Membranes & Enzymes. Practice Questions. Slide 1 / 91. Slide 2 / 91. Slide 3 / 91

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1 New Jersey Center for Teaching and Learning Slide 1 / 91 Progressive Science Initiative This material is made freely available at and is intended for the non-commercial use of students and teachers. These materials may not be used for any commercial purpose without the written permission of the owners. NJCTL maintains its website for the convenience of teachers who wish to make their work available to other teachers, participate in a virtual professional learning community, and/or provide access to course materials to parents, students and others. Click to go to website: Slide 2 / 91 Membranes & Enzymes Practice Questions 1 How does a phospholipid membrane create an isolated internal environment? Slide 3 / 91

2 2 Draw and label a phospholipid. Slide 4 / 91 3 In what way do the screen on a window and a cell membrane serve a similar function? What characteristic is used to describe this function? Slide 5 / 91 4 What essential role does a cell membrane play in maintaining homeostasis? Slide 6 / 91

3 5 If you stir a cube of sugar into a glass of water, which of these materials would be a solute, and which would be a solvent? Slide 7 / 91 6 If you have a solution consisting of 5 grams of NaCl in 200 ml of water, what is the molarity of your solution? Slide 8 / 91 7 What characteristic of passive transport makes it passive? Slide 9 / 91

4 8 What role does a concentration gradient play in the process of passive transport? Slide 10 / 91 9 Which image below is in a state of equilibrium? Explain your answer. Slide 11 / Dialysis tubing contains 0.5 M glucose solution. It is placed in a beaker of 1.0 M glucose solution. Describe the direction of diffusion. Slide 12 / 91

5 11 A cell with an O2 concentration of 8 mm and a CO2 concentration of 5 mm is placed in a solution of 10 mm O2 and 1 mm CO2. Describe the direction of diffusion of each gas. Homework Slide 13 / Compare a phospholipid membrane to a chain link fence. How are these two structures similar? What function do they both serve? Slide 14 / How do amphiphilic phospholipids prevent their hydrophobic ends from coming into contact with water? Slide 15 / 91

6 14 Why is it necessary for cellular health that a cell membrane be selectively permeable? Slide 16 / Make a correction to the following statement to make it true: A solute has the ability to dissolve a solvent. Slide 17 / If you have a solution consisting of 100 grams of C6H12O6 in 1000 ml of water, what is the molarity of your solution? Slide 18 / 91

7 17 Suppose you have a solution consisting of 20 grams of carbon dioxide in 750 ml of water. What is the molarity of your solution? Slide 19 / What type of cellular transport would you use to describe a ball rolling down a hill? Explain your answer. Slide 20 / Suppose you spray air freshener into the corner of a room. Explain how the air freshener will move throughout the room. Be sure to use the term concentration gradient in your response. At what point will the air freshener molecules stop moving through the room? Slide 21 / 91

8 20 What impact does the state of equilibrium have on the rate of diffusion? Slide 22 / Suppose you have a cell that is freely permeable to H2O. There are more H2O molecules outside of the cell than inside of the cell. In what direction will the net movement of H2O molecules occur? Why? Slide 23 / A cell with an O2 concentration of 2 mm and a CO2 concentration of 10 mm is placed in a solution of 9 mm O2. Describe the direction of diffusion of each gas. Osmosis Classwork Slide 24 / 91

9 23 Since osmosis is passive transport, in which direction does water move related to its concentration gradient? What direction does it move in relation to the solution concentration gradient? Slide 25 / If a cell is placed in a hypertonic solution, in which direction will water flow in relation to the cell? Slide 26 / Sometimes, doctors will recommend that patients experiencing a sore throat should gargle saltwater to relieve their symptoms. Explain, in terms of solute concentration, how gargling saltwater could help reduce swelling in the throat. Slide 27 / 91

10 26 Suppose a cell is placed in an unknown solution. After examining the cell under a microscope, you see that the cell membrane has expanded, like a tight water balloon. What kind of solution, hypertonic, hypotonic or isotonic, is the unknown substance? Why did you come to this conclusion? Slide 28 / If there is equal concentration of free water molecules inside of a cell compared to its surrounding solution, what type of environment is the surrounding solution? Slide 29 / Suppose you have a houseplant that has begun to wilt. Would it be more beneficial to water this plant with a solution that was hypertonic or hypotonic when compared to the plant cells? Explain your answer. Slide 30 / 91

11 29 A cell with a sucrose concentration of 0.65 M is placed in a 1.2 sucrose solution. Describe the net flow of water. Homework Slide 31 / Does osmosis require the input of energy? Why or why not? Slide 32 / What will happen to a cell that is placed in a hypertonic solution? Slide 33 / 91

12 32 One way to preserve perishable food, such as meat, is to pack the food in a heavy concentration of salt. Knowing that bacteria survive well in a moist environment, explain why this method of food preservation can be effective. Slide 34 / If a cell lyses after being submerged in a solution, would you suggest this solution is hypertonic, hypotonic or isotonic? Why? Slide 35 / If a cell membrane were impermeable to water molecules, how would this change the process of osmosis in our cells? Slide 36 / 91

13 35 What is the relationship between osmosis and diffusion? Slide 37 / A cell with an O2 concentration of 0.4 M and a glucose concentration of 0.1 M is placed in a 0.5 M glucose solution. Describe the net flow of both solutes and water. Plasma Membrane, Transport Through Proteins Classwork Slide 38 / Explain why a cell that requires only passive transport of small molecules may not require the presence of membrane proteins. Slide 39 / 91

14 38 What similarities exist between peripheral vision and peripheral proteins? Why is the same adjective used to describe both of these things? Slide 40 / Why might a polar molecule have a difficult time moving across a phospholipid bilayer, even if it were a small molecule? Slide 41 / Explain why the term fluid mosaic is used to describe the structure of a phospholipid bilayer. Slide 42 / 91

15 41 Do you think an integral protein or a peripheral protein is more useful for the transport of molecules across a cell membrane? Justify your answer. Slide 43 / Identify one similarity that exists between the processes of active transport and facilitated diffusion. Slide 44 / Suppose you need to determine whether glucose is being transported using active transport or facilitated diffusion. The only clue you have is that ATP molecules are required for the movement to occur. Which type of transport do you suggest is being used? Why? Slide 45 / 91

16 44 Cl- ions often move across cell membranes through a membrane protein that does not change shape to accommodate their transport. Is this protein more likely a channel protein or carrier protein? Justify your response. Slide 46 / What type of cell transport is required to move a substance from an area of low concentration to an area of high concentration? Slide 47 / Describe one function that peripheral proteins may provide for the cell. Slide 48 / 91

17 47 In order for nerve cells to conduct electrical signals appropriately, certain ions need to be transported against their concentration gradient. What type of cell transport is necessary for this to occur? Is ATP required for this process to occur? Homework Slide 49 / Why are membrane proteins necessary for the movement of some larger molecules across cell membranes? Slide 50 / What is the difference between a peripheral membrane protein and an integral membrane protein? Slide 51 / 91

18 50 Are the phospholipids and proteins that construct a cell membrane anchored in a stationary position? What is the term used to describe the arrangement of a phospholipid bilayer? Slide 52 / Why are integral proteins sometimes also called transmembrane proteins? Slide 53 / Even though ions are very small, they often require the assistance of a membrane protein to enter or leave a cell. What characteristic of ions makes this necessary? Slide 54 / 91

19 53 Even though they both require the use of membrane proteins, if a molecule needs to move against a concentration gradient, would active transport or facilitated diffusion be a more likely method to accomplish this task? Explain your answer. Slide 55 / What do facilitated diffusion and osmosis have in common? Slide 56 / Knowing that molecules will naturally move from an area of high concentration to an area of low concentration, why do you think active transport may require the input of energy? Slide 57 / 91

20 56 Suppose a cell needs to move a small, uncharged molecule against its concentration gradient. What type of transport would be required to accomplish this task? Slide 58 / In what way is active transport similar to pushing a ball up a hill? Enzymes, Catalytic Cycle Classwork Slide 59 / Explain the impact that an enzyme can have on a chemical reaction. Slide 60 / 91

21 59 What is the relationship between enzymes and catalysts? Slide 61 / Which class of biological macromolecules would contain enzymes? Slide 62 / Suppose you are diagnosed with lactose intolerance. What enzyme would you not find naturally occurring in your body? How would this affect the digestion of lactose in your body? Slide 63 / 91

22 62 What is an active site? Why is an active site important for the completion of chemical reactions? Slide 64 / How is an induced fit with an enzyme similar to having your shirt tailored? Explain your answer. Slide 65 / How are the reactants altered over the course of a chemical reaction? Slide 66 / 91

23 65 What is activation energy? Slide 67 / How do enzymes affect the amount of activation energy required for a reaction? Homework Slide 68 / Suppose a friend of yours accidentally begins a food fight by flicking a grape off of your lunch table. Identify the catalyst of the food fight. Slide 69 / 91

24 68 Identify two ways in which an enzyme impacts a chemical reaction. Slide 70 / Explain the lock and key relationship between enzymes and substrates. Slide 71 / How would activation energy be affected if a reaction occurred in the absence of an enzyme? Temperature, ph, Inhibition Classwork Slide 72 / 91

25 71 Explain the role that optimal temperature has on enzyme activity? Slide 73 / How is an enzyme affected when the environment exceeds its optimal temperature? Slide 74 / If enzymes were a different kind of biological molecule, would temperature and ph have the same affect on their activity? Explain your answer. Slide 75 / 91

26 74 What role do cofactors have for enzyme activity? Slide 76 / How do competitive inhibitors interact with an enzyme? Slide 77 / Would the same solution for negating the impact of a competitive inhibitor work for a noncompetitive inhibitor? Why or why not? Homework Slide 78 / 91

27 77 How does increasing temperature affect enzyme activity? Slide 79 / Why does denaturing an enzyme impact its ability to influence a chemical reaction? Slide 80 / Draw a graph of enzyme activity for an enzyme that has an optimal ph range of 6-8. Slide 81 / 91

28 80 What is the relationship between cofactors and inhibitors? Slide 82 / Explain one way in which your body may negate the impact of a competitive inhibitor. Explain why this would work. Slide 83 / What affect does non-competitive inhibition have on the active site of an enzyme? Allosteric Regulation, Feedback Inhibition Classwork Slide 84 / 91

29 83 What is the difference between an allosteric site and an active site? Slide 85 / Explain how allosteric inhibitors function through feedback inhibition. Slide 86 / Even though allosteric regulation and denaturation both affect the shape of an enzyme, they are very different processes. Explain the difference between these two processes. Homework Slide 87 / 91

30 86 Explain why allosteric activators and inhibitors may be able to work on the same enzyme. Slide 88 / Explain the process by which an allosteric inhibitor influences an enzyme. Slide 89 / Provide a hypothesis for why scientists use the term feedback inhibition. Slide 90 / 91

31 89 Compare and contrast an allosteric activator and a coenzyme. Slide 91 / 91