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WorksheetsEnzyme Kinetics Quiz
Total questions: 10
Worksheet time: 5mins
What does Vmax represent?
The substrate concentration at which the reaction rate is half its maximum.
The initial rate of reaction before any substrate is added.
The maximum initial rate of an enzyme-catalysed reaction when the enzyme is saturated.
The affinity of the enzyme for its substrate.
The Michaelis-Menten constant (Km) is defined as:
The rate of reaction at half the maximum substrate concentration.
The substrate concentration at which the reaction rate is exactly half of Vmax.
The maximum possible rate of the reaction (Vmax).
A measure of the total number of active sites in an enzyme.
What is the relationship between Km and an enzyme's affinity for its substrate?
A high Km means a high affinity.
A low Km means a low affinity.
A low Km means a high affinity.
Km and affinity are not related.
When the initial reaction rate has reached the plateau known as Vmax, what is the limiting factor?
Substrate concentration
Product concentration
Enzyme concentration
Temperature
Enzyme A has a Km of 5 µmol dm⁻³. Enzyme B has a Km of 15 µmol dm⁻³. Which statement is correct?
Enzyme B has a higher affinity and is more efficient at low substrate concentrations.
Enzyme A has a higher affinity and is more efficient at low substrate concentrations.
Both enzymes have the same affinity for their substrate.
Enzyme A has a higher Vmax than Enzyme B.
According to the lesson plan, what is the first step to determine the Km value from a graph of reaction rate versus substrate concentration?
Find the value of the substrate concentration on the x-axis.
Calculate half of the final substrate concentration.
Read across from the y-axis to the curve.
Estimate the Vmax from the graph's plateau.
A common misconception is that Km is a measure of the reaction rate. What does Km actually represent?
A time
A rate
A substrate concentration
An enzyme's size
Why is an enzyme with a low Km considered to have a high affinity for its substrate?
It needs a high substrate concentration to work efficiently.
It reaches half its maximum speed at a low substrate concentration.
It has a very high maximum rate (Vmax).
It works best at a low temperature.
Using the data from the 'Affinity Ranking' plenary activity, which enzyme has the highest affinity for its substrate?
Lysozyme (Km = 6 µmol dm⁻³)
Penicillinase (Km = 50 µmol dm⁻³)
Carbonic anhydrase (Km = 8000 µmol dm⁻³)
It's impossible to tell from the Km values.
At which point on a standard enzyme kinetics graph is the enzyme's active sites completely saturated with substrate?
At Km
At ½Vmax
At Vmax
At the very beginning of the reaction (time = 0)
