1 (a) It is recommended that people eat a balanced diet. Place a tick (3) next to the sentence that best describes a balanced diet. A balanced diet contains all the required nutrients in the correct amounts. A balanced diet contains the correct amounts of carbohydrates. A balanced diet contains lots of fruit and vegetables. A balanced diet contains no fats or salt. [1] (b) The boxes on the left show some nutrients. The boxes on the right show why the nutrients are needed by the body. Draw lines to link each nutrient with why it is needed by the body. nutrient why it is needed carbohydrate for bones and teeth fats insulation protein main source of energy vitamin D used for growth and repair [3] (c) List the three chemical elements that make up carbohydrates. … [1] (d) Benedict’s solution can be used to test for the presence of one type of carbohydrate. Name the carbohydrate that Benedict’s solution is used to test for. … [1] (e) Name the component of the diet that prevents constipation. … [1] (f) Eating less sugar can help prevent tooth decay. Describe one other way of taking care of teeth. … … [1] (g) Circle the two processes that occur in the mouth. ingestion digestion egestion fertilisation photosynthesis pollination transpiration [2] [Total: 10]

1(a) A diet containing all the required nutrients in the correct amounts ticked ; 1 1(b) carbohydrate for bones and teeth fats insulation protein main source of energy vitamin D used for growth and repair ;;; 3 1(c) carbon, hydrogen and oxygen ; 1 1(d) (reducing) sugar ; 1 1(e) fibre ; 1 1(f) regular brushing / AVP ; 1 1(g) ingestion circled ; digestion circled ; 2 (a) To earn the mark, you must tick the sentence that accurately defines a balanced diet as containing all required nutrients in the correct amounts. (b) To earn marks, you must correctly draw lines linking each of the four nutrients (carbohydrate, fats, protein, vitamin D) to their specific functions in the body. (c) To earn the mark, you must list all three chemical elements: carbon, hydrogen, and oxygen. (d) To earn the mark, you must name 'sugar' or 'reducing sugar' as the carbohydrate tested by Benedict's solution. (e) To earn the mark, you must name 'fibre' as the dietary component that prevents constipation. (f) To earn the mark, you must state 'regular brushing' or another valid preventative action for tooth decay. (g) To earn marks, you must circle both 'ingestion' and 'digestion' from the provided options.

10 (a) A student writes a definition of an enzyme. The definition is not correct. ‘Enzymes are fats that function as chemical catalysts.’ Circle the two words in the student’s definition that are not correct. [2] (b) Enzymes are used to break down large molecules into smaller molecules. Table 10.1 shows some large molecules and the smaller molecules they are made from. Complete Table 10.1. Table 10.1 large molecules smaller molecules 1. starch 2. … glucose … amino acids fats 1. fatty acids 2. … [3] (c) List the three chemical elements that make up fats. 1 … 2 … 3 … [1] (d) Fig. 10.1 is a graph showing the enzyme activity at different temperatures of four different enzymes, A, B, C and D. –10 enzyme activity 0 10 20 30 40 50 temperature / °C 60 70 80 90 100 110 A B C D Fig. 10.1 Table 10.2 shows average temperatures in different environments. Table 10.2 type of environment average temperature / °C hot springs 50 arctic sea –2 hydrothermal vent region 95 deep sea 2 volcano sediment 75 (i) Describe the effect of temperature on the enzyme activity of enzyme B. Use data to support your answer. … … … … [2] (ii) Use Fig. 10.1 and Table 10.2 to identify the enzyme, A, B, C or D, found in bacteria that can survive in: hydrothermal vent regions … arctic seas … the same environment as enzyme C … [3] [Total: 11]

10(a) fats ; chemical ; 2 10(b) glycogen ; protein ; glycerol ; 3 10(c) carbon hydrogen and oxygen ; 1 10(d)(i) as temperature increases enzyme activity increases then decreases ; peak / optimum at 33 °C ; 2 10(d)(ii) D ; A ; D ; 3 For (a), circle 'fats' and 'chemical'. For (b), complete the table with 'glycogen', 'protein', and 'glycerol'. For (c), list 'carbon', 'hydrogen', and 'oxygen'. For (d)(i), describe the trend as enzyme activity increasing then decreasing with temperature, with a peak/optimum at 33 °C. For (d)(ii), identify enzymes D, A, and D for the respective environments.

1 You are going to investigate the nutrient content of three solutions, A, B and C. You are provided with Benedict’s solution, biuret solution and iodine solution. (a) Procedure • Add about 1 cm depth of solution A to each of three test-tubes. • Add the same depth of Benedict’s solution to one test-tube and place it in a hot water-bath for at least 3 minutes. You should continue with the rest of this procedure while you are waiting. • Add the same depth of biuret solution into the second test-tube. • Add a few drops of iodine solution to the third test-tube. Record in Table 1.1 your observations of the final colours observed for each of the test-tubes. Table 1.1 solution final colour with biuret solution final colour with iodine solution final colour with Benedict’s solution A B C [3] (b) Using clean test-tubes repeat the procedure in (a) with solution B instead of solution A. Record in Table 1.1 your observations of the final colours observed for each of the test-tubes. [2] (c) Using clean test-tubes repeat the procedure in (a) with solution C instead of solution A. Record in Table 1.1 your observations of the final colours observed for each of the test-tubes. [2] (d) Use your results in Table 1.1 to state the nutrients present in each solution. solution A contains … solution B contains … solution C contains … [3] (e) State and explain one safety precaution you used when doing these tests. safety precaution … explanation … [1] (f) A student investigates the nutrient concentration in some food samples using Benedict’s solution. Benedict’s solution will give a range of colours depending on the concentration of the nutrient for which it is testing. State two variables which need to be controlled in this investigation. variable 1 … variable 2 … [2] [Total: 13]

1(a) A blue with biuret solution ; blue-black with iodine solution ; yellow / green / orange / red with Benedict’s solution ; 3 1(b) B purple with biuret solution ; is brown / orange with iodine and blue with Benedict’s ; 2 1(c) C blue with biuret solution and brown / orange with iodine solution ; yellow / green / orange / red with Benedict’s solution ; 2 1(d) A contains starch and reducing sugar ; B contains protein C contains reducing sugar ; 3 1(e) goggles protect eyes from hot water / chemicals / gloves protect skin / hands from hot water / chemicals 1 1(f) any two from: volume / concentration of Benedict’s solution ; mass / volume / concentration of food ; time (in water bath) / left for same time ; temperature (of water bath); 2

1 You are provided with a slice of pepper. (a) In the box, make an enlarged detailed pencil drawing of the cut surface of the slice of pepper. [3] (b) (i) Measure the diameter of the slice of pepper. Record this diameter in millimetres to the nearest millimetre. diameter of slice of pepper = … mm [1] (ii) Draw a line to show this diameter on your drawing in (a). Record the length of this line in millimetres to the nearest millimetre. diameter on drawing = … mm [1] (iii) Use your measurements in (b)(i) and (b)(ii) to calculate the magnification m of your drawing. Use the equation shown. m = diameter on drawing diameter of slice of pepper m = … [1] (c) You are going to test some egg white and potato for the presence of nutrients. (i) Procedure • Half-fill two wells of the spotting tile with egg white. • Add a few drops of iodine solution to one well containing egg white. • Add a few drops of biuret solution to the other well containing egg white. • Record the final colours observed in Table 1.1. Repeat the procedure using potato puree instead of egg white. Table 1.1 test solution final colour observed with egg white final colour observed with potato puree iodine biuret [4] (ii) State conclusions for your observations. egg white … … potato puree … … [2] (iii) Suggest why it is difficult to test a red pepper using biuret solution. … … [1] [Total: 13]

1(a) clear and continuous outline, 2 single lines ; size at least half of the box in both directions ; detail – 3 lobes ; 3 1(b)(i) measurement in mm ; 1 1(b)(ii) draw line and measurement correct ; 1 1(b)(iii) calculation correct and correctly rounded ; 1 1(c)(i) brown / orange ; blue-black ; purple / lilac ; blue ; 4 1(c)(ii) egg – protein + no starch; potato – starch + no protein ; 2 1(c)(iii) colour of the pepper masks the result ; 1 (a) To earn marks, your drawing must have a clear, continuous outline with no double lines, be large enough to fill at least half the box in both directions, and show three distinct lobes as detail. (b)(i) You must record the measured diameter in millimetres. (b)(ii) You need to draw the diameter line on your drawing and record its length in millimetres. (b)(iii) You must correctly calculate the magnification using the provided formula and round the answer appropriately. (c)(i) You earn marks for recording the correct final colours for each test: brown/orange for iodine with egg white, blue-black for iodine with potato, purple/lilac for biuret with egg white, and blue for biuret with potato. (c)(ii) You must conclude that egg white contains protein but no starch, and potato contains starch but no protein. (c)(iii) The mark is for stating that the pepper's colour would mask the result of the test.

3 What are the molecules that make up fats and oils? A amino acids and glycerol B fatty acids and glycerol C glucose and amino acids D glucose and fatty acids

Answer: B To earn the mark, a student must correctly identify fatty acids and glycerol as the molecules that make up fats and oils.

Cambridge IGCSE Co-ordinated Sciences · 0654

IGCSE Co-ordinated Sciences (0654) Biological molecules past paper questions

Revise IGCSE Co-ordinated Sciences (0654) — Biological molecules with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

116 free questions from 2016–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

Biological molecules in IGCSE Co-ordinated Sciences 0654 exams, 2020–2025

Across 2020–2025, Biological molecules accounted for 169 questions worth 942 marks in Cambridge IGCSE Co-ordinated Sciences (0654) papers.

By year
Year	Questions	Marks
2020	31	174
2021	28	162
2022	29	160
2023	33	159
2024	25	140
2025	23	147

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B4.1 Biological molecules859 marks

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Paper 1 · 40 qs
Paper 2 · 43 qs
Paper 3 · 21 qs
Paper 4 · 9 qs
Paper 5 · 23 qs
Paper 6 · 33 qs

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2021 Feb/Mar · Paper 3 · Q1 · 10 marks
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2021 Oct/Nov · Paper 3 · Q10 · 11 marks
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2021 May/Jun · Paper 5 · Q1 · 13 marks
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2021 May/Jun · Paper 5 · Q1 · 13 marks
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2021 Feb/Mar · Paper 1 · Q3 · 1 mark
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Mark scheme — 2021 Paper 1 Q3
Answer: B
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