Lesson · B.2.3

Respiration and photosynthesis

How cells convert glucose to ATP through glycolysis, the citric acid cycle, and the electron transport chain, and how plants run the reverse process in photosynthesis.

ObjectiveB.2.3Read6 minExam weightCell Biology ≈ 24% of Biology

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What you will be able to do

Name the three stages of aerobic cellular respiration and where each one happens in the cell
Compare aerobic respiration with anaerobic fermentation, including why the ATP yield differs so much
Explain how photosynthesis and respiration are chemical opposites that share the same glucose

What the lesson concludes

Aerobic respiration has three stages: glycolysis, the citric acid cycle, and the electron transport chain
Glycolysis happens in the cytosol without oxygen; the other two stages happen inside the mitochondrion and need oxygen
One glucose molecule yields roughly 30 to 32 ATP by the aerobic route, versus 2 ATP by fermentation alone
Photosynthesis in chloroplasts runs the respiration equation in reverse, using light energy to build glucose from carbon dioxide and water
The HESI A2 tests the equations, the stage order, and the location of each stage more often than exact ATP counts