Does raising the light intensity increase the rate of photosynthesis?

Does raising the light intensity increase the rate of photosynthesis?

Aim: To see if raising the light intensity increases the rate of

photosynthesis.

Prediction:I predict that raising the light intensity will increase

the rate of photosynthesis. I think this because light is the most

important thing needed for photosynthesis. I then think that the rate

of photosynthesis will stay the same when it reaches a certain point.

I think this because the plant may use up all of the carbon dioxide

(Sodium hydro carbonate) and the plant can have as much light as it

needs but if it does not have any carbon dioxide it will not be able

to photosynthesise. The temperature also has to be right. If it is too

hot the enzymes will be destroyed and the plant will not be able to

photosynthesise. The temperature and the amount of carbon dioxide are

called the limiting factors.

I think a graph of the results would look like this:

Apparatus list:

* Piece of weed

* Paperclip

* Sodium hydro carbonate

* Water

* Test tube

* Beaker

* Lamp

* Stopwatch

* Scissors

* Spatula

* Meter Rule

* Glass Rod

* Measuring Cylinder

Diagram:

Method:

1. Collect the equipment on the equipment list.

2. Darken the room, so that the plant cannot use light for

photosynthesising from other places.

3. Cut a piece of weed that is about 5 cm long.

4. Put a spatula measure of sodium hydro carbonate in a test tube

with 40ml cold tap water and stir. This provides the plant with

enough CO2 to photosynthesise.

5. Fill a 1000ml beaker with 700ml water and put the test tube into

it. This will act as heat shield from the lamp, so that the

temperature will not affect the experiment.

6. Put the weed in the test tube with the cut end facing upwards.

7. Put the lamp 10cm away form the beaker and switch on.

8. Leave the weed to adjust to the conditions for 1 minute.

9. Time one minute and count the bubbles coming out of the cut end

of the leaf for 1 minute.

10. Record the results in a table.

11. Then do the whole experiment 3 times for accuracy, then find the

average and record in your table.

12. Do the whole experiment 6 times for 20cm, 30cm, 40cm, 50cm, and

60cm away from the lamp.

Fair Test: To make this a fair test I will not let any of the

variables change apart from the light intensity because this is part