Cancer-causing agents are called
a.
carcinoids
b.
tumors
c.
sarcomas
d.
carcinogens

1infants internalize what they take in through their senses and                a.  show no signs of remembering it.      b.  vocalize it.      c.  display it in physical movements.      d.  forget it immediately.2 early experiences have a impact on the architecture of the brain.                a.  decisive      b.  mild      c.  minimal      d.  moderate  3which of the following is an infant's main learning tool in the first months after birth?                 a.  mouth      b.  music      c.  book exposure      d.  hands

How could natural selection best be used to explain the evolution of the white fur of arctic fox

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.