The rate of release of nutrients into the atmosphere is regulated by –

1. pH and moisture

2. Temperature

3. Soil

4. All of the above.

Which is the natural reservoir of Phosphorous?

1. Ocean

2. Fossils

3. Rock

4. Soil

How much of the total quantity of global carbon is dissolved in the oceans?

1. 50%

2. 62%

3. 71%

4. 84%

Approximately how much of carbon is fixed in the biosphere through photosynthesis annually.

1. 4 × ${10}^{13}$ kg

2. 5.4 x ${10}^{15}$ kg

3. 6.4 x ${10}^{11}$ kg

4. 13 x ${10}^4$ kg

How could human activities affect the carbon cycle?
1. By rapid forestation
2. By massive burning of fossil fuel for energy and transport
3. By forest fire
4. More than one of the options given above are correct

Which of the following contribute to the atmospheric CO₂?
1. Producers
2. Herbivores
3. Saprotrophs
4. All of the above

Which of the following reservoir regulates the amount of carbon dioxide in the atmosphere?

1. Ocean

2. Earth’s crust

3. Land

4. Fossil

What per cent of the dry weight of organisms constitutes carbon?

1. 17%

2. 28%

3. 49%

4. 67%

Which is the second abundant matter in the body of an organism?

1. Phosphorous

2. Hydrogen

3. Carbon

4. Calcium