Suppose you are planning experiments to measure oxygen consumption in cells. Which of the following methods would be most appropriate for directly quantifying the rate of cellular respiration?

• A. Using a respirometer to measure the decrease in oxygen levels over time
• B. Observing the color change of a pH indicator
• C. Counting the number of cells under a microscope
• D. Measuring the change in pH of the surrounding medium

Answer: (A)

Verified step by step guidance

1. Understand the concept of cellular respiration: Cellular respiration is the process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water. Oxygen consumption is a direct indicator of the rate of cellular respiration.
2. Identify the goal of the experiment: The goal is to directly quantify the rate of oxygen consumption, which is a key measure of cellular respiration.
3. Evaluate the methods provided: A respirometer is a device specifically designed to measure the rate of oxygen consumption by tracking the decrease in oxygen levels over time. This makes it the most appropriate tool for directly quantifying cellular respiration.
4. Analyze the other options: Observing the color change of a pH indicator or measuring the change in pH of the surrounding medium might indirectly indicate cellular respiration but are not direct measures of oxygen consumption. Counting the number of cells under a microscope does not provide any information about the rate of respiration.
5. Conclude that using a respirometer is the most appropriate method for directly quantifying the rate of cellular respiration, as it directly measures the decrease in oxygen levels over time.