Question 1

Which of the following is NOT an agricultural product made by DNA techniques?

Accepted Answer

Answer reason: Frost retardant strains (e.g., engineered bacteria), Bt-based pest control strategies, glyphosate-resistant crops, and industrial enzymes like pectinase are established outputs of DNA technology used in agriculture/food processing. Nitrogenase is a naturally occurring enzyme complex used by certain bacteria for nitrogen fixation and is not itself a standard marketed “product” produced via DNA techniques for agricultural use. While genes related to nitrogen fixation are studied and manipulated experimentally, that differs from being a common commercial agricultural biotech product like the other options.

Question 2

The miRNAs in a cell?

Accepted Answer

Answer reason: miRNAs are small non-coding RNAs in eukaryotic cells that regulate gene expression after transcription by binding target mRNAs, leading to translational repression or mRNA degradation. This post-transcriptional control is a key mechanism that helps different cell types express different sets and amounts of proteins despite sharing the same genome. They are not structural components of ribosomes, so describing them as part of prokaryotic or eukaryotic ribosomes is incorrect. Operons are a prokaryotic gene-regulation system primarily controlled by repressors/activators and small molecules, not by miRNAs.

Question 3

Gene therapy is currently used to treat all of the following diseases EXCEPT?

Accepted Answer

Answer reason: Gene therapy has had established clinical use/success primarily in single-gene disorders where target cells can be accessed and a functional copy of a gene can be delivered with measurable benefit. SCID is a classic condition with successful gene therapy approaches in hematopoietic cells, and LDL-receptor deficiency has approved gene-based approaches aimed at lowering LDL via modifying related pathways. Duchenne muscular dystrophy has also seen clinically used gene-therapy strategies (e.g., micro-dystrophin delivery) in recent years. In contrast, cystic fibrosis remains difficult to treat effectively with gene therapy because delivering and sustaining adequate CFTR expression across airway epithelium is technically challenging, and routine clinical gene-therapy treatment is not broadly established.

Question 4

You want to determine whether a person has a certain mutant gene. The process involves using a primer and a heat-stable DNA polymerase. This process is?

Accepted Answer

Answer reason: PCR is the standard method to amplify a specific DNA sequence using short primers and a thermostable DNA polymerase (e.g., Taq) that tolerates repeated high-temperature denaturation cycles. Amplifying the region of interest allows detection of a mutant allele by subsequent analysis (e.g., size, sequencing, or allele-specific probes). Translation refers to protein synthesis from mRNA and does not use DNA polymerase or primers. Site-directed mutagenesis is used to create deliberate sequence changes rather than to detect whether a mutation is present in a patient sample.

Question 5

Gene silencing involves all of the following EXCEPT?

Accepted Answer

Answer reason: RNA interference–mediated gene silencing works mainly at the post-transcriptional level by targeting mRNA for cleavage or translational repression. Double-stranded RNA is processed by Dicer into siRNAs, which are then loaded into the RNA-induced silencing complex (RISC) to guide sequence-specific binding to complementary mRNA. Binding to a gene promoter is characteristic of transcription-factor/DNA interactions; siRNA classically binds RNA targets rather than promoter DNA. Therefore promoter binding is the exception among the listed RNAi components/steps.

Question 6

Protein synthesis in eukaryotes is similar to the process in prokaryotes in that both eukaryotes and prokaryotes?

Accepted Answer

Answer reason: The core shared principle of translation is that mRNA is read in triplet codons that specify amino acids via the genetic code. This codon-based decoding mechanism is conserved across prokaryotes and eukaryotes, allowing both to determine polypeptide sequence from mRNA. Exons, introns, and snRNPs relate to eukaryotic RNA processing/splicing and are not universal to prokaryotes. Also, while eukaryotes initiate with methionine, bacteria typically initiate with N-formylmethionine, so that statement is not strictly the same in both.

Question 7

Which of the following is NOT a desired characteristic of DNA vectors used in gene cloning procedures?

Accepted Answer

Answer reason: As vector size increases, transformation/transfection efficiency typically drops and the DNA becomes harder to ligate, propagate stably, and recover at high yield. In contrast, an origin of replication (self-replication) and a selectable marker are core requirements to maintain and identify recombinant clones. Many vectors are circular plasmids or can integrate into host genomes, and some are engineered with broader host-range replication, all of which are potentially desirable depending on the cloning system.

Question 8

An advantage of synthetic DNA over genomic or cDNA is the ability to?

Accepted Answer

Answer reason: Synthetic DNA can be designed with any chosen nucleotide sequence, allowing researchers to engineer specific features that may not naturally exist in genomic DNA or cDNA. Adding restriction enzyme recognition sites at defined positions is a common design advantage because it enables predictable cloning, assembly, and subcloning workflows. By contrast, making DNA from RNA using reverse transcriptase describes cDNA generation, not a unique benefit of synthetic constructs. Likewise, lack of introns is a property of cDNA relative to genomic DNA and is not uniquely achieved by choosing synthetic DNA.

Question 9

Assume you have discovered a cell that produces a lipase that works in cold water for a laundry additive. You can increase the efficiency of this enzyme by changing one amino acid. This is done by?

Accepted Answer

Answer reason: Changing exactly one amino acid requires a precise, targeted change in the gene encoding the enzyme. This is accomplished by introducing a specific nucleotide substitution at a chosen position so the resulting codon encodes the desired amino acid. Random methods like irradiation can create many unpredictable mutations and are inefficient for a single planned residue change. Processes like selection or enrichment can only choose among existing variants and do not directly engineer a specific amino-acid substitution.

Question 10

A gene is best defined as?

Accepted Answer

Answer reason: A gene is defined by its informational content that is expressed to yield a functional product, either a protein (via mRNA translation) or a functional RNA molecule. This option captures both the molecular substrate (DNA) and the purpose (functional product), which is the key concept in genetics. “Three nucleotides that code for an amino acid” describes a codon, not an entire gene. Options describing RNA alone or the RNA product confuse the gene (DNA sequence) with its transcript (RNA).

Question 11

The cancer gene ras produces mRNA containing an extra exon that includes a number of UAA codons. Cancer cells produce ras mRNA missing this exon. This mistake most likely is due to a mistake by?

Accepted Answer

Answer reason: Pre-mRNA splicing requires accurate recognition of intron–exon junctions by spliceosome components, particularly snRNPs. Skipping an exon in the mature ras mRNA is a classic consequence of defective splice-site recognition or spliceosome assembly, producing an mRNA missing that exon. The presence of UAA stop codons in the exon is incidental; the key error described is abnormal exon inclusion/exclusion rather than a DNA base substitution. In contrast, DNA polymerase errors or mutagens/UV typically cause point mutations or DNA damage, not a consistent exon-skipping splicing pattern.

Question 12

Parents ask the nurse about the cause of their child’s cystic fibrosis. Which statement best describes this autosomal-recessive disorder?

Accepted Answer

Answer reason: Autosomal-recessive conditions occur when an individual inherits two pathogenic variants, one from each parent. Parents are typically asymptomatic carriers, each contributing a nonfunctioning allele, leading to disease expression in the child. X-linked inheritance would primarily involve transmission via the X chromosome and show sex-linked patterns, which does not describe cystic fibrosis. A single defective gene from one parent usually results in a carrier state rather than the full disorder in classic autosomal-recessive diseases.

Question 13

Which of the following are used to silence specific genes and hold promise for treating cancer or viral diseases, such as hepatitis B?

Accepted Answer

Answer reason: RNA interference uses small interfering RNAs (siRNA) or microRNAs loaded into the RISC complex to bind complementary mRNA, leading to mRNA cleavage or translational repression. This targeted post-transcriptional knockdown is why it has therapeutic potential in cancers and viral infections where suppressing specific transcripts can reduce pathogenic protein production. In contrast, cDNA synthesis and RT-PCR are primarily laboratory methods for creating DNA from RNA and detecting/quantifying nucleic acids, not for silencing genes. DNA fingerprinting is for identification, and Ti plasmids are plant genetic engineering vectors rather than a standard human gene-silencing therapy.

Question 14

If you knew the sequence of nucleotides within a gene, which one of the following could you determine with the most accuracy?

Accepted Answer

Answer reason: That linear amino-acid sequence is the protein’s primary structure and is the most directly predictable feature from DNA sequence information. Higher-order folding (secondary and tertiary) depends on additional factors such as local interactions, chaperones, post-translational modifications, and cellular environment, so it cannot be determined with comparable accuracy from sequence alone. Quaternary structure additionally depends on assembly with other subunits and expression/stoichiometry, making it even less directly inferable from the gene sequence.

Question 15

The necessary ingredients for DNA synthesis can be mixed together in a test tube. The DNA polymerase is from Thermus aquaticus, and the template is from a human cell. The DNA synthesized would be most similar to?

Accepted Answer

Answer reason: DNA polymerase synthesizes a complementary DNA strand by copying the sequence information from the template strand, so the product’s base sequence is determined by the human template rather than the enzyme’s species of origin. Taq polymerase mainly contributes heat stability and catalytic function; it does not “imprint” Thermus-specific sequence features onto the new DNA. Because the reaction is DNA synthesis (not transcription), RNA options are incorrect. A “mixture” implies incorporation of bacterial genomic sequence, which would not occur unless bacterial DNA template were present.

Question 16

Which statement is appropriate for a nurse to make to the parents of a child with cystic fibrosis who are planning to have a second child?

Accepted Answer

Answer reason: " Cystic fibrosis is an autosomal recessive disorder, so parents who already have an affected child are obligate carriers and face a 25% affected risk with each pregnancy. The recurrence-risk details (25% affected, 50% carrier, 25% unaffected non-carrier) are nuanced and are best communicated with appropriate education and support for informed reproductive decision-making. Genetic counseling provides accurate risk calculation, discussion of carrier testing, and available prenatal or preimplantation testing options. The numeric statements offered are inaccurate, making referral for counseling the safest and most appropriate nursing guidance.

Question 17

The use of "suicide" genes in genetically modified organisms is designed to?

Accepted Answer

Answer reason: Suicide (kill-switch) genes are biosafety mechanisms engineered to limit survival or replication of a GMO outside controlled conditions, reducing environmental persistence and spread. They are typically activated by loss of a required laboratory-supplied factor or by specific environmental triggers, leading to growth arrest or cell death in natural settings. This directly matches the goal of preventing proliferation in the environment rather than enhancing fitness traits like pesticide resistance. Options describing pre-release killing or deleting essential genes are too narrow/misframed compared with the broader containment purpose.

Question 18

DNA is constructed of?

Accepted Answer

Answer reason: DNA’s double helix is made of two polynucleotide strands oriented in opposite directions (5′→3′ and 3′→5′), which is essential for accurate base pairing and replication. This antiparallel alignment allows hydrogen bonding between complementary bases and proper fit of the sugar-phosphate backbones in the helix. Option B is incorrect because the base-pairing rule is A–T and G–C (not A–C and G–T). Options A and D are incorrect because genomic DNA is typically double-stranded, and the strands are not parallel nor composed of identical sequences.

Question 19

The following steps must be performed to make a bacterium produce human protein X. 1-Translation 2-Restriction enzyme 3-Prokaryotic transcription 4-DNA ligase 5-Transformation 6-Eukaryotic transcription 7-Reverse transcription Which of the following places the steps in the correct order?

Accepted Answer

Answer reason: The mRNA is first converted into intron-free cDNA via reverse transcription, then the cDNA and plasmid are cut with restriction enzymes and joined with DNA ligase to create a recombinant plasmid. The recombinant plasmid is introduced into bacteria by transformation, after which the inserted gene is transcribed by prokaryotic RNA polymerase and finally translated into protein. Sequences that begin with bacterial transcription/translation before cloning or place transformation before ligation are not biologically feasible for establishing stable expression.

Question 20

The Human Genome Project, which was completed in 2003, was focused on?

Accepted Answer

Answer reason: The core goal of the Human Genome Project was to map and sequence human DNA to produce a reference genome. Sequencing establishes the order of nucleotides across the genome, enabling later identification of genes and their locations. Protein determination is the domain of proteomics and is not achievable directly from sequencing alone because expression varies by tissue and time. Curing genetic disorders and cloning genes were not objectives of the project; they are downstream applications that may be enabled by genomic information.

Question 21

The restriction enzyme EcoRI recognizes the sequence G↓AATTC. Which of the following is TRUE of DNA after it is treated with EcoRI?

Accepted Answer

Answer reason: Restriction enzymes cut DNA at specific recognition sites and can generate staggered cuts that create complementary single-stranded “sticky ends.” EcoRI cleaves between G and A in the sequence, producing an overhang that leaves one set of fragment ends with the protruding AATT sequence while the complementary strand ends have the corresponding recessed/paired bases at that junction. Because cleavage occurs on both strands in a staggered fashion, the two ends produced at each cut are not identical and can be described as having different terminal bases depending on strand orientation. Blunt ends would require a straight cut across both strands at the same position, which is not how EcoRI cuts.

Question 22

Which of the following statements is FALSE?

Accepted Answer

Answer reason: Bacterial DNA replication is bidirectional from a single origin (oriC), creating two replication forks that move in opposite directions around the circular chromosome. This makes the “only one direction” claim incorrect because both forks progress simultaneously until they meet near the terminus region. The other statements align with core replication principles: polymerases synthesize 5’→3’, the leading strand is continuous, and lagging strand synthesis requires RNA primers to initiate Okazaki fragments. A common confusion is equating circular DNA with unidirectional movement, but circularity does not prevent bidirectional fork progression.

Question 23

Baby's sex is determined by...?

Accepted Answer

Answer reason: The ovum always provides an X chromosome, while sperm may provide either X or Y; an X-bearing sperm yields XX and a Y-bearing sperm yields XY. Therefore, the paternal gamete is the variable factor that determines the baby’s chromosomal sex. Hormones influence later sexual differentiation, but they do not set the initial chromosomal sex at conception.

Question 24

"Genetic condition caused by the presence of three chromosomes 21 in the cells of individuals, instead of two" what is it called?

Accepted Answer

Answer reason: The stem specifies three copies of chromosome 21, which is trisomy 21. Trisomy 21 is the genetic basis of this condition, most commonly due to meiotic nondisjunction (less commonly translocation or mosaicism). In contrast, Patau syndrome is trisomy 13, and trisomy 18 refers to Edwards syndrome, while Klinefelter syndrome involves sex chromosomes (47,XXY).

Question 25

A gene is a functional unit of __?

Accepted Answer

Answer reason: Because genes are defined as segments within the DNA molecule, the most accurate match is DNA. Chromosomes are larger structures composed of DNA and associated proteins that contain many genes, so they are not the functional unit itself. “Cell” and “life” are broader organizational concepts rather than the molecular substrate that directly constitutes genes.

Question 26

A mother has recently been informed that her child has Down’s syndrome. You will be assigned to care for the child at shift change. Which of the following characteristics is not associated with Down’s syndrome?

Accepted Answer

Answer reason: Typical associated features include a single transverse palmar (simian) crease, brachycephaly with a flat occiput, and generalized hypotonia in infancy. Skin findings are more commonly described as dry skin and hair rather than increased oiliness. Therefore the option describing oily skin does not fit the classic phenotype compared with the other listed features.

Question 27

A nurse in the family planning clinic is counseling a couple about genetic risk for having a child with sickle cell disease, an autosomal recessive disease. Both parents carry the sickle cell trait. Which statement by the couple indicates understanding of the likelihood of having a child with sickle cell disease?

Accepted Answer

Answer reason: ” Autosomal recessive disorders require a child to inherit two mutant alleles to be affected. When both parents are carriers (heterozygous), a Punnett square yields a 25% chance of an affected child, 50% chance of a carrier child, and 25% chance of an unaffected non-carrier child for each pregnancy. This probability resets with each conception and does not accumulate across pregnancies. The 1 in 2 figure reflects the carrier probability, not the affected-disease probability.

Question 28

A nurse should recognize that hemophilia is transmitted genetically by which of the following inheritance patterns?

Accepted Answer

Answer reason: Because males have only one X chromosome, inheriting a single mutated copy typically results in disease expression. Females usually have two X chromosomes, so one normal allele can compensate, making them asymptomatic carriers unless they inherit two mutated alleles or have skewed X-inactivation. This inheritance pattern also explains the typical pedigree of affected males with carrier mothers and no father-to-son transmission.

Question 29

The zygote formed is __?

Accepted Answer

Answer reason: Each gamete contributes one set of chromosomes (n), so their fusion produces a zygote with two sets (2n). This makes the zygote the first diploid cell of the new organism and the starting point for mitotic divisions during development. A haploid state characterizes gametes, not the post-fertilization zygote, while triploidy/tetraploidy reflect abnormal additional chromosome sets rather than normal zygote formation.

Question 30

The parents of a child with muscular dystrophy ask the nurse what causes this condition. What is the best response by the nurse?

Accepted Answer

Answer reason: Muscular dystrophy, particularly Duchenne muscular dystrophy, is caused by mutations in specific genes (e.g., the dystrophin gene). These mutations lead to progressive muscle degeneration. It is a genetic disorder, not caused by chromosomal abnormalities, environmental factors, or unknown origins.

Question 31

The random shotgun method is used in?

Accepted Answer

Answer reason: The random shotgun method (shotgun sequencing) involves randomly breaking DNA into many small fragments, sequencing those fragments, and then assembling them computationally to reconstruct the entire genome. It is a foundational technique used in large-scale genome sequencing projects. The other options refer to different techniques such as PCR amplification, genetic transformation, or restriction analysis.

Question 32

Newborn screening is usually done to detect?

Accepted Answer

Answer reason: The core screening panel is aimed at inborn errors of metabolism and other genetic disorders (e.g., phenylketonuria, congenital hypothyroidism, certain hemoglobinopathies, cystic fibrosis depending on jurisdiction). These conditions are often clinically silent at birth, making population screening particularly valuable. By contrast, dehydration and nutritional status are assessed clinically and are not the primary targets of standard newborn blood spot screening. Hearing is commonly screened in newborns, but the phrase “newborn screening” typically refers to the metabolic/genetic blood spot screen rather than physiologic screening tests.

Question 33

Female sex chromosomes are —?

Accepted Answer

Answer reason: Individuals with two X chromosomes generally develop female reproductive anatomy and secondary sex characteristics in the absence of a Y chromosome. Options containing Y (XY, YY) indicate male-associated karyotypes or nonviable patterns, not typical female sex chromosomes. XO corresponds to Turner syndrome, a chromosomal disorder that can present phenotypically female but is not the standard female sex-chromosome complement.

Question 34

Cystic fibrosis is transmitted as an autosomal recessive trait. This means that?

Accepted Answer

Answer reason: When parents are unaffected carriers, each pregnancy has a 25% chance of producing an affected child, a 50% chance of producing a carrier, and a 25% chance of producing an unaffected non-carrier. Because the trait is autosomal, it is not sex-linked, so transmission is not limited to sons or daughters. Having both parents clinically affected is not required for an affected child; carrier status in both parents is sufficient.

Question 35

Meiosis is a process that helps make ________________ and ________________?

Accepted Answer

Answer reason: Meiosis is the specialized cell division that produces haploid gametes by reducing the chromosome number from diploid to haploid. It also increases variation through crossing over in prophase I and independent assortment of homologous chromosomes during metaphase/anaphase I. These mechanisms directly explain why the products are sex cells and why offspring can have genetic differences. In contrast, body cells (including brain cells) are produced by mitosis, which preserves chromosome number and generates genetically identical daughter cells.

Question 36

The Y chromosome is called?

Accepted Answer

Answer reason: Therefore, its presence is classically associated with male (masculine) sex determination in humans. By contrast, “autosomal” refers to non-sex chromosomes (chromosomes 1–22), so it cannot describe the Y chromosome. “Feminine” is inconsistent because typical female karyotype lacks a Y chromosome (46,XX).

Question 37

During which phase of meiosis does crossing over occur?

Accepted Answer

Answer reason: This process occurs during prophase I of meiosis I (specifically the pachytene stage), when homologs are paired closely enough for chiasmata to form. It is a key mechanism generating genetic variation in gametes by recombining alleles on the same chromosome. Metaphase I is when homologous pairs align at the metaphase plate, and anaphase II/telophase II involve separation and completion of haploid gametes rather than recombination.

Question 38

What is the process by which genetic information is passed from DNA to RNA?

Accepted Answer

Answer reason: RNA polymerase binds to the DNA, reads the template strand, and produces complementary RNA (e.g., mRNA for protein-coding genes). Translation is the next step where RNA is used to build protein, not to create RNA from DNA. Replication copies DNA into DNA, and mutation refers to changes in nucleotide sequence rather than an information-transfer process.

Question 39

You are reinforcing counseling for two parents that are preparing for the birth of their first child. They decided to undergo genetic testing and find out that they are both carriers for sickle cell anemia. You tell them that their baby has what chance of having sickle cell anemia?

Accepted Answer

Answer reason: Sickle cell disease is inherited in an autosomal recessive pattern, meaning an affected child must inherit two abnormal alleles (one from each parent). When both parents are carriers (heterozygous), a Punnett square yields 1/4 homozygous normal, 1/2 carriers, and 1/4 affected. Therefore, each pregnancy has a 25% probability of producing a child with sickle cell anemia. A common confusion is selecting 50%, which actually represents the chance the child will be a carrier, not affected.

Question 40

A human haploid cell (such as a sperm or egg cell) contains how many chromosomes?

Accepted Answer

Answer reason: In humans the diploid number is 46 (2n), therefore the haploid number is 23 (n). Meiosis reduces chromosome number by half during formation of sperm and ova, ensuring genetic stability across generations. The larger values reflect diploid or replicated DNA states, not the chromosome count in a mature gamete.

Question 41

What is the process of cell division in reproductive cells?

Accepted Answer

Answer reason: This reduction division occurs through two successive divisions (meiosis I and II) with homologous chromosome separation and recombination, increasing genetic variation. Mitosis instead produces genetically identical diploid somatic cells for growth and repair. Binary fission and budding are asexual reproductive methods typical of prokaryotes or some unicellular eukaryotes, not human gametogenesis.

Question 42

What is the study of heredity and variation called?

Accepted Answer

Answer reason: The scientific field that specifically examines genes, alleles, inheritance patterns, and mechanisms of variation (e.g., mutation and recombination) is genetics. Evolution addresses population-level change over generations, but it is broader and not the direct study of inheritance mechanisms. Ecology and taxonomy focus on organism–environment interactions and classification, respectively, not inheritance.

Question 43

Which molecule carries genetic information in most organisms?

Accepted Answer

Answer reason: DNA’s double-stranded structure and complementary base pairing enable high-fidelity replication and long-term information storage. RNA serves mainly as an intermediary in gene expression (mRNA, tRNA, rRNA) and is the genetic material only in some viruses, not most organisms. Proteins and lipids are essential cellular components but do not function as the primary repository of inherited genetic code.

Question 44

What is the term for organisms with the same genetic makeup?

Accepted Answer

Answer reason: Clones arise from a single parent organism or cell line via asexual reproduction or laboratory techniques, producing the same DNA sequence (barring rare mutations). Hybrids result from crossing genetically different parents and therefore have mixed genetic material. A species is a broader taxonomic group and does not imply identical genomes among its members, while variants explicitly differ genetically.

Question 45

Which type of RNA carries genetic information from DNA to the ribosome?

Accepted Answer

Answer reason: Messenger RNA is the transcript that carries codon sequences copied from DNA out of the nucleus (in eukaryotes) to the ribosome for translation. Transfer RNA instead delivers specific amino acids by matching anticodons to mRNA codons, and ribosomal RNA forms the structural/catalytic core of the ribosome. Small nuclear RNA mainly participates in RNA splicing within the nucleus rather than delivering the coding message to ribosomes.

Question 46

What is the process of creating an exact copy of DNA?

Accepted Answer

Answer reason: It is catalyzed primarily by DNA polymerases and is described as semiconservative because each new double helix contains one original strand and one newly synthesized strand. Transcription is a different process that copies DNA information into RNA, not DNA-to-DNA copying. Translation uses mRNA to assemble proteins, and mutation refers to a change in DNA sequence rather than a normal copying mechanism.

Question 47

What's the process by which organisms adapt to their environment?

Accepted Answer

Answer reason: Natural selection is the mechanism that consistently links environmental pressures to differential reproductive success, driving directional change in trait frequencies. Genetic drift changes allele frequencies by chance, especially in small populations, and does not necessarily produce better environmental fit. Mutations create new variation and gene flow moves alleles between populations, but neither alone explains the environment-driven increase of advantageous traits.

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