Rate of Photosynthesis in Pond-Weed

Rate of Photosynthesis in Pond-Weed

Plan

The aim of this activity is to investigate one of the factors that

affect the rate of photosynthesis in pond-weed. I am trying to find

out if the distance of the pond-weed from a lamp will change the rate

of photosynthesis. I will measure the rate of photosynthesis by

counting the number of bubbles that are released by the stem of the

pond-weed when the lamp is shone on it from different distances. What

I think will happen is as the pond weed is moved further away from the

lamp, less bubbles will be produced. I think this will happen because

the light intensity will be less on the pond-weed as it gets further

from the lamp therefore the rate of photosynthesis will not be as

high. The word equation for photosynthesis is:

Carbon Dioxide + Water = Glucose + Oxygen + Energy

Pond-weed is being used fro this experiment because with a normal

plant that does not live in water it would be a lot more difficult to

view photosynthesis taking place because you can not see bubbles being

produced. To make this a fair test we are going to make sure the

temperature is the same for every reading we take. I am going to

record the rate of photosynthesis on 10 different distances, three

times each.to ensure the results are accurate.

For this experiment I am going to need;

-A lamp

-About 4cm of pond-weed (Elodea)

-A paperclip

-Sodium Hydrogen Carbonate

-A metre rule

-A stopwatch

-A thermometer

-A test tube

I can't think of any major risks in this experiment just make sure not

to break the thermometer because it contains mercury, which is

poisonous.

-First of all plug the lamp into a plug power socket.

-Attach a paperclip to the top of the 4cm of Elodea you have cut so

that the Elodea can be held upside down.

-Place the Elodea into a test tube and fill with water.