SESSION 13

Role of Oxygen in Cellular Respiration: Oxygen is the final electron acceptor in the Electron Transport Chain (ETC). In its absence, cells switch to fermentation, a less efficient pathway.

Efficiency of Fermentation vs. Cellular Respiration:

• Fermentation: Produces 2 ATP per glucose molecule.

• Cellular Respiration: Yields 29 ATP per glucose, making it significantly more efficient.

Chloroplast Structure and Function: Chloroplasts, the site of photosynthesis, contain thylakoid membranes (where light reactions occur) and the stroma (site of the Calvin cycle).

Oxidative vs. Photophosphorylation:

• Oxidative phosphorylation occurs in mitochondria, using energy from NADH and FADH2 to generate ATP.

• Photophosphorylation happens in chloroplasts, where light energy drives ATP production.

Photosynthesis vs. Cellular Respiration:

• Photosynthesis: An endergonic process that converts light energy into glucose (6CO2 + 6H2O → C6H12O6 + 6O2).

• Cellular Respiration: An exergonic process that releases energy from glucose (C6H12O6 + 6O2 → 6CO2 + 6H2O + 29 ATP).