13) What is one way that incorrect nucleotides are removed from a newly synthesized molecule
of DNA?
A) Crossing over replaces regions with DNA errors with new segments of DNA.
B) DNA ligases both remove and replace incorrectly positioned nucleotides.
C) Any DNA strand with an error is destroyed, and an entire new strand is synthesized.
D) DNA polymerases remove incorrect nucleotides and replace them with correct ones.
E) DNA ligases remove incorrect nucleotides for replacement by DNA polymerases.
14) Imagine that the DNA replication error rate for a strain of bacterium that has a defective
repair mechanism is 1 in 10 million. If the cell’s genome is 5 million nucleotide pairs, how often
will the genome sustain a mutation in this strain, keeping in mind that both strands of a DNA
molecule are replicated at once?
A) once every five cell divisions
B) once per cell division
C) twice per cell division
D) four times per cell division
E) once every ten cell divisions
15) What is the function of DNA polymerase?
A) synthesizing nucleotides from free sugars, phosphates, and bases
B) halting DNA replication if a cell becomes cancerous
C) breaking sugar-phosphate bonds to release free nucleotides for DNA synthesis
D) introducing mutations into DNA for evolutionary adaptation
E) joining together nucleotides as they are base-paired during DNA replication
16) Which of the following statements about the two strands of a DNA molecule is true?
A) An A base on one strand always pairs with a G base on the other strand.
B) The strands are a pair of sister chromatids.
C) The strands are connected to each other by sugar-phosphate bonds.
D) A T base on one strand always pairs with an A base on the other strand.
E) The strands have identical base sequences.