Question 1

Which of the following best describes the main goal of gene therapy?

Accepted Answer

To modify cellular DNA in order to treat or cure disease by replacing, inactivating, or introducing genes.

Question 2

Which delivery method is used in ex vivo gene therapy?

Accepted Answer

Modification of cells outside the body followed by transplantation back into the patient.

Question 3

A patient with ADA-SCID was successfully treated by gene therapy. Which approach was used?

Accepted Answer

Ex vivo addition of ADA gene to T-cells.

Question 4

What is a major risk associated with the use of adenovirus vectors in gene therapy?

Accepted Answer

Insertional mutagenesis leading to unintended genetic changes.

Question 5

Which equation represents the probability of matching a DNA profile at a single STR locus, assuming two alleles with frequencies $$p$$ and $$q$$?

Accepted Answer

$$P = p^2$ + q^2$

Question 6

In STR-based DNA profiling, what is the primary reason different individuals produce PCR products of different sizes?

Accepted Answer

They have different numbers of repeats at each STR locus.

Question 7

A forensic scientist analyzes three STR loci from a crime scene sample. The suspect’s STR sizes match the sample at all loci. What is the most likely conclusion?

Accepted Answer

The suspect is likely the source of the biological material.

Question 8

Which of the following is a common characteristic engineered into genetically modified (GM) crops?

Accepted Answer

Resistance to herbicides such as glyphosate.

Question 9

What is the main environmental concern associated with GMOs?

Accepted Answer

Emergence of herbicide and insecticide resistance.

Question 10

Which gene is commonly expressed in GM plants to confer insect resistance?

Accepted Answer

A gene from Bacillus thuringiensis (Bt).

Question 11

A plant is genetically engineered using a Ti plasmid from Agrobacterium tumefaciens. What is the purpose of the Ti plasmid in this process?

Accepted Answer

To transfer the desired gene into plant cells.

Question 12

Which of the following best describes the process of generating GM plants as shown in the study materials?

Accepted Answer

Introduce Ti plasmid into A. tumefaciens, infect cultured cells, select for desired traits, grow into plants.

Question 13

Which of the following is NOT a source material for DNA profiling?

Accepted Answer

Urine

Question 14

In the context of gene therapy, what is the function of CRISPR/Cas9?

Accepted Answer

To precisely edit genes by creating targeted double-strand breaks in DNA.

Question 15

Which of the following equations best represents the Hardy-Weinberg equilibrium for two alleles $$A$$ and $$a$$ with frequencies $$p$$ and $$q$$?

Accepted Answer

$$p^2 + 2pq$$ + $$q^2 = 1$

Question 16

A GM crop is engineered for glyphosate resistance. Which mechanism allows the plant to survive glyphosate application?

Accepted Answer

Expression of a bacterial gene that detoxifies glyphosate.

Question 17

Which step in STR-based DNA profiling ensures that only the target region is amplified?

Accepted Answer

Use of specific primer pairs flanking the STR locus.

Question 18

A patient receives in vivo gene therapy for a genetic liver disorder. Which method is most likely used?

Accepted Answer

Direct delivery of a normal gene to liver cells using viral vectors.

Question 19

Which of the following is a plausible reason for the failure of gene therapy in some patients?

Accepted Answer

Immune reactions to the gene therapy vectors.

Question 20

Which of the following best explains why STR loci are useful for DNA fingerprinting?

Accepted Answer

They are highly variable in repeat number among individuals.

Special Topics in Molecular Genetics: Gene Therapy, DNA Profiling, and Genetically Modified Organisms

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