Photosynthesis

• Photosynthesis uses light energy to change carbon dioxide and water into glucose and oxygen.
• It takes place in chloroplasts in the green pigment called chlorophyll that absorbs light.
• Photosynthesis is endothermic (energy is transfered from the enviroment during the reaction)

Plants use the glucose from photosynthesis:

1) For respiration, plants use the glucose from photosynthesis for respiration.

2) Making cellulose,glucose is converted into cellulose to make the cell walls stronger/

3) Making amino acids, glucose is combined with nitrate ions (from the soil) to make amino acids which are then made into proteins.

4) Converted to lipids to be stored in seeds.

5) Stored as starch, glucose is turned into starch and stored in roots, leaves and stems, so that it can be made back into glucose when the plant cannot do photosynthesis such as in the wintor. Starch is insoluble whereas glucose is soluble, this means that if glucose was stored it would draw in lots of water and swell up.

The rate of photosynthesis.

1) Limiting factors: things that stop the rate of photosynthesis.

• Night time- theres no light, so light is the limiting factor.
• In winter the temperature is the limiting factor.
• when its warm and bright enough the amount of CO is usually limiting.
• When the plant has a disease which means theres enviromental stress or lack of neutrients the chloroplasts can be effected and not make enough chlorophyll, so in this case chlorophyll is the limiting factor.

2) By increasing the levels of either CO / light intensity / temperaure over a short period the rate of photosynthesis will steadily increase but there will be a point when there not enough of the other two…