http://www.ck12.org Chapter 3. Chemical Interactions
3.42 Photosynthesis Reactions
- Summarize the process of photosynthesis.
- State the importance of photosynthesis.
- Identify photosynthetic organisms.
Look at the amazing meat-eating plants pictured here! Called pitcher plants, they use their “pitchers” to capture
and digest insects. But even these pitcher plants—like all other plants—make food by photosynthesis. They “eat”
insects just to get extra nutrients.
Food from Light
Most of the energy used by living things comes either directly or indirectly from the sun. That’s because sunlight
provides the energy for photosynthesis. This is the process in which plants and certain other organisms synthesize
glucose (C 6 H 12 O 6 ). The process uses carbon dioxide and water and also produces oxygen. The overall chemical
equation for photosynthesis is:
6CO 2 + 6H 2 O + Light Energy→C 6 H 12 O 6 + 6O 2
Photosynthesis changes light energy to chemical energy. The chemical energy is stored in the bonds of glucose
molecules. Glucose, in turn, is used for energy by the cells of almost all living things. Photosynthetic organisms
such as plants make their own glucose. Other organisms get glucose by consuming plants (or organisms that consume
plants).
Q:How do living things get energy from glucose?
A:They break bonds in glucose and release the stored energy in the process of cellular respiration.