The Effect of Light Intensity and Temperature on the Rate of Photosynthesis

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The Effect of Light Intensity and Temperature on the Rate of Photosynthesis

Aim

The aim of my experiment is to determine whether intensity of light

and temperature would affect the rate of photosynthesis in a plant. To

do this, I will place a piece of pondweed in varying light intensities

and temperatures, and observe the amount of oxygen being given off. I

am using pondweed because of its unusual quality of giving off bubbles

of gas from a cut end, when placed in water.

Introduction

Photosynthesis occurs only in the presence of light, and takes place

in the chloroplasts of green plant cells. Photosynthesis can be

defined as the production of simple sugars from carbon dioxide and

water causing the release of sugar and oxygen.

The chemical equation for photosynthesis can be expressed as:

(light)

6CO2 + 6H2O-------------- C6H12O6 + 6O2

(In the presence of chlorophyll)

The word equation:

Carbon dioxide + Water------------ Glucose + Oxygen

The fact that all plants need light in order to photosynthesise has

been proven many times in experiments, and so it is possible to say

that without light, the plant would die. The reason that light

intensity does affect the rate of photosynthesis is because light is

the source of energy which, falls on the chloroplasts in a leaf and is

trapped by the chlorophyll, which then makes the energy available for

chemical reactions in the plant. Thus, as the amount of sunlight, or

in this case light from a bulb, falls on the plant, more energy is

absorbed, so more energy is available for the chemical reactions, and

so more photosynthesis takes place in a given time.

The...

... middle of paper ...

...ary the amount of CO2. The plant would be

kept at a constant distance from the lamp and a constant volume of

water would be added to the sodium hydrogen carbonate. Another

experiment using almost identical apparatus would be to vary the color

of the light the plant absorbs. Using translucent color filters in

front the lamps could vary this. Since light wave length has already

been identified as a variable of photosynthesis, it would be

interesting to actually test it. The only problem of this experiment

is that there is no way to define or "measure" the color of light.

Wave length would be a solution but this cannot be measured with

available equipment. We only have a general idea of how to class

colors. Because of this, the colored light experiment should not be

taken as seriously as light intensity or carbon dioxide.

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