Question 1

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

Accepted Answer

Agarose gel

Question 2

During PCR, what is the primary purpose of the denaturation step at $$95^\circ C$$?

Accepted Answer

To separate the double-stranded DNA into single strands

Question 3

A forensic scientist is analyzing a crime scene sample using STR analysis. Why are STRs particularly useful for individual identification?

Accepted Answer

They have high variability in repeat number among individuals

Question 4

Which enzyme is used in PCR due to its ability to withstand high temperatures, and from which organism is it originally derived?

Accepted Answer

Taq DNA polymerase from Thermus aquaticus

Question 5

If a PCR reaction is run for 25 cycles, how many copies of the target DNA sequence are theoretically produced from a single template molecule? Use the formula $$2^n$$, where $$n is $$the number of cycles.

Accepted Answer

$$2^{25}$$

Question 6

In gel electrophoresis, why do smaller DNA fragments move farther through the gel than larger fragments?

Accepted Answer

They experience less resistance moving through the gel matrix

Question 7

A paternity test compares the STR profiles of a child, mother, and two alleged fathers. What result would indicate the true biological father?

Accepted Answer

The true father shares all the STR bands with the child that are not present in the mother

Question 8

Which of the following best describes the principle behind gel electrophoresis?

Accepted Answer

Charged molecules move through a gel matrix when an electric current is applied, separating by size and charge

Question 9

Why is it important to use primers that are complementary to the 3' ends of the target sequence in PCR?

Accepted Answer

To ensure DNA polymerase can extend the primers and synthesize new DNA in the 5' to 3' direction

Question 10

Which of the following is a real-world application of PCR in medicine?

Accepted Answer

Detecting the presence of pathogens in patient samples

Question 11

A scientist wants to confirm that a PCR reaction successfully amplified the target DNA. Which technique should they use?

Accepted Answer

Gel electrophoresis to visualize DNA bands

Question 12

Which statement about genetic fingerprinting is correct?

Accepted Answer

It relies on analyzing polymorphisms in non-coding regions of DNA

Question 13

What is the main reason that DNA moves toward the positive electrode (anode) during gel electrophoresis?

Accepted Answer

DNA has a negatively charged phosphate backbone

Question 14

Which of the following best explains why PCR is considered a 'molecular photocopier'?

Accepted Answer

It rapidly produces billions of copies of a specific DNA segment

Question 15

A DNA sample is loaded into an agarose gel and subjected to electrophoresis. After staining, three distinct bands are observed. What does each band represent?

Accepted Answer

A DNA fragment of a specific size

Question 16

Which of the following is a key ethical consideration in the use of genetic fingerprinting for forensic analysis?

Accepted Answer

Ensuring privacy and sample integrity

Question 17

Why is it important to include a DNA ladder (molecular weight marker) when running gel electrophoresis?

Accepted Answer

To estimate the sizes of DNA fragments in the sample

Question 18

Which step in PCR involves primers binding to their complementary sequences on the template DNA?

Accepted Answer

Annealing

Question 19

A missing person case involves highly degraded DNA samples. Which combination of techniques would be most effective for identification?

Accepted Answer

PCR amplification followed by STR analysis and gel electrophoresis

Question 20

Which of the following best describes the role of buffer solution in gel electrophoresis?

Accepted Answer

It maintains a stable pH and conducts electricity during the process

DNA Tools & Biotechnology: PCR, Genetic Fingerprinting, and Gel Electrophoresis

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