Starting with a cross between aa and aa, what percentage will be heterozygotes in the f1 generation? 25% 50% 0% 100%

"a.) well–developed vascular system."

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