Scientists think that four-legged mammals might be the distant ancestors of modern-day whales. what evidence seems to support this idea?
a. a series of closely related fossils
b. animals with similar embryo development
c. dna evidence
d. migration patterns

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.

those characteristics are cellular organization, reproduction, metabolism, homeostasis, heredity, response to stimuli, growth and development, and adaptation through evolution. some things, such as a virus, demonstrate only a few of these characteristics and are, therefore, not alive