Question 1: Define the term 'alveolus' and explain its role in the respiratory system.

Answer: An alveolus is a tiny air sac in the lungs where gas exchange occurs; it allows oxygen to enter the blood and carbon dioxide to be removed.

Question 2: Describe the mechanism by which oxygen moves from the alveoli into the bloodstream.

Answer: Oxygen diffuses across the alveolar and capillary walls into the blood due to the concentration gradient, moving from an area of higher to lower concentration.

Question 1: Calculate the total surface area of alveoli in a human lung if there are approximately 300 million alveoli, each with an average surface area of 0.2 mm².

Answer: Total surface area = number of alveoli × surface area of each alveolus = 300,000,000 × 0.2 mm² = 60,000,000 mm² or 60 m²

Question 2: If the tidal volume of a person is 500 mL and their respiratory rate is 12 breaths per minute, what is their minute ventilation in litres per minute?

Answer: Minute ventilation = tidal volume × respiratory rate = 0.5 L × 12 = 6 L per minute

Question 1: Describe a safe method to investigate the effect of exercise on lung capacity.

Answer: Use a spirometer in a well-ventilated area, ensure the participant is healthy, and avoid overexertion to prevent dizziness or fainting.

Question 2: List three variables that should be controlled during an experiment measuring lung capacity.

Answer: Age, size of participant, and breathing technique.

Question 1: A group of students measures their lung volumes and finds an average tidal volume of 0.5 L and an average vital capacity of 4.5 L. Explain what these measurements indicate about their lung function.

Answer: The tidal volume indicates the amount of air moved during normal breathing, while vital capacity shows the maximum amount of air they can exhale after a deep breath; these suggest healthy lung function if within normal ranges.

Question 1: Explain how the structure of alveoli is specialised for efficient gas exchange. Include details about surface area, thin walls, and blood supply.

Answer: Alveoli are tiny sacs with large surface areas to maximise gas exchange. Their walls are only one cell thick, allowing gases to diffuse easily. A dense capillary network surrounds each alveolus, maintaining steep concentration gradients for efficient transfer of oxygen into the blood and carbon dioxide out.

Question 1: Discuss the importance of understanding lung structure in developing treatments for respiratory diseases such as emphysema and fibrosis.

Answer: Understanding lung structure helps in designing effective drugs and treatments that target damaged alveoli or lung tissue, improving gas exchange. It also aids in developing lung support devices or regenerative therapies to restore or replace damaged tissue.