Paper 2 Specimen (set 1) - Q3 Answers
Questions
3) A scientist investigated the effect of light intensity on the rate of photosynthesis of the aquatic Cabomba plant.
A lamp was used as a source of light. The lamp was placed at different distances (d) from the Cabomba plant, and the number of bubbles produced in 60 seconds was counted.
The number of bubbles produced in 60 seconds was used to calculate the rate of photosynthesis.
The light intensity was then calculated using the inverse square law:
3) A scientist investigated the effect of light intensity on the rate of photosynthesis of the aquatic Cabomba plant.
A lamp was used as a source of light. The lamp was placed at different distances (d) from the Cabomba plant, and the number of bubbles produced in 60 seconds was counted.
The number of bubbles produced in 60 seconds was used to calculate the rate of photosynthesis.
The light intensity was then calculated using the inverse square law:
Figure 6 shows the scientist’s results.
(a) (i) Calculate the light intensity when the lamp is 25cm from the Cabomba plant. [2 marks]
light intensity = ........................................ arbitrary units
(ii) Use information from Figure 6 to describe the effect of light intensity on the rate of photosynthesis. [2 marks]
(iii) Give another method of measuring light intensity rather than calculating it. [1 mark]
(iv) The scientist counted the number of bubbles produced by the Cabomba plant.
Another scientist stated that this was not the best method of measuring the volume of gas produced.
Explain how you could improve the method to measure the volume of gas released more accurately. [2 marks]
(b) Explain what would happen to the levels of gas produced if the light intensity decreased to 0.0001 arbitrary units. [2 marks]
(Total for Question 3 = 9 marks)
(iii) Give another method of measuring light intensity rather than calculating it. [1 mark]
(iv) The scientist counted the number of bubbles produced by the Cabomba plant.
Another scientist stated that this was not the best method of measuring the volume of gas produced.
Explain how you could improve the method to measure the volume of gas released more accurately. [2 marks]
(b) Explain what would happen to the levels of gas produced if the light intensity decreased to 0.0001 arbitrary units. [2 marks]
(Total for Question 3 = 9 marks)