Photosynthesis uses light energy to make food.

subheader icon Explore photosynthesis in action.

OBJECTIVE: To closely examine sugar production in the Calvin cycle

Congratulations! You've discovered that sugar is produced in the stroma of the chloroplast. Here sugar is made from carbon dioxide in a series of chemical reactions called the Calvin cycle. Sugar synthesis requires the chemical energy provided by ATP and NADPH.

In thylakoid membranes, the necessary chemical energy is produced by the light reactions, during which light energy powers the production of ATP and NADPH.

View the animation below, and then scroll down to answer the questions at the bottom of the page.

Answer the following questions in the boxes provided. When you have completed a question, click the Check Your Answer button for feedback.

1. Which molecule(s) supply the chemical energy to make the sugar (G3P)?

2. Is oxygen produced in the Calvin cycle?

3. Is light energy required for the Calvin cycle?

When you have answered all of the questions, go to page page 7 to locate the source of ATP, NADPH, and oxygen.

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