wunder beta🌿 Photosynthesis
How plants turn sunlight, water, and CO2 into the sugar that fuels life.
What you’ll learn
- Explain what photosynthesis is, where it occurs, and read its balanced equation.Photosynthesis converts light energy into chemical energy stored in sugar. It happens in chloroplasts, where chlorophyll absorbs light. The balanced equation shows CO2 and water becoming glucose and oxygen.
- Describe how the light-dependent reactions capture light and produce ATP and NADPH.In the thylakoid membranes, photosystems absorb light and split water, releasing oxygen. A proton gradient powers ATP synthase, and the products ATP and NADPH carry energy to the next stage.
- Explain how the Calvin cycle builds sugar and how the two stages depend on each other.The Calvin cycle in the stroma uses ATP and NADPH to fix carbon dioxide into sugar via RuBisCO. The two stages are linked, and photosynthesis underpins food chains, oxygen, and the carbon cycle.
Questions this course answers
Where does the carbon in the sugar made by photosynthesis come from?
The balanced equation shows carbon dioxide from the air is the source of carbon in glucose; water supplies electrons and hydrogen.
Why do healthy leaves appear green?
Chlorophyll absorbs violet, blue, and red wavelengths but reflects green, so green light reaches our eyes.
Inside the chloroplast, where are the light-capturing reactions carried out?
The thylakoid membranes hold the photosystems that capture light; the stroma is where the Calvin cycle builds sugar.
What gas is released when water is split during the light-dependent reactions?
Splitting water (photolysis) releases oxygen, which is the byproduct plants give off into the atmosphere.
What two energy-carrying products do the light reactions make for the next stage?
The light reactions produce ATP and NADPH, which power the Calvin cycle to build sugar.
What drives the enzyme ATP synthase to produce ATP?
Protons build up inside the thylakoid, then rush back through ATP synthase, spinning it to make ATP.
Grounded in trusted sources
- OpenStax Biology for AP Courses, 'The Light-Dependent Reaction of Photosynthesis' (openstax.org)
- Khan Academy, 'The Calvin cycle' (khanacademy.org)
- National Geographic Education, 'Photosynthesis' (education.nationalgeographic.org)
- Biology LibreTexts, 'The Two Parts of Photosynthesis' (bio.libretexts.org)
Every Wunder lesson is built from real, reputable sources — never invented.
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