Biology Test Practice 2026 - Comprehensive Study Resource

Chlorophyll’s job is to capture light energy and start the energy conversions that power photosynthesis. It sits in the thylakoid membranes of chloroplasts and absorbs light, mainly blue and red wavelengths. The absorbed energy excites chlorophyll’s electrons and drives the light-dependent reactions, feeding the electron transport chain to generate ATP and NADPH that fuel sugar production in the Calvin cycle. It doesn’t store genetic information—that’s DNA. It isn’t part of glycolysis or cellular respiration, which handle glucose breakdown elsewhere. It also doesn’t dissolve pigments; it’s a pigment that helps harvest light. So absorbing light energy to drive photosynthesis is its essential role.