In the ames test, the appearance of his+ revertants in the presence of a non-mutagenic control compound indicates that
a. there is some low-level contamination in most experiments
b. the growth medium contains factors that are mildly mutagenic
c. some of the reversion mutations are not caused by the mutagen being tested
d. liver extract increases the potency of some mutagens

after receiving a stimus, the sensory receptors send(s) signals to the appropriate area of the body.  

the must be sensory neurons.  

hope its .

brain development. a child's brain undergoes an amazing period of development from birth to three—producing more than a million neural connections each second. the development of the brain is influenced by many factors, including a child's relationships, experiences and environment.

explanation:

airlines i think? or a cruise boat? does this work out for u? ?