Investigating Factors that Affect the Rate of Photosynthesis in Elodea

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Investigating Factors that Affect the Rate of Photosynthesis in Elodea

Aim: To find out which factors affect the rate of photosynthesis in

Elodea.

Variables: The variables that might affect the rate of photosynthesis

in this experiment are:

Temperature: When the temperature rises so does the rate of

photosynthesis; this is because as the temperature around the plant

rises the enzymes controlling photosynthesis inside the chloroplasts

heat up and start moving around faster, the fast moving molecules

collide with other fast moving enzymes causing them to react.

The rate of diffusion of carbon dioxide into the leaves will also ride

as temperature does. This happens because fast moving carbon dioxide

molecules will hit the surface of the leaf far more often than in a

colder atmosphere therefore more molecules will be taken into the leaf

and diffusion will happen faster. However, the rate of photosynthesis

will only keep on rising until the temperature reaches 45'c at that

temperature the enzymes in the chlorophyll will be destroyed and

photosynthesis will stop all together. On the other hand, if the

temperature is too cold then temperature will become the limiting

factor and the enzymes will stop working.

Carbon dioxide: The amount of carbon dioxide in the atmosphere around

the elodea affects the rate at which it will photosynthesise. The

plant needs carbon dioxide to react with water molecules to make

glucose. If there isn't enough carbon dioxide for the plant to take in

the plant wouldn't have enough glucose or food and would die. For the

plant to keep on photosynthesising at a steady rate there needs to be

plenty of water and the temperature needs to be kept at a certain

level because once carbon dioxide is no longer the limiting factor

simply giving the plant more wont have any effect.

Light intensity: It is impossible for plants to photosynthesise in the

dark and they can only photosynthesise slowly in dim light, this is

because the light energy splits up the water into hydrogen and oxygen

it does this by releasing a highly charged electron when sunlight is

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