Answer:
The alveolar walls and capillary walls share a membrane. That's how close they're getting. This allows oxygen and carbon dioxide to readily pass from the respiratory system to the circulation. Oxygen molecules bind to red blood cells as they return to the heart.
The initials will still be 4 feet above the ground.
Trees do not grow from the bottom up. At the branch tips there is meristem tissue, so called the apical meristem. Trees grow in height from these apical meristems, so trees grow from the top and the initials on the bottom of the tree will stay at the same height above the ground.
