13. Cuando la concentración de solutos dentro de la célula es igual a la concentración externa, se dice que la solución es
a. hipertónica
b. hipotónica
c. Isotónica
d. Contráctil

•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation:

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