Biological molecules — Paper 2 · IGCSE Science - Combined 0653

4 Which statement about enzymes is correct? A They are killed by high temperatures. B They are made from amino acids. C They are unaffected by pH. D They are used up in biological reactions.

1 marks

Answer: B

This question in 0653/22 May/June 2017

4 Which chemical is used to test for a food substance that contains the elements carbon, hydrogen, nitrogen and oxygen? A Benedict’s solution B biuret solution C ethanol D iodine solution

1 marks

Answer: B

This question in 0653/21 Oct/Nov 2017

4 Tests were performed on four samples of food. The results are shown in the table. Which food contains protein only? results of food tests Benedict’s test biuret test iodine test A blue blue blue/black B blue purple brown C red blue blue/black D red purple brown

1 marks

Answer: B

This question in 0653/22 Feb/March 2018

8 Nitrates in the soil are taken up by the roots of a plant. What are the nitrates used to make? A fat B glucose C protein D starch

1 marks

Answer: C

This question in 0653/22 Oct/Nov 2019

3 Which row shows the elements that occur in all proteins? carbon hydrogen nitrogen oxygen A yes yes yes no B yes yes no yes C yes no yes yes D yes yes yes yes

1 marks

Answer: D

This question in 0653/21 May/June 2021

3 A biological molecule is analysed and found to contain carbon, oxygen, hydrogen and nitrogen. What is this biological molecule? A fat B glucose C protein D starch

1 marks

Answer: C

This question in 0653/22 Oct/Nov 2021

3 Which small molecules are used to make proteins? A amino acids B fatty acids C glucose D glycerol

1 marks

Answer: A

This question in 0653/23 Oct/Nov 2021

4 Which foods are rich in carbohydrate? 1 eggs 2 meat 3 potatoes 4 rice A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

1 marks

Answer: D

This question in 0653/21 May/June 2022

3 A student tests samples of four different foods. Which row is the correct result for a sample containing only fat and starch? Benedict’s biuret ethanol iodine solution test emulsion solution A blue purple clear blue-black B blue blue cloudy blue-black C red purple clear brown D red blue cloudy brown

1 marks

Answer: B

This question in 0653/21 Oct/Nov 2022

3. Food tests are carried out on a biscuit. The results of the food tests are shown. test for colour observed fat white emulsion protein blue reducing sugar orange starch blue-black Which biological molecules are present in the biscuit? fat protein sugar starch A Jv x x x B v x v v Cc x v v v D x v x x

1 marks

Answer: B

This question in 0653/22 Oct/Nov 2022

3. Which row contains all of the elements in fats? carbon hydrogen nitrogen oxygen 0 OO WwW PY x SO a LN K&N \ 4 x

1 marks

Answer: C

This question in 0653/23 Oct/Nov 2023

3 Which small biological molecules are used to make proteins? A amino acids B fatty acids C glucose D glycerol

1 marks

Answer: A

This question in 0653/22 Feb/March 2024

5 Which type of molecule is starch? A carbohydrate B fat C protein D vitamin

1 marks

Answer: A

This question in 0653/22 May/June 2024

4 Which small molecules are used to make proteins? A amino acids B fatty acids C glucose D glycerol

1 marks

Answer: A

This question in 0653/23 May/June 2024

4 The table shows the results of tests carried out on different food samples. food ethanol . Benedict’s emulsion biuret test ; sample test solution test | x Jv x 2 Jv x x 3 x Jv WA 4 Jv x WA Which food samples contain reducing sugar? A i1iand2 B 1and3 key ¥ = positive result X = negative result C 2and4 D 3and4

1 marks

Answer: D

This question in 0653/22 May/June 2025