Question

1.4.2 test (cst): heredity
question 12 of 25
which assumption about dna did the experiments of chemist erwin chargaff disprove?
a. genetic information in an organism is carried by dna molecules.
b. dna contains equal amounts of the four nitrogenous bases.
c. dna molecules are found only in multicellular organisms.
d. the nitrogenous bases form chemical bonds with each other.

Explanation:

Erwin Chargaff's experiments showed that in DNA, the amount of adenine (A) equals thymine (T), and the amount of guanine (G) equals cytosine (C), but the amounts of A + T and G + C can vary. This disproves the idea that DNA has equal amounts of all four nitrogenous bases (A, T, G, C). Option A is a correct statement (DNA carries genetic info). Option C is wrong as DNA is in unicellular organisms too. Option D is incorrect as hydrogen bonds (not just any chemical bonds) form between complementary bases.

Answer:

B. DNA contains equal amounts of the four nitrogenous bases.