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Photosynthetic membranes and organelles

The typical plant leaf includes the following

  • Upper and lower epidermis – the upper epidermis is the outer layer of the cells that controls the amount of water that is lost through transpiration.
  • Stomata – these are pores (holes) in the leaves that are responsible for the exchange of gases between the plant leaves and the atmosphere.  Carbon dioxide is absorbed from the atmosphere and oxygen is released.
  • Mesophyll – these are photosynthetic (parenchyma) cells that are located between the upper and lower epidermis. These cells contain the chloroplasts.
  • Vascular bundle – these are tissues that form part of the transport system of the plant.  Vascular bundles consist of xylem and phloem vessels which transport water, dissolved minerals and food to and from the leaves.

Process of Photosynthesis (step-by-step)

The light-dependent reactions and the Calvin Cycle are the two main stages of photosynthesis in plants.

Light-dependent Reactions

The first stage of photosynthesis is the light dependent reactions.  These reactions take place on the thylakoid membrane inside the chloroplast.  During this stage light energy is converted to ATP (chemical energy) and NADPH (reducing power).

Light-dependent Reactions