Photosysnthesis – UPSC Prelims

Photosynthesis is the process by which green plants and certain other organisms transform light energy into chemical energy.

During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.

Factors Affecting Photosynthesis: Photosynthesis is under the influence of several factors, both internal (plant) and external.
  • Internal: Number, size, age and orientation of leaves, mesophyll cells and chloroplasts, internal CO2 concentration and the amount of chlorophyll.
  • External: Availability of sunlight, temperature, CO2 concentration and water. For example, despite the presence of a green leaf and optimal light and CO2 conditions, the plant may not photosynthesise if the temperature is very low.
  • Important for maintenance of life on Earth.
  • If photosynthesis ceased, there would soon be little food or other organic matter on Earth.
  • Most organisms would disappear, and in time Earth’s atmosphere would become nearly devoid of gaseous oxygen.
  • Energy produced by photosynthesis carried out by plants millions of years ago is responsible for the fossil fuels (i.e., coal, oil, and gas) that power industrial society.
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