Biology A2 Jan 2003 Planning exercise Watch
You are required to plan an investigation to find out the relationship between the transpiration of a shoot and the degree of opening of the stomata of its leaves
I came up with separate methods of determining each factor i.e. using the nail varnish impression for stomata density and using a potometer for transpiration rate.
1) I do not know what to keep constant and what to vary?? Basically, I do not know the investigation's main process
2) by "degree of opening" do they mean determining the actual diameter of the stoma or can we, more easily, just find out how many stomatal pores are open within a given area?
Any help would be most appreciated
I'd say you could use the number of pores open as a measure of the degree of stomatal opening; with the equipment you have available at A level I can't imagine it'll be easy to measure how much the pores are open by!
Sounds like you need to vary the transpiration rate, so you need to pick something that affects transpiration. At a guess, temperature would be a good one. I'd keep everything else constant.
Sorry if any of this is grossly inaccurate! Hope it helps a bit.
As it increases, stomata should open so you should see transpiration rate increase.