Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth? 1. Volcanic action 2. Respiration 3. Photosynthesis 4. Decay of organic matter Select the correct answer using the code given below.

What would happen if phytoplankton of an ocean is completely destroyed for some reason? 1. The ocean as a carbon sink would be adversely affected. 2. The food chains in the ocean would be adversely a…

With reference to the planet Earth, consider the following statements: I. Rain forests produce more oxygen than that produced by oceans. II. Marine phytoplankton and photosynthetic bacteria produce a…

Which one of the following is the correct order of biological organisation ranging from organism to biosphere?

Given below are two statements one is labelled as Assertion (A) and the other as Reason (R). Assertion (A): Phytoplankton grow in abundance in the limnetic zone. Reason (R): Limnetic zone is open wat…

Given below are two statements, one is labelled as Assertion (A) and other as Reason (R). Assertion (A): Various components of an ecosystem are not interdependent. Reason (R): Human activities have t…