The correct option is (c).
Explanation
The oxygen cycle describes the movement of oxygen within the atmosphere, biosphere, and lithosphere. It is maintained primarily through the balance between photosynthesis (production) and respiration/combustion (consumption).
Statement-wise Analysis:
- Statement 1 is Incorrect. Respiration is a fundamental cellular process for all aerobic organisms, including plants. Plants consume oxygen to break down glucose and generate energy (ATP) through cellular respiration. While plants produce oxygen during the day via photosynthesis, they continuously consume oxygen for respiration day and night.
- Statement 2 is Correct. Plants play a critical role in the oxygen cycle by returning oxygen to the atmosphere. This release offsets the oxygen consumed by respiration, combustion, and decomposition.
- Statement 3 is Correct. Photosynthesis is the biological process by which green plants, algae, and cyanobacteria convert light energy into chemical energy. During the light-dependent reactions of photosynthesis, water molecules are split (photolysis), releasing oxygen as a by-product.
Key Takeaway:
While plants are the primary producers of atmospheric oxygen through photosynthesis, they also consume oxygen for cellular respiration. The net release of oxygen occurs because the rate of photosynthesis during the day generally exceeds the rate of respiration.