What is the difference between physical and psychological dependence?

Awoman comes to your genetic counseling center because she knows that huntington disease occurs in members of her family. her paternal grandfather was afflicted, but so far her father shows no symptoms. her two great-great grandmothers on her father's side were healthy well into their 90s, and one of her great-great grandfathers died of unknown causes at 45. testing for huntington disease is extremely expensive, but she is concerned that she may fall victim to this disease and wants to plan her life accordingly. after examining her pedigree you advise her to

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.

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