Essay by laola1988High School, 11th gradeB, October 2003

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In this coursework I'm going to investigate the factors that affect the rate of photosynthesis, but first am going to explain:

1. What photosynthesis is?

2.What the rate of photosynthesis is?

3.And list the factors that affect photosynthesis.

The aim of my experiment was to see whether intensity of light would affect the rate of photosynthesis in a plant. To do this, I placed a piece of Canadian pondweed in varying light intensities, and observed the amount of oxygen being given off. I used Canadian pondweed because of its unusual quality of giving off bubbles of gas from a cut end, when placed in water.


Plants produce their own food. This is why they are called producers.All organisms, including you, depend on plants for food. The method plant use to produce food is called photosynthesis.

Photosynthesis is a chemical reaction and it can be written down as a word equation:

Carbon Dioxide + Water (Light energy) = Glucose + Oxygen

reactants prducts

( raw materials )


The rate of photosynthesis is how fast it is happening.

We can often measure this by finding out how much glucose or O2 is produced in a certain time.

Background information:

The rate of photosynthesis is affected by a number of factors including light levels, temperature, availability of water and availability of nutrients. If the conditions that the plant needs are improved the rate of photosynthesis should increase.

the maximum rate of photosynthesis will be constrained by a limiting factor. This factor will prevent the rate of photosynthesis from rising above a certain level even if other conditions needed for photosynthesis are improved. This limiting factor will control the maximum possible rate of the photosynthesis reaction.

The fact that all plants need light...