- Nitrogen fixation is the process of converting free nitrogen gas of atmosphere into nitrogen compounds (nitrites and nitrates)
- There are three types of nitrogen fixation :-
- Atmospheric Nitrogen fixation (by lightning)
- Industrial Nitrogen fixation (by chemical fertilizers)
- Biological Nitrogen fixation (by bacteria and blue green algae)
- The root nodules of legimonous plants (soybean, pea, bean) contain symbiotic nitrogen fixing bacteria (Rhibozium) which converts atmospheric nitrogen into water soluble nitrates and fixes in the soil. It increases the fertility of soil with the increase in productivity. So, farmers are suggested to cultivate leguminous plant on certain interval of years.
- The bacteria, that convert ammonia into nitrates are called as nitrifying bacteria. Example :- Nirosomanous (Nitrite bacteria) and Nitrobacter (Nitrate bacteria).
- Dinitrification is the process of conversion of nitrate salts present in the soil into free nitrogen gas. Pseudomonas helps in this process.
- During lightning, due to high temperature, atmospheric N2 fixation takes place to form nitrates in the soil, which increases the fertility of it for better growth and development of the crops. So, it is beneficial for farmers when lightning occurs.
- Important classification :-
- Producers :- Grass, Phytoplanktons, Spirogyra
- Primary consumer :- Grasshopper, Rabbit, Deer, Zoo planktons
- Secondary consumers :- Snake
- Tertiary consumers :- Eagle, Vulture, Tiger, Whale
- Decomposers :- Mushroom, Saprophytic Bacteria, Fungi
- Abiotic factors :- Water, light.
1. Ecological pyramid is also known as food pyramid.
Ans-The sketch of ecological pyramid is usually based on the consumption of food materials so ecological pyramid is also known as food pyramid
2 The no of producers is greater than that of consumers in every ecosystem
Ans– Various types of consumers depend on producers directly or indirectly to obtain their food. Only 10% of the total energy is transferred from one trophic level to another. So, an eco-systern cannot run smoothly if the no. of producers is less. Hence, the no. of producers is always more in nature.
3. Rainfall with lightening is very good for agriculture.
Ans– During lightening in the atmosphere, the nitrogen is oxidized into their oxides. Such oxides are swept down to the earth and assimilated by the plant as a source of food as soon as it is nitrified by nitrifying bacteria. Hence, rainfall with lightening is very good for agriculture.
4. Nitrification and denitrification are required for nitrogen cycle.
Ans– Nitrogen cycle involves consumption of nitrogen from atmosphere and release of nitrogen to atmosphere. In nitrification, ammonia or ammonium salts are converted to unstable form, however, in denitrification, nitrates and nitrites are converted to free nitrogen. One process consumes nitrogen gas and another releases nitrogen gas which help to continue nitrogen cycle. So, nitrification and denitrification are required for nitrogen cycle.
5. Farmers are suggested to grow leguminous plants once in 2–3 years.
Ans-Leguminous plants are good for soil because their roots containing nodules with nitrogen fixing symbiotic bacterium, Rhizobium that fixes free atmospheric nitrogen into water soluble nitrate compounds in the soil and the soil becomes fertile. Hence, farmers are suggested to grow leguminous plants once in 2–3 years.
6. The ecological pyramid of aquatic ecosystem is inverted on the basis of biomass, however, it is erect on the basis of bio-number.
Ans– In aquatic ecosystem, the biomass of producer like phytoplankton is minimum whereas those of primary, secondary and tertiary consumers increase proportionally. Hence, the bio mass of pyramid in aquatic ecosystem is inverted in shape.
7. The nitrogen cycle in biosphere is known as perfect cycle.
Ans– The nitrogen cycle in biosphere is known as perfect cycle because the cycling keeps the overall amount of nitrogen constant in the atmosphere and in the water bodies.
8. Leguminous plants are good for soil.
Ans– Leguminous plants are good for soil because their roots containing nodules with nitrogen fixing bacterium, Rhizobium that fixes free atmospheric nitrogen into water soluble nitrate compounds in the soil and the soil becomes fertile.
9. The plants are also called producers.
Ans– The plants are also called producers because they produce food by process of photosynthesis.
10. The producers are also called transducers.
Ans– The producers are also called transducers because they are able to change light energy into chemical form.
11. The plants are called producers or autotrophs.
Ans– The plants are called producers or autotrophs because they are capable of synthesizing their own food from inorganic compounds by photosynthesis process.
12. Pyramid of biomass of an aquatic ecosystem is inverted in shape;
Ans– Pyramid of biomass of an aquatic ecosystem is inverted in shape because of the progressive increase in the biomass of organisms from the second trophic level to the final trophic level.
13. It is not good to kill or remove all the snakes from the point of view of balance in ecosystem.
Ans– because snakes absorb the poisonous chemicals found in the environment. Removal of snakes may result the over population of rats, frogs etc. which destroys the crops and imbalance the ecosystem.
14. If secondary consumers are killed off, ecosystem will be imbalanced.
Ans-. If secondary consumers are killed off, primary consumers gets multiplied in a fast rate due to which there will be the condition of lacking of food which creates imbalance in the ecosystem.
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