What is photosynthesis? • Photosynthesis is the process in which a plant uses energy from the sun to make food for itself. • Photo means “light”; synthesis means “to put together”. • Therefore, photosynthesis is the process of using light to make food.
The Process • Photosynthesis is a very complicated process. • Plants use energy from the sun to convert carbon dioxide and water into oxygen and sugar.
The Sun’s Energy • Plants capture the sun’s energy using its leaves and other green parts of the plant. • Plants mainly use leaves because they contain more chloroplasts, which are green organelles inside plant cells.
Chloroplasts • Chloroplasts in plant cells are the source of their green color. • The color comes from pigments, which are chemical compounds that absorb light. • The main pigment in chloroplasts is chlorophyll. • Chloroplasts may contain yellow and orange pigments.
Using the energy • The plant uses the energy from the sun to produce food. • The plant will need two raw ingredients: six water molecules and six carbon dioxide molecules. • The water comes from the roots. • The carbon dioxide comes from the leaves through the stomata • Stomata are tiny openings on the undersides of the leaves.
The Photosynthesis Equation • 6 CO2 + 6 H2O --- light energy --- C6H12O6 + 6 O2 • Carbon Dioxide + Water >>> Glucose + Oxygen • Glucose is used for food. • Oxygen is released as a waste.
Photosynthesis and Life • The plant is an autotroph, an organism that makes its own food. • A caterpillar is eating a leaf, so it gets its energy from the sun in an indirect way. • A bird eats the caterpillar, so it gets its energy indirectly from the sun as well. • The bird and caterpillar represent heterotrophs, which is an organism that cannot produce it own food. • Almost all living things obtain energy directly or indirectly from photosynthesis. • Photosynthesis brings oxygen into the air which is essential for many living things.