Question

n a single organism, what do you notice about the relative proportions of DNA bases?

A and T occur in similar proportions.

T and G occur in similar proportions.

A and C occur in similar proportions.

G and C occur in similar proportions.
A 5-column table labeled Relative Proportions of Bases in D N A has 7 rows. The first column is labeled Organism with entries human, chicken, grasshopper, sea urchin, wheat, yeast, and E. coli. The second column is labeled A with entries 30.9, 28.8, 29.3, 32.8, 27.3, 31.1, 24.7. The third column is labeled T with entries 29.4, 29.2, 29.3, 32.1, 27.1, 32.9, 23.6. The fourth column is labeled G with entries 19.9, 20.5, 20.5, 17.7, 22.7, 18.7, 26. The fifth column is labeled C with entries 19.8, 21.5, 20.7, 17.3, 22.8, 17.1, 25.7.

Answer 1

Both A and T occur in similar proportions, and likewise G and C do.
(Example: human A 30.9% vs T 29.4%; G 19.9% vs C 19.8% — this follows Chargaff’s rules: A ≈ T and G ≈ C.)