Paper 1 H - SAMPLE SET 1 Q17
17) Puj investigates how light intensity affects the rate of photosynthesis in pondweed.
The diagram shows how he sets up his investigation.
The diagram shows how he sets up his investigation.
Puj places the lamp at distances 10 cm, 30 cm, 50 cm, 70 cm and 90 cm from the beaker.
At each distance he counts how many bubbles of oxygen gas the pondweed gives off in 1 minute.
(a) (i) Puj counts the number of bubbles to get a measure of the amount of gas given off in photosynthesis.
Why is counting bubbles not an accurate way of measuring the amount of gas given off? [2]
(ii) Bob’s teacher says that collecting the gas, for example in a gas syringe, would give a more accurate measurement. Explain why. ……………………………………………………………………………………............. [1]
(b) (i) Sketch a line on the axes below to show the results you would expect. [2]
At each distance he counts how many bubbles of oxygen gas the pondweed gives off in 1 minute.
(a) (i) Puj counts the number of bubbles to get a measure of the amount of gas given off in photosynthesis.
Why is counting bubbles not an accurate way of measuring the amount of gas given off? [2]
(ii) Bob’s teacher says that collecting the gas, for example in a gas syringe, would give a more accurate measurement. Explain why. ……………………………………………………………………………………............. [1]
(b) (i) Sketch a line on the axes below to show the results you would expect. [2]
(ii) Explain the shape of the graph. Two explanations are required. [2]
(c) (i) Describe how and where oxygen is produced in photosynthesis. [3]
(ii) Explain why the amount of oxygen gas given off is not a true measure of the rate of photosynthesis.
(Total for Question 17 = 12 marks)
(c) (i) Describe how and where oxygen is produced in photosynthesis. [3]
(ii) Explain why the amount of oxygen gas given off is not a true measure of the rate of photosynthesis.
(Total for Question 17 = 12 marks)