which zone is considered the aerobic zone for not only improving health, but also athletic conditioning by strengthening the cardiovascular and pulmonary systems of the body.

Which of the following best describes homeostasis? a. keeping the internal environment in a stable state b. keeping the external environment in a stable state c. beneficial characteristics resulting from mutation d. reproduction that results in offspring identical to the parent.

Which would be an adaptation in a rainforest, but not in a tundra? a. ability to store water for a long time b. fur that blends in with snow c. strong claws for killing prey d. a beak that can dig into thick trees

How are the testes and ovaries similar? a. both produce sex cells. b. both connect internal reproductive organs to the exterior. c. both transport sex cells from their site of production. d. both store mature sex cells.