7.4.4 Digestion. 110 minutes. 151 marks. Page 1 of 40

Transcription

1 7.4.4 Digestion 110 minutes 15s Page 1 of 40

2 Q1. The human body has organs and organ systems which have different functions. (a) In which organ does the foetus develop? In which organ is oxygen absorbed into the blood? (b) Complete the table. 2 marks (c) Give one function of the skeleton Maximum 5 marks Q2. (a) The diagram represents the flow of blood to and from a muscle. What type of blood vessel is B?... Page 2 of 40

3 Respiration takes place in the cells of the muscle. In the table, tick one box in each row to compare the concentrations of oxygen, glucose and carbon dioxide in blood vessels A and B. 3 marks (b) Blood flows into and out of all organs. Name the organ represented in the diagram below. Name of organ... A different organ is represented in the diagram below. Name this organ. Name of organ... (c) When a person has an alcoholic drink, the alcohol passes into blood and is circulated throughout the body. Alcohol in the blood causes the blood vessels in the skin to become wider. What effect will this have on the body? Page 3 of 40

4 Alcohol abuse has short-term and long-term effects. Which one of the following is a long-term effect on alcohol abuse? Tick the correct box. shorter reaction time short sightedness damage to liver damage to bones Maximum 8 marks Q3. The drawing shows part of an organ system. (a) Which organ system is it part of? Tick the correct box. circulatory system reproductive system digestive system respiratory system Page 4 of 40

5 (b) Where is this part of the organ system found in the body? Tick one box. Maximum 2 marks Q4. (a) Egg white contains a protein called albumen. A pupil carried out an experiment to investigate the digestion of three identical cubes of cooked egg white using the enzyme pepsin. She set up the experiment as follows. Into beaker A, she put 50 cm 3 pepsin solution and a cube of egg white left whole. Into beaker B, she put 50 cm 3 pepsin solution and a cube of egg white which had been cut into eight small cubes. Into beaker C, she put 50 cm 3 pepsin solution and a cube of egg white which had been cut into sixty four tiny cubes. She added 1 cm 3 hydrochloric acid to each beaker and placed the three beakers in a waterbath at 37 C. The table gives the pupil s observations five hours later. Page 5 of 40

6 Why was the cube of egg white which had been cut into sixty four pieces digested most quickly? When protein is digested it is broken down into smaller molecules. What name is given to these smaller molecules? (b) In another experiment, it was found that pepsin does not digest sucrose (sugar). Explain why sucrose is not digested by pepsin (c) The graph below shows how quickly pepsin digests meat protein at different temperatures. Explain why pepsin does not digest protein at temperatures above 60 C.... (d) Glands in the stomach wall produce mucus, hydrochloric acid and an inactive form of pepsin called pepsinogen. In the stomach hydrochloric acid reacts with the pepsinogen to produce pepsin. Suggest one other purpose of acid in the stomach. Suggest one reason why pepsin is secreted in its inactive form. Page 6 of 40

7 (iii) Suggest one purpose of mucus produced in the wall of the stomach. (iv) Bile from the liver makes the duodenum alkaline. Give one reason why the contents of the duodenum need to be alkaline. Maximum 8 marks Q5. A medical researcher used a tube to remove some of the liquid from a person's stomach. The researcher put the liquid into a flask which had a piece of boiled beef in it. The beef was digested in six hours. The diagrams show the flask at different stages of the experiment. (a) What type of substance in the liquid from the stomach caused the beef to be digested in six hours? The researcher kept the flask at 37 C. Explain why. Page 7 of 40

8 (b) In the human body, the digestion of protein in meat begins in the stomach and is completed in the small intestine. What is digested protein used for in the body? Describe how the products of digestion get from inside the small intestine to the cells in the rest of the body. 2 marks Maximum 5 marks Q6. The diagram below shows a single-cell organism called Chlamydomonas. It lives in pond water. Use the information in the diagram to help you answer the questions below. (a) Give two features of Chlamydomonas which show that it is more like a plant cell than an animal cell marks (b) Chlamydomonas makes a sugar called glucose. Give the name of the process in which Chlamydomonas makes glucose. Page 8 of 40

9 Chlamydomonas produces starch grains from glucose. Suggest what will happen to the number of starch grains in the cell if Chlamydomonas is kept in the dark. (c) The diagram below shows another single-cell organism called Amoeba. It also lives in pond water. Amoeba traps a Chlamydomonas and digests it. not to scale Starch is a carbohydrate. Amoeba's digestive enzymes break down the starch in the Chlamydomonas. Suggest what substance is produced from the starch and what it is used for marks Maximum 6 marks Page 9 of 40

10 ## The diagram below shows a villus. There are several thousand villi in every square centimetre of the lining of the small intestine. The cells in the lining of each villus have folds called microvilli on their outer surfaces. One of these cells is shown magnified in the diagram. (a) Explain two ways in which the structure of the villus enables the products of digestion to be absorbed efficiently marks (b) Mucus is produced by some cells in the lining of the small intestine. One function of mucus is to protect the lining of the small intestine against the action of certain chemicals. Give the name of one type of chemical present in the small intestine which would otherwise damage the lining.... Suggest one other function of mucus produced in the small intestine. Page 10 of 40

11 (c) Bile, produced by the liver, enters the small intestine through the bile duct. Describe the effect which bile has on fats in the small intestine Maximum 5 marks Q8. Drawings A, B, C, D and E show the positions of five organ systems in the human body. (a) The names of the five organ systems are given in the table. By each name, write the letter of the drawing which shows the organ system. 5 marks Page 11 of 40

12 (b) Which one of these organ systems is completely different in a man and a woman?... Maximum 6 marks Q9. Sadie and Tom carried out an experiment to investigate the digestion of starch using an enzyme called amylase. (a) Why was the mixture of enzyme and starch kept in a water bath?... Sadie and Tom placed drops of iodine solution on a white tile. They know that starch will turn the iodine solution from brown to dark blue. Every 30 seconds they added a drop of the mixture of enzyme and starch to a drop of iodine solution on the tile. At first the drops turned blue, but after 240 s they stayed brown. (b) Why did the mixture stop turning the drops of iodine solution blue after 240 s? (c) They then carried out the experiment with the water bath at 35 C. This time, the drops stopped turning blue after 120 s. How does raising the temperature from 25 C to 35 C affect the digestion of starch? (d) Sadie and Tom want to compare the experiment at 35 C with the results from the experiment at 25 C. Describe what they need to do to make this a fair comparison Page 12 of 40

13 (e) A balanced diet includes all of the substances in the following list. Starch fat fibre minerals protein vitamins Give the names of the two substances in the list which are absorbed into the blood without being digested Which substance in the list passes through the body without being digested?.... Maximum 6 marks ## The following are important parts of a balanced diet. carbohydrates proteins fats vitamins water A pupil has a sweet, juicy orange to eat. (a) Complete the following sentences using words from the list above. An orange is a good source of... and marks An orange is a poor source of... and marks (b) Give the names of two parts of a balanced diet which are not shown in the list above marks Page 13 of 40

14 (c) In order to obtain the nutrients, food must be chewed Give two reasons why it is important to chew food marks Maximum 8 marks Q11. The diagrams below represent what happens to the energy in the food eaten by a herbivore and a carnivore. The width of each pathway indicates the amount of energy gained or used in a particular way. (a) What percentage of the total energy, taken in by a herbivore, is stored in its tissues? Use the diagram to help you answer.... % The energy stored in an animal s tissues is passed on to the next animal in the food chain. Use information in the diagrams above to explain why there are usually no more than four or five stages in a food chain. Page 14 of 40

15 (b) Respiration takes place in cells, in structures called mitochondria. Why do muscle cells contain large numbers of mitochondria? (c) Cows eat plants, but cannot digest the cellulose cell walls. Micro-organisms in the cow s stomach are able to digest the plant cell walls. Suggest why cows cannot digest the cell walls but micro-organisms can (d) The diagram below shows cells from the inner lining of a mammal s intestine. The cell membranes in contact with the food are folded. Explain why it is an advantage that these cells are adapted in this way marks Maximum 6 marks Q12. New-born mammals produce an enzyme called rennin which clots the protein in milk. Newborn mammals can only digest the protein after it clots. (a) Pat investigated how ph affects the time for rennin to clot the protein in milk. She put 2 cm 3 of milk into each of four test-tubes, A, B, C and D. She put these test-tubes and a test-tube of rennin into a water-bath at 35 C. After a few minutes, Pat transferred 4 drops of the rennin into test-tubes A, B and C. She varied the ph by adding the chemicals shown in the table. To test-tube D she added 2 drops of hydrochloric acid only. Page 15 of 40

16 The table below shows the results of Pat s experiment. Use the results of test-tubes C and D to state the function of the enzyme in the clotting process. Use Pat s results to explain why rennin clots milk quickly in the stomach. (iii) Suggest what happens to the activity of rennin as it passes from the stomach into the small intestine. Explain your answer. 2 marks Page 16 of 40

17 (b) Pat then investigated how temperature affects the time for rennin to clot milk. She prepared four water-baths, at 0 C, 25 C, 35 C and 60 C. Into each water-bath she put a test-tube containing 2 cm 3 of milk and a test-tube containing rennin plus a chemical to give the correct ph. In each water-bath, she transferred four drops of the rennin into the test-tube of milk and timed how long it took for the milk to clot. The table shows her results. temperature of water-bath, in C time for milk to clot, in seconds 0 no clotting no clotting Explain why no clotting occurred in the test-tube at 60 C. Pat took the test-tube out of the water-bath at 0 C and put it into the water-bath at 35 C. The milk clotted. Why was clotting still possible in this test-tube? (iii) Raising the temperature from 25 C to 35 C made the milk clot more quickly. How could Pat change her experiment to show more precisely how temperature affects the time it takes for milk to clot? (c) After rennin clots milk protein, a different enzyme helps to digest the protein. What are the products of protein digestion?... Maximum 8 marks Page 17 of 40

18 Q13. The diagram shows some of the organs of the human body. (a) Give the names of two labelled parts where food is digested.... and... (b) Why do we need to chew our food and mix it with saliva? marks Page 18 of 40

19 (c) Draw one line from each bad habit to the organ it harms. 3 marks Which organ in the list below can be harmed if we eat too much fat? Tick the correct box. brain heart lung ribs Maximum 7 marks Page 19 of 40

20 Q14. The drawings show Sofia taking part in four different sports. The table below shows the average energy needed for each sport for one hour. sport average energy need for one hour (kj) bowling 1030 tennis 1760 football 2260 running 3700 (a) Sofia plays football for two hours each week. She also goes bowling for two hours each week. Explain why Sofia uses up her food reserves more quickly when playing football than when bowling. Page 20 of 40

21 Athletes should not drink alcohol before taking part in sport. Give two effects of alcohol which would affect an athlete s performance (b) Some athletes take glucose tablets before a 100 metre race. They can also obtain glucose from starch in their diet. A starch molecule is made up of many glucose molecules joined together as shown below. In the digestive system, starch is broken down into glucose: An athlete can obtain energy more quickly by eating glucose rather than starch. Explain why maximum 4 marks Q15. Hydrochloric acid is a strong acid. (a) Winston used universal indicator solution to find the ph of some hydrochloric acid. Suggest the colour of the mixture of universal indicator solution and the hydrochloric acid.... Suggest the ph of the hydrochloric acid.... Page 21 of 40

22 (b) Indigestion can be caused when too much hydrochloric acid is produced in the stomach. Magnesium carbonate can be used to treat indigestion. Winston crushed some indigestion tablets containing magnesium carbonate. He added them to hydrochloric acid in a test-tube. The mixture fizzed. The word equation for the reaction is shown below. magnesium + hydrochloric magnesium + carbon + water carbonate acid chloride dioxide Use the word equation to explain why the mixture fizzed when the reaction took place. Winston continued to add crushed tablets to the acid until the mixture stopped fizzing. Why did the fizzing stop? (c) When magnesium carbonate reacts with hydrochloric acid, magnesium chloride is formed. Which two words describe magnesium chloride? Tick the two correct boxes. a compound a mixture an element a salt a metal a solvent 2 marks Page 22 of 40

23 (d) It is important that the hydrochloric acid in the stomach is not completely neutralised by indigestion tablets. Why is hydrochloric acid needed in the stomach? maximum 7 marks Q16. (a) The graph below shows how the concentration of alcohol in a person s blood changed after drinking alcoholic drinks. It is illegal to drive if the concentration of alcohol in the blood is higher than 80 mg/100 cm 3. Use the graph to find out how long the concentration of alcohol in this person s blood was higher than 80 mg/100 cm hours (b) Why does alcohol in the blood increase the chance of having an accident? Tick the correct box. It causes slurred speech. It increases the size of the pupil in the eye. It dulls the senses of taste and smell. It increases the time taken to react. Page 23 of 40

24 (c) Alcohol is absorbed into the bloodstream from the stomach. Digested food is absorbed into the blood from a different part of the digestive system. Give the name of this part.... (d) Give the name of one organ that is damaged by drinking a lot of alcohol over a long period of time.... (e) The drawing below shows a foetus in its mother s uterus. If a pregnant woman drinks large quantities of alcohol, the blood vessels in the umbilical cord may get very narrow for a while. Give one way this could affect the foetus maximum 5 marks Page 24 of 40

25 Q17. The diagram shows some of the organs of the human body. (a) The heart pumps blood around the body. What useful gas does the blood take in from the air in the lungs?... What useful substance does the blood take in from the intestine?... Page 25 of 40

26 (b) Blood vessels carry blood to organs of the body. Sometimes a blood clot forms in a blood vessel as shown below. a blood vessel not to scale A blood clot may stop an organ working properly. Give one reason for this (c) Rahma cut his foot on a piece of glass. A scab formed over the cut. Give one way a scab protects the body maximum 4 marks Q18. Andy investigated the digestion of a protein called gelatin. He used an enzyme called pepsin from the human stomach, and three cubes of gelatin each 1 cm 3. He set up the experiment shown below and put the test-tubes in a water-bath at 37 C. He measured the time for the digestion of the gelatin. Page 26 of 40

27 (a) Why did Andy choose a temperature of 37 C for the water-bath? (b) In test-tube C, the cube of gelatin that had been cut into pieces was digested more quickly than the whole cube in test-tube A. Give the reason for this (c) The boiled pepsin in test-tube B did not digest the gelatin. Why did boiling this enzyme stop it working? (d) Protein is needed for growth and repair. The digestion of protein begins in the stomach and is completed in the small intestine. What are the products of the digestion of protein? Tick the correct box. amino acids energy sugars vitamins Why is it necessary to digest protein before it can be used for growth and repair? maximum 5 marks Page 27 of 40

28 Q19. (a) The diagram shows a group of cells from the lining of the mouth. Give the name and function of part P. name of part P function of part P Which word describes this group of cells? Tick the correct box. compound organism organ tissue (b) The diagram below shows muscle cells from the wall of the human intestine. Muscle cells can contract. Give one reason why muscles are needed in the intestine. Page 28 of 40

29 Other cells in the intestine produce enzymes. What effect do enzymes in the intestine have on nutrients such as protein? (iii) Which of the following is required in the diet to keep food moving through the intestine? Tick the correct box. fat fibre protein starch maximum 6 marks Q20. The diagram below shows the digestive system. (a) Give the letter which labels the stomach.... Page 29 of 40

30 Give the letter which labels the small intestine.... (iii) Glucose is absorbed in the small intestine. What carries glucose from the intestine to other parts of the body? (b) Some athletes take glucose tablets before a race. Why do they take glucose? Tick the correct box. for growth for healthy bones and teeth to prevent disease to provide energy (c) The table below shows what four people ate for lunch. name Jon Nadia Clare Zak lunch chicken and salad cheeseburger and chips lemonade and a jam doughnut mushroom soup and an orange Whose lunch had the most sugar in it?... Whose lunch had the most fat in it?... (iii) Eating too much fat is bad for you. Give one reason for this. maximum 7 marks Page 30 of 40

31 Q21. (a) The diagram shows a sperm cell. Sperm cells are adapted for fertilisation. Sperm cells use their tails to swim towards an ovum (egg). Give one other way the sperm cell is adapted for fertilisation (b) The diagrams below show two other cells. not to scale Look at the diagrams above. What is the difference between the location of the genetic material in the bacterium and in the cell from the lining of the intestine? What is the function of the genetic material in a cell?.... Page 31 of 40

32 (c) Cells in the lining of the intestine are adapted to absorb digested food. How does the folded membrane of these cells enable them to absorb the maximum amount of digested food? (d) A group of cells in the lining of the intestine is a tissue. Why is a number of sperm cells not a tissue? maximum 5 marks Q22. The drawing below shows the human rib cage. (a) The rib cage protects organs in the chest. Give the names of two organs in the chest marks (b) The ribs are attached to the breast bone by cartilage which bends easily. This lets the space in the chest get bigger. Why is it important that the space can get bigger? Page 32 of 40

33 (c) The drawings below show parts of three different organ systems. Draw a line from each organ system to its function. Draw only three lines. 3 marks maximum 6 marks Page 33 of 40

34 Q23. (a) Green beans contain vitamin C. Which other food is a good source of vitamin C? Tick the correct box. cheese chicken eggs oranges (b) The amount of vitamin C changes in the beans and in the water as the beans are cooked. The shading shows how it changes. Use the diagram. How does the amount of vitamin C in the beans and in the water change as the beans are cooked? Tick one box in each row. amount of vitamin C increases decreases stays the same in the beans in the water Page 34 of 40

35 (c) Cheese is a source of calcium. Why do we need calcium?... (d) Draw a line from each nutrient to a good source of that nutrient in our diet. 2 marks (e) The diagram shows part of the human digestive system. Write the letter which labels the small intestine.... Write the letter which labels the stomach.... maximum 7 marks Page 35 of 40

36 Q24. (a) Pineapple juice contains a substance that speeds up the digestion of protein. What is the name for substances that speed up digestion?... What happens to a molecule of protein during digestion?.... (b) Asim did an experiment to investigate the digestion of gelatin. Gelatin is the protein in jelly. In test tubes A and B he used one cube of jelly in each. In test tube C he used one cube of jelly that he had chopped up. A B C 5 g jelly cube 5 g jelly cube 5 g jelly cube + + chopped into 15 cm 3 15 cm 3 fresh pieces cold water pineapple + juice 15 cm 3 fresh pineapple juice He recorded how long it took for the jelly to be digested in each test tube. The table below shows his results. test tube A B C result not digested after 2 hours jelly digested in 2 hours jelly digested in 1 hour What was the purpose of test tube A?.... Page 36 of 40

37 It is helpful to chew your food. How do the results in test tube C show this?.... (c) The substances that speed up digestion stop working when they have been boiled. What does Asim need to put in a fourth test tube to test this in his experiment? Label test tube D. Test tubes A, B and C contain the same as in the first experiment. A B C D 5 g jelly 5 g jelly cube 5 g jelly cube... cube + chopped into + 15 cm 3 fresh pieces cm 3 pineapple + + cold water juice 15 cm 3 fresh pineapple marks Predict what Asim would observe in test tube D after 2 hours... maximum 7 marks Page 37 of 40

38 Q25. Sally investigated how the human body digests and absorbs starch. She used saliva to digest the starch. To model digestion she used special bags made from a semi-permeable membrane. These bags have lots of very small holes. Sally sets up the equipment as shown below. There is one special bag in each beaker. She keeps the water in the beakers at 37ºC. After 20 minutes, Sally tested the contents of each beaker and bag for starch and sugar. The table below shows Sally s results. Was starch found in the bag? Was sugar found in the bag? Was starch found in the water? Was sugar found in the water? beaker A beaker B beaker C (a) Suggest why Sally kept the water at 37ºC.... (b) Explain why sugar was found in the bag in beaker A. Starch was not found in the water outside the bag in any beaker. Suggest why. Page 38 of 40

39 (c) Why did Sally set up beaker C? Tick the correct box. for a fair test for accuracy for reliability for a control (d) Sally used diagrams to show what happened in her investigation. Use the diagrams above to answer the following questions. Which diagram shows the results of beaker B? Write the letter.... Which diagram shows the results of beaker A? Write the letter.... (e) What does saliva contain that causes starch to change in beaker A?... (f) Sally chewed a piece of bread for 5 minutes without swallowing. What would she notice about the taste of the bread after chewing for 5 minutes? Use Sally s results to help you.... maximum 8 marks Page 39 of 40

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