Question 1: Define osmosis in biological terms.

Answer: Osmosis is the movement of water molecules from a region of higher water potential to a region of lower water potential through a semi-permeable membrane.

Question 2: Explain how a semi-permeable membrane influences osmosis.

Answer: A semi-permeable membrane allows only certain molecules, such as water, to pass through, preventing solutes from crossing and thereby facilitating osmosis.

Question 3: What is meant by water potential and how does it affect osmosis?

Answer: Water potential is a measure of the tendency of water to move from one area to another. Water moves from regions of higher water potential to lower water potential during osmosis.

Question 1: Calculate the water potential of a solution with an osmotic pressure of 600 kPa at 25°C. (Use the formula: Water potential = Osmotic potential + Pressure potential. Assume osmotic potential = -RT * C, where R = 8.31 J/(mol·K), T in Kelvin, C in mol/m³).

Answer: Approximately -1.98 MPa

Question 2: A plant cell has a internal water potential of -0.5 MPa. If the external solution has a water potential of -1.0 MPa, in which direction will water move? Calculate the potential difference.

Answer: Water moves out of the cell; potential difference = 0.5 MPa

Question 1: Describe a simple experiment to demonstrate osmosis using potato slices. Include the variables involved and safety precautions.

Answer: Cut potato slices and immerse them in solutions of different concentrations (e.g., pure water, salt solution). Measure the change in mass over time. Variables include solution concentration (independent), change in mass (dependent), and time. Safety precautions involve handling sharp knives carefully and wearing safety goggles to prevent splashes.

Question 2: Identify the independent, dependent, and control variables in the potato osmosis experiment.

Answer: Independent variable: Solution concentration; Dependent variable: Change in potato mass; Control variables: Temperature, type of potato, duration of experiment.

Question 1: A set of data shows that potato slices in pure water gained 10% of their initial mass, while those in 0.5 M salt solution lost 8%. Explain what this indicates about water potential in these solutions.

Answer: The data indicates that water potential in pure water is higher than inside the potato cells, causing water to enter. In 0.5 M salt solution, water potential is lower outside, causing water to leave the cells.

Question 1: Explain the importance of osmosis in medical treatments such as intravenous (IV) therapy.

Answer: Osmosis is crucial in IV therapy to ensure that fluids are balanced across cell membranes. Using solutions with appropriate water potential prevents cells from swelling or shrinking, maintaining proper cellular function and avoiding tissue damage.

Question 2: How does osmosis affect plant roots and their ability to absorb water from the soil?

Answer: Osmosis allows water to move from the soil, where water potential is higher, into the root cells, which typically have lower water potential, thus enabling plants to absorb water efficiently.