Problem 8 - Biology: The Dynamic Science

Question

Oxygen enters the blood in the lungs because relative to alveolar air: a. the \(\mathrm{CO}_{2}\) concentration in the blood is high. b. \(\quad\) the \(\mathrm{CO}_{2}\) concentration in the blood is low. c. the \(\mathrm{O}_{2}\) concentration in the blood is high. d. the \(\mathrm{O}_{2}\) concentration in the blood is low. e. the process is independent of gas concentrations in the blood.

Step-by-Step Solution

Answer

The correct answer is (d). The \(\mathrm{O}_{2}\) concentration in the blood is low relative to alveolar air, enabling diffusion of \(\mathrm{O}_{2}\) from alveolar air into the blood.

Step 1: Understand the Diffusion Process

In the process of respiration, the red blood cells in the lungs take up oxygen at the alveoli (small air sacs in the lungs designed for gas exchange). This exchange happens due to diffusion, which is the movement of particles from an area of higher concentration to an area of lower concentration.

Step 2: Analyze the Gas Concentrations

In the question, four scenarios of gas concentrations are provided, and we have to find the correct condition that facilitates the entrance of oxygen into the blood. We know that for diffusion to occur, there should be a higher concentration of oxygen in the alveolar air and a lower concentration of oxygen in the blood.

Step 3: Identify the Correct Option

Given the principles of diffusion and the mechanics of gas exchange in the lungs, oxygen enters the blood in the lungs because relative to alveolar air, the \(\mathrm{O}_{2}\) concentration in the blood is low. This generates a concentration gradient, which facilitates the movement of \(\mathrm{O}_{2}\) molecules from the alveoli (higher concentration) to the blood (lower concentration). So, the correct option is (d).