Word Equation

Carbon dioxide + Water + Sunlight ------> Carbohydrate + Oxygen


In plants, photosynthesis occurs in chloroplasts. The light reactions occur along the thylakoid membranes within the chloroplasts, where pigments capture light energy. The Calvin cycle occurs in the stroma, the fluid between the inner membrane of the chloroplast and the thylakoids. In the light reactions, light is absorbed by chlorophyll and other pigment molecules, exciting their electrons. The energy of excited electrons is then used by electron carriers to produce NADPH molecules and generate a concentration gradient that powers the synthesis of ATP. This process splits water and releases oxygen. In the Calvin cycle, energy from ATP, electrons from NADPH, and carbon from carbon dioxide are combined to produce sugar molecules.

Above is a diagram of photosynthesis....the light and dark reactions.

C3, C4, and CAM Plants

C3 plants- named this because their first organic product of carbon fixation is a three-carbon compound, 3-phosphoglycerate. C4 plants- named this because they preface the Calvin cycle with an alternate mode of carbon fixation that forms a four-carbon compound as its first product. CAM plants- named such that the mesophyll cells of these plants store the organic acids they make during the night in their vacuoles until morning when the stomata close.

Evolutionary consequences of photosynthesis

Plants adapt to the environment to maximize suface area to get sunlight and minimize water lose. An example would be in a desert environment plants close their stomata during the day and open them at night to minimize water lose.

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