question_answer

  Wenyong set up an experiment to investigate the effect of light on photosynthesis (see diagram). He counted the number of bubbles of oxygen gas produced. His results are given in the table

Disance of lamp from tube (cm)	20	40	60	80	100	120
Number of bubbles per minute	24	12	7	4	2	2

(a) Plot a graph with the independent variable of distance on the x-axis and the dependent variable of number of bubbles on the y-axis. (b) Explain the shape of the graph.

Answer:

                  (a)    Number of bubbles (per minute)              (b) The further away the light is from the plant, the lower the light intensity. Light is needed for photosynthesis so less photosynthesis takes place and fewer bubbles of oxygen gas are produced.