Which pigment within chloroplasts captures light energy for photosynthesis?

Which pigment within chloroplasts captures light energy for photosynthesis?

• A. Chlorophyll
• B. Stroma
• C. Thylakoid sac
• D. Carotenoids

Answer: (A)

Chlorophyll is the primary light-harvesting pigment in chloroplasts. It sits in the thylakoid membranes where photosystems I and II are located, and it absorbs blue and red light most effectively. When chlorophyll absorbs light, its electrons become excited and drive the electron transport chain, powering the production of ATP and NADPH that fuel the subsequent steps of photosynthesis. Stroma is the fluid where the Calvin cycle occurs, not a pigment. Thylakoid sacs are membrane compartments that house the photosystems and pigments, not pigments themselves. Carotenoids are accessory pigments that broaden the range of light absorbed and help protect chlorophyll from damage, but they don’t drive the main light capture. Therefore, chlorophyll best fits as the pigment that captures light energy for photosynthesis.

Chlorophyll is the primary light-harvesting pigment in chloroplasts. It sits in the thylakoid membranes where photosystems I and II are located, and it absorbs blue and red light most effectively. When chlorophyll absorbs light, its electrons become excited and drive the electron transport chain, powering the production of ATP and NADPH that fuel the subsequent steps of photosynthesis. Stroma is the fluid where the Calvin cycle occurs, not a pigment. Thylakoid sacs are membrane compartments that house the photosystems and pigments, not pigments themselves. Carotenoids are accessory pigments that broaden the range of light absorbed and help protect chlorophyll from damage, but they don’t drive the main light capture. Therefore, chlorophyll best fits as the pigment that captures light energy for photosynthesis.