Observation

This question was one of the unpopular questions answered by candidates because of its mathematics nature. The candidates that knew it scored high marks in plotting the graph. However, some candidates did not obey the instruction given and the scales provided. Some candidates also interchanged the axes. Some candidates did not also title the graph, hence losing marks. Some candidates could state the effect of light intensity on the rate of photosynthesis. Many candidates could state other factors that affect the rate of photosynthesis. Many candidates lhe nost marks to the spelling of tame of the enzymes and the part of the alimentary canals of humans where the enzymes are most active.

The expected answer are:

(a) (i) Graph

Note: Wrong axes, no score for graph; Wrong scale, no mark for scale; The two scales must be correct to score.

(ii)Effect of light intensity on the rate of photosynthesis

The rate of photosynthesis rises steadily; with increasing light intensity up to a point/optimum light intensity; the optimum point is maintained; and further increase in the light intensity does not result in a corresponding rise in the rate of photosynthesis/levels up.

(iii)Other factors affecting the rate of photosynthesis

- Carbon dioxide concentration;

- Chlorophyll concentration;

- Temperature;

- Water;

- Leaf structure;

- Product accumulation (e.g Oxygen concentration- high concentration);

- Pollution; sulphur oxide and ozone damage leaves;

- Inhibitors e.g. urea.

Note: spellings must be correct to score.

(b) (i) Enzymes that digest starch

- Amylase

- Ptyalin

Note: spellings must be correct to score.

(ii) Parts of the alimentary canal where the enzymes are most active

- Duodenum;;

- Mouth

Note: spellings must be correct to score.