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3.2 Photosynthesis 🌳


Introduction to photosynthesis

Photosynthesis is a core JC2 topic in H2 BIO A levels. It comprises the light dependent reaction and Calvin cycle. These processes occur in the thylakoids and stroma of the chloroplast predominantly found in plant mesophyll cells. Depending on the type of plant (C3, C4, CAM), photosynthesis may differ. But the outcome remains the same, eventually producing glucose and storage in the form of starch.
This topic is an important prerequisite for climate change. Also, it builds upon the foundation of biomolecules.

Materials for photosynthesis

Phrasing errors

  • In the light, light dependent reactions occur, Calvin cycle cannot occur.
  • Carbon dioxide is used to fix RuBP.
  • Transfer of electrons occurs in light harvesting complexes.
  • Per Calvin cycle 1 glucose molecule is produced, of which the excess are stored subsequently.

Exam tips

  • There are strong links with cellular respiration, prep the 2 topics together in anticipation of essays.
  • Instead of memorizing the intermediates of the Calvin’s cycle, understand and account for the way the carbon containing molecules differ in each of the 3 phases.
  • Many schools do not describe the concept of C3 plants. You must know the significance of the term as well as what it means to the efficacy of photosynthesis.
  • There are 2 ETCs in the light dependent reactions each with a different outcome/purpose, know the difference.