Which of the following characteristics of living things best explains why some North American birds fly
south for the winter?
a. Living things respond to their environment.
b. Living things maintain internal balance.
c. Living things are made up of units called cells.
d. Living things are bazed on a universal genetic code.

Restless tectonic plates move (shift) between one and fifteen centimeters per year month day minute

Zoo geographic regions are characterized by the presence of specific groups of animals these regions are determined by the taxonomic or phylogenetic relationships of animals. the map shows the zoogeographic regions proposed by the naturalist alfred russel wallace in 1876. the similarities of organisms in which two areas numbered above provide the best evidence for common ancestry between the organisms in both locations ?

What are the two causes of density in deep current waters? a. salinity (how much salt) of the water and high temperaturesb. salinity (how much salt) of the water and low temperatures c. oxygen content of the water and high temperatures. d. oxygen content of the water and low temperatures