Which of the following statements about metabolism are correct?
I and IV only
II and III
All of the statements
I, II and III
Which of the following is not a correct description of the “transition state” in enzyme-controlled reactions?
The enzyme-substrate complex, prior to the products being formed, can be said to be in the transition state.
The enzyme-product complex, prior to the products being released, can be said to be in the transition state.
The transition state occurs when a substrate binds to the enzyme’s active site.
Transition state is a temporary state
The graph below shows the energy changes during a reaction.
What effect would adding an enzyme have on the energy changes of the reaction?
Reduction in energy at A
Reduction in energy at B
Reduction in energy at C
Reduction in energy at D
What is the difference between a competitive and non-competitive inhibitor?
|
Competitive inhibitor |
Non-competitive inhibitor |
|
| A |
Interferes with active site |
Interferes with an alternative site |
| B |
Interferes with an alternative site |
Interferes with the active site |
| C |
Changes the active site |
Changes the substrate |
| D |
Changes the substrate |
Changes the active site |
Cyanide ions are an example of an allosteric inhibitor that targets the enzyme cytochrome c oxidase in aerobic respiration.
Which row best describes the action of cyanide ions?
|
Can bind to an alternative site |
Can bind to the active site |
|
| A |
Yes |
Yes |
| B |
Yes |
No |
| C |
No |
Yes |
| D |
No |
No |
Isoleucine can be described as an end-product inhibitor.
Which statement best describes the action of isoleucine?
It acts as a competitive inhibitor to threonine and it binds to an allosteric site on threonine deaminase.
It acts as a competitive inhibitor to threonine and it binds to the active site on threonine deaminase.
It acts as a non-competitive inhibitor to threonine and it binds to an active site on threonine deaminase.
It acts as a non-competitive inhibitor to threonine and it binds to an allosteric site on threonine deaminase.
The protein sequence of an enzyme involved in the Plasmodium parasite’s metabolism has been identified in order to support research into anti-malarial drugs.
Which terms best fill the gaps in the sentence about Plasmodium parasite research below?
Bioinformatics can be used to screen ………I……….. against a database of chemicals to identify potential ………II………..
|
I |
II |
|
| A |
Enzymes |
Enzyme inhibitors |
| B |
Proteomes |
Products |
| C |
Enzymes |
Active sites |
| D |
Proteomes |
Substrates |
Which graph shows the rate of a reaction taking place in the presence of a competitive inhibitor compared to the rate of a reaction in the absence of an inhibitor?
The table below gives information on the rates of several enzyme-catalysed reactions.
|
Rate of reaction / product formed sec⁻¹ |
Enzyme |
|
1.0 x 10⁶ |
Citrate synthase |
|
5.2 x 10³ |
Aconitase |
|
9.2 x 10⁴ |
Fumarase |
|
3.7 x 10⁷ |
Malate dehydrogenase |
Which enzyme catalyses the reaction with the fastest rate of product formation?
Citrate synthase
Aconitase
Fumarase
Malate dehydrogenase
Which statement best describes how to calculate the initial rate of a reaction from a graph such as the one below?
Draw a tangent that crosses the origin and that corresponds to the first part of the curve, calculate the rate by dividing change in volume by change in time.
Draw a tangent that corresponds to an area part way along the curve, calculate the rate by dividing change in volume by change in time.
Draw a tangent that crosses the origin and that corresponds to the first part of the curve, calculate the rate by dividing change in time by change in volume.
Draw a tangent that corresponds to an area part way along the curve, calculate the rate by dividing change in time by change in volume
