how the concentration of carbon dioxide affects the rate of photosynthesis

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In this course work, I will be discussing how the concentration of carbon dioxide affects the rate of photosynthesis. To find this out I will do an experiment to find out how much oxygen a piece of Elodea (Canadian pondweed) produces over a set period under controlled supervision.

Back Ground Knowledge

All plants photosynthesise, They do this in order to create their own food by converting sunlight, carbon dioxide and water into glucose and oxygen, which is a by-product (6Co  + 6H O  C H O + 6O ) Plants have a part in their cell called chloroplast which contain chlorophyll the diagram below explains:

What are the limiting factors of photosynthesis?

Although the diagram shows you what you need for photosynthesis it does not tell you what the limiting factors are. The limiting factors in photosynthesis are carbon dioxide, water, light and chlorophyll. This is because up to a point the more of each factor that is available to the plant will result in an increase in the photosynthesizing rate.

Why did I use pondweed?

I used pondweed so I could measure the amount of oxygen it produced accurately. I can do this by catching the oxygen bubbles under water, because of this choosing an aquatic plant was the best choice. I will use 5cm of elodea because it is a big enough piece to get a measurable result. I will know how quickly the elodea has photosynthesised by taking readings of how much solution was left in the burette after 24 hours and again after 48 hours.

Why use the sodium bicarbonate?

I used sodium bicarbonate solution in the experiment because it reacts with water to make carbon dioxide, which meant I could control the amount of carbon dioxide available to the pondweed. However, because of the time limitations I got my results by sharing the class results, this meant that I had to use the following concentrations of sodium bicarbonate: 0% 1.25% 0.5% 1% 5%. I used these percentages so that I had a good range of percentages but this didn’t give very good results because I made a big jump from 1% to 5%. If I did the experiment, again I would use these percentages: 0% 0.5% 1% 2% 3% 4%and 5% so that it had a steady increase.

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How will I control the variables other than the Co  concentration?

To control the other variables (water, light and chlorophyll). I will be using a set amount of water, I will be using the same lamps at the same voltage and I will be using a set amount of pondweed so that the amount of chlorophyll level should be the same. They will all have the same window letting in natural light and the temperature will be the same because they are in the same room.

Plan

I plan to set up an experiment using pondweed to see ...

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