Enzymes

Question 1

Explain the ‘lock and key’ model for enzyme activity

Answer 1

Explain the ‘lock and key’ model for enzyme activity
This means they can bind together and form enzyme-substrate complexes.
Therefore enzymes can only catalyse specific reactions.

Question 2

Why do enzymatic reactions stop working at high temperatures?

Answer 2

Bonds within the enzyme will begin to break.

Enzymes will become denatured (lose their specific shape).

Changes to the shape of the active site mean substrates cannot bind (enzyme-substrate complexes cannot form).

Enzymes cannot catalyse the reaction.

Question 3

A student is carrying out an experiment to investigate the effect of temperature on the breakdown of starch to maltose using amylase. They carry out the investigation with the solutions at different temperatures using water baths. They take samples every
10
seconds
10 seconds and place them on a spotting tile filled with iodine solution.

Answer 3

Rate of reaction

Rate of reaction (s
−1
)=
Time (s)
1000
​

1000
90
Rate of reaction=
90
1000
​

11.11
s
−
1
Rate of reaction=11.11 s
−1