Multiple Choice Review Membranes and Proteins

Transcription

1 Multiple Choice Review Membranes and Proteins 1. What is the difference between carrier proteins and channel proteins? a. Carrier proteins change shape when a specific molecule binds to move it across the membrane while channel proteins provide corridors for specific molecules to pass through. b. Channel proteins change shape when a specific molecule binds to move it across the membrane while carrier proteins provide corridors for specific molecules to pass through. c. Carrier proteins assist molecules via diffusion. d. Channel proteins are attracted to glycolipids and carrier proteins change shape slightly when a specific molecule binds to help. 2. Which of the following physiological responses is an example of positive feedback? a. The body s production of red blood cells, which transport oxygen from the lungs to other organs, is stimulated by low concentrations of oxygen. b. A high concentration of glucose in the blood causes deeper, more rapid breathing, which expels carbon dioxide. c. Pressure of the baby s head near the opening of the uterus stimulates uterine contractions which cause greater pressure against the uterine opening. d. Heightened body temperature induces sweating which disposes of metabolic heat and cools the body. 3. Many organisms are able to regulate their internal environments. What is this process called? a. Selective permeability b. Plasmolysis c. Upregulation d. Homeostasis 4. Osmosis refers to the movement of water. Which of the following statements is an accurate description of osmosis? a. The diffusion of water through a semi-permeable membrane. b. The active transport of water. c. The diffusion of water through a gap junction. d. The diffusion of water from an area of low concentration to an area of high concentration. 5. Catalysts are essential to allowing many reactions to occur. What happens to a catalyst in a reaction? a. It is unchanged. b. It is incorporated into the products. c. It is incorporated into the reactants. d. It evaporates away. 6. Which of the following enzymes or hormones is incorrectly paired with the molecule with which it interacts? a. Amylase carbohydrates b. Pepsin protein c. Insulin sucrose d. Glucagon - glycogen

2 7. Some cells use chemical messengers to communicate with nearby cells and to respond to population density. What is this process called? a. Cell junctions b. Communicating junctions c. Quorum Sensing d. Single-celled signaling 8. Thermoplasmatales picrophilus is the most acidophilic of all known organisms on Earth. These archaea can live in environments with a ph as low as 0.6. Which of the following statements is likely true about this organism? a. Their enzymes have lost the ability to denature. b. Their enzymes have a low optimal ph. c. Their enzymes are insensitive to ph. d. They use molecules other than proteins as their main catalysts. 9. What structures shown below move molecules across the membrane using energy? a. Surface proteins assist the transport of molecules across the membrane. b. Glycoproteins assist in moving molecules through the membrane with their concentration gradients. c. The phospholipid bilayer absorbs energy and opens to allow certain molecules to cross. d. Carrier proteins are used to move molecules across the membrane against their concentration gradient. 10. A U-tube is set up with two solutions, solution A and solution B, separated from each other by a semi-permeable membrane. Solution A has a water potential of 3 and solution B has a water potential of 1.5. Which of the following is true? a. Water will move from solution A into solution B. b. Solution A is hypertonic compared to solution B. c. Water will move from solution B into solution A. d. Solution B has a higher pressure potential.

3 11. Choose the correct negative feedback loop that regulates human body temperature: a. High blood temperature is sensed by neurons, muscles are activated to shiver, goose bumps are raised. b. Sweat glands are activated, neurons sense sweating, blood vessels in the skin constrict to conserve body warmth. c. Blood vessels constrict, brain senses raised ph, brain activates sweating. d. High blood temperature is sensed by neurons, blood vessels in the skin dilate, sweat glands are activated 12. There are several methods for molecules to move across the plasma membrane. Which of the following statements accurately describes active transport? a. Molecules move against their concentration gradients without the use of energy. b. Molecules move against their concentration gradients using energy. c. Molecules move with their concentration gradients without the use of energy. d. Molecules move with their concentration gradients using energy. 13. Based on the beaker shown below, which solute(s) will exhibit a net diffusion out of the cell? a. Sucrose will exhibit a net diffusion out of the cell due to its much higher concentration. b. Glucose and fructose will exhibit a net diffusion out of the cell, because molecules will move from an area of higher concentration to an area of lower concentration. c. Glucose will exhibit a net diffusion out of the cell due to its much lower concentration. d. Sucrose and glucose will exhibit a net diffusion out of the cell, because molecules will move from an area of higher concentration to an area of lower concentration. 14. Which system of the body depends upon the sodium potassium pump to transmit signals from one place to another? a. The urinary system b. The digestive system c. The nervous system d. The integumentary system

4 15. The plasma membrane is embedded with a variety of proteins. Which of the following is not a function of proteins in the plasma membrane? a. Gather information from the surrounding environment. b. Interact and recognize other cells. c. Produce lipid molecules. d. Assist in the passage of materials into the cell. 16. The control of blood sugar levels is accomplished by coordination of several components of the body. Which of the following is not involved in blood sugar control? a. Liver b. Insulin c. Pancreas d. Glucagon 17. Lipase is an enzyme that catalyzes the hydrolysis of fats into fatty acids and glycerol molecules. In this catalyzed reaction, where does the fat bind to lipase? a. Substrate b. Active site c. Allosteric site d. Receptor 18. Plants must uptake mineral salts from the surrounding soil. The mineral salts, however, are more abundant inside the plant and therefore must use ATP in order to move the salts across the membrane, against their concentration gradient. Which method of movement does this describe? a. Simple diffusion b. Facilitated diffusion c. Active transport d. Osmosis Questions #19-20 refer to the diagram below, illustrating Neuron A transmitting a signal to Neuron B.

5 19. Which of the following statements correctly describes the transport of neurotransmitter out of Neuron A? a. The vesicle (2) fuses to the membrane (7) emptying its contents into the synaptic cleft (4)in a process called exocytosis. b. Using endocytosis, Neuron A passively transports the chemicals into the synaptic cleft (4). c. The vesicle (2) facilitates diffusion of the neurotransmitter through the channel protein (3). d. Simple diffusion occurs at the membrane (7) moving the neurotransmitter with its concentration gradient. 20. For signal transduction to occur Neuron B must uptake ions from the synaptic cleft (4). Which of the following correctly describes the transport of these ions into Neuron B? a. Ions diffuse directly across the phospholipid bilayer. b. The ions must be actively transported through the integral proteins (5.) c. The neurotransmitter activates the integral proteins (5) opening channels to ion flow. d. The ions enter Neuron B through endocytosis. 21. Why will some molecules such as oxygen, carbon dioxide, nitrogen freely move through the lipid bilayer of the cell membrane? a. They are polar. b. They are small. c. They are hydrophobic. d. They are ions. 22. Solute potential depends upon which of the following? a. Molar concentration of the solute b. Temperature in degrees Kelvin c. Temperature, type, and concentration of solute d. The pressure constant R which is L bar/mol K 23. Bacterial cells and plants cells are less likely than animal cells to lyse in a hypotonic environment because: a. The cells have mechanisms which actively transport water outside the cell. b. Bacteria and plant cells have plasma membranes less permeable to water than most animal cells. c. These cells increase their rates of photosynthesis in hypotonic environments. d. Bacterial cells and plants cells are surrounded by cell walls which provide support to the cell membrane under high osmotic pressure. 24. Glycolipids differ from other membrane lipids in that they a. Have hydrophobic heads. b. Have molecules of a monosaccharide associated with them. c. Have saturated and partially unsaturated tails. d. Have hydrophobic heads.

6 25. The mammalian urinary system depends upon which of these processes to conserve and regulate water? a. Osmosis only b. Facilitated diffusion and osmosis c. Active transport and diffusion d. Osmosis, facilitated diffusion, and active transport 26. The cellular membrane is often called the fluid mosaic model. To what does this refer? a. The fluidity of proteins and the pattern of phospholipids in the membrane. b. The ability of proteins to switch sides in the membranes. c. The fluidity of phospholipids and the pattern of proteins in the membrane. d. The fluidity of hydrophobic regions and proteins, and the mosaic pattern of hydrophilic regions. 27. A blood cell (0.9M NaCl) is placed in distilled water. What would most likely occur to the blood cell? a. The cell would swell and lyse. b. The cell would remain unchanged. c. The cell would shrivel. d. Turgor pressure would increase. 28. Diabetes is a disease that affects a feedback regulation pathway of the cell, specifically the cell s ability to lower the blood glucose level. Which of the following is a not an accurate statement regarding this disease? a. Diabetics fail to produce or respond to insulin, a hormone that decreases blood glucose levels. b. Synthetic insulin can replace regular insulin in the feedback mechanism. c. Diabetics experience a positive rather than negative feedback regulation of glucose levels. d. In people without diabetes, increases in glucose intake initiate the production of insulin. 29. Your mom buys celery on Saturday at the grocery store and stores it in the refrigerator. By Thursday, the celery is wilted and bendy. She places the celery in a container of water for an hour, after which the celery is crispy again. What process is responsible for this transformation? a. Osmosis b. Denaturation c. Active transport d. Electron pump 30. Pseudomonas aeruginosa are bacteria that grow within a host without harming it until the population reaches a certain density. At this point, they release a signal to aggressively replicate. To do so, they create a layer that completely covers the host s tissue inside of which they replicate at an exponential rate, in order to overcome the host s immune system. What is the name of this layer? a. Follicle b. Biofilm c. Quorum sensing d. Plasmodesmata

7 31. If an enzyme in solution is saturated with competitive inhibitors, the most effect way to increase the yield of products is to? a. Add more substrate. b. Heat the solution to 70 o C. c. Add an allosteric inhibitor. d. Decrease the ph of the solution. 32. A fungal cell is placed in a solution of 1.0M glucose. How will this glucose enter the cell? a. Via simple diffusion. b. Via facilitated diffusion. c. Via active transport. d. Via exocytosis. 33. Facilitated diffusion and active transport both rely on proteins embedded in the phospholipid bilayer of the cell. Which of the following statements provides the best explanation of the differences between active transport and facilitated diffusion? a. Active transport is powered by ADP phosphorylation while facilitated diffusion is powered by the hydrolysis of ATP. b. Active transport is powered by the hydrolysis of ATP while facilitated diffusion is powered by anabolic reactions of cells. c. Facilitated diffusion moves molecules up their concentration gradient until equilibrium is reached; active transport moves molecules against their concentration gradient. d. Facilitated diffusion moves molecules from areas of high concentration to areas of low concentration; active transport uses ATP hydrolysis to move molecules from areas of low concentration to areas of high concentration. 34. Receptor proteins are responsible for responding to chemical stimuli. Different receptors produce different responses. For example, epinephrine is the hormone that creates the fight or flight response. If epinephrine interacts with a β receptor on the skeletal muscle blood vessel, the blood vessel will dilate. If epinephrine interacts with an α receptor on the same blood vessel, the blood vessel will constrict. Which of the following can be used to explain why two molecules that interact with the same hormone can create different responses? a. When the α receptor is denatured, it becomes a β receptor. b. One receptor has tertiary structure while the other has quaternary structure c. The constriction caused by the α receptor is a symptom of a buildup of saturated fats in the blood. d. The proteins have different structures which result in similar receptor sites but different functions. 35. Paramecium, a single celled protist, lives in water that is hypotonic to its cell. It has adapted a contractile vacuole that is able to pump out water that enters the cell. If it did not have this adaptation, what would happen to the paramecium? a. It would lyse. b. It would become flaccid. c. It would plasmolyze.

8 d. It would become turgid. Questions # refer to the following scenario: Respiration is the process that creates energy (ATP) from glucose. The first step of respiration is glycolysis, in which glucose is converted into a molecule called pyruvate. Shown below are the steps in this conversion. The final step, in which phosphenol pyruvate (PEP) is converted into pyruvate is catalyzed by pyruvate kinase, an enzyme composed of several subunits. The equation of the conversion of PEP into pyruvate is shown below: PEP + ADP Pyruvate kinase pyruvate + ATP + NADH You are asked to determine the effects of two different molecules on the effectiveness of pyruvate kinase. You set-up 15 test tubes with the reactants and pyruvate kinase. To five test tubes, you also add ATP. To the last five test tubes, you add fructose-1,6-bisphosphate. You then measure the reaction rate in all test tubes. Your results show that ATP negatively affects reaction rate while fructose-1.6-bisphosphate positively affects it. 36. Which of the following statements explains the results of ATP on pyruvate kinase? a. ATP degrades PEP which slows the reaction by removing a reactant. b. A buildup of ATP is toxic and stops all reactions. c. ATP reacts with ADP, slowing the reaction by removing a reactant. d. ATP is a product of the reaction. If too much product builds up, it will stop the reaction to conserve energy. 37. From the experimental results, it appears that pyruvate kinase undergoes what type of regulation? a. Denaturation b. Allosteric c. Phosphorylation d. Signal transduction 38. What was the purpose of the five test tubes that only contained the reactants and pyruvate kinase? a. These test tubes measured the amount of PEP necessary to make the reaction run. b. These test tubes allowed the optimal conditions of the enzyme to be measured. c. These test tubes provided a baseline of how quickly the reaction went when no additional molecules were added. d. These test tubes were prepared in case the experiment had to quickly be repeated. 39. What is the independent variable in this experiment? a. Molecules added to reaction b. Reaction rate c. PEP amount

9 d. Temperature 40. What is the sample size? a. 2 b. 5 c. 10 d. 15

10 Quantitative Review Membranes and Proteins 1. A flaccid plant cell with a solute potential of MPa is placed in pure water. Time passes and the cell reaches osmotic equilibrium with its surroundings. Calculate the pressure potential of the cell just after it has been placed in the water and the potential at equilibrium. 2. In an animal cell, the solute potential is MPa. Calculate the water potential for this cell. 3. What are the values for Ψ, Ψp and Ψs for a solution of pure water at atmospheric pressure? Show calculations. 4. A turgid plant cell has a pressure potential of bar when placed in a hypotonic solution. Calculate the solute potential of the solution at equilibrium. 5. A bacterial cell in a beaker has reached equilibrium with the surrounding solution. The cell contains 0.5M of sucrose. What is the solute potential at 0 degrees Celsius? Round your answer to the nearest tenth. 6. Suppose an artificial animal-type cell was constructed out of dialysis tubing and contained 1.0M of a NaCl solution. If the cell is stored at 203 degrees Kelvin, what is the water potential of the cell? 7. A reverse osmosis water purification system can render brackish water useable by industry. What would be the operational (osmotic) pressure of such a system for a sample of water at 12 degrees Celsius? (For brackish water, C = 0.64M and i = 2) 8. What would be the molar concentration of solutes purified by a reverse osmosis water purification system for a sample of seawater at 8 degrees Celsius? The solute potential is - 2,283.7 bars, and the number of particles/ions in one molecule of solute after dissociation is 2.

11 ANSWER KEY 1. A 2. C 3. D 4. A 5. A 6. C 7. C 8. B 9. D 10. A 11. D 12. B 13. D 14. C 15. C 16. A 17. B 18. C 19. A 20. C 21. C 22. C 23. D 24. B 25. D 26. C 27. A 28. C 29. A 30. B 31. A 32. B 33. D 34. D 35. A 36. D 37. B 38. C 39. A 40. B MPa MPa 3. 0 MPa, 0 MPa, 0 Mpa bar bars bars bars M