Fishes, amphibians, reptiles, birds, and mammals all have an internal skeleton with a fill in the blank.

If the coding part of an mrna molecule is 1800 nucleotides (bases) in length, this molecule will contain codons and code for a polypeptide that is amino acids long.

Approximately what portion of the foods that we eat have been genetically modified in some way? a.fewer than 10% b.about 50% c.nearly 100%

Natural selection changes allele frequencies because some survive and reproduce more successfully than others.