Effects of substrate concentration and temperature on rate of enzyme activity | Exit Quiz | Oak National Academy

True or false? The concentration of substrate will affect the rate of reaction.

• True

• False

Answer explanation

The higher the concentration of substrate, the higher the number of collisions with the enzyme. Conversely, the lower the concentration of enzyme the less collisions that will take place.

At high temperatures the shape of the enzyme's active site can change, and it no longer fits the substrate. We say the enzyme has become ...

• denatured

• energised

• unbonded

• denaturalised

Answer explanation

Denaturing occurs when enzymes are exposed high temperatures outside of their working range.

Match the labels to what is happening.

• b- At the optimum temperature

• there are fewer successful collisions so the reaction rate is lower.

• c- At high tmeperatures

• the enzyme is denatured. The reaction cannot be catalysed.

• a- At low temperatures

• all active sites are full and reaction rate is as high as it can be.

Answer explanation

As the temperature increases, the number of successful collisions increases and the rate of reaction increases to its maximum. If the temperature becomes too high, the enzyme becomes denatured and can no longer work, so the rate of reaction decreases

Which part of an enzyme does the substrate need to collide with for a reaction to take place?

Answer explanation

The active site is a specific site on the enzyme where the substrate fits and a reaction can then take place.

What is the rate of reaction?

• how much substrate has been used up

• how much substrate has not been used up

• how long it took for the reaction to finish

• how much product is formed per unit of time

Answer explanation

You need to know how much product is formed over a period of time. This is usually given in grams per second.