Question

1.4.2 test (cst): heredity
question 23 of 25
which sentence describes a substitution error that could occur during dna replication?
a. a cytosine is left off the growing strand where a cytosine was supposed to be added.
b. a cytosine is added to the template strand when it was supposed to be added to the growing strand.
c. a cytosine is added where an adenine is supposed to be in the growing strand.
d. two cytosine bases are added where a single cytosine was supposed to be in the growing strand.

Explanation:

A substitution error in DNA replication occurs when one nucleotide is replaced by another. In option C, cytosine (a different nucleotide) is added instead of adenine, which fits the definition of a substitution error. Option A is a deletion (leaving off a base), option B is an addition (adding an extra base to the template), and option D is an insertion (adding extra bases). Only option C shows substitution of one base for another.

Answer:

C. A cytosine is added where an adenine is supposed to be in the growing strand.