Correct Option
The correct option is 2 only
Explanation
Photosynthesis is a physicochemical process by which green plants and certain other organisms use light energy to synthesize organic compounds. It serves as the fundamental energy capture mechanism for the biosphere and plays a critical role in regulating atmospheric gases.
Statement-wise Analysis
- Statement 1 is Incorrect: Photosynthesis is the primary source of all food on Earth. It transforms solar energy into chemical energy stored in carbohydrates. All living organisms depend on this energy either directly (herbivores) or indirectly (carnivores) through food chains.
- Statement 2 is Correct: Photosynthesis is responsible for the release of oxygen into the atmosphere, not carbon dioxide. During this process, plants absorb carbon dioxide and water to produce glucose and release oxygen as a by-product. It is the process of cellular respiration that releases carbon dioxide.
- Statement 3 is Incorrect: Photosynthesis is not the only pathway for ATP generation in plants. While plants generate ATP through photophosphorylation in chloroplasts during photosynthesis, they also generate ATP through cellular respiration (oxidative phosphorylation) in mitochondria. Respiration is continuous and essential for survival, particularly in non-green tissues and during the absence of light.
Key Takeaway: Photosynthesis captures energy and releases oxygen, serving as the food base for the biosphere. However, plants also perform cellular respiration to generate ATP, consuming oxygen and releasing carbon dioxide.