Enzymes: function, structure and specificity | Exit Quiz | Oak National Academy

Match each keyword to its meaning.

• Active site

• substance which is acted upon by the enzyme

• Enzyme

• substance which speeds up the rate of a reaction without being used up

• Catalyst

• part of an enzyme where the substrate binds

• Substrate

• protein which acts as a biological catalyst

Answer explanation

Enzymes are biological catalysts which speed up the rate of a reaction. The substrate binds with the enzyme at the active site. The reaction takes place and the products are then released.

True or false? All enzymes are proteins.

• True

• False

Answer explanation

All enzymes are proteins because they are made of amino acids. However, not all proteins are enzymes.

Put the following steps in order to describe how an enzyme works.

• The substrate(s) binds to the active site.

• The product(s) is released.

• An enzyme-substrate complex is formed.

• The enzyme can be re-used.

Answer explanation

The substrate(s) binds to the active site as their shapes are complimentary; an enzyme-substrate complex is formed; the reaction takes place and the product(s) are released. The enzyme is unaffected and can be re-used.

What part of the enzyme is A?

Answer explanation

The active site is the part of an enzyme whose shape is complimentary to the shape of the substrate and they bind together.

Who is correctly describing the effect of adding an enzyme on the activation energy of an enzyme controlled reaction?

• 
• 

Answer explanation

Enzymes speed up reactions by lowering the activation energy needed for a reaction to take place.

In the lock and key model of enzyme action, what is the lock?

• substrate

• enzyme

• product(s)

Answer explanation

In the lock and key model, the enzyme is the lock and the substrate is the key that matches the shape of the lock.