Digestive system — Paper 3 · IGCSE Science - Combined 0653

1 (a) Use lines to connect the box on the left to different boxes on the right. As an example one has been done for you. The sentence reads ‘Human liver cells take in oxygen by diffusion’. Draw three more lines to form three more correct sentences. contain cytoplasm. build up starch molecules from glucose molecules. destroy hormones. Human liver cells contain chloroplasts. take in oxygen by diffusion. carry out cell respiration in the nucleus. have a cell membrane. [3] (b) Fig. 1.1 shows a diagram of the human alimentary canal and associated organs. mouth tongue liver stomach small intestine colon rectum Fig. 1.1 On Fig. 1.1 label the oesophagus and the gall bladder. [2] (c) A person has a disease of the small intestine which prevents the small intestine from working properly. Choose two words or phrases from the list below to describe which two functions of the small intestine will be affected by this disease. Explain the reasons for your choices. absorption chemical digestion destroying hormones egestion ingestion producing bile function 1 … explanation … … … function 2 … explanation … … … [4] (d) The pH of the mouth cavity varies during the day. After a sugary meal the pH of the mouth cavity becomes more acidic. (i) Describe what causes the change in pH. … … … … [2] (ii) Describe the effect of increased acidity on teeth. … … [1]

12 marks

Mark scheme: 1(a) three lines drawn to connect ‘Human liver cells’ to contain cytoplasm ; destroy hormones ; have a cell membrane ; 3 1(b) oesophagus correctly labelled ; gall bladder correctly labelled ; 2 1(c) in either order chemical digestion ; many (digestive) enzymes are found there / food is broken down here ; absorption ; products of digestion enter the blood here ; 4 1(d)(i) bacteria; feed on / breakdown sugar ; produce acid ; 2 1(d)(ii) attacks enamel / causes decay ; 1

This question in 0653/32 Feb/March 2017

7 Table 7.1 shows the mass of some of the contents of three foods in a 100 gram sample of each food. Table 7.1 number of grams in the 100 gram food sample food fat carbohydrate protein water bread 7 60 13 20 egg 11 1 13 75 milk 3 5 3 89 (a) State the two nutrient groups needed for a balanced diet which are missing from Table 7.1. … and … [2] (b) The energy for the body provided by one gram of each nutrient is shown below. fat 37 kJ carbohydrate 17 kJ protein 17 kJ A student cooked a meal using 100 grams of eggs. Use the information contained in Table 7.1 to calculate the energy provided by the 100 grams of eggs. Show your working. energy provided = … kJ [2] (c) (i) The energy from food is released by respiration. Complete the word equation for respiration. glucose + oxygen + [1] (ii) Describe how oxygen is transported by the blood. … … … [2] (d) Fats, carbohydrates and proteins are made up from large molecules. They have to be broken down by chemical digestion into small molecules. State the three areas of the alimentary canal where chemical digestion occurs. 1. … 2. … 3. … [3]

10 marks

Mark scheme: 7(a) vitamins ; mineral salts / minerals ; 2 7(b) energy from eggs = 37 × 11 + 17 + 13 × 17 ; = 645 (kJ) ; 2 7(c)(i) carbon dioxide and water ; either order 1 7(c)(ii) carried by haemoglobin ; in red blood cells ; red cells carried in plasma ; Max 2 7(d) in any order mouth ; stomach ; small intestine duodenum / ileum ; 3

This question in 0653/31 May/June 2017

4 A student does an experiment to investigate the germination of barley seeds. The treatment of the seeds before the experiment is shown in Table 4.1. Table 4.1 seed treatment of seeds before the experiment pH of soaking solution A boiled in water for 10 minutes 7 B soaked at room temperature for a few hours 3 C soaked at room temperature for a few hours 7 • After treatment, a piece of each seed is placed on an agar plate containing starch. • After two days a test solution is added to the plate. This solution changes colour when starch is present. The results are shown in Fig. 4.1. barley seed barley seed piece piece A B A B area containing starch C C area containing starch clear area at the start after a few days Fig. 4.1 (a) Name the test solution and the colour change that occurs when starch is present. name of solution … colour change … [2] (b) The student thinks that an enzyme is produced by the barley seed C which causes the starch to be broken down in the clear area. Explain how the results for seed A and seed B, shown in Fig. 4.1, support this idea. seed A … … … seed B … … … [3] (c) The breaking down of starch is an example of chemical digestion. Explain why chemical digestion is necessary in the human alimentary canal. … … … [2] (d) In the human alimentary canal, food is broken down by both chemical and mechanical digestion. The teeth are involved in mechanical digestion. Fig. 4.2 shows one type of tooth found in the human mouth. Fig. 4.2 Name this type of tooth and explain how the structure of the tooth makes it suitable for its function. name … explanation … … … [3]

10 marks

Mark scheme: 4(a) iodine ; goes (from brown) to blue-black ; 2 4(b) Any three from results show starch present (around A and / or B) ; inactive / denatured enzyme ; because A is boiled ; because B is acidic / pH3 ; max 3 4(c) Any two from breaks down large / insoluble molecules ; into small / soluble molecules ; so that they can be absorbed ; max 2 4(d) molar ; flat / has cusps / large surface area ; for grinding food into smaller pieces ; 3

This question in 0653/32 Oct/Nov 2017

4 Fig. 4.1 shows a diagram of the alimentary canal. The main areas where digestion takes place are labelled. mouth cavity (approximately neutral) A stomach (acidic) duodenum (alkaline) B Fig. 4.1 (a) Name structures A and B shown in Fig. 4.1. A … B … [2] (b) A student is investigating human digestive enzymes. He has three test-tubes, 1, 2 and 3, containing protein solution at different pH values. He then adds the same enzyme to all three test-tubes and keeps them at 35 °C. The protein solution is cloudy at the start of the experiment. If the protein in the solution is broken down the solution becomes clear and colourless. The results are shown in Fig. 4.2. tube 1 tube 2 tube 3 clear cloudy colourless protein solution solution pH 2 pH 7 pH 8 Fig. 4.2 (i) Use the information in Fig. 4.1 to identify the likely source of the digestive enzyme that produces the result in tube 1 in Fig. 4.2. Explain your answer. source of enzyme … explanation … … … … [3] (ii) Suggest why a temperature of 60 °C is not suitable for this experiment. … … [1] (iii) Explain why the change that takes place in tube 1 is an example of chemical digestion. … … … [2] (iv) Describe one example of mechanical digestion. … … [1]

9 marks

Mark scheme: 4(a) A oesophagus ; B colon / large intestine ; 2 4(b)(i) stomach ; any two from stomach has acidic conditions ; pH 2 is acidic ; enzyme only worked in tube 1 / tube 1 was acidic / at the optimum pH ; max 3 4(b)(ii) enzyme will become inactive / destroyed at this temperature ; 1 4(b)(iii) large / protein molecules are broken down ; by the action of an enzyme / acid ; 2 4(b)(iv) chewing food (in mouth) ; 1

This question in 0653/33 Oct/Nov 2017

1 (a) The boxes on the left show some structures of the alimentary canal and associated organs. The boxes on the right show their functions. Draw one line from each structure on the left to its correct function on the right. One line has been done for you. structure function anus assimilation liver digestion and absorption mouth digestion only small intestine egestion stomach ingestion [3] (b) Large pieces of food are broken down by the action of teeth. It is important that teeth are cared for so that they do not decay. The composition of 100 cm3 of a soft drink is shown in Table 1.1. Table 1.1 substance mass / g fat 0 carbohydrate as sugar 9.9 fibre 0 protein 0.1 Use the information in Table 1.1 to explain in detail why the soft drink is harmful for teeth. … … … … [3] (c) State two ways in which people can care for their teeth. 1. … 2. … [2]

8 marks

Mark scheme: 1(a) three lines drawn as follows anus assimilation liver digestion and absorption mouth digestion only small intestine egestion stomach ingestion All 4 lines correct = 3 marks 3 or 2 lines correct = 2 marks 1 correct line = 1 mark 3 1(b) idea of large amount of sugar in the drink ; bacteria feed on sugar ; produce acid ; acid attacks enamel ; max 3 1(c) brush teeth regularly ; visit dentist regularly ; reduce consumption of sugar ; max 2 Que estion Answer Ma arks

This question in 0653/32 May/June 2018

1 (a) The boxes on the left show some structures of the alimentary canal and associated organs. The boxes on the right show their functions. Draw one line from each structure on the left to its correct function on the right. One line has been done for you. structure function anus assimilation liver digestion and absorption mouth digestion only small intestine egestion stomach ingestion [3] (b) Large pieces of food are broken down by the action of teeth. It is important that teeth are cared for so that they do not decay. The composition of 100 cm3 of a soft drink is shown in Table 1.1. Table 1.1 substance mass / g fat 0 carbohydrate as sugar 9.9 fibre 0 protein 0.1 Use the information in Table 1.1 to explain in detail why the soft drink is harmful for teeth. … … … … [3] (c) State two ways in which people can care for their teeth. 1. … 2. … [2]

8 marks

Mark scheme: 1(a) three lines drawn as follows anus assimilation liver digestion and absorption mouth digestion only small intestine egestion stomach ingestion All 4 lines correct = 3 marks 3 or 2 lines correct = 2 marks 1 correct line = 1 mark 3 1(b) idea of large amount of sugar in the drink ; bacteria feed on sugar ; produce acid ; acid attacks enamel ; max 3 1(c) brush teeth regularly ; visit dentist regularly ; reduce consumption of sugar ; max 2 Que estion Answer Ma arks

This question in 0653/33 May/June 2018

4 (a) Fig. 4.1 shows a diagram of part of the alimentary canal and its associated organs. A liver stomach gall bladder B duodenum Fig. 4.1 (i) Name structures A and B shown on Fig. 4.1. A … B … [2] (ii) During digestion food passes through the duodenum. State where the food goes to immediately after passing through the duodenum. … [1] (iii) Describe the function of the gall bladder. … [1] (b) Table 4.1 shows the approximate pH values in some areas of the alimentary canal. Table 4.1 area of alimentary canal approximate pH in area mouth cavity 7 stomach 2 duodenum 8 Enzymes in the mouth begin the digestion of starch in food. Suggest why more enzymes must be secreted into the small intestine to complete the digestion of starch. … … … [2] (c) Glucose is transported to the body cells in the blood plasma. List two other soluble substances which are transported by the plasma. 1. … 2. … [2] (d) Describe how oxygen is transported in the blood around the body. … … … [2]

10 marks

Mark scheme: 4(a)(i) A oesophagus ; B pancreas ; 2 4(a)(ii) ileum ; 1 4(a)(iii) stores bile ; 1 4(b) amylase from mouth cavity doesn’t work ; in the acidic environment of the stomach ; 2 Question Answer Marks 4(c) any two of ions / named ion, e.g. chloride ; carbon dioxide ; hormones ; any other soluble nutrient, e.g. amino acids ; Max 2 2 4(d) in red (blood) cells ; by haemoglobin ; 2

This question in 0653/33 Oct/Nov 2018

7 (a) Fig. 7.1 is a simplified diagram which shows the human alimentary canal. food mouth alimentary A canal B body tissues C D anus Fig. 7.1 The alimentary canal is a tube going through the body from mouth to anus. The tube is surrounded by body tissues. The letters A, B, C and D show the basic stages of digestion of food. On Fig. 7.2 the boxes on the left show the letters of the stages of digestion of food as shown in Fig. 7.1. The boxes in the middle show the names of these stages. The boxes on the right show descriptions of what is happening to the food. Draw one line to link each letter with its stage, and draw one line to link each stage with its description. Stage B, digestion, is done for you. letter of stage name of stage description A absorption faeces leave the body food is taken into B digestion the body insoluble food molecules C egestion are broken down soluble food molecules D ingestion enter the blood Fig. 7.2 [3] (b) Describe the function of the gall bladder. … … [1] (c) (i) State what is meant by the term balanced diet for humans. … … … [2] (ii) State why proteins are needed as part of a balanced diet. … [1] (iii) Describe the chemical test for protein, and the colour of the positive result. chemical test … colour of positive result … [2] [Total: 9]

9 marks

Mark scheme: 7(a) A absorption faeces leave the body B digestion food is taken into the body C egestion insoluble food molecules are broken down D ingestion soluble food molecules enter the blood ; ; ; 3 7(b) stores bile ; 1 7(c)(i) contains all the nutrients ; in the (correct / appropriate) proportions / amounts / quantities / to meet a person’s needs / for health ; 2 7(c)(ii) growth / repair of tissues ; 1 7(c)(iii) biuret solution ; (biuret solution) goes purple ; 2

This question in 0653/33 May/June 2019

7 (a) Chemical digestion occurs in the alimentary canal. Use words from the list to complete the sentence about chemical digestion. Each word may be used once, more than once, or not at all. absorbed atoms egested excreted ions molecules Chemical digestion in the alimentary canal produces small, soluble … that can be … . [2] (b) Amylase is an enzyme that breaks down starch into simpler reducing sugars. Starch solution is placed in each of two test‑tubes. Amylase solution is added to test‑tube 1 and water is added to test‑tube 2. The apparatus is shown in Fig. 7.1. amylase solution water starch solution test-tube 1 test-tube 2 starch solution and amylase starch solution and water Fig. 7.1 After 10 minutes the contents of each test‑tube are tested with Benedict’s solution. The results of the investigation are shown in Table 7.1. Table 7.1 reducing sugar colour of result of test‑tube amylase present present Benedict’s test 1 yes yes 2 no no (i) Complete Table 7.1 with the colours of the Benedict’s test results. [2] (ii) The experiment is repeated with boiled enzyme in test‑tube 1. This time there is no reducing sugar present in test‑tube 1 after 10 minutes. Explain why there is no reducing sugar in test‑tube 1. … … … [1] (c) Table 7.2 shows four main processes that occur in the alimentary canal. Complete each row of Table 7.2 with one region of the alimentary canal where each process takes place. One is done for you. Table 7.2 process one region of the alimentary canal absorption small intestine digestion egestion ingestion [3] [Total: 8]

8 marks

Mark scheme: 7(a) molecules ; absorbed ; 2 7(b)(i) (test-tube 1) red / orange / yellow / green ; (test-tube 2) blue ; 2 7(b)(ii) boiling makes the enzyme inactive ; 1 7(c) (digestion) mouth / stomach / small intestine ; (egestion) anus ; (ingestion) mouth ; 3

This question in 0653/32 Oct/Nov 2019

7 (a) Chemical digestion occurs in the alimentary canal. Use words from the list to complete the sentence about chemical digestion. Each word may be used once, more than once, or not at all. absorbed atoms egested excreted ions molecules Chemical digestion in the alimentary canal produces small, soluble … that can be … . [2] (b) Amylase is an enzyme that breaks down starch into simpler reducing sugars. Starch solution is placed in each of two test‑tubes. Amylase solution is added to test‑tube 1 and water is added to test‑tube 2. The apparatus is shown in Fig. 7.1. amylase solution water starch solution test-tube 1 test-tube 2 starch solution and amylase starch solution and water Fig. 7.1 After 10 minutes the contents of each test‑tube are tested with Benedict’s solution. The results of the investigation are shown in Table 7.1. Table 7.1 reducing sugar colour of result of test‑tube amylase present present Benedict’s test 1 yes yes 2 no no (i) Complete Table 7.1 with the colours of the Benedict’s test results. [2] (ii) The experiment is repeated with boiled enzyme in test‑tube 1. This time there is no reducing sugar present in test‑tube 1 after 10 minutes. Explain why there is no reducing sugar in test‑tube 1. … … … [1] (c) Table 7.2 shows four main processes that occur in the alimentary canal. Complete each row of Table 7.2 with one region of the alimentary canal where each process takes place. One is done for you. Table 7.2 process one region of the alimentary canal absorption small intestine digestion egestion ingestion [3] [Total: 8]

8 marks

Mark scheme: 7(a) molecules ; absorbed ; 2 7(b)(i) (test-tube 1) red / orange / yellow / green ; (test-tube 2) blue ; 2 7(b)(ii) boiling makes the enzyme inactive ; 1 7(c) (digestion) mouth / stomach / small intestine ; (egestion) anus ; (ingestion) mouth ; 3

This question in 0653/33 Oct/Nov 2019

7 (a) Fig. 7.1 shows part of the alimentary canal and associated organs. W pancreas Fig. 7.1 (i) Name the part W shown in Fig. 7.1. … [1] (ii) Some people need to have their pancreas removed due to illness. Describe how removing the pancreas may affect the person’s digestion. … … … [2] (iii) The pancreas also produces hormones. Place ticks (✓) in two boxes to show the correct ideas about hormones. alter the activity of organs HIV is one example of a hormone they are chemical substances produced by target organs transported in red blood cells [2] (b) Fig. 7.2 shows a food web. jaguar deer fox squirrel pine cones on a pine tree berries on a bush Fig. 7.2 (i) Identify one animal shown in Fig. 7.2 that feeds on the pine tree. … [1] (ii) The fox is both a primary consumer and a secondary consumer. Use the names of organisms shown in Fig. 7.2 to complete these sentences to explain why. The fox is a primary consumer when … … The fox is a secondary consumer when … … [2] (iii) Berries contain seeds. Seeds germinate and grow into new plants. State two environmental conditions needed for germination of seeds. 1 … 2 … [2] [Total: 10]

10 marks

Mark scheme: 7(a)(i) gall bladder ; 1 7(a)(ii) the pancreas secretes, pancreatic juice / enzymes (for digestion) ; (therefore) less digestion can take place ; 2 Question Answer Marks 7(a)(iii) alter the activity of organs  breakdown large insoluble molecules chemical substances  produced by target organs transported in red blood cells ;; all correct = 2 mark two ticks one correct = 1 mark three ticks two correct = 1 mark more than 3 ticks = 0 marks ;; 2 7(b)(i) squirrel / deer ; 1 7(b)(ii) (The fox is a primary consumer when) eats berries ; (The fox is a secondary consumer when) eats squirrel ; 2 7(b)(iii) any two from: water ; oxygen ; suitable temperature ; max 2

This question in 0653/32 Feb/March 2020

4 (a) Fig. 4.1 is a graph showing the vitamin C content in 100 g of different foods. 200 180 vitamin C 160 content in 100 g of food / mg 140 120 100 80 60 40 20 0 peppers broccoli oranges strawberries melon mango type of food Fig. 4.1 (i) Name two foods from Fig. 4.1 that contain exactly 60 mg of vitamin C in 100 g of the food. … and … [1] (ii) Calculate the mass of mango needed to provide 80 mg of vitamin C. mass = … g [2] (b) Fig. 4.2 shows the names and functions of some parts of the human alimentary canal. Draw one line from the name of each part to its correct function. name function anus absorption liver ingestion mouth produces bile small intestine egestion Fig. 4.2 [3] (c) (i) Proteins and carbohydrates are made up of chemical elements. List the chemical elements found in both proteins and carbohydrates. … [1] (ii) Proteins are digested by the enzyme pepsin. Pepsin works best in the stomach. The pH of the stomach is pH 2. Complete Fig. 4.3 by sketching a curve to show how the activity of the enzyme pepsin changes with pH. enzyme activity 0 0 2 4 6 8 10 pH Fig. 4.3 [2] (iii) Proteins are made from small molecules that have reacted together. Name these small molecules. … [1] [Total: 10]

10 marks

Mark scheme: 4(a)(i) oranges AND strawberries ; 1 4(a)(ii) (mass =) 200 (g) ;; (if answer is incorrect then 100 80 40 × for one mark) 2 Question Answer Marks 4(b) anus absorption liver ingestion mouth produces bile small intestine egestion ;;; all 4 correct = 3 marks 2–3 correct = 2 marks 1 correct = 1 mark 3 4(c)(i) carbon AND oxygen AND hydrogen ; 1 4(c)(ii) line going up and coming back down ; peak / optimum, at pH 2; 2 4(c)(iii) amino acids ; 1

This question in 0653/31 May/June 2020

4 (a) Fig. 4.1 shows the human alimentary canal and associated organs. A B Fig. 4.1 (i) Identify parts A and B shown in Fig. 4.1. A … B … [2] (ii) Use a label line and the letter X to show a possible position of a salivary gland in Fig. 4.1. [1] (b) Large food molecules are made from smaller molecules. Table 4.1 shows some large molecules and the smaller molecules they are made from. Complete Table 4.1. Table 4.1 large molecules smaller molecules glycogen … amino acids … oils … and … [3] (c) Fig. 4.2 shows a graph of the activity of two enzymes A and B from the alimentary canal. enzyme enzyme B activity enzyme A 0 2 4 6 8 10 pH Fig. 4.2 (i) Describe the effect of changes in pH on the activity of enzyme B. Use data from Fig. 4.2 to support your answer. … … … [2] (ii) The stomach produces hydrochloric acid to kill bacteria in food. Identify which enzyme A or B works best in the stomach. Explain your answer. enzyme … explanation … … [1] [Total: 9]

9 marks

Mark scheme: 4(a)(i) A stomach ; B large intestine ; 2 4(a)(ii) label line to salivary gland area ; 1 4(b) glucose ; protein ; fatty acids and glycerol ; 3 4(c)(i) as pH increases enzyme activity increases then falls ; peaks at pH 8 ; 2 4(c)(ii) (enzyme) A (no mark) (explanation) enzyme A activity is higher, in acidic conditions / pH 2 ; 1

This question in 0653/32 May/June 2020

1 (a) Fig. 1.1 shows some of the organs of the human body. … … … X Fig. 1.1 (i) Complete the labels in Fig. 1.1 to show the names of the organs. [3] (ii) One function of organ X is digestion. State one other function of organ X. … [1] (iii) Name the organ that pumps blood around the body. … [1] (iv) Name the part of the body where egestion occurs. … [1] (b) Enzymes are involved in digestion. Fig. 1.2 is a graph that shows the effect of pH on the activity of three enzymes. enzyme A enzyme B enzyme C enzyme activity 0 1 2 3 4 5 6 7 8 9 10 11 pH Fig. 1.2 (i) Describe the effect of pH on enzyme A. Use data from the graph in your answer. … … … … [2] (ii) The mouth has an average pH of 6.7. Identify which enzyme in Fig. 1.2 is found in the mouth. Explain your answer. enzyme … explanation … … [2] (iii) Enzymes are involved in the clotting of blood. Circle the component of blood which is also involved in clotting. plasma platelets red blood cells white blood cells [1] [Total: 11]

11 marks

Mark scheme: 1(a)(i) lung(s) ; liver ; large intestine ; 3 1(a)(ii) absorption ; 1 1(a)(iii) heart ; 1 1(a)(iv) anus ; 1 1(b)(i) activity increases then decreases (as pH increases) ; maximum activity at pH 2 ; 2 1(b)(ii) B ; maximum activity at pH 6.5 / other enzymes do not work at pH 6.7 ; 2 1(b)(iii) platelets (circled) ; 1

This question in 0653/32 Feb/March 2021

7 (a) Fig. 7.1 is a diagram of the alimentary canal and associated organs. A B E C D Fig. 7.1 (i) State the letters on Fig. 7.1 that identify where egestion and ingestion take place. egestion … ingestion … [2] (ii) State one function of the part labelled E in Fig. 7.1. … [1] (iii) Name the part of the blood that transports the products of digestion around the body. … [1] (b) In one day a person eats a diet that includes cheese, eggs, fish, kidney beans and meat. The protein, carbohydrate and fibre content of each food is shown in Table 7.1. Table 7.1 protein carbohydrate fibre foodstuff / g per 100 g of food / g per 100 g of food / g per 100 g of food cheese 18 1 0 eggs 13 1 0 fish 22 0 0 kidney beans 24 50 25 meat 26 0 0 One part of this diet is needed to move food through the alimentary canal. Identify the part of the diet and explain your answer. part of diet … explanation … [2] (c) Fig. 7.2 shows the male reproductive system. P Q Fig. 7.2 Identify the parts labelled P and Q in Fig. 7.2. P … Q … [2] (d) Table 7.2 compares asexual and sexual reproduction. Place ticks (✓) and crosses (✗) to show the correct features of asexual and sexual reproduction. One row has been done for you. Table 7.2 asexual sexual reproduction reproduction genetically identical offspring involves fusion of nuclei involves gametes usually involves two parents ✗ ✓ [2] [Total: 10]

10 marks

Mark scheme: 7(a)(i) egestion: D ; ingestion: A ; 2 7(a)(ii) digestion / absorption ; 1 7(a)(iii) plasma ; 1 7(b) part of diet: kidney beans ; explanation: contain fibre ; 2 7(c) P urethra ; Q scrotum ; 2 7(d) asexual reproduction sexual reproduction genetically identical offspring  x involves fusion of nuclei x  involves gametes x  usually involves two parents (x) () ;; 2 marks for all 6 correct 1 mark for 4 correct 2

This question in 0653/31 May/June 2021

1 (a) Nutrition is one of the characteristics of living organisms. Identify the characteristics of living organisms defined as the chemical reactions in cells that break down nutrient molecules and release energy … the ability to detect and respond to changes in the environment. … [2] (b) Fig. 1.1 shows part of the alimentary canal and associated organs. Fig. 1.1 (i) Draw the letter X on Fig. 1.1 to identify the position of the liver. [1] (ii) The arrow shows the direction the food moves as it passes into the small intestine. Complete these sentences about what happens in the small intestine. Large insoluble molecules are broken down by the process of … . Small food molecules are then moved into the blood by the process of … . [2] (c) A student investigates nutrition in plants. Sugar is stored as starch in a leaf. The student puts black paper around a green leaf still attached to the plant. After two days she takes the leaf from the plant and removes the black paper. She then tests the leaf for starch using iodine solution. Fig. 1.2 shows the results. leaf attached to plant iodine solution stays orange-brown black paper strip starch test clip to iodine solution hold paper turns blue-black Fig. 1.2 Explain the results seen in Fig. 1.2 for the area that was covered by black paper. … … … [2] (d) Different plant tissues in the stem have different functions. Name the tissue that transports sugars in the stem. … [1] (e) Starch and sugar are carbohydrates. Table 1.1 shows the mass of carbohydrates in some different food types. Table 1.1 mass of carbohydrate food type in 100 g of food / g bread 40 cake 59 cheese 2 lentils 18 rice 25 tomato 3 (i) Identify the food type that contains the most carbohydrate. … [1] (ii) A man eats 200 g of bread and 50 g of cheese. Calculate the mass of carbohydrate he eats. mass of carbohydrate = … g [2] [Total: 11]

11 marks

Mark scheme: 1(a) respiration ; sensitivity ; 2 1(b)(i) centre of X must be on liver ; 1 1(b)(ii) digestion ; absorption ; 2 1(c) no starch is made ; as light is needed for photosynthesis ; 2 1(d) phloem ; 1 1(e)(i) cake ; 1 1(e)(ii) (40 x 2) + (2 x 0.5) ; 81 (g) ; 2

This question in 0653/33 May/June 2021

4 (a) Table 4.1 shows the names and functions of some organs associated with the alimentary canal. Complete Table 4.1. Table 4.1 organ function pancreas produces enzymes used in the … intestine for digestion … produces bile which is stored in the gall bladder salivary gland makes saliva and releases it into the … for digestion [3] (b) Enzymes in saliva break down large starch molecules into smaller glucose molecules. (i) Glucose is a reducing sugar. State the name of the test solution used to identify the presence of a reducing sugar in food. … [1] (ii) Circle the name of one other large molecule made from glucose molecules. amino acids fatty acids glycerol glycogen [1] (c) Food labels show the quantities of nutrients found in the food. Fig. 4.2 shows a food label from a box of burgers. Each grilled burger (94 g) contains Energy Fat Saturated Sugars Salt fat 898 kJ 12 g 5.8 g 0.7 g 0.6 g Fig. 4.2 (i) A person eats two burgers. Calculate the mass of salt the person eats. … g [1] (ii) The label does not show a value for fibre. State the importance of eating fibre in a balanced diet. … … [1] [Total: 7]

7 marks

Mark scheme: 4(a) small ; liver ; mouth ; 3 4(b)(i) Benedict's (solution) ; 1 4(b)(ii) glycogen ; 1 4(c)(i) 1.2 (g) ; 1 4(c)(ii) idea of keeping food moving (through alimentary canal) ; 1

This question in 0653/31 Oct/Nov 2021

7 (a) Fig. 7.1 shows information about four organisms living in an ocean habitat. • Krill eat microscopic producers called phytoplankton. • Fish eat krill. • Penguins eat fish. Fig. 7.1 (i) Construct a food chain using the information in Fig. 7.1. … [2] (ii) Identify the herbivore in Fig. 7.1. … [1] (b) Fig. 7.2 shows a photomicrograph of phytoplankton. chloroplasts containing chlorophyll Fig. 7.2 Explain why phytoplankton need chlorophyll. … … … [2] (c) Food is digested in the alimentary canal. Fig. 7.3 shows some of the pathway taken by food in the human alimentary canal. Complete Fig. 7.3. mouth oesophagus … small intestine … anus Fig. 7.3 [2] [Total: 7]

7 marks

Mark scheme: 7(a)(i) 2 7(a)(ii) krill ; 1 7(b) any two of: to absorb light energy; for photosynthesis ; to make carbohydrates ; 2 7(c) stomach ; large intestine ; 2

This question in 0653/32 May/June 2022

1 (a) Fig. 1.1 shows part of the alimentary canal and associated organs. A B C D E Fig. 1.1 (i) State the letter in Fig. 1.1 that identifies the stomach. … [1] (ii) State the letter in Fig. 1.1 that identifies where egestion occurs. … [1] (b) Chemical digestion takes place in the alimentary canal. (i) Explain why chemical digestion is needed before some nutrients can be absorbed. … … … [2] (ii) Biological catalysts are used in chemical digestion. Circle the name of these biological catalysts. acids enzymes hormones platelets [1] (c) Table 1.1 shows the recommended daily intake of some different nutrients for males and females of different ages. Table 1.1 males females 11–14 years 15–18 years 11–14 years 15–18 years protein / g 42 55 41 45 recommended vitamin C / mg 35 40 35 40 daily intake iron / mg 11 11 14 14 (i) State the recommended daily intake of protein for 12-year-old males. … g [1] (ii) Calculate the difference in recommended daily intake of iron for 15-year-old males and 15-year-old females. … mg [1] (iii) Between the ages of 15 and 18, males usually grow more than females. Identify evidence from Table 1.1 to support this statement. … … [1] (d) State the importance of calcium in the diet. … … [1] [Total: 9]

9 marks

Mark scheme: Question Answer Marks 1(a)(i) B ; 1 1(a)(ii) E ; 1 1(b)(i) breaks down, large / insoluble, molecules into small molecules ; 2 (small / new, molecules are) soluble ; 1(b)(ii) enzymes ; 1 1(c)(i) 42 (g) ; 1 1(c)(ii) 3 (mg) ; 1 1(c)(iii) the recommended daily allowance for protein for (15–18-year-old males) is higher than for females / AW ; 1 1(d) needed for, bones / teeth ; 1

This question in 0653/31 Oct/Nov 2022

1 (a) Fig. 1.1 is a diagram of the alimentary canal and associated organs. E A B D C Fig. 1.1 (i) State the letter in Fig. 1.1 that identifies the liver. … [1] (ii) State the letter in Fig. 1.1 that identifies the pancreas. … [1] (iii) On Fig. 1.1, draw a label line and the letter S to show the position of one salivary gland. [1] (iv) State the function of salivary glands. … [1] (b) Starch is a large molecule that is made from smaller molecules. (i) State the name of the smaller molecules that starch is made from. … [1] (ii) Some starch is mixed with an orange indicator solution, and the indicator solution turns blue‑black in colour. State the name of this indicator solution. … [1] (iii) An enzyme that breaks down starch molecules is added to the mixture of indicator solution and starch. When the enzyme has broken down all the starch molecules, the mixture turns orange again. Table 1.1 shows the time taken for the mixture to turn orange at different temperatures. Table 1.1 time taken for mixture temperature to turn orange / °C / s 25 547 30 279 35 185 40 221 45 485 Use Table 1.1 to describe the effect of temperature on the enzyme activity. … … … [2] [Total: 8]

8 marks

Mark scheme: Question Answer Marks 1(a)(i) E ; 1 1(a)(ii) B ; 1 1(a)(iii) label line to any of the salivary glands ; 1 1(a)(iv) make / secrete, saliva / enzymes ; 1 1(b)(i) glucose ; 1 1(b)(ii) iodine (solution) ; 1 1(b)(iii) as temperature increases, enzyme activity increases then decreases / AW ; 2 idea of highest activity between 30 °C and 40 °C ;

This question in 0653/32 Oct/Nov 2022

1 (a) Fig. 1.1 is a diagram of the alimentary canal and associated organs. E A B D C Fig. 1.1 (i) State the letter in Fig. 1.1 that identifies the liver. … [1] (ii) State the letter in Fig. 1.1 that identifies the pancreas. … [1] (iii) On Fig. 1.1, draw a label line and the letter S to show the position of one salivary gland. [1] (iv) State the function of salivary glands. … [1] (b) Starch is a large molecule that is made from smaller molecules. (i) State the name of the smaller molecules that starch is made from. … [1] (ii) Some starch is mixed with an orange indicator solution, and the indicator solution turns blue‑black in colour. State the name of this indicator solution. … [1] (iii) An enzyme that breaks down starch molecules is added to the mixture of indicator solution and starch. When the enzyme has broken down all the starch molecules, the mixture turns orange again. Table 1.1 shows the time taken for the mixture to turn orange at different temperatures. Table 1.1 time taken for mixture temperature to turn orange / °C / s 25 547 30 279 35 185 40 221 45 485 Use Table 1.1 to describe the effect of temperature on the enzyme activity. … … … [2] [Total: 8]

8 marks

Mark scheme: Question Answer Marks 1(a)(i) E ; 1 1(a)(ii) B ; 1 1(a)(iii) label line to any of the salivary glands ; 1 1(a)(iv) make / secrete, saliva / enzymes ; 1 1(b)(i) glucose ; 1 1(b)(ii) iodine (solution) ; 1 1(b)(iii) as temperature increases, enzyme activity increases then decreases / AW ; 2 idea of highest activity between 30 °C and 40 °C ;

This question in 0653/33 Oct/Nov 2022

1 (a) The alimentary canal of a human and a bear are similar. Fig. 1.1 shows the alimentary canal and associated organs of a bear. A B stomach C E small intestine D Fig. 1.1 (i) Table 1.1 shows the names and functions of some of the parts labelled A–E in Fig. 1.1. Complete Table 1.1 by writing your answers in the boxes. Table 1.1 name of part letter in Fig. 1.1 function B ingestion oesophagus moves food to the stomach anus [4] (ii) Digestion takes place in the stomach. Complete this sentence about digestion. Digestion breaks down large food molecules using chemical and … processes. [1] (b) Chemical digestion uses enzymes to break down large food molecules. Fig. 1.2 shows the effect of temperature on the activity of two different enzymes, J and K. J K 100 percentage enzyme activity 50 0 0 20 40 60 80 100 temperature / °C Fig. 1.2 (i) Identify the temperature in Fig. 1.2 when both enzymes have the same percentage activity value. temperature = … °C. [1] (ii) Describe the effect of temperature on the activity of enzyme K in Fig. 1.2. Use data in your answer. … … … [2] (c) All enzymes are made from one type of molecule. Circle this type of molecule. fat fibre protein vitamin [1] [Total: 9]

9 marks

Mark scheme: Question Answer Marks 1(a)(i) 4 name of part letter in Fig. 1.1 function mouth (B) (ingestion) (oesophagus) A (moves food to the stomach) (anus) D egestion ;;;; 1(a)(ii) mechanical ; 1 1(b)(i) 49 (°C) ; 1 1(b)(ii) (as temperature increases) activity / rate, increases then decreases ; 2 reaches maximum at 80 °C ; 1(c) protein (circled) ; 1

This question in 0653/32 Feb/March 2023

4 (a) Fig. 4.1 is a diagram of the alimentary canal and associated organs. … … Fig. 4.1 (i) Complete the labels in Fig. 4.1 with the names of the parts shown. [2] (ii) Draw a label line and the letter G to identify the gall bladder on Fig. 4.1. [1] (b) Blood transports digested food away from the alimentary canal. (i) State the name of the component of blood that transports the digested food. … [1] (ii) State the name of the main blood vessel that transports blood back to the heart from all the organs in the body. … [1] (c) Males and females have different reproductive systems. (i) The urethra and penis are part of the male reproductive system in humans. State the names of two other parts of the male reproductive system in humans. 1 … 2 … [2] (ii) The uterus is one part of the female reproductive system in humans. Describe what happens to the lining of the uterus between day 0 and day 5 of the menstrual cycle. … [1] [Total: 8]

8 marks

Mark scheme: 4(a)(i) small intestine ; stomach ; 2 4(a)(ii) gall bladder labelled ; 1 4(b)(i) plasma ; 1 4(b)(ii) vena cava ; 1 4(c)(i) any two from: testes ; scrotum ; sperm duct ; prostate gland ; 2 4(c)(ii) thickness decreases / is shed ; 1

This question in 0653/33 May/June 2023

7 (a) Fig. 7.1 shows a food web. alligator raccoon heron frog carp mosquito bladderwort orchid Fig. 7.1 (i) The food web is not complete. The heron eats the carp. The alligator eats the heron. Draw two arrows on Fig. 7.1 to show these feeding relationships. [1] (ii) State the name of one producer shown in Fig. 7.1. … [1] (iii) Complete the sentences about the food web in Fig. 7.1. The mosquito eats the orchid. The mosquito is a … consumer. The frog eats the mosquito. The frog is a secondary consumer. The raccoon eats the frog. The raccoon is a … consumer. [2] (b) All living organisms respire. State the word equation for aerobic respiration. … [2] (c) (i) Fig. 7.2 shows some of the pathway taken by food in the human alimentary canal. Complete Fig. 7.2. mouth … stomach … large intestine anus Fig. 7.2 [2] (ii) Circle the function of the anus. absorption digestion egestion ingestion [1] [Total: 9]

9 marks

Mark scheme: 7(a)(i) arrows from carp to heron AND from heron to alligator ; 1 7(a)(ii) bladderwort / orchid ; 1 7(a)(iii) primary ; 2 tertiary ; 7(b) glucose + oxygen ; 2 → carbon dioxide + water ; 7(c)(i) oesophagus ; 2 small intestine ; 7(c)(ii) egestion ; 1

This question in 0653/31 Oct/Nov 2023

1 (a) Fig. 1.1 is a diagram of the alimentary canal and associated organs in humans. A F B C D E Fig. 1.1 (i) State the letter on Fig. 1.1 that identifies the position of: a salivary gland … the liver. … [2] (ii) Circle one function of the part labelled D in Fig. 1.1. absorption egestion ingestion synthesis [1] (b) Enzymes digest food in the human alimentary canal. Fig. 1.2 shows the effect of temperature on the activity of two different enzymes. X Y enzyme activity 0 10 20 30 40 50 60 70 80 90 100 temperature / °C Fig. 1.2 (i) Identify the temperature where both enzyme X and enzyme Y have the same enzyme activity. Tick (✓) the correct box. 15 °C 40 °C 48 °C 55 °C 90 °C [1] (ii) The temperature of the human body is usually within the range 36.5 °C to 37.5 °C. State why enzyme Y is not found in the human alimentary canal. … … [1] (c) (i) The boxes on the left show some types of biological molecules. The boxes on the right show some tests used to identify biological molecules. Draw one straight line from each biological molecule to its correct test. biological test molecule Benedict’s solution starch biuret protein ethanol emulsion iodine solution [2] (ii) State the name of the smaller molecules that large protein molecules are made from. … [1] (iii) Starch is a carbohydrate. List all the chemical elements that make up carbohydrates. … [1] [Total: 9]

9 marks

Mark scheme: 1(a)(i) A ; F ; 2 1(a)(ii) absorption (circled) ; 1 1(b)(i) 48 °C (ticked) ; 1 1(b)(ii) inactive in that temperature range (36.5–37.5 °C) / active at temperatures above body temperature ; 1 1(c)(i) Benedict’s solution starch biuret protein ethanol emulsion iodine solution one mark for each correct answer ;; 2 1(c)(ii) amino acids ; 1 1(c)(iii) carbon and hydrogen and oxygen ; 1

This question in 0653/31 May/June 2024

1 (a) Fig. 1.1 shows the alimentary canal and associated organs of a human. E A D B C Fig. 1.1 (i) State the letter in Fig. 1.1 that identifies the: liver … oesophagus. … [2] (ii) Circle the function of the part labelled E in Fig. 1.1. egestion excretion ingestion reproduction [1] (b) Enzymes are found in the alimentary canal. (i) Complete the definition of enzymes. Enzymes are … that function as biological … . [2] (ii) Fig. 1.2 is a graph showing the effect of temperature on an enzyme. enzyme activity 0 0 10 20 30 40 50 60 70 80 temperature / °C Fig. 1.2 Describe the effect of temperature on enzyme activity shown in Fig. 1.2. Include data in your answer. … … … … [2] (c) Fats are digested in the alimentary canal. (i) Circle one food that is a principal source of fat. bread cheese oranges tomatoes [1] (ii) Use two words to complete the sentence. The name of the test for fats is the … … test. [1] [Total: 9]

9 marks

Mark scheme: Question Answer Marks 1(a)(i) D ; 2 A ; 1(a)(ii) ingestion ; 1 1(b)(i) proteins ; 2 catalysts ; 1(b)(ii) idea that as temperature increases, enzyme activity increases then decreases ; 2 peaks at 50(C) / AW ; 1(c)(i) cheese ; 1 1(c)(ii) ethanol emulsion ; 1

This question in 0653/32 Oct/Nov 2024

1 (a) Fig. 1.1 shows the alimentary canal and associated organs of a human. E A D B C Fig. 1.1 (i) State the letter in Fig. 1.1 that identifies the: liver … oesophagus. … [2] (ii) Circle the function of the part labelled E in Fig. 1.1. egestion excretion ingestion reproduction [1] (b) Enzymes are found in the alimentary canal. (i) Complete the definition of enzymes. Enzymes are … that function as biological … . [2] (ii) Fig. 1.2 is a graph showing the effect of temperature on an enzyme. enzyme activity 0 0 10 20 30 40 50 60 70 80 temperature / °C Fig. 1.2 Describe the effect of temperature on enzyme activity shown in Fig. 1.2. Include data in your answer. … … … … [2] (c) Fats are digested in the alimentary canal. (i) Circle one food that is a principal source of fat. bread cheese oranges tomatoes [1] (ii) Use two words to complete the sentence. The name of the test for fats is the … … test. [1] [Total: 9]

9 marks

Mark scheme: Question Answer Marks 1(a)(i) D ; 2 A ; 1(a)(ii) ingestion ; 1 1(b)(i) proteins ; 2 catalysts ; 1(b)(ii) idea that as temperature increases, enzyme activity increases then decreases ; 2 peaks at 50(C) / AW ; 1(c)(i) cheese ; 1 1(c)(ii) ethanol emulsion ; 1

This question in 0653/33 Oct/Nov 2024

1 (a) Fig. 1.1 shows the main organs of the digestive system. E A D stomach C B Fig. 1.1 State the letter on Fig. 1.1 that identifies: the large intestine … the salivary gland. … [2] (b) Proteins are digested in the stomach. (i) Describe the importance of proteins as part of a balanced diet. … … [1] (ii) Circle the name of the smaller molecules that proteins are made from. amino acids glucose fatty acids glycerol [1] (c) Fig. 1.2 shows a food web that includes humans. eagle lizard snake fish dragonfly frog human mayfly phytoplankton Fig. 1.2 (i) Identify the food source for the human in Fig. 1.2. … [1] (ii) Identify the producer in Fig. 1.2. … [1] (iii) Explain why the frog in Fig. 1.2 is a carnivore. … … [1] (d) In some parts of the world, eagles are endangered. Suggest two reasons why eagles may become endangered. 1 … … 2 … … [2] [Total: 9]

9 marks

Mark scheme: Question Answer Marks 1(a) C ; 2 E ; 1(b)(i) needed for, growth / repair ; 1 1(b)(ii) amino acids ; 1 more than one answer circled = 0 marks 1(c)(i) fish ; 1 1(c)(ii) phytoplankton ; 1 1(c)(iii) (only) gains energy from animals ; 1 1(d) any two from: 2 climate change ; habitat destruction ; hunting ; introduced species ; overharvesting ; pollution (in environment) ; AVP, e.g. new disease ;

This question in 0653/32 Feb/March 2025

1 (a) Fig. 1.1 is a diagram of the human digestive system. F A E B D C Fig. 1.1 (i) State the letter in Fig. 1.1 that identifies the liver. … [1] (ii) The boxes on the left show the letters of some parts labelled in Fig. 1.1. The boxes on the right show the functions of the parts. Draw one straight line from each part to its function. part function A absorption of water before egestion D ingestion of food F movement of food to the stomach [2] (iii) Physical digestion takes place in the alimentary canal. Place a tick (✓) in the box next to the description of physical digestion. Pieces of food are broken down using enzymes. Insoluble molecules are broken down into soluble molecules. Large food pieces are broken down into smaller food pieces. Large molecules are broken down into smaller molecules. [1] (b) Some substances in the digestive system move into the blood by diffusion. (i) Complete the sentence to describe diffusion. Diffusion is the … movement of particles from a region of their higher concentration to a region of their lower concentration (i.e. down a concentration … ). [2] (ii) Water moves through partially permeable membranes by a type of diffusion. Name this type of diffusion. … [1] (c) A student adds food to a test solution. The test solution changes colour from blue to purple (violet). Identify the biological molecule present in the food and name the test solution used. biological molecule … test solution … [2] [Total: 9]

9 marks

Mark scheme: Question Answer Marks 1(a)(i) E ; 1 1(a)(ii) 2 part function A absorption of water before egestion D ingestion of food F movement of food to the stomach one line correct ; three lines correct ; 1(a)(iii) large food pieces are broken down into smaller food pieces ; 1 1(b)(i) net ; 2 gradient ; 1(b)(ii) osmosis ; 1 1(c) protein ; 2 biuret (solution) ;

This question in 0653/31 Oct/Nov 2025

3 Tigers are endangered animals that live wild only in parts of Asia. Tigers catch and eat many different animals. (a) (i) Table 3.1 shows some information about the number of tigers that live wild. Table 3.1 estimated number of tigers year that live wild 1900 100 000 2000 3500 2020 4500 Suggest two reasons for the difference in the number of tigers between 1900 and 2000. 1 … 2 … [2] (ii) Circle all the words that describe the tiger. carnivore consumer decomposer herbivore producer [2] (b) Tigers are part of an ecosystem. (i) Circle two words in bold to give a correct description of an ecosystem. An ecosystem is a community of habitats / organisms and their climate / environment, interacting together. [1] (ii) State the word that describes the number of different species that live in an area. … [1] (c) Tigers have a similar alimentary canal to humans. The flow chart in Fig. 3.1 shows the direction that food moves as it passes through the alimentary canal. Complete Fig. 3.1. mouth … stomach … large intestine Fig. 3.1 [2] [Total: 8]

8 marks

Mark scheme: 3(a)(i) any two from: 2 • climate change ; • habitat destruction / deforestation ; • hunting ; • pollution ; 3(a)(ii) consumer ; 2 carnivore ; 3(b)(i) organisms AND environment circled ; 1 3(b)(ii) biodiversity ; 1 3(c) oesophagus ; 2 small intestine ;

This question in 0653/32 Oct/Nov 2025

3 Tigers are endangered animals that live wild only in parts of Asia. Tigers catch and eat many different animals. (a) (i) Table 3.1 shows some information about the number of tigers that live wild. Table 3.1 estimated number of tigers year that live wild 1900 100 000 2000 3500 2020 4500 Suggest two reasons for the difference in the number of tigers between 1900 and 2000. 1 … 2 … [2] (ii) Circle all the words that describe the tiger. carnivore consumer decomposer herbivore producer [2] (b) Tigers are part of an ecosystem. (i) Circle two words in bold to give a correct description of an ecosystem. An ecosystem is a community of habitats / organisms and their climate / environment, interacting together. [1] (ii) State the word that describes the number of different species that live in an area. … [1] (c) Tigers have a similar alimentary canal to humans. The flow chart in Fig. 3.1 shows the direction that food moves as it passes through the alimentary canal. Complete Fig. 3.1. mouth … stomach … large intestine Fig. 3.1 [2] [Total: 8]

8 marks

Mark scheme: 3(a)(i) any two from: 2 • climate change ; • habitat destruction / deforestation ; • hunting ; • pollution ; 3(a)(ii) consumer ; 2 carnivore ; 3(b)(i) organisms AND environment circled ; 1 3(b)(ii) biodiversity ; 1 3(c) oesophagus ; 2 small intestine ;

This question in 0653/33 Oct/Nov 2025