GPT on Question 12, Sep 19

Photosynthesis is the process plants, algae, and some bacteria use to convert light energy into chemical energy stored in sugar.

Overall equation

\[
6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2
\]

In words:

carbon dioxide + water + light → glucose + oxygen

Where it happens

In plants, photosynthesis occurs mainly in leaf cells inside structures called chloroplasts. Chloroplasts contain chlorophyll, the green pigment that absorbs light.

The two main stages

• 1.Light-dependent reactions
• •Occur in the thylakoid membranes of chloroplasts.
• •Chlorophyll absorbs sunlight.
• •Water molecules are split, releasing oxygen.
• •Light energy is converted into temporary chemical energy.

• 2.Calvin cycle
• •Occurs in the fluid-filled stroma of chloroplasts.
• •Uses carbon dioxide and the energy produced in the first stage.
• •Builds energy-rich sugar molecules, which the plant can use to make glucose and other compounds.

Why it matters

Photosynthesis:

• •Produces much of the oxygen in Earth’s atmosphere.
• •Provides plants with stored energy for growth.
• •Forms the base of most food chains.
• •Removes carbon dioxide from the atmosphere.

A simple way to think about it is: plants use sunlight to turn water and carbon dioxide into food, releasing oxygen as a byproduct.