1. Molecules based on are the major

components of living organisms.

a. carbon

b. nitrogen

c. sulfur

d. calcium

Carbon is a major component of organisms. That's why they are also called carbon-based life forms.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands