What dose the 'a' in front of asexual mean?

Asexual is where somebody does not experience sexual attraction. Although, there is something very interesting. An asexual person does not experience sexual attraction but they still desire romantic relationships. This means that they're still looking for that strong bond with another person, but they're just not interested in the sexual activity.

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