The table shows a set of results obtained by students investigating the effect of light intensity on photosynthesis. They varied the distance of the plant from the light source.
|Distance from light source in cm||Rate of photosynthesis = Number of bubbles produced per minute|
If we draw a graph of this data:
Note that the graph is a curve.
From the graph, suggest the rate of oxygen production after 18 minutes.
40 bubbles per minute.
Using the graph:
The effect of the presence or absence of chlorophyll on photosynthesis can be investigated using a variegated plant. Variegated plants have regions of their leaves with, and without, chlorophyll.
Only those areas of the leaf with chlorophyll photosynthesise. They will test positive for starch, which is built up from the glucose produced.
One way of testing for starch on a leaf is to remove the chlorophyll and then stain it to see where the starch had been stored.
Care must be taken when using boiling ethanol. Make sure that no Bunsen burners are turned on as the ethanol is highly flammable.