Explain the role of enzymes in living cells

​(a) Explain the role of enzymes in living cells (1mk)

• Enzymes speed up/slows down the rate of chemical reaction/metabolism in the body; without being used up

​(b) The graph below shows the effects of temperature on the rate of reaction of the enzymes salivary amylase

The graph above shows the effects of temperature on the rate of reaction of the enzymes salivary amylase

​(i) Account for the changes in the curve between C and D (1mk)

• The rate of reaction decrease/drop as temperature increase (beyond 40 degrees C) due to denaturation of enzymes

​(ii) What does the dotted line represent? (1mk)

• Normal human temperature/the optimum for the enzyme salivary amylase

​(c) Explain how the following factors affect the rate of enzyme activity
(i) Temperature (2mks)

Enzyme are proteinous in nature; are sensitive to temperature, changes/ work best within narrow range of temperature /have maximum activity at optimum temperature; temperatures above optimum destroy enzymes structure/denature enzyme  while those  below optimum lower enzyme activity  due to inactivation enzymes.

​(ii) Substrate concentration (2mks)

Increases in substrate concentration increases enzyme activity up to a certain level; this is due to an increase in the number of active sites; until all active sites of the enzyme are occupied.