The correct option is (c) 2 and 3 only.
Explanation
The oxygen cycle is a biogeochemical cycle that describes the movement of oxygen within the atmosphere, biosphere, and lithosphere. The stability of atmospheric oxygen levels depends on the equilibrium between processes that produce oxygen and those that consume it.
Statement-wise Analysis:
- Statement 1 is Incorrect. Respiration is a metabolic process performed by animals, plants, and microorganisms wherein oxygen is consumed to break down organic matter (glucose) for energy. This process releases carbon dioxide and water, thereby depleting rather than replacing atmospheric oxygen.
- Statement 2 is Correct. Photosynthesis is the primary mechanism responsible for the replenishment of oxygen in the atmosphere. In this process, photoautotrophs (plants, algae, and cyanobacteria) absorb carbon dioxide and water in the presence of sunlight to produce carbohydrates, releasing oxygen as a byproduct.
- Statement 3 is Correct. Oxygen is classified as a renewable resource because it is continuously circulated and regenerated through the oxygen cycle. Nature maintains its availability through the interplay of production (photosynthesis) and consumption (respiration, decomposition, and combustion).
Key Takeaway:
Atmospheric oxygen is replenished primarily through photosynthesis and is consumed by respiration; this continuous biogeochemical cycling ensures it remains a renewable resource.