What are two major public agencies that track the spread of diseases? a. the national institutes of health (nih) and the world health organization (who) b. the world health organization (who) and the centers for disease control and prevention (cdc) c. the centers for disease control and prevention (cdc) and the national institutes of health (nih)

Are needed by the body in large amounts in order to maintain good health

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.

The idea that some faces are inherently more attractive than others is supported by research demonstrating that people we like seem more attractive to us. people prefer averaged composite faces to individual faces. people from different cultures enhance their appearance in different ways. standards of beauty change over time.