15. Which macromolecule does not polymerize?

Plzz hurry im being timed during times of vigorous physical activity, muscles require a constant supply of oxygen. how does the body respond to these needs? a. breathing rate and heart rate both decrease. b. breathing rate and heart rate both increase. c. heart rate decreases, but breathing rate remains stable. d. breathing rate increases, but heart rate remains stable.

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain

When a person is exercising the body needs to deliver increased amounts of oxygen to the muscles which component of blood ensures that the muscles will receive it