Question 1

Which of the following is NOT a required component for a standard Polymerase Chain Reaction (PCR)?

Accepted Answer

Ribosomal RNA

Question 2

During PCR, what is the primary purpose of the denaturation step?

Accepted Answer

To separate the DNA strands by breaking hydrogen bonds

Question 3

A researcher wants to quantify the amount of a specific RNA transcript in a cell sample. Which PCR variation should they use?

Accepted Answer

Reverse transcriptase PCR (RT-PCR)

Question 4

Which of the following best describes the function of dideoxynucleotides (ddNTPs) in Sanger sequencing?

Accepted Answer

They cause chain termination by lacking a 3’ hydroxyl group

Question 5

In real-time PCR (qPCR), what is measured to determine the amount of DNA template present?

Accepted Answer

The change in fluorescence from detector molecules

Question 6

Why is a thermostable DNA polymerase, such as Taq polymerase, essential for PCR?

Accepted Answer

It remains active after repeated heating cycles during denaturation

Question 7

A scientist is using Sanger sequencing to identify a mutation in a gene. What would be the result if only dNTPs (and no ddNTPs) were included in the reaction?

Accepted Answer

Only full-length DNA strands would be produced, and no sequence information could be obtained

Question 8

Which step in PCR is responsible for the specificity of the DNA region that is amplified?

Accepted Answer

Annealing of primers

Question 9

A COVID-19 diagnostic test uses RT-qPCR. What is the sequence of steps in this test?

Accepted Answer

RNA extraction → Reverse transcription to cDNA → Quantitative PCR amplification

Question 10

Which of the following best explains why Sanger sequencing can be used to determine the order of nucleotides in a DNA fragment?

Accepted Answer

It generates DNA fragments of varying lengths terminated at each nucleotide position, which are then separated and detected

Question 11

A student is analyzing a gel after PCR and sees multiple bands. Which of the following is the most likely explanation?

Accepted Answer

The primers were not specific enough, leading to amplification of non-target regions

Question 12

Which of the following equations correctly represents the exponential amplification of DNA during PCR, where $$n is $$the number of cycles and $$N_0 is $$the initial number of DNA molecules?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 13

Which of the following is a real-world application of DNA sequencing?

Accepted Answer

Identifying genetic mutations associated with inherited diseases

Question 14

In Sanger sequencing, what is the role of fluorescently labeled ddNTPs?

Accepted Answer

They allow visualization of DNA fragments after gel electrophoresis

Question 15

A researcher wants to compare the amount of a specific DNA sequence in two different tissue samples. Which technique should they use?

Accepted Answer

Real-time PCR (qPCR)

Question 16

Which of the following statements about PCR primers is TRUE?

Accepted Answer

They are typically 15-20 nucleotides long and are complementary to sequences flanking the target region

Question 17

Which of the following best describes the difference between dNTPs and ddNTPs?

Accepted Answer

dNTPs have a 3’ hydroxyl group, while ddNTPs lack it, causing chain termination

Question 18

Which of the following is a critical reason why PCR is widely used in forensic science?

Accepted Answer

It can amplify trace amounts of DNA from crime scene samples for identification

Question 19

A patient’s DNA is sequenced to identify a genetic disorder. The sequencing output shows overlapping peaks at a single nucleotide position. What does this most likely indicate?

Accepted Answer

The patient is heterozygous at that position

Question 20

Which of the following best explains why PCR can be used to detect viral infections such as COVID-19?

Accepted Answer

PCR can amplify viral genetic material present in patient samples, allowing for sensitive detection

Molecular Techniques in Genetics: PCR and DNA Sequencing

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