1. The document contains questions about respiratory and circulatory systems. It includes diagrams of gas exchange in the lungs and systemic circulation. 2. For cigarette smokers, the concentration of gas Y (carbon dioxide) is higher in the blood, while the concentration of gas X (oxygen) is lower compared to non-smokers. Smoking reduces the amount of oxygen that can diffuse into the bloodstream and be transported to tissues. 3. Questions assess understanding of pulmonary gas exchange, systemic circulation, and the role of different blood vessels and organs in transporting oxygenated and deoxygenated blood. Key processes like diffusion and the partial pressures of oxygen and carbon dioxide driving gas exchange are also tested.