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Photosynthesis is the process by which Carbon dioxide and water are converted into Glucose and Oxygen, with the help of the sun. This is an extremely important process of life on earth as we now it. Without Photosynthesis we could not survive.

Photosynthesis is used by plants and some unicellular organisms to create their own food source. This means they are Autotrophic.


An interesting plant that you may come across is the Venus fly trap. These are carnivorous plants and although this plant eats insects, it still undergoes photosynthesis.

The insects it eats are used for nitrogen, as these plants often grow in nitrogen poor soil

Overall these plants are considered to be autotrophic


Photosynthesis converts light energy into chemical energy, stored as sugars.

The formula for Photosynthesis is:

However you will often see the equation written without water on the right, and only 6 on the right side, (as seen below) because we are concerned with the net production of water.

Photosynthesis occurs in the chloroplast's of the cell. These little green organelles are filled with, among other things, chlorophyll, a green fluid which is responsible for catching sun light.

Chlorophyll is found in plants, algae, purple and green bacteria and cynobacteria.

Chlorophyll captures light energy and assists in forming ATP.

Chloroplast the reason for being green  


Factors affecting photosynthesis (click here for more information)

Just briefly we will discuss the factors which can affect photosynthesis. There are three main factors which affect photosynthesis, they are:

             The amount of light obviously affects the rate of photosythesis. Without an              andequet light source choloplast can not split water molecules, providing the              raw materials to produce glucose. Also the intensity of light can affect the rate              of photosynthesis. Plants absorbs Blue and Red light much more efficiently than              green.

             The amount of Carbon dioxide in the atmosphere can also affect the rate of              photosynthesis. With Carbon dioxide, plants can not synthesise Glucose.

              As with most cellular processes, temperature can make or break the reaction.               To high and enzymes which catalyse the reaction denature, to low and cells can               move as efficiently, slowing down the process. Often in the temperatures are               not correct, the plant will go into a state of dormancy, and wake up when               conditions are favourable.

As stated in the video above

Within these chloroplast are flattened membranes called Thylakoid. These thylakoids are stacked on top of each other, forming columns through out the organelle. These columns are called granums. The light dependant stage occurs in these thylakoid membranes (more detail bellow). They are filled with chlorophyll and other light catching pigments.

The Stroma is the space within the chloroplast. This is where the Light - independent phase of photosynthesis occurs. This phase is also know as the Calvin cycle (more bellow).  

Chloroplast Formula Photosynthesis + Photosynthesis Quiz

Click here for a document of the questions in the quiz above

Click here to see a practical on cellular respiration and photosynthesis

The two stages of photosynthesis are shown in the animation bellow

An important part of photosynthesis is the light and dark phase.

That’s right, Light and DARK phase. Photosynthesis is made up of two phases a light phase, which requires sunlight, and a dark phase, which can be completed in the absence of light.

Light dependant phase

Above you can see the equation for the light dependant phase. This process requires light to split the water molecule into Hydrogen and oxygen. When we break the molecule we release energy, which is captured to form ATP. Hydrogen and ATP will continue onto the next phase, however oxygen will not.

This reaction occurs in the membranes of the thylakoid

Light independent phase (Calvin Cycle)

Above you can see the equation for the light independent phase. This phase does not require light. This process is called the Calvin Cycle. It uses the ATP and Hydrogen ions created from the light dependant phase, along with Carbon dioxide, to create Glucose and water.

This reaction occurs in the Stroma of the chloroplast.

2 stages of photosynthesis

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