Question 1: Define diffusion in biological systems.

Answer: Diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration.

Question 2: Explain why diffusion is important for oxygen supply in microgravity environments.

Answer: Diffusion is essential for oxygen to pass from the air in the spacecraft into the bloodstream of astronauts, especially since active transport methods may be less effective in microgravity.

Question 3: What factors affect the rate of diffusion?

Answer: Factors include concentration gradient, temperature, surface area, and the nature of the diffusing substances.

Question 1: Calculate the diffusion flux (J) of oxygen molecules passing through a membrane with a concentration difference of 0.2 mol/m³, a membrane area of 2 m², and a diffusion coefficient of 1.0 x 10⁻⁵ m²/s. Use the formula J = D * (ΔC / Δx). Assume Δx (thickness of membrane) is 0.01 m.

Answer: J = 2.0 x 10⁻⁸ mol/m²·s

Question 1: Describe a simple experiment to test how microgravity affects the rate of diffusion of a dye in a liquid.

Answer: Students could set up a container with dyed water in a microgravity environment (such as aboard a spacecraft) and compare the diffusion rate to that on Earth, considering variables like dye concentration and temperature. Safety precautions include ensuring proper handling of dyes and equipment to prevent contamination or spills in microgravity.

Question 1: In a microgravity environment, the concentration of carbon dioxide in the spacecraft cabin air increased from 0.04% to 0.08% over 24 hours. Explain what this suggests about the diffusion process in microgravity and possible causes.

Answer: This suggests that diffusion of CO₂ from the bloodstream into the cabin air may be less efficient in microgravity, possibly due to altered gas exchange dynamics or reduced convection, leading to accumulation of CO₂.

Question 1: Discuss how understanding diffusion is crucial for designing life support systems in spacecraft. Include examples of gases and nutrients involved, and explain challenges posed by microgravity.

Answer: Understanding diffusion allows engineers to design efficient life support systems that facilitate the transfer of oxygen, removal of CO₂, and nutrient delivery without relying solely on active pumping. Microgravity reduces natural convection, making passive diffusion less effective; thus, systems must incorporate mechanisms like fans or specialised membranes to ensure proper gas exchange and nutrient transfer, ensuring astronaut safety and system reliability.

Question 1: Describe how diffusion principles are used in designing portable oxygen concentrators for astronauts or space tourists.

Answer: Diffusion is used to separate oxygen from ambient air by allowing nitrogen and other gases to pass through membranes while oxygen diffuses and is collected for breathing. This process relies on diffusion gradients and membrane selectivity to ensure a pure oxygen supply.

Question 2: Predict how the rate of diffusion might change if the temperature aboard a spacecraft increases by 10°C, and explain why.

Answer: The rate of diffusion would increase because higher temperatures increase molecular movement and kinetic energy, leading to faster diffusion rates.