Q.(a) Write the significance of photosynthesis. OR

Photosynthesis is the foundation of almost all life on Earth: it captures solar energy as food, releases the oxygen that supports aerobic respiration, removes atmospheric CO2, and is the ultimate origin of both organic raw materials and fossil fuels.

(a) Significance of photosynthesis (answering the primary part of this question):

1. Primary source of food and energy: Photosynthesis is the process by which green plants, algae, and cyanobacteria convert light energy into chemical energy stored in glucose. This makes photosynthetic organisms the primary producers, forming the base of nearly all food chains and food webs; virtually all other organisms depend, directly or indirectly, on this captured energy for survival.

2. Release of oxygen: Photosynthesis releases molecular oxygen (O2) as a by-product of the photolysis of water. This oxygen is essential for aerobic respiration in almost all living organisms (plants, animals, most microbes), and photosynthesis is responsible for maintaining the oxygen content of the Earth's atmosphere.

3. Regulation of atmospheric carbon dioxide: By fixing atmospheric CO2 into organic compounds, photosynthesis helps regulate and moderate the concentration of this greenhouse gas in the atmosphere, playing a crucial role in the global carbon cycle and in mitigating climate change.

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