What is the main source of energy for photosynthesis?

What is the main source of energy for photosynthesis?

• A. Light
• B. Water
• C. Carbon dioxide
• D. Glucose

Answer: (A)

Light provides the energy that drives photosynthesis. When pigments like chlorophyll absorb photons, that light energy powers the light-dependent reactions, pushing electrons through a transport chain and converting it into chemical energy in the form of ATP and NADPH. Those energy carriers then fuel the Calvin cycle, where carbon dioxide is fixed into sugars like glucose. Water plays a supporting role by donating electrons during the light reactions and releasing oxygen, but it is not the energy source itself. Carbon dioxide is the raw material for making sugars, not the energy input, and glucose is the product, not the energy source.

Light provides the energy that drives photosynthesis. When pigments like chlorophyll absorb photons, that light energy powers the light-dependent reactions, pushing electrons through a transport chain and converting it into chemical energy in the form of ATP and NADPH. Those energy carriers then fuel the Calvin cycle, where carbon dioxide is fixed into sugars like glucose. Water plays a supporting role by donating electrons during the light reactions and releasing oxygen, but it is not the energy source itself. Carbon dioxide is the raw material for making sugars, not the energy input, and glucose is the product, not the energy source.