A graph shows the rate of photosynthesis measured as oxygen produced (cm³ per minute) at different temperatures ranging from 5°C to 45°C. The rate increases from 5°C to 30°C, peaks at 30°C with 12 cm³/min, then decreases sharply at higher temperatures.
Calculate the difference in oxygen production rate between 30°C and 40°C. Use 12 cm³/min at 30°C and read the 40°C value from the graph (estimate).
Show answer, mark scheme and Mentor explanation
MP1: Uses/identifies 12 cm³/min at 30°C and an estimated value at 40°C read from the graph (allow ≈ 5 cm³/min).
MP2: Calculates the difference: 12 − 5 = 7 cm³/min (allow answers consistent with their read-off).
Can you spot the two things the mark scheme needs here?
This 2-mark question is testing whether you can do both parts of the calculation. First, you need to use the given 12 cm³/min at 30°C and read an estimated value at 40°C from the graph. The mark scheme allows about 5 cm³/min at 40°C. Then you calculate the difference between the two values. Using 12 and 5 gives 7 cm³/min. If your 40°C estimate is slightly different, the calculation mark can still be awarded if it matches your own read-off.