1. The ________ portion of the cell membrane is responsible for the isolating functions of the membrane, while the ________ portion regulates exchange and communication with the environment. 03.01Q 1.lipid; protein 2.cholesterol; lipid 3.protein; cholesterol 4.carbohydrate; lipid 5.nucleic acid; lipid

2. The ________ portion of the cell membrane is responsible for the isolating functions of the membrane, while the ________ portion regulates exchange and communication with the environment. 03.01A 1.lipid; protein 2.cholesterol; lipid 3.protein; cholesterol 4.carbohydrate; lipid 5.nucleic acid; lipid

3. Answer: lipid; protein Explanation: Lipids are not soluble in the water found both inside and outside the cell. They serve as a barrier to passage of most hydrophilic substances. Proteins allow passage of some of these materials by facilitated diffusion or active transport. The ________ portion of the cell membrane is responsible for the isolating functions of the membrane, while the ________ portion regulates exchange and communication with the environment. 03.01E

4. 1.They move laterally along the plane of the membrane. 2.They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. According to the fluid mosaic model of cell membranes, which of the following is a TRUE statement about membrane phospholipids? 03.02Q 3.They can depart from the membrane and become dissolved in the surrounding solution. 4.They have hydrophilic tails in the interior of the membrane.

5. 1.They move laterally along the plane of the membrane. 2.They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. According to the fluid mosaic model of cell membranes, which of the following is a TRUE statement about membrane phospholipids? 03.02A 3.They can depart from the membrane and become dissolved in the surrounding solution. 4.They have hydrophilic tails in the interior of the membrane.

6. Answer: They can move laterally along the plane of the membrane. Explanation: In cell membranes, phospholipids form a bilayer with the hydrophilic portions on the outside surfaces and the hydrophobic portion in the interior. Proteins with hydrophobic sections can penetrate this bilayer. According to the fluid mosaic model of cell membranes, which of the following is a TRUE statement about membrane phospholipids? 03.02E

7. 1.Sugar and amino acid entry 2.Diffusion and osmosis What would continue to occur if plasma membranes were composed solely of phospholipids and no proteins? 03.03Q 3.Movement of ions through channels 4.Immune reactions 5.Cell adhesions

8. 1.Sugar and amino acid entry 2.Diffusion and osmosis What would continue to occur if plasma membranes were composed solely of phospholipids and no proteins? 03.03A 3.Movement of ions through channels 4.Immune reactions 5.Cell adhesions

9. Answer: Diffusion and osmosis Explanation: Without membrane proteins, the movement of most hydrophilic substances across the membrane (by facilitated diffusion or active transport) would not occur. However, the movement of substances directly through the phospholipid bilayer (by diffusion or osmosis) would continue. What would continue to occur if plasma membranes were composed solely of phospholipids and no proteins? 03.03E

10. 1.The red ink is uniformly distributed in one half of the tray and the green ink is uniformly distributed in the other half of the tray. 2.The red and green inks are both uniformly distributed throughout the tray. You fill a shallow tray with water and place a drop of red ink in one end of the tray and a drop of green ink in the other end. Which of the following is TRUE at equilibrium? 03.04Q 3.Each ink is moving down its concentration gradient. 4.The concentration of each ink is higher at one end of the tray than at the other end. 5.No predictions can be made without knowing the size of the ink molecules.

11. 1.The red ink is uniformly distributed in one half of the tray and the green ink is uniformly distributed in the other half of the tray. 2.The red and green inks are both uniformly distributed throughout the tray. You fill a shallow tray with water and place a drop of red ink in one end of the tray and a drop of green ink in the other end. Which of the following is TRUE at equilibrium? 03.04A 3.Each ink is moving down its concentration gradient. 4.The concentration of each ink is higher at one end of the tray than at the other end. 5.No predictions can be made without knowing the size of the ink molecules.

12. Answer: The red and green inks are both uniformly distributed throughout the tray. Explanation: Before and during diffusion of the ink particles, there will be net movement of particles down the concentration gradient. After diffusion has occurred and equilibrium is reached, the concentration of both ink particles will be uniform throughout the tray. You fill a shallow tray with water and place a drop of red ink in one end of the tray and a drop of green ink in the other end. Which of the following is TRUE at equilibrium? 03.04E

13. 1.The cells swell and burst because water moves into the cells. 2.The cells shrivel up because water leaves the cells. If red blood cells are taken from the body and placed in a hypertonic solution, what happens to the cells? 03.05Q 3.The cells remain unchanged due to equal solute concentration inside and outside the cells. 4.The cells remain unchanged due to equal water concentrations inside and outside the cells.

14. If red blood cells are taken from the body and placed in a hypertonic solution, what happens to the cells? 03.05A 1.The cells swell and burst because water moves into the cells. 2.The cells shrivel up because water leaves the cells. 3.The cells remain unchanged due to equal solute concentration inside and outside the cells. 4.The cells remain unchanged due to equal water concentrations inside and outside the cells.

15. Answer: The cells shrivel up because water leaves the cells. Explanation: A hypertonic solution is one in which the solute concentration is greater than that within the cells. Because of osmosis, water will move from the area of lesser concentration to the area of greater concentration: from the inside to the outside of the cells. If red blood cells are taken from the body and placed in a hypertonic solution, what happens to the cells? 03.05E

16. 1.dye particles in water at 10°C 2.dye particles in water at 20°C 3.dye particles in water at 30°C 4.dye particles in water at 40°C 5.dye particles in water at 80°C The slowest rate of diffusion of dye particles in water will occur in which situation? 03.06Q

17. 1.dye particles in water at 10°C 2.dye particles in water at 20°C 3.dye particles in water at 30°C 4.dye particles in water at 40°C 5.dye particles in water at 80°C The slowest rate of diffusion of dye particles in water will occur in which situation? 03.06A

18. Answer: dye particles in water at 10°C Explanation: By definition, particles move faster at higher temperatures. Diffusion results from the random motion of particles, and will occur slowest at the lowest temperature. The slowest rate of diffusion of dye particles in water will occur in which situation? 03.06E

19. 1.Water will diffuse from solution A to solution B. 2.Water will diffuse from solution B to solution A. 3.Starch will diffuse from solution A to solution B. 4.Starch will diffuse from solution B to solution A. 5.Both 2 and 4 will occur. Two aqueous solutions are separated by a semipermeable membrane. Solution A is 10% starch, and solution B is 5% starch. What will occur? 03.07Q

20. 1.Water will diffuse from solution A to solution B. 2.Water will diffuse from solution B to solution A. 3.Starch will diffuse from solution A to solution B. 4.Starch will diffuse from solution B to solution A. 5.Both 2 and 4 will occur. Two aqueous solutions are separated by a semipermeable membrane. Solution A is 10% starch, and solution B is 5% starch. What will occur? 03.07A

21. Two aqueous solutions are separated by a semipermeable membrane. Solution A is 10% starch, and solution B is 5% starch. What will occur? Answer: Water will diffuse from solution B to solution A. Explanation: A semipermeable membrane would not allow the passage of starch (a large molecular complex), but would allow osmosis, the movement of small water molecules. Since osmosis occurs from the lower concentration solution to that of higher concentration, water will diffuse from solution B to solution A. 03.07E

22. The cytoplasm of a certain cell, such as a neuron, already has a high concentration of K + ions. How can K + ions continue to enter the cell? 1.active transport 2.facilitated diffusion 3.osmosis 4.endocytosis 5.exocytosis 03.08Q

23. The cytoplasm of a certain cell, such as a neuron, already has a high concentration of K + ions. How can K + ions continue to enter the cell? 1.active transport 2.facilitated diffusion 3.osmosis 4.endocytosis 5.exocytosis 03.08A

24. Answer: active transport Explanation: The movement of the ions is against the concentration gradient. The cell must expend ATP energy to pump the ion into the cell against the gradient; this is active transport. The cytoplasm of a certain cell, such as a neuron, already has a high concentration of K + ions. How can K + ions continue to enter the cell? 03.08E

25. If you were able to use a high-powered microscope to look inside a cell as it synthesized a colored protein that was going to be secreted from the cell, where would you first see the protein inside the cell? 1.Smooth endoplasmic reticulum 2.Rough endoplasmic reticulum 03.09Q 3.Golgi 4.Lysosome 5.Secretory vesicle

26. If you were able to use a high-powered microscope to look inside a cell as it synthesized a colored protein that was going to be secreted from the cell, where would you first see the protein inside the cell? 1.Smooth endoplasmic reticulum 2.Rough endoplasmic reticulum 03.09A 3.Golgi 4.Lysosome 5.Secretory vesicle

27. Answer: Rough endoplasmic reticulum Explanation: Proteins that belong in a membrane or that are to be secreted from the cell are synthesized on ribosomes on the surface of the rough endoplasmic reticulum. They are then sorted into secretory vesicles in the Golgi. If you were able to use a high-powered microscope to look inside a cell as it synthesized a colored protein that was going to be secreted from the cell, where would you first see the protein inside the cell? 03.09E

28. 03.10Q Individuals that have severe forms of the disease familial hypercholesterolemia may be candidates for treatment with gene therapy because their disease is caused by a mutation… 1.…that is not hereditary. 2.…resulting from a mutant channel protein which can readily be repaired and inserted into the body. 3.…in a single gene, and thus can be corrected by inserting multiple copies of that gene into the body. 4.…in a gene carried by red blood cells, and thus which is readily accessible to genetic engineers.

29. 3.…in a single gene, and thus can be corrected by inserting multiple copies of that gene into the body. 4.…in a gene carried by red blood cells, and thus which is readily accessible to genetic engineers. 03.10A Individuals that have severe forms of the disease familial hypercholesterolemia may be candidates for treatment with gene therapy because their disease is caused by a mutation… 1.…that is not hereditary. 2.…resulting from a mutant channel protein which can readily be repaired and inserted into the body.

30. 03.10E Individuals that have severe forms of the disease familial hypercholesterolemia may be candidates for treatment with gene therapy because their disease is caused by a mutation… Answer: …in a single gene, and thus can be corrected by inserting copies of that gene into the body. Explanation: Genetic diseases caused by genetic defects in multiple genes will be much harder to correct by gene therapy because we will have to identify and then insert a large number of corrected genes.