1. The process of nitrogen-fixation by bacteria does not take place in the presence of –
A. molecular form of hydrogen
B. elemental form of oxygen
C. water
D. elemental form of nitrogen
2. Rainfall patterns depend on –
A. the underground water table
B. the number of water bodies in an area
C. the density pattern of human population in an area
D. the prevailing season in an area
3. The nitrogen molecules present in an air can be converted into nitrates and nitrites by –
A. a biological process of nitrogen fixing bacteria present in soil
B. a biological process of carbon fixing factor present in soil
C. any of the industries manufacturing nitrogenous compounds
D. the plants used as cereal crops in field
4. Flow of energy in an ecosystem is always –
A. unidirectional
B. bidirectional
C. multi directional
D. no specific direction
5. The % of solar radiation absorbed by all the green plants for the process of photosynthesis is about –
A. 1 %
B. 5 %
C. 9 %
D. 10 %
6. Low visibility during cold weather is due to –
A. formation of fossil fuel
B. unburnt carbon particles or hydrocarbons suspended in air
C. lack of adequate power supply
D. none of these
7. Marked temperature changes in aquatic environment can affect –
A. breeding of animals
B. more growth of aquatic plants
C. process of digestion in animals
D. availability of nutrients
8. Which one of the following is not important for individual health?
A. living in clean space
B. good economic condition
C. social equality and harmony
D. living in a large and well-furnished house
9. The atmosphere of the earth is heated by radiations which are mainly –
A. radiated by the sun
B. re-radiated by land
C. re-radiated by water
D. re-radiated by land and water
10. In desert plants, rate of water loss gets reduced due to the presence of –
A. stomata
B. cuticle
C. lignin
D. suberin
