoologist

Cell theory was proposed by a German botanist M.J. Schleiden and another German, a zoologist T.S. Schwann in 1839.

C.

These are different arrangements of ovule attachment to inner surface of ovary wall. (A) represents marginal, (B) represents axile, (C) represents parietal, (D) represents free central, (E) represents basal placentation

A.

structure of lenticel

The figure shows structure of lenticel which facilitates gaseous exchange and transpiration. These are aerating pores in the bark of woody trees. These are surrounded by loosely arranged thin walled complementary cells enclosing intercellular spaces for gaseous exchange.

C.

In given diagram (A) represents denitrification and (B) represents ammonification. Denitrification is conversion of nitrates into nitrogen gas by some microorganisms e.g., Pseudomonas denitrificans, Thiobacillus denitrificans, Micrococcus denitrificans. Ammonification is conversion of dead remains of living organisms into ammonia with the help of microorganisms like Bacillus ramosus, B.vulgaris, B. mesentericus etc.