Question 1: Define osmosis and explain its significance in human cells.

Answer: Osmosis is the diffusion of water across a semi-permeable membrane from a region of lower solute concentration to a higher solute concentration. It is vital for maintaining cell turgor, nutrient transport, and waste removal.

Question 2: Describe the difference between hypertonic, hypotonic, and isotonic solutions in relation to cells.

Answer: A hypertonic solution has a higher solute concentration than the cell, causing water to move out and potentially leading to cell shrinkage. A hypotonic solution has a lower solute concentration, causing water to move into the cell, possibly resulting in swelling. An isotonic solution has equal solute concentration on both sides, maintaining cell size.

Question 1: Calculate the osmotic pressure exerted by a solution with a solute concentration of 0.5 mol/L at 37°C. (Use van 't Hoff's law: π = iCRT). Assume the solute dissociates into 2 particles (i=2).

Answer: π = iCRT = 2 x 8.31 J/(mol·K) x 310 K x 0.5 mol/L = 2583.30 pascals

Question 2: A human red blood cell has a diameter of approximately 8 micrometers. If placed in a solution with a solute concentration of 0.2 mol/L, what is the expected movement of water across the cell membrane?

Answer: Water will tend to move into the cell if the solution is hypotonic, causing swelling, or out if hypertonic, causing shrinkage. The direction depends on the relative solute concentrations inside and outside the cell.

Question 1: Describe a simple experimental setup to investigate the effect of different solutions on plant or animal cells, including variables and safety precautions.

Answer: An experiment could involve placing cells in solutions of varying solute concentrations and observing changes in size or shape. Independent variable: concentration of solution. Dependent variable: cell size or shape. Controlled variables: temperature, type of cell. Safety precautions include handling solutions carefully, wearing gloves, and disposing of biological materials properly.

Question 1: A patient with a brain tumour undergoes a procedure where a hypertonic saline solution is injected to reduce swelling. Explain how osmosis plays a role in this treatment and the potential risks involved.

Answer: The hypertonic saline causes water to move out of brain cells into the extracellular space, reducing swelling. However, excessive removal of water can cause cells to shrink too much, leading to tissue damage or neurological issues. Proper regulation of solution concentration is crucial for safety.

Question 1: Explain how osmosis is involved in the absorption of water in the human small intestine. (4 marks)

Answer: Water moves into the small intestine from the bloodstream through osmosis, following the movement of nutrients and solutes. The difference in solute concentration between the blood and intestinal contents drives water absorption, aiding digestion.

Question 2: A solution has a solute concentration of 1 mol/L. If the osmotic pressure exerted is measured as 8200 Pa at 298 K, what is the van 't Hoff factor (i) assuming the solute dissociates completely? (Use π = iCRT).

Answer: i = π / (CRT) = 8200 / (8.31 x 298 x 1) ≈ 3.3, indicating partial dissociation or measurement variation.

Question 1: Explain how understanding osmosis is critical in the formulation of IV (intravenous) fluids used in hospitals.

Answer: IV fluids must be isotonic to blood to prevent cells from shrinking (hypertonic) or swelling (hypotonic). Proper osmolarity ensures cells maintain their shape and function during treatment.

Question 2: Discuss how osmosis influences the preservation of food in industry, such as in curing or dehydration processes.

Answer: Osmosis is used to draw water out of food items, inhibiting microbial growth and spoilage. Techniques like dehydration and curing reduce water activity, thus extending shelf life by creating a hypertonic environment that dehydrates microbes.