The large flat muscle that moves up and down in order to bring air in and out of the lungs is called the
a. trachea.
b. epiglottis.
c. diaphragm.
d. larynx.

Wanting to know the rules and the right person to ask for are characteristics of the safety reassurances required by preschoolers. infants. school-age children. toddlers.

What angle should your knees not bend past when squatting? a. 30 degrees b. 45 degrees c. 90 degrees d. 120 degrees

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.