Each kidney contains nephrons that filter the blood and remove waste.

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.

Which practice is harmful to the land? a. using animal waste as fertilizer b. composting with peels from commercial fruit c. throwing paint cans in the garbage d. cutting the lawn with a gas-powered mower

Recognizing your emotions is an important first step toward a. dealing with them in a healthy way b. acting on them immediately c. using defense mechanisms to deal with them d. denying that they exist