Question

Ava conducted an experiment to determine respiratory rates during different activities. She counted the number of breaths per minute. Ava noted that the number of breaths increases as physical activity increases. Why is there an increase in the number of breaths per minute as activity increases? As activity increases, more oxygen is exhaled. As activity increases, more oxygen is exhaled. As activity increases, breathing becomes more efficient. As activity increases, breathing becomes more efficient. As activity increases, the oxygen needs of cells increase. As activity increases, the oxygen needs of cells increase. As activity increases, the rate of the heart beating increases.

Answer 1

There is an increase in the number of breaths per minute as activity increases because:

As activity increases, the oxygen needs of cells increase.

Step-by-step explanation:

When we exercise, our muscles work harder than they do when our bodies are resting. For that reason, the muscle cells need more oxygen - think of oxygen as the fuel we consume; the more we move, the more fuel we need. To provide that extra oxygen the cells need so much, we begin to breathe faster. For that reason, the best option for the question above is: as activity increases, the oxygen needs of cells increase.