Ecosystem - C. Science

• 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 :-

1. Atmospheric Nitrogen fixation (by lightning)
2. Industrial Nitrogen fixation (by chemical fertilizers)
3. 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 :- 

1. Producers :- Grass, Phytoplanktons, Spirogyra
2. Primary consumer :- Grasshopper, Rabbit, Deer, Zoo planktons 
3. Secondary consumers :- Snake
4. Tertiary consumers :- Eagle, Vulture, Tiger, Whale
5. Decomposers :- Mushroom, Saprophytic Bacteria, Fungi
6. 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.