Lactic acid fermentation occurs in muscle cells when is in low supply.
a. carbon dioxide
b. oxygen
c. ethyl alcohol
d. water

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