Enzymes — Paper 1 · IGCSE Sciences - Co-ordinated (9-1) 0973

4 The graph shows the activity of an enzyme at different temperatures. rate of reaction 0 20 40 60 80 temperature / °C What is the optimum temperature for this enzyme? A 20 °C B 40 °C C 60 °C D 80 °C

1 marks

Answer: C

This question in 0973/11 May/June 2019

4 Which graph shows the effect of temperature on the activity of a mammalian enzyme? A B rate of rate of reaction reaction 0 60 0 60 temperature / °C temperature / °C C D rate of rate of reaction reaction 0 60 0 60 temperature / °C temperature / °C

1 marks

Answer: C

This question in 0973/11 May/June 2020

4 Which smaller molecules make up enzymes? A amino acids B fatty acids C glucose D glycerol

1 marks

Answer: A

This question in 0973/12 May/June 2020

4 A mixture of starch and saliva was set up at four different temperatures. Each mixture was tested with iodine solution after 15 minutes and again after 30 minutes. The results are shown in the table. temperature colour with iodine solution / C 15 minutes 30 minutes 0 blue-black blue-black 15 blue-black brown 35 brown brown 95 blue-black blue-black What do the results suggest? A The enzyme in saliva is inactive at 95 C. B The enzyme in saliva is slow to work at 35 C. C The enzyme in saliva works equally well at 15 C and 35 C. D The enzyme in saliva works faster at higher temperatures.

1 marks

Answer: A

This question in 0973/11 Oct/Nov 2020

4 What is an enzyme? A a carbohydrate that speeds up the rate of a reaction B a carbohydrate that alters the activity of a target organ C a protein that alters the activity of a target organ D a protein that speeds up the rate of a reaction

1 marks

Answer: D

This question in 0973/11 May/June 2021

4 Which type of molecule are enzymes? A fat B carbohydrate C protein D DNA

1 marks

Answer: C

This question in 0973/12 May/June 2021

4 A student investigated the effect of pH on an enzyme that digests starch. Which chemical will be needed to determine if any starch has been digested? A Benedict’s solution B biuret solution C iodine solution D ethanol

1 marks

Answer: A

This question in 0973/11 Oct/Nov 2021

4 Fungus can live at the base of human hair where the activity of one of its enzymes can cause dry skin. The graph shows the action of the fungal enzyme at different pH values. rate of reaction 0 1 2 3 4 5 6 7 8 9 pH Different shampoos have different pH values. Which shampoo causes the greatest amount of dry skin? A pH 3 B pH 5 C pH 7 D pH 9

1 marks

Answer: B

This question in 0973/11 May/June 2022

4 Catalase is an enzyme that breaks down hydrogen peroxide to form a foam of water and oxygen. The maximum height of the foam produced at different temperatures in a given length of time is measured. The rate of the reaction is proportional to the height of foam. The table shows the results. temperature / C height of foam / mm 10 1.2 20 3.1 30 4.2 40 5.4 50 3.6 60 0.0 Which conclusion can be drawn from these results? A Increasing the temperature decreases the rate of the reaction up to 50 C. B Increasing the temperature decreases the rate of the reaction up to 60 C. C Increasing the temperature increases the rate of the reaction up to 40 C. D Increasing the temperature increases the rate of the reaction up to 50 C.

1 marks

Answer: C

This question in 0973/12 May/June 2022

4 Which elements can be found in an enzyme molecule? 1 carbon 2 nitrogen 3 oxygen A 1, 2 and 3 B 1 and 3 only C 1 only D 2 only

1 marks

Answer: A

This question in 0973/11 Oct/Nov 2022

4 Which type of molecule are enzymes? A amino acids B carbohydrates C fats D proteins

1 marks

Answer: D

This question in 0973/11 May/June 2023

4 Which type of molecules speed up chemical digestion? A carbohydrates B enzymes C hormones D fatty acids

1 marks

Answer: B

This question in 0973/12 May/June 2023

4 Which graph shows the effect of temperature on enzyme activity? A B enzyme enzyme activity activity temperature temperature C D enzyme enzyme activity activity temperature temperature

1 marks

Answer: D

This question in 0973/11 Oct/Nov 2023

4 Which type of molecules are enzymes? A carbohydrates B fats C oils D proteins

1 marks

Answer: D

This question in 0973/11 May/June 2024

4 One method of preventing food spoilage is to store it at 4 C in a refrigerator. Why does storing food at low temperatures help to prevent food spoilage? A It decreases enzyme activity. B It denatures enzymes. C It increases enzyme production. D It kills cells.

1 marks

Answer: A

This question in 0973/11 Oct/Nov 2024

5 Which type of molecules are enzymes? A carbohydrates B fats C hormones D proteins

1 marks

Answer: D

This question in 0973/11 May/June 2025

4 Which statements about enzymes are correct? 1 Enzymes are biological catalysts. 2 Enzymes are made of fat. 3 Enzymes are made of protein. A 1 and 2 B 1 and 3 C 1 only D 3 only

1 marks

Answer: B

This question in 0973/12 May/June 2025

5 Which statements are correct for all enzymes? 1 They are proteins. 2 They are not affected by temperature. 3 They increase the rate of chemical reactions. 4 They work best at a high pH. A 1, 2 and 4 B 1, 3 and 4 C 1 and 3 only D 2 and 4 only

1 marks

Answer: C

This question in 0973/11 Oct/Nov 2025