Genetics Quiz Answers and Explanations

Genetics Quiz

With Answers and explanations

15 Questions

Test your understanding of Genetics

1 | What is the function of tRNA in protein synthesis?
A. Carries the genetic information from DNA to the ribosomes
B. Binds to the mRNA and catalyzes the formation of peptide bonds
C. Transfers amino acids to the ribosomes according to the mRNA sequence
D. Participates in the proofreading of the protein sequence

Answer: c
Explanation: tRNA transfers amino acids to the ribosomes based on the mRNA codon sequence during protein synthesis.



2 | What is the significance of alternative splicing in gene expression?

A. Increases the gene transcription rate
B. Results in the production of multiple proteins from a single gene
C. Prevents mutations in the DNA sequence
D. Decodes the genetic information in ribosomes

Answer: b
Explanation: Alternative splicing allows different combinations of exons to be joined together, leading to the production of multiple protein isoforms from a single gene.



3 | What is the role of helicase in DNA replication?

A. Joins Okazaki fragments together
B. Unwinds and separates the DNA double helix
C. Proofreads the newly synthesized DNA strands
D. Catalyzes the formation of phosphodiester bonds between nucleotides

Answer: b
Explanation: Helicase unwinds the double-stranded DNA during DNA replication to allow the replication machinery access to the separated strands.



4 | What is the function of RNA polymerase II in gene expression?

A. Synthesizes mRNA from DNA template
B. Produces rRNA for ribosome assembly
C. Reads the genetic code on tRNA molecules
D. Forms peptide bonds between amino acids during translation

Answer: a
Explanation: RNA polymerase II synthesizes mRNA by transcribing the DNA template in gene expression.



5 | What is the purpose of the lac operon in bacteria?

A. Replicates the DNA sequence
B. Regulates the expression of lactose metabolism genes
C. Prevents mutations in the DNA sequence
D. Catalyzes the breakdown of proteins

Answer: b
Explanation: The lac operon controls the expression of genes involved in lactose metabolism in bacteria.



6 | In epigenetics, what is the role of DNA methylation?

A. Inhibits RNA polymerase activity
B. Activates gene expression
C. Attaches methyl groups to histones
D. Modifies the DNA structure to regulate gene expression

Answer: d
Explanation: DNA methylation modifies the DNA structure by adding methyl groups, regulating gene expression without changing the DNA sequence.



7 | What is the key role of the CRISPR-Cas9 system in genetic engineering?

A. Amplifies DNA fragments for sequencing
B. Integrates foreign DNA into the host genome
C. Edits specific regions of the DNA sequence
D. Protects cells from viral infections

Answer: c
Explanation: CRISPR-Cas9 is used to edit specific regions of the DNA sequence, allowing precise modifications in genetic engineering.



8 | What is the function of siRNA in gene regulation?

A. Transcriptional activation of genes
B. Degradation of mRNA transcripts
C. Binding to promoter regions to initiate transcription
D. Increasing the stability of mRNA molecules

Answer: b
Explanation: siRNA triggers the degradation of complementary mRNA transcripts, leading to gene silencing and regulation.


9 | How does gene silencing occur through RNA interference (RNAi)?

A. Reduces the translation of mRNA into proteins
B. Inhibits transcription of RNA from DNA
C. Enhances the activity of RNA polymerase
D. Stabilizes mRNA molecules

Answer: a
Explanation: RNA interference (RNAi) reduces the translation of mRNA into protein by targeting specific mRNA molecules for degradation.



10 | What is the significance of telomeres in maintaining genome stability?

A. Prevents DNA replication errors
B. Regulates gene expression in cells
C. Protects the ends of chromosomes from degradation
D. Induces DNA mutation rate in cells

Answer: c
Explanation: Telomeres protect the ends of chromosomes from degradation and maintain genome stability during cell division.



11 | What is the function of restriction enzymes in genetic engineering?

A. Repair DNA damage in cells
B. Amplify specific DNA sequences by PCR
C. Cut DNA at specific recognition sequences
D. Facilitate the uptake of foreign DNA by cells

Answer: c
Explanation: Restriction enzymes cut DNA at specific recognition sequences, enabling the insertion of foreign DNA into a host genome in genetic engineering.



12 | What is the role of the p53 gene in cell cycle regulation?

A. Promotes cell division
B. Prevents apoptosis in damaged cells
C. Initiates DNA replication
D. Halts the cell cycle in response to DNA damage

Answer: d
Explanation: The p53 gene is a tumor suppressor that halts the cell cycle in response to DNA damage, allowing for repair or triggering apoptosis in damaged cells.



13 | What is the function of reverse transcriptase in retroviruses?

A. Catalyzes the formation of peptide bonds
B. Reads the genetic code on tRNA molecules
C. Converts RNA into DNA
D. Initiates DNA replication

Answer: c
Explanation: Reverse transcriptase converts the viral RNA genome of retroviruses into DNA, which can then be integrated into the host cell’s genome.



14 | What is the process of RNA interference (RNAi) in gene silencing?

A. Binding of proteins to DNA promoter regions
B. Degradation of siRNA molecules by ribonucleases
C. Silencing of gene expression by complementary base pairing
D. Coding of genetic information into mRNA molecules

Answer: c
Explanation: RNA interference (RNAi) involves the silencing of gene expression by complementary base pairing between siRNA molecules and mRNA transcripts.



15 | How do enhancer sequences contribute to gene regulation?

A. Inhibit the binding of transcription factors
B. Activate the expression of target genes
C. Form the template for RNA polymerase binding
D. Replicate the DNA sequence to increase gene copy number

Answer: b
Explanation: Enhancer sequences activate the expression of target genes by facilitating the binding of transcription factors and promoting gene transcription.


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