required practical - photosynthesis

Question 1

what is the practical for

Answer 1

to test the effect of light intensity on the rate of photosynthesis

Question 2

explain the process of the practical

Answer 2

1. take a boiling tube and place 10 cm away from LED light
2. fill boiling tube with sodium hydrogen carbonate solution which releases co2
3. put a piece of pondweed into the boiling tube with the cut end on the top
4. leave for five minutes - to acclimate to conditions
5. should see bubbles of oxygen. start stopwatch. count the amount of bubbles produced in one minute and repeat this multiple time sand calculate a mean
6. do the whole experiment again from the start at 20cm then 30, 40

Question 3

what is one problem of the experiment

Answer 3

the number of bubbles produced can be too fast to count accurately

Question 4

what is another problem of the experiment and how can both of these be solved

Answer 4

the bubble aren’t always the same size

• solve by measuring the volume of oxygen produced. place pondweed under a funnel and catch the bubbles in a measuring cylinder with water

Question 5

explain the inverse square law

Answer 5

if the distance is doubled, the light intensity falls by four times. because light is needed for photosynthesis, that also causes the number of oxygen bubbles to fall by four times