Biological molecules — Paper 2 · IGCSE Biology (9-1) 0970

9 The table shows the results of food tests carried out on a fruit. test Benedict’s biuret ethanol iodine result positive positive negative negative What did the fruit contain? A fat and reducing sugar B fat and starch C protein and reducing sugar D protein and starch

1 marks

Answer: C

This question in 0970/21 May/June 2018

7 The data show the concentrations of sugar and starch in an onion. total sugar including starch reducing sugar / g per 100g / g per 100g 3.7 0.0 The onion is tested with Benedict’s solution and iodine solution. Which set of results is correct? Benedict’s iodine solution solution A blue blue-black B blue brown C brick red blue-black D brick red brown

1 marks

Answer: D

This question in 0970/22 Oct/Nov 2018

8 Four solutions were tested to see whether they contained protein, starch or glucose. The colours of the solutions after the tests are recorded in the table. Which solution contained protein and glucose but not starch? biuret test iodine test Benedict’s test A blue brown orange B blue blue-black blue C purple brown orange D purple blue-black blue

1 marks

Answer: C

This question in 0970/21 May/June 2019

9 Small molecules are used as the basic units in the synthesis of large food molecules. Which statement is correct? A Amino acids are basic units of carbohydrates. B Fatty acids are basic units of glycogen. C Glycerol is a basic unit of oils. D Simple sugar is a basic unit of protein.

1 marks

Answer: C

This question in 0970/21 May/June 2019

8 Which row shows the chemical elements contained in fats? carbon hydrogen nitrogen oxygen A Jv v x v B Jv Jv Jv v Cc x v v x D Jv x v v key / = present X = absent

1 marks

Answer: A

This question in 0970/22 May/June 2019

9 Small molecules are used as the basic units in the synthesis of large food molecules. Which statement is correct? A Amino acids are basic units of carbohydrates. B Fatty acids are basic units of glycogen. C Glycerol is a basic unit of oils. D Simple sugar is a basic unit of protein.

1 marks

Answer: C

This question in 0970/22 May/June 2019

10 The diagrams show a protease enzyme catalysing the breaking of part of a protein molecule into smaller pieces. Which diagram has three correct labels? A B product active site substrate product enzyme enzyme C D active site active site substrate enzyme substrate product

1 marks

Answer: C

This question in 0970/22 May/June 2019

8 Which identifies the chemical elements found in proteins? carbon hydrogen oxygen nitrogen v v v v key J/ = present 0 0O WwW > J WA J x Jv x Jv x X = absent x Jv x WA

1 marks

Answer: A

This question in 0970/22 Oct/Nov 2019

9 A student carries out a test to see whether the solution in a test-tube contains protein. Which row shows the correct food test and a positive result? colour seen with a name of test positive result A Benedict’s test blue-black B Benedict’s test purple C biuret test blue-black D biuret test purple

1 marks

Answer: D

This question in 0970/22 Oct/Nov 2019

12 The pie charts show the composition of 100 g of four different foods. Which food provides the most energy? A B C D key carbohydrate fats and oils protein water

1 marks

Answer: B

This question in 0970/22 Oct/Nov 2019

8 Which food-testing solution shows a positive result when it turns from blue to purple? A Benedict’s solution B biuret solution C ethanol D iodine solution

1 marks

Answer: B

This question in 0970/21 May/June 2020

9 What is the definition of an enzyme? A a carbohydrate that acts as a catalyst B a DNA molecule that acts as a catalyst C a fat that acts as a catalyst D a protein that acts as a catalyst

1 marks

Answer: D

This question in 0970/21 May/June 2020

22 Which row correctly completes the balanced equation for aerobic respiration? X + 6O2 → 6CO2 + Y X Y A 6C6H12O6 H2O B C6H12O6 6H2O C 6H2O C6H12O6 D C6H10O6 6H2O

1 marks

Answer: B

This question in 0970/21 May/June 2020

8 Which food-testing solution shows a positive result when it turns from blue to purple? A Benedict’s solution B biuret solution C ethanol D iodine solution

1 marks

Answer: B

This question in 0970/22 May/June 2020

7 Which substances are made by linking together glucose molecules only? A cellulose, glycogen and starch B fats, cellulose and proteins C proteins, oils and glycogen D starch, fats and oils

1 marks

Answer: A

This question in 0970/22 Oct/Nov 2020

12 The graph shows how the percentage of protein found in potatoes was affected by the concentration of nitrate fertiliser added to the crop when it was growing. percentage of protein in potatoes concentration of nitrate fertiliser added These results suggest that greater concentrations of nitrate fertiliser allow the potatoes to make more A amino acids. B cellulose. C lipid. D starch.

1 marks

Answer: A

This question in 0970/22 Oct/Nov 2020

9 Which element is found in proteins but not carbohydrates? A carbon B hydrogen C nitrogen D oxygen

1 marks

Answer: C

This question in 0970/21 May/June 2021

16 What are the products when proteins are broken down? A amino acids B fatty acids C glycerol D simple sugars

1 marks

Answer: A

This question in 0970/21 May/June 2021

9 Which element is found in proteins but not carbohydrates? A carbon B hydrogen C nitrogen D oxygen

1 marks

Answer: C

This question in 0970/22 May/June 2021

7 What are the smaller basic units of starch and glycogen molecules? starch glycogen A amino acids fatty acids and glycerol B amino acids glucose C glucose fatty acids and glycerol D glucose glucose

1 marks

Answer: D

This question in 0970/21 May/June 2022

8 In a length of DNA, 20% of the bases were T. What is the percentage of base G in this length of DNA? A 10% B 20% C 30% D 80%

1 marks

Answer: C

This question in 0970/21 May/June 2022

7 What are the smaller basic units of starch and glycogen molecules? starch glycogen A amino acids fatty acids and glycerol B amino acids glucose C glucose fatty acids and glycerol D glucose glucose

1 marks

Answer: D

This question in 0970/22 May/June 2022

9 Which type of molecule are enzymes made of? A carbohydrates B fats C proteins D vitamins

1 marks

Answer: C

This question in 0970/22 May/June 2022

7 The diagram shows part of a protein molecule. X What does X represent? A amino acid B fatty acid C glycerol D sugar

1 marks

Answer: A

This question in 0970/21 May/June 2023

8 DNA contains pairs of bases. Which pair shows a correct combination of bases? A A and C B C and G C G and A D T and G

1 marks

Answer: B

This question in 0970/22 May/June 2023

8 Which row identifies the chemical elements in proteins? carbon hydrogen oxygen nitrogen A v J J J key B Jv x Jv x / = present Cc x v v v X = absent D J J x x

1 marks

Answer: A

This question in 0970/22 Oct/Nov 2023

9 The table shows some large biological molecules and some small biological molecules. large biological small biological molecules molecules 1 cellulose glucose 2 oil amino acids 3 glycogen glucose 4 protein ethanol Which rows correctly pair large molecules with the smaller molecules used to make them? A 1 and 2 B 1 and 3 C 2 and 3 D 3 and 4

1 marks

Answer: B

This question in 0970/22 Oct/Nov 2023

8 A test was performed on a food substance. A positive result was shown by a colour change to blue-black. What solution was used for the test? A biuret solution B DCPIP solution C iodine solution D Benedict’s solution

1 marks

Answer: C

This question in 0970/21 May/June 2024

6 What is the test for protein? name of the test heat colour change A Benedict’s yes blue to purple B biuret yes blue to red C biuret no blue to purple D Benedict’s no blue to red

1 marks

Answer: C

This question in 0970/21 May/June 2025

8 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 proteins that act as substrates

1 marks

Answer: C

This question in 0970/22 May/June 2025

21 What is the chemical formula of glucose? A C6H6O6 B C6HO6 C C6H12O6 D C12H12O6

1 marks

Answer: C

This question in 0970/22 May/June 2025

6 Which substance is an enzyme? A fibrinogen B mRNA C pepsin D saliva

1 marks

Answer: C

This question in 0970/22 Oct/Nov 2025