Question

The following ratio is generally constant for a given species

Options

• T + C / G + A

• G + C / A + T

• A + C / T + 6

• A + G / C + T

Answer 1

G + C / A + T

Explantion:

Purines and pyrimidines occur in equal proportions, according to Chargaff's principles. Adenine has the same quantity as thymine (A = T and G = C). The amount of A or T, however, differs from the amount of C or G, i.e. A + T / G + C is variable. As a result, it remains constant for a given species.