In the lungs, do oxygen and co2 move in opposite directions?

What are hormones? a. they are minerals needed for proper bone formation. b. they are the parts of the body targeted by endocrine glands. c. they are substances needed for muscle and nerve activity. d. they are substances released by endocrine glands.

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.

Whihc type of medicine kills cancer cells in the body, but also kills healthy cells