Question 1: Define osmosis and describe the process in your own words.

Answer: Osmosis is the diffusion of water molecules across a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration, aiming to equalise solute concentrations on both sides.

Question 2: Explain why plant cells become turgid when placed in a dilute solution and plasmolysed when in a concentrated solution.

Answer: In a dilute solution, water enters the plant cell via osmosis, causing the cell to swell and become turgid. In a concentrated solution, water exits the cell, leading to plasmolysis where the cell membrane pulls away from the cell wall.

Question 3: Calculate the osmotic water potential in a solution where the water moves into a cell with an osmotic potential of -0.5 MPa. If the water potential outside the cell is -0.2 MPa, what is the net movement of water?

Answer: Water moves into the cell because the outside potential (-0.2 MPa) is higher than the inside (-0.5 MPa), so water will enter the cell until equilibrium is reached.

Question 4: Identify which of the following scenarios involves osmosis:

Answer: Water moving into a red blood cell in a hypotonic solution.

Question 5: Fill in the blank: The movement of water across a semi-permeable membrane from a _______ solute concentration to a _______ solute concentration is called osmosis.

Answer: lower, higher

Question 6: Describe an experiment to demonstrate osmosis in plant tissue, including the variables you would control and safety precautions.

Answer: An experiment can involve placing a piece of potato in solutions of different sucrose concentrations. The independent variable is sucrose concentration; the dependent variable is the mass or turgidity of the potato. Control variables include temperature and time. Safety precautions include handling solutions carefully to avoid spills and skin contact, and ensuring the equipment is clean to prevent contamination.

Question 7: A solution has a solute concentration of 0.3 mol/L of sodium chloride. If a cell with a solute concentration of 0.2 mol/L is placed in this solution, will water move into or out of the cell? Explain your answer.

Answer: Water will move out of the cell because the external solution has a higher solute concentration (0.3 mol/L) than the inside of the cell (0.2 mol/L), resulting in water moving from the inside to the outside via osmosis.

Question 8: Interpret the following scenario: In an experiment, the mass of a potato sample increased by 15% after 30 minutes in distilled water. What does this indicate about the water potential inside the potato cells?

Answer: This indicates that the water potential inside the potato cells is lower than that of distilled water, leading to water entering the cells and increasing their mass.

Question 9: Identify a real-world application of osmosis in industry or technology and briefly explain its importance.

Answer: Reverse osmosis is used in water purification to remove salts and impurities from seawater or contaminated water, making it safe for drinking and industrial use. It is important for providing clean water in areas lacking natural fresh water sources.

Question 10: What safety precautions should be followed when conducting experiments involving concentrated salt solutions?

Answer: Wear protective gloves and goggles to prevent skin and eye contact, handle solutions carefully to avoid spills, and dispose of chemicals safely according to safety guidelines.