GPT on Question 12, Sep 13

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

The 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 mainly occurs in leaf cells inside structures called chloroplasts. Chloroplasts contain chlorophyll, the green pigment that absorbs light—especially red and blue wavelengths.

The two main stages

• 1.Light-dependent reactions
• •Occur in the chloroplast’s thylakoid membranes.
• •Chlorophyll absorbs sunlight.
• •Water molecules are split, releasing oxygen.
• •Light energy is converted into temporary chemical energy in molecules called ATP and NADPH.

• 2.The Calvin cycle
• •Occurs in the chloroplast’s stroma.
• •Uses carbon dioxide, ATP, and NADPH to build sugar molecules.
• •These sugars can later be used for energy, growth, or stored as starch.

Why photosynthesis matters

Photosynthesis:

• •Produces much of the oxygen in Earth’s atmosphere.
• •Creates food and stored energy for plants.
• •Supports nearly all food chains, since animals obtain this energy by eating plants or other animals.
• •Removes carbon dioxide from the atmosphere.

A simple way to remember it: plants capture sunlight and store its energy in sugar, releasing oxygen as a byproduct.