Q1. During osmosis, individual molecules move:1) Toward lower concentrations2)Toward lower osmotic pressure3)All directions with equal probability4) Toward higher concentrationsQ2. When the Sim Cell membrane in the Cell-O-Scope simulator jiggled back and forth, this was due to:1)Pressure against the membrane2) Osmosis causing molecules to flow across the membrane3) The membrane not being at equilibrium4) None of the aboveQ3. Placing blood cells into a solution that is hypertonic to the cells will cause the osmotic pressure of the cells to:1) Increase2) Decrease3) Neither increase nor decreaseQ4. Placing blood cells into a solution that is isotonic to the cells will cause the osmotic pressure of the cells to:1) Increase2) Decrease3) Neither increase nor decreaseQ5. According to the rules of osmosis, a system will reach a state of equilibrium when there are equal numbers of __ molecules on both sides of a water-permeable membrane.1) solute2) solvent3) water4) none of the aboveQ6. A SimCell with a water-permeable membrane that contains 20 hemoglobin molecules and 480 water molecules is placed into an extracellular fluid that contains 20 dextrose molecules and 480 water molecules. Which of the following should happen?1) More water molecules will flow from the SimCell into the extracellular fluid than from the extracellular fluid into the SimCell.2) More water molecules will flow from the extracellular fluid into the SimCell than from the SimCell into the extracellular fluid.3) There will be no movement of water molecules across the membrane.4) Water molecules will move back and forth equally across the membrane.Q7. A SimCell with a water-permeable membrane that contains 20 hemoglobin molecules and 480 water molecules is placed in an extracellular fluid that contains 40 dextrose molecules and 960 water molecules. Which of the following should happen?1) More water molecules will flow from the SimCell into the extracellular fluid than from the extracellular fluid into the SimCell.2) More water molecules will flow from the extracellular fluid into the SimCell than from the SimCell into the extracellular fluid.3) There will be no movement of water molecules across the membrane.4) Water molecules will move back and forth equally across the membrane.Q8. A SimCell with a water-permeable membrane that contains 50 dextrose molecules, 25 glucose molecules, 25 hemoglobin molecules and 900 water molecules is placed in an extracellular fluid that is one part solute to 15 parts water (its solute-to-solvent ratio is 1:15). Which of the following should happen?1) More water molecules will flow from the SimCell into the extracellular fluid than from the extracellular fluid into the SimCell.2) More water molecules will flow from the extracellular fluid into the SimCell than from the SimCell into the extracellular fluid.3) There will be no movement of water molecules across the membrane.4) Water molecules will move back and forth equally across the membrane.Q9. A SimCell has a special membrane that is permeable to alcohol but not to water. This SimCell contains 20% alcohol and 80% water and is placed in a solution containing 40% alcohol and 60% water. What will happen to the cell?1) It will expand due to net movement of water into the cell.2) It will expand due to net movement of alcohol into the cell.3) It will contract due to net movement of water out of the cell.4) It will contract due to net movement of alcohol out of the cell.Q10. Fish that live in saltwater and fish that live in freshwater both have water balance challenges that deal with osmosis. What is the best characterization of the challenges for each, based on your investigations in this lab?1) Both types of fish must constantly get rid of excess water.2) Freshwater fish must get rid of excess water and saltwater fish must retain the water they have.3) Freshwater fish must retain the water they have and saltwater fish must get rid of excess water.4) Both kinds of fish must retain as much water as they can.
The correct answer and explanation is:
Q1. During osmosis, individual molecules move:
Answer: 3) All directions with equal probability
Explanation: Osmosis is the movement of solvent molecules (such as water) across a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration. Individual molecules of solvent move randomly in all directions, but the net movement is from low solute concentration to high solute concentration. The random movement occurs in all directions with equal probability, but the overall direction is influenced by concentration gradients.
Q2. When the Sim Cell membrane in the Cell-O-Scope simulator jiggled back and forth, this was due to:
Answer: 3) The membrane not being at equilibrium
Explanation: The jiggling of the membrane in the simulator represents a dynamic process. When the system is not at equilibrium, the molecules are constantly moving, and the membrane responds to these movements. As solute and solvent molecules move, they exert pressure on the membrane, causing it to shift or jiggle. When equilibrium is reached, the movement should stabilize, and no further net movement of molecules will occur.
Q3. Placing blood cells into a solution that is hypertonic to the cells will cause the osmotic pressure of the cells to:
Answer: 1) Increase
Explanation: A hypertonic solution has a higher solute concentration compared to the inside of the blood cells. When blood cells are placed in a hypertonic solution, water will move out of the cells in an attempt to balance the solute concentrations. As water leaves the cells, the osmotic pressure inside the cells increases because the remaining solute molecules inside are more concentrated.
Q4. Placing blood cells into a solution that is isotonic to the cells will cause the osmotic pressure of the cells to:
Answer: 3) Neither increase nor decrease
Explanation: An isotonic solution has the same solute concentration as the inside of the blood cells. When blood cells are placed in an isotonic solution, there is no net movement of water in or out of the cells, and the osmotic pressure inside the cells remains unchanged.
Q5. According to the rules of osmosis, a system will reach a state of equilibrium when there are equal numbers of ______ molecules on both sides of a water-permeable membrane.
Answer: 3) water
Explanation: Osmosis refers to the movement of water molecules across a semipermeable membrane. The system will reach equilibrium when the concentrations of water molecules are equal on both sides of the membrane, as water moves from regions of lower solute concentration to regions of higher solute concentration. At equilibrium, there is no net movement of water, and both sides have the same number of water molecules.
Q6. A SimCell with a water-permeable membrane that contains 20 hemoglobin molecules and 480 water molecules is placed into an extracellular fluid that contains 20 dextrose molecules and 480 water molecules. Which of the following should happen?
Answer: 4) Water molecules will move back and forth equally across the membrane.
Explanation: The osmotic pressure is determined by the relative concentrations of solute and solvent molecules. In this case, the solute concentration in the SimCell (20 hemoglobin molecules) and the extracellular fluid (20 dextrose molecules) is the same, meaning the osmotic pressure is also balanced. As a result, water molecules will move freely in both directions across the membrane with no net movement, leading to equilibrium.
Q7. A SimCell with a water-permeable membrane that contains 20 hemoglobin molecules and 480 water molecules is placed in an extracellular fluid that contains 40 dextrose molecules and 960 water molecules. Which of the following should happen?
Answer: 1) More water molecules will flow from the SimCell into the extracellular fluid than from the extracellular fluid into the SimCell.
Explanation: The extracellular fluid has a higher concentration of solute (40 dextrose molecules) compared to the SimCell (20 hemoglobin molecules). Since osmosis occurs from an area of lower solute concentration to higher solute concentration, water will move out of the SimCell into the extracellular fluid, causing the SimCell to shrink.
Q8. A SimCell with a water-permeable membrane that contains 50 dextrose molecules, 25 glucose molecules, 25 hemoglobin molecules, and 900 water molecules is placed in an extracellular fluid that is one part solute to 15 parts water (its solute-to-solvent ratio is 1:15). Which of the following should happen?
Answer: 2) More water molecules will flow from the extracellular fluid into the SimCell than from the SimCell into the extracellular fluid.
Explanation: The extracellular fluid has a lower solute concentration than the SimCell, which contains a higher concentration of dextrose, glucose, and hemoglobin molecules. Water will move from the area of lower solute concentration (extracellular fluid) into the SimCell, increasing the volume of the SimCell.
Q9. A SimCell has a special membrane that is permeable to alcohol but not to water. This SimCell contains 20% alcohol and 80% water and is placed in a solution containing 40% alcohol and 60% water. What will happen to the cell?
Answer: 2) It will expand due to net movement of alcohol into the cell.
Explanation: Since the membrane is permeable to alcohol but not to water, alcohol will move into the SimCell from the solution to equalize the alcohol concentrations on both sides of the membrane. This will cause the SimCell to expand.
Q10. Fish that live in saltwater and fish that live in freshwater both have water balance challenges that deal with osmosis. What is the best characterization of the challenges for each, based on your investigations in this lab?
Answer: 2) Freshwater fish must get rid of excess water and saltwater fish must retain the water they have.
Explanation: Freshwater fish live in an environment where the water is less concentrated with solutes than the fish’s body, leading to the fish gaining excess water. To maintain osmotic balance, freshwater fish excrete large amounts of dilute urine to get rid of this excess water. In contrast, saltwater fish live in an environment with high solute concentrations, causing water to flow out of their bodies. Saltwater fish must conserve water by drinking seawater and excreting concentrated urine to retain as much water as possible.