Question 1

Which of the following best describes the role of Taq DNA polymerase in the Polymerase Chain Reaction (PCR)?

Accepted Answer

It synthesizes new DNA strands by adding nucleotides to primers at high temperatures.

Question 2

During PCR, what is the purpose of the annealing step?

Accepted Answer

To allow primers to bind to the complementary sequences on the template DNA.

Question 3

If a PCR reaction is run for 25 cycles, how many copies of the target DNA sequence will be produced, assuming perfect efficiency?

Accepted Answer

$$2^{25}$$

Question 4

Which of the following is NOT an application of PCR?

Accepted Answer

Protein purification

Question 5

Short Tandem Repeats (STRs) are used in genetic fingerprinting because:

Accepted Answer

They are highly variable in repeat number between individuals.

Question 6

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

Accepted Answer

Smaller fragments encounter less resistance moving through the gel matrix.

Question 7

A forensic scientist analyzes DNA from a crime scene using STR loci. If the probability of two unrelated people having the same STR profile at 13 loci is less than $$1 	ext{ in } 10$$^{12}$$, what does this imply about the reliability of STR-based identification?

Accepted Answer

STR-based identification is highly reliable for distinguishing individuals.

Question 8

Which of the following best explains why DNA moves toward the positive electrode during gel electrophoresis?

Accepted Answer

DNA is negatively charged due to its phosphate backbone.

Question 9

A child’s STR profile contains alleles from both the mother and the alleged father. What does this indicate in a paternity test?

Accepted Answer

The child inherited half of its STR alleles from the mother and half from the alleged father.

Question 10

Which of the following is a critical ethical consideration in the use of genetic fingerprinting for forensic purposes?

Accepted Answer

Ensuring sample integrity and privacy of genetic information.

Question 11

In a gel electrophoresis experiment, a DNA ladder is used. What is the primary purpose of the DNA ladder?

Accepted Answer

To provide a reference for estimating the size of DNA fragments.

Question 12

Which step in PCR involves the formation of hydrogen bonds between primers and the template DNA?

Accepted Answer

Annealing

Question 13

A scientist wants to amplify a specific DNA segment from a degraded sample. Which technique should they use?

Accepted Answer

Polymerase Chain Reaction (PCR)

Question 14

Which of the following is NOT required for a standard PCR reaction?

Accepted Answer

Restriction enzymes

Question 15

In gel electrophoresis, what would happen if the buffer solution was omitted?

Accepted Answer

DNA fragments would not migrate properly due to lack of ionic conduction.

Question 16

Which of the following best describes the principle behind DNA fingerprinting?

Accepted Answer

Comparing unique patterns of STRs in non-coding regions of DNA.

Question 17

Agarose gel is used in electrophoresis primarily because:

Accepted Answer

It provides a matrix that separates DNA fragments based on size.

Question 18

Which of the following scenarios best illustrates the use of genetic engineering in historical identification?

Accepted Answer

Tracing the migration patterns of ancient populations using mitochondrial DNA.

Question 19

In a gel electrophoresis experiment, which fragment will be found closest to the positive electrode after the run?

Accepted Answer

The smallest DNA fragment

Question 20

Which equation correctly represents the exponential amplification of DNA during PCR, where $$n is $$the number of cycles?

Accepted Answer

$$N = 2^n$$

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

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