Most living things need oxygen to survive. these two body systems bring oxygen into your body and then move to all your body parts. what are these two body systems?
a) respiratory and muscular
b) digestive and circulatory
c) respiratory and digestive
d) circulatory and respiratory

Which best describes a gene? a. a sister chromatid b. a chromosome c. a tetrad d. a piece of a chromosome

Across of blue x blue (both heterozygous) would result in

Abeaker of water was heated and then placed on a bench in the laboratory. the water cooled until it was the same temperature as the air in the laboratory. which of these explains the mechanism by which the water cooled? a. heat energy was transferred from the water to the air. b. water molecules from the water formed warm water currents. c. the water molecules absorbed energy from the molecules in the air. d. the water released radiation until it contained no heat energy.