Teens are often more vigorously active than adults. For this reason some people say that teens should begin to do lifestyle or more moderate activity so that they will stay active later in life. Do you think you will become more or less active as you grow older? Do you think your attitudes toward activity will change? What types of activity do you think you will do? *

Viruses use the host's machinery to make copies of themselves. however, some human viruses require a type of replication that humans do not normally have. for example, humans normally do not have the ability to convert rna into dna. how can these types of viruses infect humans, when human cells cannot perform a particular role that the virus requires? a) the virus causes mutations in the human cells, resulting in the formation of new enzymes that are capable of performing these roles. b) the viral genome codes for specialized enzymes not in the host. c) the virus infects only those cells and species that can perform all the replication roles necessary. d) viruses can stay in a quiescent state until the host cell evolves this ability.