Problem : What are two characteristics by which viruses are classified?

Viruses are classified according to the type of genetic material they have and by the shape of their capsid.

Problem : What types of genetic material might a virus carry?

Viruses are known to carry single-stranded and double-stranded DNA and single- stranded and double-stranded RNA. The molecules may be linear or circular.

Problem : What are the two main types of capsid shape?

Capsids may be helical (tube-like) or icosahedral (ball-like).