Question

7.Humans breathe more rapidly during exercisethan before it because during exercise the bloodcontainsA.an increased level of oxygenB.a decreased number of red blood cellsC.an increased level of carbon dioxideD.a decreased amount of hemoglobin

Answer 1

When we exercise or do any physical activity the muscles require more energy to work.

To produce this energy, muscle cells must consume more oxygen and metabolize more glucose. This increase in metabolic rate leads to an increase in CO2 because this is a waste product of metabolism.

To prevent this CO2 from causing damage, the respiratory rate increases to expel CO2 and increase blood O2 levels. Therefore, the answer is c.