Photosynthesis Chapter 3

What’s Photosynthesis A process in which cells capture sunlight and uses it to make food. “photo” = light “synthesis” = to make or put together Only occurs in plants, algae, and some bacteria

Two Stage Process to Photosynthesis Use energy from sun to convert carbon dioxide and water into oxygen and sugars (includes glucose).

First stage: Capturing the sun’s energy This stage occurs in the leaves and other green parts of the plant. (Like chloroplasts) Chloroplasts give the plant its green color. The green color comes from pigments, or the colored chemical compound that absorbs light. Main pigment is chlorophyll Chlorophyll captures the light energy and uses it to power the 2nd stage.

Stage 2: Using energy to make food Uses the captured energy to produce sugars. Needs water and carbon dioxide (CO2) for this stage to happen. Get water from roots and CO2 from the air. Carbon dioxide enters through stomata, small openings underneath the leave. Water and CO2 move into the chloroplasts Water and CO2 undergo a series of chemical reactions. Products from this reaction are oxygen & sugars.

Photosynthesis Equation Carbon Dioxide + Water → Glucose + Oxygen ↑ ↑ These are the reactants These are the products

Photosynthesis & Life Plants use some of the sugars for food Some sugars maybe stored for future use. When you eat potatoes & carrots you are eating the plant’s stored food. Oxygen leaves the leaves & enters into the atmosphere. Nearly all living things obtain energy directly or indirectly from the energy of the sunlight.