03. Past Public Examination Questions on Movement across cell membrane.pdf

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Past Public Examination Questions on Movement across cell membrane P. 1 / 6 Past Public Examination Questions on Movement across cell membrane (C.3) Conventional Questions 1. A sample of human blood was dropped onto 3 clean slides, each containing a salt solution. (i) Explain why the red blood cells are not visible in solution B. (ii) Which salt solution has a concentration similar to that of human plasma? Explain your answer. (iii) Briefly describe the part played by the kidneys in regulating the salt concentration of the plasma in order to avoid shrinkage of the red blood cells. (iv) A plant cell, whose cell-sap concentration is similar to the concentration of the contents of human red blood cells, is placed in solution B. Describe and explain its appearance after half an hour. (11 marks) Jane disagreed with Keith because she found that the shopkeeper also stored whole pears in water tanks. Explain why this observation provides Jane with evidence to oppose Keith's idea. (2 marks) (c) Suggest one possible hygienic problem of storing the cut pears in water tank. (HKCEE 1982) 2. In order to study the conditions for osmosis, a student prepared two set-ups as shown in the diagrams below. The skin of each potato was removed and a cavity was made for holding the sucrose solution. (i) Explain why the level of sucrose solution of set-up A rose after 12 hours. (3 marks) (ii) What can you conclude from the results of the two set-ups? (2 marks) (iii) Referring to set-up A, draw a labeled diagram to show the possible appearance of a complete potato cell which is in contact with (1) the sucrose solution, (2) the distilled water. (4 marks) (iv) At the end of the experiment, sucrose was found in the distilled water in set-up B. Explain why this occurred. (2 marks) 4. A student carried out an investigation to determine the water potential of potato tissue. He immersed five identical potato strips separately into five beakers containing sucrose solution of different concentrations for one hour. The masses of the potato strips before and after the immersion were measured and recorded. He then made the following calculation for each potato strip: The graph below shows the results of the investigation: 3. One day, when Keith and Jane walked past a fresh fruit juice shop, Keith noticed that some pears were cut into pieces and stored in a tank of water before use. (a) Keith thought that the shopkeeper stored the cut pears in water in order to extract more juice. Explain the biological principle behind Keith's idea. (3 marks) (b) Jane disagreed with Keith because she found that the shopkeeper also stored whole pears in water tanks. Explain why this observation provides Jane with evidence to oppose Keith's idea. (2 marks) (c) Suggest one possible hygienic problem of storing the cut pears in water tank. (1 mark) (HKCEE 2007) 4. A student carried out an investigation to determine the water potential of potato tissue. He immersed five identical potato strips separately into five beakers containing sucrose solution of different concentrations for one hour. The masses of the potato strips before and after the immersion were measured and recorded. He then made the following calculation for each potato strip: The graph below shows the results of the investigation:
Past Public Examination Questions on Movement across cell membrane P. 2 / 6 (a) (i) When the ratio of final mass to initial mass is 1.0, the potato tissue has the same water potential as the corresponding sucrose solution. Explain the biological principle behind this statement.

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