Topic 3: Movement of substances across cell membrane

Transcription

1 Topic 3: Movement of substances across cell membrane 1. What is/are the role(s) of structure A? (1) For cell recognition. (2) For carrying water-soluble substances across cell membrane. (3) For supporting the cell. A. (1) only B. (2) only C. (1) and (2) only D. (1) and (3) only 2. Which of the following correctly shows the path through which sugar and alcohol molecules pass through the membrane? Sugar Alcohol A Path X Path X B Path X Path Y C Path Y Path X D Path Y Path Y 3. According to the fluid mosaic model of cell membrane, which of the following statements is true about membrane phospholipids? A. They have water-loving tails in the interior of the membrane. B. They occur in a bilayer, with membrane proteins restricted to the surface of the membrane. C. They are free to depart from the membrane and dissolve in the surrounding aqueous solution. D. They can move laterally along the plane of the membrane. 4. Microorganisms could not grow on honey because microorganisms: A. Cannot oxidize honey B. Are dehydrated by the sugars solution in the honey C. Cannot absorb the honey D. Contains no enzymes to digest honey 5. Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large amount of glucose from the intestinal lumen into their cytoplasm which has a low glucose concentration. Using this information, which transport mechanism is most probably functioning in the intestinal

2 cells? A. phagocytosis B. active transport C. diffusion D. osmosis 6. The graph below shows the change in the weight of a potato strip when it is immersed in salt solution of different concentrations. loss (g) gain (g) Change in weight of potato strip with concentration of salt solution J K L M N O concentration of salt in solution (%) The reason for joining the points by a best straight line is that A. averaging experimental results allows one to establish relationships. B. the individual points are wrong. C. the individual points are assumptions, while the best straight line is a fact. D. the best straight line shows the accuracy of the experimental results. 7. There are two cups of salt water with different concentrations. When diffusion of water molecules reaches equilibrium, it means: A. No water movement will be taken place B. No net water movement will be taken place C. No salt molecules will move D. Diffusion of water molecules from higher water potential to the lower

3 Directions: Questions 8 to 10 refer to the experiment below. 8. What will happen to the sugar crystals inside potatoes P and Q after an hour? P Q A. dissolve dissolve B. no change dissolve C. dissolve no change D. no change no change 9. Which process(es) is/are responsible for the changes mentioned above? A. Active transport B. Diffusion C. Osmosis D. Diffusion and osmosis 10. In doing this experiment, the skin of the potatoes must be peeled. Why? A. The skin contains sugar which will affect the results. B. The skin contains many soluble substances. C. The skin consists of cells with higher osmotic potential. D. The skin consists of impermeable dead cells. 11. Which of the following graphs represents the change of the liquid level from the start of the experiment to the time when equilibrium has been reached? Key: H = Relative height of the liquid level

4 12. Which of the following can increase the final height of the liquid level in the capillary tube? (1) raising the temperature of water to 30 (2) using a capillary tube with a smaller internal diameter (3) using a 10% sucrose solution A. (1) and (2) only B. (2) and (3) only C. (1) and (3) only D. (1), (2) and (3) 13. Which of the following can increase the rate of rise of the liquid level in the capillary tube? (1) raising the temperature of water to 30 (2) using a capillary tube with a smaller internal diameter (3) using a 10% sucrose solution (4) using a larger beaker to hold more water A. (1) and (2) only B. (2) and (3) only C. (1), (2) and (3) D.(2), (3) and (4)

5 14. In this study, if a 5% glucose solution were used instead of the 5% sucrose solution and the dialysis tubing was permeable to glucose, which of the following graphs represents the rise of the liquid level from the start of the experiment to the time when equilibrium has been reached? Key: H = Relative height of the liquid level