Enzymes — IGCSE Biology (0610) questions by topic

The graph shows the activity of three digestive enzymes at differing pH values. (The graph plots enzyme activity (y-axis) against pH from 1 to 12 (x-axis) for three enzymes.…

Which graph shows the effect of pH on enzyme activity? Four graphs of enzyme activity (y-axis) against pH (x-axis) are shown: A is a U-shaped curve (high at low and high pH,…

The graph shows the effect of temperature on an enzyme-controlled reaction. At which point on the graph is the enzyme completely denatured? The graph plots rate of reaction…

The graph shows how enzyme activity is affected by temperature. The curve of enzyme activity (y-axis) against temperature in degrees C (x-axis, marked 0 to 60) rises from a low…

What is the correct definition of enzymes? A carbohydrates that act as biological catalysts B carbohydrates that act as substrates C proteins that act as biological catalysts D…

The diagram shows a process involving an enzyme in the human stomach. [Diagram: a Pac-Man-shaped enzyme (with a notch) combines with a triangular substrate labelled 1; an…

A scientist investigated the effect of changes in pH on the activity of two different protease enzymes. Each enzyme was placed in a hole in the centre of a jelly layer in a Petri…

Enzymes are biological catalysts. Describe what is meant by a catalyst.

A student investigated the effect of lactase on three different liquids: milk, lactose-free milk, and sucrose solution. The student used an indicator to test for glucose (the…

Which type of biological molecule are enzymes made of? A carbohydrate B fat C oil D protein

The diagrams show molecules involved in the action of a digestive enzyme. What is the substrate? A option A molecule shape B option B molecule shape C option C molecule shape D…

The graph shows how the activity of an enzyme varies with temperature (rate of enzyme activity vs temperature 0-70 C). What is the optimum temperature for this enzyme, and at…

Which statements about enzymes are correct? 1 Enzymes are biological catalysts. 2 Enzymes are carbohydrates. 3 Enzymes have an active site. A 1 and 2 B 1 and 3 C 2 and 3 D 3 only

The diagram represents the shape of an enzyme molecule with an active site. With which substrate would this enzyme most easily form an enzyme-substrate complex? A substrate A B…

The graph shows how temperature affects an enzyme-controlled reaction, with points A, B, C and D marked on the curve. Where on the graph do the enzyme and substrate molecules have…

The diagram shows the steps in an enzyme-controlled reaction, with a part labelled X (formed when the substrate is bound in the enzyme). What describes the part labelled X? A…

The graph shows the effect of temperature on the time taken for the complete digestion of starch (time for complete digestion / minutes against temperature 0-60 C); time is…

What are the characteristics of an enzyme? (columns: the active site is the same shape as the substrate; it is used up during the reaction; it is made of protein) A no; no; yes B…

An enzyme in potato cells causes oxygen to be produced from the breakdown of hydrogen peroxide. Cubes of potato tissue were placed in a hydrogen peroxide solution at different…

Tick (✓) all the boxes that describe enzymes. The statements are: 'they are permanently changed by the reaction', 'they are involved in all metabolic reactions', 'they are…

For this investigation, you need to identify when all of the starch has been broken down in each test-tube. Describe how you can tell if the starch has been broken down.

The student needed to identify when all of the starch had been broken down in each test-tube. Describe how the student can tell if the starch has been broken down.

What is true of all enzymes? The table has columns: they are sugars; they are most effective at pH 7. Each row A–D shows yes/no for each statement (key: ✓ = yes, blank = no). A…

The diagram shows enzyme X with four possible molecules A, B, C and D of different shapes near its active site. What is the substrate for enzyme X? (The correct substrate is the…

Which processes depend on the action of enzymes? 1 digestion 2 osmosis 3 respiration A 1 and 2 B 1 and 3 C 1 only D 2 and 3

Which diagram of an enzyme, active site and substrate is correct? Each option A–D shows an enzyme shape with an active site and a substrate; the correct diagram (C) shows the…

What is a characteristic of all catalysts? A They are broken down in the reaction. B They are made in the pancreas. C They are not changed by the reaction. D They do not change…

This sequence of diagrams shows how an enzyme works, with parts labelled P, Q, R and S. The active site is the part of the enzyme into which the substrate fits. Which labelled…

What is true of all enzymes? Columns: they are sugars; they are most effective at pH 7 (key: ✓ = yes, blank = no). Which row A–D is correct? A B C D

Which statement about human enzymes is correct when they are at temperatures above 80 °C? A The enzyme molecules are denatured. B The shape of the active site is stable. C More…

The graphs show the effect of temperature on enzyme activity. This enzyme has an optimum temperature of 30 °C. Each option A–D plots enzyme activity against temperature (0–60 °C).…

The statements are about enzymes. 1 Enzymes are catalysts. 2 Enzymes are proteins. 3 Enzymes are used up during chemical reactions. Which statements are correct? A 1, 2 and 3 B 1…

When the temperature increases, the rate of an enzyme-catalysed reaction increases until the optimum temperature is reached. Which statement explains why the rate increases? A The…

Which graph shows the effect of temperature on enzyme activity? Each option A–D plots enzyme activity against temperature. The correct graph (C) rises to a peak at the optimum…

Fig. 3.1 shows the action of an enzyme. On Fig. 3.1 use label lines and labels to identify: an enzyme; a product; a substrate.

The graph shows the effect of temperature on the activity of four different enzymes (P, Q, R, S) against temperature (0–110 °C). Which conclusion about the data in the graph is…

The diagram shows a test-tube at the start and at the end of an enzyme experiment (enzyme + substrate → enzyme + products, after 10 minutes at 35 °C). At the end of the…

Which changes could cause an enzyme to denature? 1 change in pH 2 change in temperature 3 change in substrate concentration A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3…

The diagrams represent an enzyme and its substrate. The enzyme is shown with four regions labelled A, B, C and D. Which part of the enzyme molecule is the active site for this…

Which statement is correct? A The active site of an enzyme has the same shape as the substrate. B The active site is not affected by changes in temperature. C The shape of the…

The diagram shows a test-tube at the start and at the end of an enzyme experiment (enzyme + substrate → enzyme + products, after 10 minutes at 35 °C). At the end of the…

The graph shows the effect of temperature on the rate of a reaction catalysed by an enzyme, with section X on the part of the curve just after the peak (where the rate falls).…