Which of the following is one observation that charles darwin made regarding variation?
a. organisms are born with variation.
b. organisms are not born with variation.
c. variation is not observable in nature today.
d. variation is acquired as organisms go through daily life.

4

scientists have discovered that hiv does not cause aids by the virus's direct effect on the host's immune cells, but rather through the cells' lethal influence on one another. researchers from the gladstone institutes have revealed that hiv does not cause aids by the virus's

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides