Question 1

Which of the following best describes the main purpose of using restriction enzymes in DNA cloning?

Accepted Answer

To cleave DNA at specific sequences, generating fragments with sticky ends.

Question 2

A scientist wants to clone a gene into a plasmid. Which enzyme is required to join the sticky ends of the gene and plasmid together?

Accepted Answer

DNA ligase

Question 3

Which of the following is a correct sequence of steps for inserting a foreign gene into a plasmid and transforming it into bacteria?

Accepted Answer

Extract plasmid DNA, cut with restriction enzymes, anneal gene fragment, ligate, transform bacteria

Question 4

Why is Taq polymerase used in the polymerase chain reaction (PCR)?

Accepted Answer

It is resistant to high temperatures required for DNA denaturation.

Question 5

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

Accepted Answer

DNA ligase

Question 6

If you start with one double-stranded DNA molecule and perform 5 cycles of PCR, how many double-stranded DNA molecules will you have at the end?

Accepted Answer

$$2^5 = 32$

Question 7

During gel electrophoresis, DNA fragments migrate toward the positive electrode because:

Accepted Answer

DNA is negatively charged and attracted to the positive electrode.

Question 8

Which property of short tandem repeats (STRs) makes them useful for DNA fingerprinting?

Accepted Answer

The number of repeats is highly variable among individuals.

Question 9

A Southern blot is used to detect:

Accepted Answer

A specific DNA sequence in a sample.

Question 10

Which of the following best explains why dideoxynucleotides (ddNTPs) terminate DNA synthesis in Sanger sequencing?

Accepted Answer

They lack a 3' OH group, preventing phosphodiester bond formation.

Question 11

Which of the following is NOT a step in the polymerase chain reaction (PCR) cycle?

Accepted Answer

Ligation

Question 12

A researcher wants to confirm the presence of a gene in a patient's DNA sample. Which technique should they use?

Accepted Answer

Southern blotting with a radioactive probe complementary to the gene

Question 13

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

Accepted Answer

Producing human insulin in bacteria for diabetic patients

Question 14

Which of the following is the correct order of steps in a single PCR cycle?

Accepted Answer

Denaturation, Annealing, Extension

Question 15

In DNA fingerprinting, what is the main reason that STR analysis can distinguish between individuals?

Accepted Answer

STRs are present in different numbers at specific loci in different individuals.

Question 16

Which of the following is NOT required for dideoxy (Sanger) sequencing?

Accepted Answer

RNA polymerase

Question 17

A scientist is analyzing DNA fragments using gel electrophoresis. Which fragments will migrate the farthest from the wells?

Accepted Answer

The smallest DNA fragments

Question 18

Which of the following best describes a transgenic organism?

Accepted Answer

An organism that contains and expresses foreign DNA

Question 19

What is the main function of a cloning vector in recombinant DNA technology?

Accepted Answer

To carry foreign DNA into a host cell for replication

Question 20

Which of the following is a direct application of the polymerase chain reaction (PCR) in forensic science?

Accepted Answer

Amplifying trace amounts of DNA from a crime scene for identification

Biotechnology & DNA Technology: Core Concepts and Applications

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