5.2.1. Photosynthesis

• The light-dependent reactions take place in the thylakoid membranes of the chloroplasts.
• A herbicide disables a proton pump in photosystem II, explain how it would kill a susceptible plant

  reduced proton pumping means less chemiosmosis>phosphorylation stops> less ATP produced> less reduced NADP produced> no calvin cycle/ carbon fixation/ light independent stage> plus no TP/ (hexose) sugars made> no respiratory substrate
• Why do plants only convert a small percentage of sunlight they receive into chemical energy?

  • not all light hits chlorophyll
  • not all light hitting leaves is absorbed, can be reflected, transmitted through the leaf or of the wrong wavelength
  • other limiting factors