Question

dna structure and replication quiz

1. a student used poster - board to construct this model of a section of dna.

gatcgatc

gatcgatc
which statement describes this model of dna?
a. the model is inaccurate because the base pairs are incorrect.
b. the model is accurate because it contains correctly paired bases.
c. the model is accurate because it shows each base - pairing is form a double helix.
d. the model is inaccurate because some typical bases in dna are missing.

1. a model of a dna molecule is shown below.

the arrow indicates—
a. the bond between adjacent phosphate and deoxyribose molecules
b. the junction of introns and exons in the sense strand of dna
c. the hydrogen bond between complementary nucleotides
d. the junction of a codon and a dna triplet

Explanation:

1. In DNA, the base - pairing rules are A - T and G - C. In the given model, the base - pairing is correct. So the model is accurate because it contains correctly paired bases.
2. The arrow in the DNA molecule model is pointing to the hydrogen bond between complementary nucleotides. Hydrogen bonds hold the two strands of the DNA double - helix together.

Answer:

1. B. The model is accurate because it contains correctly paired bases.
2. C. the hydrogen bond between complementary nucleotides