IB HL - Enzymes & Metabolism Intro

Which of the following describes the active site?

• the part of an enzyme that binds only to the product molecules

• the sequence of amino acids responsible for the catalytic activity of enzymes

• the sequence of amino acids responsible for the structure of an enzyme

• the specific area responsible for the activity of all proteins

What determines the specificity of an enzyme for its substrate?

• the temperature at which is it operating

• the optimum pH of the enzymes

• the concentration of the substrate

• the structure of the enzyme molecule

Which levels of protein structure can determine the specificity of an enzyme?

• primary

  secondary

  tertiary

• primary

  secondary

  tertiary

  quaternary

• tertiary

  quaternary

• primary

  secondary

  quaternary

Which of the following determines the specificity of an enzyme?

1 - the bonding between the R groups of the polypeptide

2 - the optimum pH of the enzyme

3 - the peptide bonds between animo acids of the polypeptide

4 - the shape of the substrate molecule

• 1, 2, 3 and 4

• 1 and 3 only

• 1 only

• 2, 3 and 4 only

According to the induced fit model of enzyme function,

which of the following statements is correct?

• active sites on enzymes are specific to a single substrate

• the shape of the active site can be changed by the binding of an allosteric inhibitor

• the binding of the substrate changes the shape of the active site slightly

• competitive inhibitors can change the shape of enzymes

Which of the following statements are correct for the induced fit hypothesis?

1 - folding of an enzyme molecule causes the formation of the active site

2 - the shape of the active site changes to enable the substrate to bind

3 - temporary bonds hold the substrate in the active site

4 - more ES complexes are formed at the optimum temperature

• 1 and 2

• 1 and 3

• 2, 3 and 4

• 2 and 4

Which of the following statements is true about enzymes?

• they lower the energy of activation for a reaction

• allosteric inhibitors bind to the active site

• they are used up in the reactions they catalyse

• they supply the energy of activation for a reaction

Which statement is true of all enzymes?

• they are denatured at temperatures above 60°C

• they are inactivated at low pH values

• they catalyse the breakdown of large molecules into smaller ones

• they reduce the amount of energy required to start a reaction

The graph shows the activation energy of an enzyme catalysed reaction and the same reaction without a catalyst.

Which arrow shows the activation energy of the uncatalysed reaction?

• A

• B

• C

• D

Tags

NGSS.HS-PS1-4

The diagram shows the energy changes in a chemical reaction. What would happen to the changes in energy if this reaction was controlled by an enzyme?

• I would increase

• II would decrease

• I and IV would decrease

• II and III would decrease

Tags

NGSS.HS-PS1-4