In mesophiles, growth rates increase gradually as the temperature is increased, until the optimum growth temperature for the organism is reached. If the temperature is increased beyond the optimum, .

Growth rate of the mesophiles decreases as the temperature increases.

Explanation:

The growth rate of the mesophiles will decrease on increasing the temperature because mesophiles defines the condition which ranges in between 20 and 45 °C (68 and 113 °F).

If the temperature of the environment is more or below this range then the growth rate of the bacteria will be affected.

These are the bacteria which is found in plain regions as the temperature there is optimum for their growth.

b.