In this slideshow we will be focusing on the subject of photosynthesis. We will explore two primary questions, what is photosynthesis and what are the stages of photosynthesis.

What is photosynthesis?

Photosynthesis is the terminology for the way in which plants produce sustenance for themselves. Unlike animals most plants cannot simply eat a plant or animal in order to stay alive they need to sustain themselves in other ways. This way is photosynthesis, the plants combine CO2 that they harvest from the air and combine it with water (H2O) and nutrients that they absorb from the soil. However they cannot do this without energy and what is better than solar energy. Solar energy is energy that is harvested from the light of the sun. Now that the plant has energy it is able to turn the CO2 and water (H2O) into glucose (sugar) and oxygen (O2).

Below is The Photosynthesis Reaction:

Light + 6CO2 + 12H20 --> C6H12O6 + 6O2 + 6H20

Stages of photosynthesisWhilst photosynthesis is a

very broad and complicated subject the four stages of photosynthesis are actually very easy to understand and follow. There are four stages of photosynthesis:

Light absorptionElectron transportGeneration of ATPCarbon fixation

Stage 1 (Light Absorption)

The first step in photosynthesis is the absorption of light. This is the plant harvesting the energy it will require for photosynthesis from solar energy in sun light. Light is absorbed by the chlorophylls which are attached to proteins in the thylakoid membranes. This energy is used to separate electrons from the water and other nutrients that the plant has absorbed from the soil. The electrons are then sent to a primary electron acceptor.

Stage 2 (Electron transport)The electrons then continue from the primary electron acceptor through the thylakoid membrane until they meet the ultimate electron acceptor which is usually NADP+ and changing it into NADPH. The electrons are then coupled with protons coming from the stroma to the thylakoid lumen which forms a pH gradient across the thylakoid membrane.

Stage 3 (generation of ATP)For the generation of ATP 3

things occur:The protons move down their

concentration gradient as they move from the thylakoid luman to the stoma which couples them to the synthesis of ATP.

The electron pairs will be passed from NADH and FADH2 to a series of other lower-energy carriers

The drop in energy this achieves is used to make ATP.

Stage 4 (carbon fixation)The final stage of photosynthesis in carbon fixation. In this the

ATP4- (Protons) and NADPH are used as the fuel cells if you will for synthesising the polymers of the six-carbon sugars from the CO2 (carbon dioxide) and H2O (water). The Carbon dioxide then joins with the hydrogen to make glucose (sugar). What separates stage four from the other three is that it can be performed in darkness, using the ATP and NADPH stores it has collected during the day. This gives it the nickname the dark reaction.