Enzymes as Biological Catalysts: Activation Energy

Overview

Recall questions on Activation Energy.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Define activation energy.

   Model answer

   Activation energy is the minimum amount of energy that the reacting molecules must have before they can react.

2. 2

   How does an enzyme increase the rate of a reaction?

   Model answer

   By holding the substrate in the active site in the correct orientation and straining its bonds, the enzyme lowers the activation energy, so a much greater proportion of molecules have enough energy to react at the temperature of the cell.

3. 3

   Does an enzyme change the products of a reaction or the overall energy change? Explain.

   Model answer

   No, it changes only the route taken and therefore the rate, leaving the products and the net energy change of the reaction exactly the same.

4. 4

   How does the energy profile of a reaction differ when an enzyme is present?

   Model answer

   The energy barrier that has to be crossed is lower, but the energy levels of the substrates and of the products are unchanged.

5. 5

   Why do organisms use enzymes rather than high temperatures to speed up reactions?

   Model answer

   Enzymes allow reactions to go fast enough at body temperature, whereas the high temperatures that would otherwise be needed would denature proteins and damage the cell.

6. 6

   What is an intracellular enzyme? Give an example.

   Model answer

   An intracellular enzyme acts inside the cell in which it was made, an example being catalase.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.