Which structure allows a virus to recognize and attach to receptors on the host cell? a. cell wall
b. capsid protein
c. cell membrane
d. nucleic acid

All viruses contain a nucleic acid genome and a protein capsid that covers the genome.

The capsid protein is the structure that allows a virus to recognize and attach to receptors on the host cell.  Correct B This protein shell of a virus provides proteins that enable the virion to penetrate the host cell membrane and, in some cases to inject the infectious nucleic acid into the cell's cytoplasm.

it has one origin of replication, but it proceeds in two directions - d)