Practice 2.5 Enzymes with authentic IB Biology exam questions for both SL and HL students. This question bank mirrors Paper 1A, 1B, 2 structure, covering key topics like cell biology, genetics, and ecology. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.
Paper
Level
Question 1
SLPaper 1A
Which of the following statements about enzyme activity is correct?
Question 2
SLPaper 2
The equation below shows the production of glucose and galactose from lactose. 
1.[1]
Glucose and galactose are examples of monosaccharides. State one other example of a monosaccharide.
2.[1]
There are several different types of carbohydrate. State which type of carbohydrate lactose is.
3.[1]
State the type of chemical reaction that occurs when lactose is digested into glucose and galactose.
4.[3]
Lactase is widely used in food processing. Explain three reasons for converting lactose to glucose and galactose during food processing.
5.[2]
Simple laboratory experiments show that when the enzyme lactase is mixed with lactose, the initial rate of reaction is highest at 48°C. In food processing, lactase is used at a much lower temperature, often at 5°C. Suggest reasons for using lactase at relatively low temperatures.
Question 3
HLPaper 2
1.[5]
Outline the first three levels of protein structure, including the types of bonding within each and the significance of each level.
2.[5]
Using a table, compare competitive and non-competitive inhibition and give one named example of each.
3.[5]
Explain the production of antibodies.
Question 4
HLPaper 1A
In an experiment the effect of changing pH on an enzymatic reaction is tested. Which could be a dependent variable in this kind of experiment?
Question 5
HLPaper 1A
The graph shows the effect of changing the substrate concentration on the early stages of an enzyme-catalysed reaction.
What can be interpreted about the rate of reaction from the graph?
Question 6
HLPaper 1A
What are features of the enzyme amylase?
| Substrate | Source | Optimum pH |
|---|---|---|
| starch | salivary glands | 7 |
| lignin | pancreas | 1.5 |
| cellulose | liver | 4 |
| glycogen | kidney | 9 |
Question 7
SLPaper 1A
What happens as an enzyme becomes denatured?
Question 8
SLPaper 2
1.[4]
Draw a labelled diagram to show the molecular structure of a membrane.
2.[6]
Some proteins in membranes act as enzymes. Outline enzyme-substrate specificity.
3.[8]
Membranes of pre-synaptic and post-synaptic neurons play an important role in transmission of nerve impulses. Explain the principles of synaptic transmission.
Question 9
SLPaper 1A
Which of the following statements best describes the induced fit model of enzyme activity?
Question 10
HLPaper 1A
The diagram below shows the energy levels of a reaction in the presence or absence of an enzyme. What is the best explanation of the different energy levels labelled I, II and III?
| I | II | III | |
|---|---|---|---|
| A. | Absence of an enzyme | Presence of an enzyme | Endergonic reaction |
| B. | Presence of an enzyme | Absence of an enzyme | Exergonic reaction |
| C. | Absence of an enzyme | Presence of an enzyme | Exergonic reaction |
| D. | Presence of an enzyme | Absence of an enzyme | Endergonic reaction |