Rate of Photosynthesis P1

Question 1

What plant do we use to investigate the effect of light intensity?

Answer 1

Canadian pondweed - produces oxygen corresponds to rate of photosynthesis

Question 2

Explain the practical to investigate the effect of light intensity on the rate of photosynthesis.

Answer 2

1. place white light a set distance from pondweed
2. let plant photosynthesise for set time.
3. at end syringe used alongside rular and length of gas bubbles is measured. This is proportional to volume of O2 produced.
4. variables like temperature and time should be controlled
5. repeat twice at same distance and find mean
6. repeat with light source at different distances from pondweed

Question 3

How could you alter the light experiment to measure effect of temperature and CO2?

Answer 3

1. place test tube of pondweed into water bath.
2. measure amount of sodium hydrogencarbonate that can be dissolved in water as this gives of CO2

This can be repeated with different temperatures of water and concentrations of sodium hydrogencarbonate