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.

Photosystem II mostly occurs in the appressed regions of granal thylakoids.

The figure shows structure of lenticelwhich 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.

In active transport, carrier proteins which are located at membrane, use energy in the form of ATP to transport molecules againstconcentration gradient of cell membrane. Transportation rate reaches maximwn when all carrier proteins are being used or are saturated. These proteins are very specific to certain substances and are sensitive to inhibitors.

Cleistogamous flowers do not open at all. In such flowers, the anthers and stigma lie close to each other. Anthers when dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination Thus, cleistogamous flowers are autogamous as there is no chance of cross-pollination. So, no pollination agent is required in these flowers.

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

Water is the most abundant chemical compound in living organism. In a cell, water occupies 70-90% of the cellular mass. So, in 50 gm of living tissue 35-45 gm of water would be present.

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

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.

After glycolysis, pyruvate forms acetyl Co-A which undergoes oxidation to form CO₂and H₂O through Krebs' cycle in mitochondrialmatrix.