Practice Questions: Chapter 15

2. In lecture we discussed mutation frequencies both within and among species. Which of the following is correct with respect to that discussion? a. the mutation frequency of a specific gene is the same in all species that have that gene. b. mutation frequencies are the same for different genes within a species. c. mutation frequencies are always higher in prokaryotes compared to eukaryotes. d. mutation frequencies in humans are so low they can't be measured. e. different genes in the same species have different mutation frequencies.

different genes in the same species have different mutation frequencies.

10. Certain repair systems operate to correct problems in DNA. Which of the following statements is correct for the photoreactivation repair system? a. small segments of DNA are cleaved from the strand, then DNA poly I replaces the missing bases. b. it corrects base substitutions by replacing the incorrect base with the correct base. c. it adds 2 bases to a single base addition mutation in order to correct the reading frame. d. it breaks the bonds between adjacent thymine (T) bases to restore proper bonding between strands. e. it is found only in prokaryotic organisms.

it breaks the bonds between adjacent thymine (T) bases to restore proper bonding between strands.

8. Let's assume that a mutation occurred in a bacterial cell. The mutation was a change in the base sequence in the gene which produces one of the components of the primase molecule. It resulted in the production of a nonfunctioning primase molecule. What effect would this mutation have on the organism? a. it would result in replication of both DNA strands to be much slower than normal. b. it would prevent DNA from being replicated. c. only one of the two DNA strands would serve as a template so there would be no increase in the number of double helices. d. transcription would occur as normal so this wouldn't be a "real" genetic mutation. e. it would have no effect on any cell process.

it would prevent DNA from being replicated.

6. Based on our "bunny trail" lecture, how would you categorize a mutation in a plant species that caused a reduction in height due to greatly reduced activity in the growth hormone? a. morphological mutation. b. behavioral mutation. c. lethal mutation. d. conditional mutation. e. bad mutation.

morphological mutation.

5. A mutation occurs in a bacterial cell which results in a nonfunctional DNA polymerase III molecule. Which of the following would most likely occur because of this mutation? a. this can't be determined since it would depend on whether it was a transversion or a transition mutation. b. only the 3'----5' strand could be synthesized. c. it would result in a tautomeric shift. d. no priming sequence would be produced, so DNA replication would not occur. e. neither DNA strand could be replicated.

neither DNA strand could be replicated.

1. Which of the following is not correct with respect to mutations? a. regardless of the species, mutations happen abundantly in nature. b. mutation frequencies vary from species to species. c. spontaneous mutations are randomly produced. d. regardless of the species, the mutation rate for a particular gene is always different. e. mutations are the primary cause of genetic variation.

regardless of the species, mutations happen abundantly in nature.

3. Mutations which arise in nature, from no particular artificial agent, are called: a. natural mutations b. induced mutations c. spontaneous mutations d. chromosomal mutations e. cosmic mutations

spontaneous mutations

7. How do base analogs produce mutations? a. they add a base directly to an existing DNA chain causing frameshift mutations. b. they are incorporated into DNA as normal nucleotides, but through tautomeric shifts pair with incorrect bases. c. they remove large portions of the DNA molecule causing deletions to occur. d. they act directly to change DNA nucleotides to other bases that pair incorrectly. e. they change thymine nucleotides to uracil, changing the chain from DNA to RNA.

they are incorporated into DNA as normal nucleotides, but through tautomeric shifts pair with incorrect bases.

11. A photoreactivation repair system is thought to operate in both prokaryotes and eukaryotes to correct what type of problem in DNA? a. tautomeric shifts b. transition mutations c. thymine dimers d. transversion mutations e. U replacement of T in DNA

thymine dimers

4. If the normal DNA sequence is AAAAA and the mutant is AATAA, this mutation would be called a: a. transition. b. transversion. c. frameshift. d. inversion. e. mistake (technically correct, but no credit for this answer)

transversion.

9. Which of the following is correct with respect to tautomeric shifts? a. these occur only when a base analogue was substituted for a normal base during DNA replication. b. a shift in the atoms (proton shift) arrangement in the bases, result in base pair changes during DNA replication. c. these are the primary source of adaptive mutations. d. these are caused in bacteria when neither DNA poly III or the secondary proofreading system corrected a base mismatch. e. these only occur when the bacteria is exposed to blue light.

a shift in the atoms (proton shift) arrangement in the bases, result in base pair changes during DNA replication.