Photosynthesis in green plants may be represented by the equation:
carbon dioxide + water $\xrightarrow{\text{light and chlorophyll}}$ carbohydrate + oxygen
A student used the apparatus shown in Fig. 2.1 to examine the rate of photosynthesis in an aquatic plant.
After the student turned the lamp on, bubbles of oxygen were produced and drawn into the syringe. The student noted the volume of oxygen made in ten minutes. The syringe was then topped up with sodium hydrogencarbonate solution and the oxygen was collected for a further ten minutes.
The student then chose to test how different colours of light affected the rate of photosynthesis. With the same plant left in the glass jar, a red transparent filter was wrapped around the glass jar so that the plant received only red light. The volume of oxygen made in ten minutes was measured. This measurement was then carried out again.
Next, the red transparent filter was swapped for a green transparent filter and then for a blue transparent filter. For each filter, the volume of oxygen made in ten minutes was also measured twice.
The measurements are shown in Table 2.1.
(a(i))[1]
Enter the volume of oxygen made in measurement 2 with the blue filter in Table 2.1.
(a(ii))[1]
Work out the mean volume of oxygen made with the blue filter, and enter it in Table 2.1.
(a(iii))[1]
Using the mean value, work out the rate of photosynthesis per minute when no filter was used.
(b(i))[4]
Draw a bar chart on the grid to show the mean volume of gas collected with no filter and with the different coloured filters.
(b(ii))[1]
Use the data provided and the bar chart to state one conclusion that can be drawn from the results of this investigation.
(c)[6]
Plan an investigation that you could do to determine the effect of light intensity on the rate of photosynthesis, using the apparatus shown in Fig. 2.1.
Worked solution & mark scheme
This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: “0.4” …