Edexcel Biology A-level Past Paper - Exchange of Substances PDF

PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Questions Q1. The fluid mosaic model of cell membranes was first proposed in 1972. The vacuoles in beetroot cells contain molecules of betalain, a red pigment. Betalains are large polar molecules. These molecules can leave bee...

PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Questions Q1. The fluid mosaic model of cell membranes was first proposed in 1972. The vacuoles in beetroot cells contain molecules of betalain, a red pigment. Betalains are large polar molecules. These molecules can leave beetroot cells if the vacuole membrane and the cell surface membrane are damaged. Explain why betalain molecules cannot move through intact cell membranes. 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(Total for question = 3 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q2. In birds and mammals, gas exchange takes place between the blood in the capillaries and the air in the alveoli. There are three layers between the blood and the air in the alveoli: the capillary wall, a layer of extracellular matrix and the alveolar wall. This is called the blood-gas barrier. The electron micrographs show the blood-gas barriers for a chicken and a dog. Explain how the blood-gas barrier of the chicken is adapted to give more efficient gas exchange than the blood-gas barrier of the dog. 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(Total for question = 3 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q3. The structure of the cell surface membrane can be explained using the fluid mosaic model. This model suggests that there are a variety of different proteins and glycoproteins present in a phospholipid bilayer. The drawing shows the cell surface membrane of a liver cell. The drawing has a magnification of 5 × 106. Calculate the actual length of the glycoprotein between points X and Y. Give your answer with an appropriate unit. (2) Answer........................................................... (Total for question = 2 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q4. Answer the question with a cross in the box you think is correct. If you change your mind about an answer, put a line through the box and then mark your new answer with a cross. The fluid mosaic model of cell membranes was first proposed in 1972. One piece of evidence that was used to support the idea of a phospholipid bilayer was the arrangement of phospholipid molecules on a surface between air and water. (i) Complete the diagram to show the arrangement of four phospholipid molecules at this surface. (2) (ii) Which of the molecules found in cell membranes have hydrophilic regions? (1) A B C D channel proteins only only phospholipids and channel proteins phospholipids, channel proteins and cholesterol phospholipids only (Total for question = 3 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q5. Diffusion and active transport are mechanisms by which molecules can enter cells. Compare and contrast these two mechanisms. 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(Total for question = 3 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q6. Endocytosis and exocytosis are processes that move large molecules into a cell or out of a cell. Compare and contrast the processes of endocytosis and exocytosis. 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(Total for question = 3 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q7. The cell surface membrane controls the movement of substances into the cell. The concentrations of two substances inside the cytoplasm of a cell and in the fluid surrounding the cell were investigated. The table shows the concentrations of these two substances. (i) Explain why ATP is required for the movement of sodium ions into the cell. (2).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (ii) Describe how glucose molecules move into the cell. 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The internal conditions within the body are maintained by homeostatic mechanisms. The regulation of blood glucose involves homeostatic mechanisms. The diagram shows part of the sequence of events when there is an increase in blood glucose levels. (i) Describe how glucose moves into cells by facilitated diffusion. (2).............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (ii) Explain how the structure of glycogen allows it to be an energy store. 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(Total for question = 5 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q9. Glycoproteins and phospholipids are molecules found in the cell surface membrane. (i) Give one function of the glycoproteins found in the cell surface membrane. (1).......................................................................................................................................................................................................................................................................................... (ii) A cell surface membrane is partially permeable. The phospholipid bilayer is important in controlling the movement of molecules through the membrane. Explain how the structure of a phospholipid molecule contributes to the partial permeability of a cell surface membrane. 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(Total for question = 4 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q10. A baby was born with an abnormal heart. The diagram shows the heart of this baby. There is a hole in the septum between the two ventricles. Oxygen diffuses between the alveoli of the lungs and the blood. Fick's Law shows how three factors affect the rate of diffusion: The diagram and the table give information about the oxygen concentration in the alveoli and in the blood. Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com * Assess the effect of this heart defect on the rate of oxygen diffusion between the alveoli and the blood. 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(Total for question = 6 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q11. Emphysema is a condition that causes changes to the tissues in the lungs. In an investigation, the surface area for gas exchange and the volume of the lungs of three groups of individuals were determined. The results are shown in the table. (i) Calculate the mean surface area for gas exchange : volume ratio for individuals with mild emphysema. (2) Answer........................................................... (ii) There appears to be a difference in the lung volume of individuals with mild emphysema and those with severe emphysema. Which of the following would be a relevant statistical test to determine whether this difference is significant? (1) A chi-squared B correlation coefficient C standard deviation D Student's t-test Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com (iii) Give reasons for the variation in the lung volumes of healthy individuals. 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(iv) Give a reason for calculating the surface area for gas exchange to volume ratio in this investigation. (1).................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... (Total for question = 6 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q12. Blood type is an example of inherited variation. Blood types A, B, AB and O are determined by a single gene. Blood types are due to the presence or absence of antigens on the cell surface membranes of red blood cells. These antigens are glycoproteins. Antigens on the cell membranes of microbes can stimulate endocytosis and exocytosis in white blood cells. These processes are involved in transport through a cell surface membrane. Give two differences between endocytosis and exocytosis. 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(Total for question = 2 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q13. All cells have a cell surface membrane. Explain how phospholipids form a cell surface membrane. 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(Total for question = 3 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q14. Emphysema is a condition that causes changes to the tissues in the lungs. In an investigation, the surface area for gas exchange and the volume of the lungs of three groups of individuals were determined. The results are shown in the table. Explain why individuals with severe emphysema will tire more easily than healthy individuals. 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(Total for question = 3 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q15. Explain why the phospholipids are arranged in two layers in a cell surface membrane. 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(Total for question = 3 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q16. Emphysema is a condition that causes changes to the tissues in the lungs. In an investigation, the surface area for gas exchange and the volume of the lungs of three groups of individuals were determined. The results are shown in the table. Fick's law of diffusion can be used to calculate a value for the effectiveness of the uptake of oxygen by the lungs. This value can be calculated using the equation The diffusion distance in alveoli is 0.5 μm. The mean oxygen concentration in alveoli is 14 kPa and in the capillaries is 5 kPa. The calculated value for healthy individuals is 2124. (i) Calculate the value for individuals with severe emphysema. (2) Answer........................................................... (ii) Calculate the percentage difference between the value for individuals with severe emphysema and the value for individuals without emphysema. (2) Answer........................................................... (Total for question = 4 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q17. Describe the function of carrier proteins in a cell surface membrane. 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(Total for question = 4 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q18. Scientists can use models to explain the need for a circulation system in animals. The shapes in the diagram represent two different animals that live in water. The figures represent the height, width and breadth of the animals. Determine why animal A does not need a circulation system but animal B does. 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(Total for question = 4 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q19. Blood plasma contains glucose dissolved in water. Glucose is a polar molecule that is taken up by muscle cells and used in the synthesis of glycogen. Describe how glucose enters muscle cells through the cell membrane. 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(Total for question = 2 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q20. The diagram shows part of a cell surface membrane. Which of the molecules labelled in the diagram is a glycoprotein? (1) A B C D (Total for question = 1 mark) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q21. Answer the questions with a cross in the boxes you think are correct. If you change your mind about an answer, put a line through the box and then mark your new answer with a cross. The structure of the cell surface membrane can be described by the fluid mosaic model. The diagram shows the fluid mosaic model of the cell surface membrane. (i) Which of the shaded structures transport charged molecules or ions across the membrane? (1) A B C D 1 and 2 only 3 and 4 only 1, 2 and 3 only 1, 2, 3 and 4 (ii) Which of the shaded structures contain both hydrophilic regions and hydrophobic regions? (1) A B C D 1 and 2 only 3 and 4 only 1, 2 and 3 only 1, 2, 3 and 4 (iii) A student measured the width of the phospholipid bilayer shown on the diagram as 2.5 cm. The actual size of this bilayer is 5 nm. What is the approximate magnification of the diagram? (1) A B C D × 5000 × 50 000 × 500 000 × 5 000 000 (Total for question = 3 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q22. *Cells use ions in many different processes. Ion transport across cell membranes is a fundamental property of all living cells. The diagram shows some typical ion concentrations in healthy human cells and in the extracellular fluid. All values are in mmol dm-3. Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com The tables show information about the human genome and types of transport channel in humans. Discuss the importance of ion transport across membranes in human health and disease. (Total for question = 9 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q23. Pickling is a technique used to preserve food. Onions can be pickled by immersing them in a solution of sodium chloride. A student investigated the effects of changing the concentration of sodium chloride solution on the mass of onion tissue. Small onions were peeled, had their tops and bottoms cut off and were weighed. The onions were then placed into covered beakers containing different concentrations of sodium chloride solution. Six beakers were set up as shown in the diagram. The beakers were left for two days. The onions were removed, blotted dry and reweighed. The investigation was repeated two more times. The mean percentage change in mass was calculated. The results of the investigation are shown in the table. (i) Explain one way in which this investigation could be improved. (2)....................................................................................................................................................................................................................................................................................................................................................................................................................................... PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances (ii) Standard deviation can be calculated using the formula shown. Calculate the standard deviation for the 2.5% sodium chloride solution. (2) Answer........................................................... (iii) Deduce the effect of increasing the concentration of sodium chloride on the change in mass of the onion tissue. 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(Total for question = 7 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q24. All cells have a cell surface membrane. Cell surface membranes regulate the movement of substances into and out of cells. (i) Which of the following describes the movement of water by osmosis? (1) (ii) The concentration of potassium ions inside an animal cell is many times higher than the concentration of potassium ions in the extracellular fluid. Which mechanism is responsible for the uptake of potassium ions by this animal cell? (1) A active transport B exocytosis C osmosis D passive diffusion (iii) Glucose enters cells by facilitated diffusion. Which part of the cell surface membrane allows facilitated diffusion of glucose? (1) A cholesterol B glycolipid C phospholipid D protein (Total for question = 3 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q25. Answer the questions with a cross in the boxes you think are correct. If you change your mind about an answer, put a line through the box and then mark your new answer with a cross. In the lungs, oxygen moves from the alveoli into red blood cells. (i) How many times does an oxygen molecule cross a cell surface membrane to move from the centre of an alveolus to the centre of a red blood cell? (1) A B C D 2 3 4 5 (ii) Oxygen enters the red blood cell by (1) A B C D active transport diffusion facilitated diffusion osmosis (Total for question = 2 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q26. All organisms exchange gases with their environment. Sailor's eyeball (Valonia ventricosa) is a single-celled, spherical organism. One of these organisms can have a diameter of 1 cm to 4 cm. The table shows the diameter, surface area and volume of different Valonia ventricosa cells. (i) The volume of a sphere can be calculated using the following equation. What is the volume of a cell with a diameter of 4 cm? (1) A 33.51 cm2 B 33.51 cm3 C 268.08 cm2 D 268.08 cm3 (ii) Describe why single-celled organisms, such as Valonia ventricosa, do not need a specialised gas exchange surface. (2)................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. (Total for question = 3 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q27. A student placed the same volume of starch suspension into two bags made of Visking tubing. Each bag had a different length and width. The thickness of the Visking tubing for each bag was the same. The membrane of the Visking tubing is partially permeable. The same volume and concentration of amylase solution was added to the starch suspension. Each bag was sealed and placed into test tubes containing the same volume of water, as shown in the diagram. The water was tested at regular intervals for the presence of maltose. Maltose was detected in the water in tube A before it was detected in the water in tube B. Assess the factors that would cause maltose to be detected in tube A before tube B. 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(Total for question = 4 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q28. Hereditary spherocytosis is a condition that affects red blood cells. This inherited condition is caused by a gene mutation that affects the shape of the cell surface membrane. Describe the structure of the cell surface membrane. 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(Total for question = 3 marks) PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q29. Answer the questions with a cross in the boxes you think are correct. If you change your mind about an answer, put a line through the box and then mark your new answer with a cross. The diagram shows the structure of a cell surface membrane. (i) The molecule labelled R is a phospholipid. Give the name of the bond that joins a fatty acid molecule to a glycerol molecule in a phospholipid. (1)............................................................................................................................................. (ii) Which of the following describes molecule P? (1) A B C D carrier protein cholesterol glycolipid glycoprotein (iii) Which of the following molecules is involved in cell recognition? (1) A B C D Q R S T (iv) Which molecule allows ions to diffuse into a cell? (1) A B C D P Q R T (Total for question = 4 marks) Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Q30. All organisms exchange gases with their environment. Mammalian lungs are adapted for rapid gas exchange. Explain how the structure of the human lungs enables rapid gas exchange. 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(Total for question = 4 marks) Edexcel Biology A-level - Exchange of Substances Mark Scheme Q1. Q2. Q3. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q4. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q5. Q6. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q7. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q8. Q9. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q10. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q11. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q12. Q13. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q14. Q15. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q16. Q17. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q18. Q19. Q20. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q21. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q22. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q23. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q24. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q25. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q26. Q27. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q28. Q29. PhysicsAndMathsTutor.com Edexcel Biology A-level - Exchange of Substances Q30. PhysicsAndMathsTutor.com