The iron-carrying protein that assists in the transport of oxygen into muscle cells is

What are genotypes? what are phenotypes?

Suggest why placing wheels under a heavy box reduces the neccessary force required to push it along at a constant speed.

Which of the following is the best definition of aerobic respiration? o a. the cellular process that releases energy by breaking down glucose o b. physical activity that involves the repeated motion of large muscle groups o c. physical activity that increases heart rate and breathing rate o d. the cellular process that converts solar energy to chemical energy