Question

A reaction is catalysed by an enzyme.

Figure 2 shows how temperature
affects the rate of this reaction.
rada
4-5
Rate of Reaction (units)
Explain why the reaction has stopped at point Z.
40
30
20
0
Figure 2
1
10 20 30 40 50 60
Temperature (°C)
Look at points X and Y on Figure 2.
Describe the relationship between rate of reaction and temperature between points X and Y.

Answer 1

2.1)As Temperature increases, the rate of reaction increases.

2.2)Enzymes are sensitive to changes in temperature. At point Z, the temperature beacame too high for the enzyme to function, thereby denaturing the enzyme. Once the enzyme was denatured the reaction could not continue.

Answer 2

The reaction has stopped at point Z because the enzyme denatures, losing its catalytic function due to excessive temperature.

Between points X and Y, the relationship between rate of reaction and temperature is positive, showing an increase in reaction rate with rising temperature.

The reaction stops at point Z due to enzyme denaturation, a process where the enzyme's three-dimensional structure is disrupted at higher temperatures, rendering it nonfunctional. This phenomenon is often referred to as the enzyme's optimal temperature being surpassed, leading to a loss of catalytic activity.

Between points X and Y on Figure 2, there is a positive relationship between the rate of reaction and temperature. As the temperature increases within this range, the kinetic energy of the reacting molecules also increases, resulting in more frequent and successful collisions. This heightened molecular activity enhances the efficiency of the enzyme, leading to an increased rate of the catalyzed reaction. However, beyond a certain temperature (point Y), the reaction rate begins to decline as the enzyme denatures, illustrating the temperature sensitivity and optimal range for enzymatic activity.