GPT on Question 12, Sep 15

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 mainly occurs in the leaves, inside cell 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 short-term chemical energy.

• 2.The Calvin cycle
• •Occurs in the chloroplast’s fluid-filled stroma.
• •Uses carbon dioxide and the chemical energy produced in the first stage.
• •Builds energy-rich sugars that the plant can use or store.

Plants use these sugars for energy, growth, and making materials such as cellulose. Photosynthesis is also crucial for most life on Earth because it supplies food at the base of many food chains, removes carbon dioxide from the atmosphere, and releases the oxygen we breathe.