Biology
Study of living organisms and their interactions with the environment.
Photosynthesis and Cellular Respiration
How Organisms Get and Use Energy
All living things need energy. Plants and some bacteria make their own food through a process called photosynthesis, while animals and plants break down this food to release energy in a process called cellular respiration.
Photosynthesis
Plants use sunlight, water, and carbon dioxide to make glucose (a sugar) and oxygen.
\[ 6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2 \]
Cellular Respiration
Cells break down glucose with oxygen to release energy, carbon dioxide, and water.
\[ C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy} \]
The Energy Cycle
Photosynthesis and respiration are opposite but connected processes that form the basis of life’s energy flow.
Examples
Trees absorb carbon dioxide and produce oxygen for us to breathe.
Humans and animals get energy from the food they eat.
In a Nutshell
Plants make food from sunlight, and both plants and animals turn that food into energy.