Chloroplasts, chlorophyll, and stomata

Summary

Chloroplasts are structures in plant cells where photosynthesis takes place, especially in the green tissues of leaves. They contain chlorophyll, a green pigment that absorbs light energy. This energy powers reactions that use carbon dioxide and water to produce glucose and oxygen. The light-dependent reactions occur in the grana of chloroplasts, producing ATP and NADPH, while the Calvin cycle uses these products and carbon dioxide to build sugars. Stomata are small openings in leaves that allow carbon dioxide to diffuse into the leaf for photosynthesis. Oxygen produced during photosynthesis leaves the plant through the stomata. The glucose made can be used in respiration, stored as starch, or converted into substances such as cellulose, nectar, amino acids, and fats.

Key Points

• 1

  Chloroplasts contain chlorophyll and are the main sites of photosynthesis in green plant tissues.

• 2

  Chlorophyll absorbs light energy, which drives the light-dependent reactions and helps produce ATP and NADPH.

• 3

  Stomata allow carbon dioxide to enter leaves and oxygen to exit during photosynthesis.

• 4

  Photosynthesis converts carbon dioxide and water into glucose and oxygen using light energy.

• 5

  Glucose may be used for respiration, stored as starch, or converted into materials needed for plant growth and reproduction.