Which source of energy is ideal for prolonged , low intensity activity

Which gas found in the earth's atmosphere greatly impacts the daily range of temperature on earth. a) oxygen b) hydrogen c) nitrogen d) water vapor

How many chromosomes does each human cell contain? a. 23 chromosomes b. 26 chromosomes c. 43 chromosomes d. 46 chromosomes

Which kind of worm has a closed circulatory system? a planarian b fluke c pinworm d an earthworm