Question 1

Which of the following best describes the role of restriction enzymes in genetic engineering?

Accepted Answer

They cut DNA molecules at specific sequences, creating fragments with sticky or blunt ends.

Question 2

A scientist wants to clone a gene using a bacterial plasmid. Which enzyme is necessary to seal the inserted gene into the plasmid after both are cut with the same restriction enzyme?

Accepted Answer

Ligase

Question 3

During the polymerase chain reaction (PCR), what is the purpose of the denaturation step at approximately $$95^\circ C$$?

Accepted Answer

To break hydrogen bonds between DNA strands, resulting in single-stranded templates.

Question 4

Why is Taq polymerase used in PCR instead of other DNA polymerases?

Accepted Answer

It is heat-stable and does not denature at high temperatures used during PCR.

Question 5

A crime scene sample contains only a few molecules of DNA. Which technique must be performed first to ensure there is enough DNA for analysis?

Accepted Answer

Polymerase chain reaction (PCR)

Question 6

In gel electrophoresis, why do smaller DNA fragments migrate farther from the wells than larger fragments?

Accepted Answer

The gel matrix acts as a sieve, allowing smaller fragments to move more easily through the pores.

Question 7

A researcher is comparing the DNA of several individuals using restriction fragment length polymorphism (RFLP) analysis. What is the primary reason two unrelated individuals are unlikely to have identical DNA fingerprints?

Accepted Answer

Each person has unique sequences at many variable regions in their genome.

Question 8

Which of the following best explains why a primer is necessary for DNA polymerase to function during PCR?

Accepted Answer

Primers provide a free 3' hydroxyl group for DNA polymerase to add nucleotides.

Question 9

A scientist wants to copy only the insulin gene from human DNA using PCR. What must be true about the primers used?

Accepted Answer

They must be complementary to sequences flanking the insulin gene.

Question 10

After three complete cycles of PCR, starting with one double-stranded DNA molecule, how many double-stranded DNA molecules will be present?

Accepted Answer

$$2^3 = 8$

Question 11

Which of the following is NOT a typical use of gel electrophoresis?

Accepted Answer

Synthesizing new DNA strands

Question 12

Which process involves the uptake of naked DNA from the environment by a bacterial cell?

Accepted Answer

Transformation

Question 13

A bacterial cell receives a plasmid carrying an antibiotic resistance gene from another cell via a pilus. What is this process called?

Accepted Answer

Conjugation

Question 14

Which of the following best describes the function of sticky ends produced by restriction enzymes?

Accepted Answer

They allow complementary DNA fragments to anneal and be joined together.

Question 15

In a paternity case, DNA samples from a child, mother, and two potential fathers are analyzed using gel electrophoresis. Which sample should match the child at all bands not present in the mother?

Accepted Answer

The biological father

Question 16

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

Accepted Answer

Identifying individuals in criminal investigations

Question 17

Which step in the PCR process determines the specific region of DNA that will be amplified?

Accepted Answer

Annealing of primers

Question 18

A scientist uses EcoRI to cut a DNA sample. What is the most likely result?

Accepted Answer

The DNA is cut at specific recognition sites, producing fragments with sticky ends.

Question 19

Which of the following best explains why PCR is essential before running a gel electrophoresis on a forensic sample?

Accepted Answer

PCR amplifies the DNA, providing enough material for visualization and analysis.

Question 20

Which of the following is a key difference between transformation and transduction in bacteria?

Accepted Answer

Transformation involves uptake of naked DNA, while transduction involves DNA transfer by a bacteriophage.

Biotechnology: DNA Technology, Genetic Engineering, and Applications

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