Question 1

Which of the following best describes the chemical bonding responsible for the double helix structure of DNA?

Accepted Answer

Hydrogen bonds between complementary base pairs

Question 2

A scientist is studying a virus with a genome composed of single-stranded RNA. Which of the following statements is TRUE regarding this viral genome?

Accepted Answer

It can be directly translated into protein if it is positive-sense RNA

Question 3

Which equation correctly represents the relationship between genome size and organism complexity in eukaryotes?

Accepted Answer

There is no simple linear relationship; genome size ($$S) $$does not always correlate with complexity ($$C$$): $$S 
ot\propto C$$

Question 4

Which enzyme is responsible for relieving supercoiling tension during DNA replication?

Accepted Answer

Topoisomerase

Question 5

A mutation occurs in the telomerase gene of a human cell. Which outcome is most likely?

Accepted Answer

Chromosome ends will shorten with each cell division

Question 6

During Sanger sequencing, which molecule is used to terminate DNA strand elongation?

Accepted Answer

Di-deoxynucleotides ($$ddNTP)$$

Question 7

Which of the following best describes the difference between leading and lagging strand synthesis during DNA replication?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments called Okazaki fragments

Question 8

A researcher uses PCR to amplify a DNA segment. Which enzyme is most critical for this process, and why?

Accepted Answer

Taq polymerase, because it is thermostable and can withstand repeated heating cycles

Question 9

Which sequence is most likely to be found at the promoter region of a prokaryotic gene?

Accepted Answer

The -10 consensus sequence: $$TATAAT$$

Question 10

Which of the following statements about tRNA is correct?

Accepted Answer

tRNA contains an anticodon that pairs with mRNA codons during translation

Question 11

A patient is diagnosed with a trinucleotide repeat disorder. Which molecular mechanism is most likely responsible for this condition?

Accepted Answer

Expansion of a specific DNA sequence, such as $$CAG$$, leading to abnormal protein function

Question 12

Which of the following best describes the function of the Shine-Dalgarno sequence in prokaryotes?

Accepted Answer

It aligns the mRNA with the ribosome for translation initiation

Question 13

A cell is exposed to a mutagen that causes a transition mutation. Which base change is most likely to occur?

Accepted Answer

A purine is replaced by another purine, such as $$A \rightarrow G$$

Question 14

Which repair mechanism is most likely to fix a mismatch in DNA after replication?

Accepted Answer

Mismatch repair

Question 15

A laboratory uses the Ames test to evaluate a chemical. What is the primary purpose of this test?

Accepted Answer

To determine if the chemical is a mutagen by measuring its ability to induce mutations in bacteria

Question 16

Which chromosomal aberration is most likely to result from nondisjunction during meiosis?

Accepted Answer

Aneuploidy, such as trisomy ($$2n+1)$$

Question 17

Which of the following is a characteristic of Class I transposable elements?

Accepted Answer

They transpose via an RNA intermediate and reverse transcription

Question 18

A maize plant exhibits a new phenotype due to a 'jumping gene.' Which mechanism best explains this phenomenon?

Accepted Answer

Transposition of a mobile genetic element disrupting gene function

Question 19

Which equation best represents the directionality of transcription in eukaryotes?

Accepted Answer

RNA is synthesized in the $$5' \rightarrow 3'$$ direction

Question 20

A geneticist observes a tetravalent complex during meiosis. Which chromosomal event is most likely responsible?

Accepted Answer

Paracentric or pericentric inversion heterozygosity

Genetics Exam 2 Study Guide: DNA, Chromosomes, Replication, Transcription, Translation, Mutation, and Chromosome Aberrations

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