Question 1: Define the primary function of the alveoli in the lungs.

Answer: The alveoli are tiny air sacs where gas exchange occurs, allowing oxygen to enter the blood and carbon dioxide to be removed.

Question 2: Explain how the structure of alveoli facilitates efficient gas exchange.

Answer: Alveoli have a large surface area, thin walls, and are surrounded by capillaries, which together allow rapid diffusion of gases between the lungs and blood.

Question 3: What role do the intercostal muscles and diaphragm play during inhalation?

Answer: They contract during inhalation to increase the volume of the thoracic cavity, reducing pressure and allowing air to flow into the lungs.

Question 1: Calculate the total surface area of alveoli in a human lung if each alveolus has an approximate surface area of 0.1 mm² and there are about 300 million alveoli.

Answer: Surface area = number of alveoli × surface area per alveolus = 300,000,000 × 0.1 mm² = 30,000,000 mm² or 30,000 cm².

Question 2: If the volume of air inhaled in a normal breath is 500 mL and the oxygen content of inspired air is 21%, how much oxygen in mL is taken in per breath?

Answer: Oxygen = 500 mL × 0.21 = 105 mL.

Question 1: Describe a simple experiment to measure the volume of air inhaled during a single breath.

Answer: Students can use a spirometer or a water displacement method. They breathe into a tube connected to a measuring device or water container, recording the change in volume to determine breath volume. Ensure safety by conducting in a well-ventilated area and avoiding forced breathing.

Question 2: Identify two variables that should be controlled in an experiment measuring lung capacity, and explain why.

Answer: Variables to control include the person's body position and measurement technique, to ensure consistent results and reduce experimental error.

Question 1: A group of students has an average lung capacity of 4.8 litres with a standard deviation of 0.3 litres. What does this data suggest about the variability of lung capacity in this group?

Answer: The data indicates that most students have lung capacities close to 4.8 litres, with some variation of about 0.3 litres, suggesting moderate variability within the group.

Question 2: If a person’s oxygen uptake during exercise increases from 250 mL/min at rest to 1500 mL/min, what does this change indicate about lung and cardiovascular function?

Answer: This increase shows enhanced lung ventilation and cardiovascular response, allowing more oxygen to reach tissues during exercise.

Question 1: Describe the structure of alveoli and explain how their features optimise gas exchange. Include in your answer the importance of surface area, wall thickness, and blood supply. (6 marks)

Answer: Alveoli are tiny, balloon-like sacs with very thin walls composed of a single layer of epithelial cells. Their large surface area, due to the high number of alveoli, maximises gas exchange. The thin walls facilitate rapid diffusion of gases between the air and blood. Surrounding capillaries ensure a continuous blood supply, maintaining a concentration gradient essential for efficient gas exchange.

Question 1: How does exposure to pollutants like sulphur dioxide and particulate matter affect lung alveoli and overall respiratory health?

Answer: Pollutants can damage alveoli, reducing surface area and impairing gas exchange, leading to respiratory diseases such as bronchitis and emphysema.

Question 2: Describe how advances in biotechnology might improve treatment for lung diseases related to alveolar damage.

Answer: Biotechnology can enable the development of tissue engineering and stem cell therapies to repair or replace damaged alveoli, improving lung function in affected patients.