pulse rate: 2 minutes

breathing rate: 3 minutes

(b)

During vigorous exercise, muscle cells contract more frequently, which increases their overall demand for energy. To meet this demand, the rate of aerobic respiration increases to release more energy, requiring a higher supply of oxygen and glucose while producing more carbon dioxide as a waste product. Consequently, breathing rate increases to absorb oxygen faster and remove carbon dioxide from the lungs, while pulse rate increases to pump blood more quickly, ensuring the rapid delivery of these essential nutrients to the active muscles and the removal of metabolic waste.