(a) The graph shows the effect of pH on the activities of three enzymes, X, Y and Z.
These enzymes help to digest food in the human digestive system.
Each enzyme is produced by a different part of the digestive system.
Activity of
enzyme
Enzyme X
Enzyme Z
Enzyme Y
1 2 3 4 5 6 7 8 9 10
pH
(i)
What is the optimum (best) pH for the action of enzyme Z?
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(ii) The stomach makes a substance that gives the correct pH for enzyme action in the
human stomach.
Name this substance.
(iii) Which enzyme, X, Y or Z, will work best in the human stomach?
