The decline in muscle mass with age is due to Both a decrease in muscle fiber size and a decrease in the number of muscle fibers are correct. None of these answers is correct. a decrease in muscle fiber size. a decrease in the number of muscle fibers.

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

In this experiment, the was intentionally manipulated. it is the independent variable. the dependent variables that were measured were the

How does science influence the decisions made about social, economic, and political issues?