biology - how light intensity affects the rate of photosynthesis

Biology Coursework ¡V Does The Light Intensity

Affect the Rate of Photosynthesis

The Investigation

In this experiment I will investigate the affect in which the light intensity will have on a plants photosynthesis process. This will be done by measuring the bubbles of oxygen and having a bulb for the light intensity variable.

Variables

The input variable which will be used in this investigation will be the light intensity (this will be a 100Watt bulb being moved closer and further away from the plant). The outcome variable which will change as a result of this experiment will be the amount of oxygen made in the experiment due to the amount of light intensity increases (causing the plant to photosynthesise more).

Prediction

I predict that as the input variable, the light intensity increases (the light moved towards the plant) the outcome variable, the amount of oxygen, produced from photosynthesis will be larger.

Plants can absorb and use light energy because they have a green pigment, chlorophyll, contained in the chloroplasts in some of their cells. Chlorophyll allows the energy in sunlight to drive chemical reactions. Chloroplasts act as a energy transducers, converting light energy into chemical energy. So as the plant has more light the chlorophyll inside the chloroplasts can react faster absorbing in more light for food and energy.

The equation for photosynthesis can help to predict the outcome of the investigation.

Light Energy

Carbon Dioxide + Water --------------„³ Glucose + Oxygen

Chlorophyll

This shows that there could be three variables in this experiment, carbon dioxide, water and light energy. So in our case the variable light energy (light intensity) will be used. The equation also shows that if there is more light energy then more glucose and oxygen will be produced.

I also predict that as the light is moved closer to the plant there will be more bubbles (oxygen) produced due to the increase of photosynthesis speed explained above. So in conclusion I predict that the more light intensity there is on the plant the faster the rate of photosynthesis there will be.

Fair Testing

The fair testing will be carefully checked so the results do not come out to be void. The light intensity will be changed for it is the only variable used in the experiment. Though the temperature, watt of the bulb, amount of water, size of the plant and posit...

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... in the chloroplasts in some of their cells. Chlorophyll allows the energy in sunlight to drive chemical reactions. Chloroplasts act as energy transducers, converting light energy into chemical energy. So as the plant has more light the chlorophyll inside the chloroplasts can react faster absorbing in more light for food and energy.¡¨ So this shows my prediction was correct for in my experiment and shown in my result table and graph the more light intensity there is on a plant the higher the rate of my photosynthesis will be. My prediction is very close to what I said the results will be so my prediction was correct and has been proven to be correct in my result table, graph and now explained again in my conclusion.

In conclusion the experiment was carried out and had great success proving my prediction to be correct and enabling solid and valid results which were able to be put in a graph. I believe my prediction could have been more accurate or more backed up if I had made a quantitative prediction. Though what I believed would happen did happen during the experiment which helped to understand the graph and the results which led me to be able to write a thorough report on them.