Which of the following activities is most likely to cause a decrease in oxygen levels within muscle cells?

• A. Intense physical exercise
• B. Sleeping
• C. Reading a book
• D. Sitting quietly

Answer: (A)

Verified step by step guidance

1. Understand the relationship between oxygen levels and muscle activity: Oxygen is required for cellular respiration, which provides energy for muscle cells. During intense physical activity, muscle cells demand more energy, increasing oxygen consumption.
2. Analyze the options provided: Intense physical exercise, sleeping, reading a book, and sitting quietly. Consider the level of physical exertion and energy demand associated with each activity.
3. Recognize that intense physical exercise involves rapid and sustained muscle contractions, which significantly increase the need for ATP (adenosine triphosphate) production through cellular respiration. This leads to a higher oxygen demand in muscle cells.
4. Compare intense physical exercise to the other activities: Sleeping, reading a book, and sitting quietly are low-energy activities that do not require significant oxygen consumption in muscle cells.
5. Conclude that intense physical exercise is most likely to cause a decrease in oxygen levels within muscle cells due to the high energy demand and increased oxygen consumption during cellular respiration.