Q&A Hero

Q: Please read the following scenario to answer the following questions. While working with cultured mouse cells, a researcher unknowingly treated the cells with a mutagen that causes the deletion or insertion of individual nucleotides in DNA. Subsequently, the researcher isolated and cultured a single cell from this group and noticed that the progeny of this cell were not producing a certain protein and that this affected their survival. The mutation would be most harmful to the cells if it resulted in ________. A) a single nucleotide insertion near the start of the coding sequence B) a single nucleotide deletion near the end of the coding sequence C) a single nucleotide in the middle of an intron D) deletion of a triplet near the middle of the gene

Q: Please read the following scenario to answer the following questions. While working with cultured mouse cells, a researcher unknowingly treated the cells with a mutagen that causes the deletion or insertion of individual nucleotides in DNA. Subsequently, the researcher isolated and cultured a single cell from this group and noticed that the progeny of this cell were not producing a certain protein and that this affected their survival. The mutation that resulted from the accident was probably ________. A) an amino acid substitution B) one that changed the triplet grouping of the genetic message C) an error in translation D) a loss in regulation of gene expression

Q: Please read the following scenario to answer the following questions If you were asked to study the pattern of bacterial growth (increase in numbers over time) during an infection, you would find that numbers of bacteria increase exponentially up to a certain point. Assume that you have been asked to interpret the growth of bacteriophages. You infect the host bacteria and measure the increase of phages over a defined period of time. You plot the results and get the graph shown here. Assume that you want to take a sample of viruses so that you could use them to infect the most bacteria. At what point on the graph should you take your sample from if you want to achieve this goal? A) A B) B C) C D) D

Q: Please read the following scenario to answer the following questions If you were asked to study the pattern of bacterial growth (increase in numbers over time) during an infection, you would find that numbers of bacteria increase exponentially up to a certain point. Assume that you have been asked to interpret the growth of bacteriophages. You infect the host bacteria and measure the increase of phages over a defined period of time. You plot the results and get the graph shown here. At what point on the graph are the viruses increasing in number the fastest? A) A B) B C) C D) D

Q: Please read the following scenario to answer the following questions If you were asked to study the pattern of bacterial growth (increase in numbers over time) during an infection, you would find that numbers of bacteria increase exponentially up to a certain point. Assume that you have been asked to interpret the growth of bacteriophages. You infect the host bacteria and measure the increase of phages over a defined period of time. You plot the results and get the graph shown here. Once viruses are detected, the number of viruses increases rapidly. This is because ________. A) lysogeny produces large numbers of bacteriophages B) DNA viruses reproduce more rapidly than RNA viruses C) the host cell speeds the release process D) the viruses lyse the hosts to release mature viruses quickly in a short amount of time

Q: Please read the following scenario to answer the following questions If you were asked to study the pattern of bacterial growth (increase in numbers over time) during an infection, you would find that numbers of bacteria increase exponentially up to a certain point. Assume that you have been asked to interpret the growth of bacteriophages. You infect the host bacteria and measure the increase of phages over a defined period of time. You plot the results and get the graph shown here. The first thing you notice is that there is no immediate increase in viruses following infection. This is because ________. A) it takes the virus time to adapt to the host B) although the virus has infected the host, it takes time to complete the lytic cycle C) the host is immune to the virus D) the virus is in a lysogenic cycle throughout the experiment

Q: An mRNA is expressed that begins with the sequence AUGCCAGGCGUC. Using the genetic code below, determine what peptide will be translated from this mRNA. A) Met Pro Gly Val B) Met Gly Pro Val C) Pro Met Val Gly D) Val Gly Pro Met

Q: Flu vaccines have been demonstrated to protect the elderly, as shown in the figure below. Assume there is a sample of 100 elderly people that normally would be hospitalized in winter. How many of them would you predict would still be hospitalized in the winter if all 100 of them received the flu vaccine? A) 27 B) 48 C) 52 D) 73

Q: Consider the following figure. It illustrates that a single amino acid substitution in the hemoglobin gene ________. A) always involves adenine and uracil B) may alter a protein so that it no longer functions properly C) is a silent mutation D) causes a nonsense mutation

Q: Examine the genetic code table shown below. The codon AGC codes for the amino acid ________. A) serine B) arginine C) threonine D) alanine

Q: The figure below shows the flow of genetic information in a eukaryotic cell. The transfer of information from DNA into an RNA molecule is known as ________. A) DNA replication B) transcription C) polypeptide D) translation

Q: Which of the following would NOT likely develop as an emerging virus? A) a virus harmful to humans that changes very slowly over time B) A virus that is normally harmless to humans undergoes rapid mutations. C) a virus that begins to infect people in New York City, a popular tourist destination D) a virus that affects primarily rabbits mutates and infects humans

Q: HIV (human immunodeficiency virus) must use its own ________ to reproduce. A) DNA polymerase B) reverse transcriptase C) RNA polymerase D) tRNA

Q: A(n) ________ is to bacteria as a ________ is to animal cells. A) retrovirus... virus B) phage... prophage C) prophage... provirus D) RNA virus... DNA virus

Q: Plant viruses ________. A) often use RNA, rather than DNA, as their genetic material B) benefit plants, rather than causing disease C) cause diseases that can be easily cured D) do not exist, as viruses attack only animals

Q: As an experiment, you infect bacteria with an unknown virus to see how the bacteriophage affects the bacteria. After a few days, you notice that the bacterial population is growing normally and that the cells appear healthy. Assuming that the infection occurred, what can you conclude from your observations? A) The virus is a bacteriophage that is reproducing the lytic cycle. B) The virus is a retrovirus that is reproducing the lytic cycle. C) The virus is a bacteriophage that is reproducing the lysogenic cycle. D) The virus is a retrovirus that is reproducing the lysogenic cycle.

Q: How can bacteriophage DNA be spread from cell to cell without causing cell death? A) by altering the way a cell splices its RNA B) via a lytic cycle C) via a lysogenic cycle D) by changing the length of its DNA molecules

Q: Mad cow disease is caused by A) a retrovirus similar to HIV. B) an enveloped virus. C) small circular RNA molecules called viroids. D) infectious proteins called prions.

Q: What is the ultimate source of all diversity? A) natural selection B) sexual recombination C) meiosis D) mutation

Q: What is the smallest number of nucleotides that must be added or subtracted to change the triplet grouping of the genetic message? A) one B) two C) three D) four

Q: A mutation within a gene that will insert a premature stop codon in mRNA would ________. A) result in a longer polypeptide chain B) result in a shortened polypeptide chain C) change the location at which transcription of the next gene begins D) have the same effect as deleting a single nucleotide in the gene

Q: Scientific research companies sell kits that allow researchers to produce proteins in test tubes via a process known as "in vitro translation." Which one of following components is NOT needed in these kits? A) amino acids B) transfer RNA C) DNA D) ribosomes

Q: Peptide bonds form between ________. A) amino acids B) an mRNA codon and a tRNA anticodon C) a tRNA and the amino acid it is carrying D) an mRNA transcript and the small ribosomal subunit

Q: During translation, what is the CORRECT order of events that occur as an amino acid is added? A) codon recognition, peptide bond formation, translocation B) translocation, codon recognition, termination C) initiation, codon recognition, termination D) peptide bond formation, translocation, codon recognition

Q: Where is translation accomplished? A) lysosomes B) smooth endoplasmic reticulum C) ribosomes D) nucleoli

Q: The DNA codon AGT codes for an amino acid carried by a tRNA with the anticodon ________. A) TCU B) AGU C) TCA D) AGT

Q: The RNA that is translated into a polypeptide is ________ RNA. A) viral B) ribosomal C) transfer D) messenger

Q: Translation converts the information stored in ________ to ________. A) DNA... RNA B) RNA... a polypeptide C) DNA... a polypeptide D) RNA... DNA

Q: The expressed (coding) regions of eukaryotic genes are called ________. A) caps B) promoters C) exons D) introns

Q: What protects mRNA from attack by cellular enzymes? A) RNA splicing B) the removal of exons C) the lack of RNA-digesting enzymes in the cytoplasm D) a cap and tail

Q: The absence of a terminator in transcription will result in ________. A) the creation of a virus B) a strand of mRNA that lacks its cap and tail C) the production of a longer RNA molecule D) the production of a shorter RNA molecule

Q: The CORRECT sequence of events occurring during transcription is ________. A) splicing, capping, tailing B) initiation, elongation, termination C) tailing, capping, splicing D) elongation, initiation, termination

Q: The region of DNA where RNA synthesis begins is the ________. A) start codon B) promoter C) stop codon D) terminator

Q: Which of the following enzymes is responsible for RNA synthesis? A) DNA polymerase B) ribosome C) reverse transcriptase D) RNA polymerase

Q: If a strand of DNA has the sequence AAGCTC, transcription will result in a(n) ________. A) single RNA strand with the sequence TTCGAG B) DNA double helix with the sequence AAGCTC for one strand and TTCGAG for the complementary strand C) single RNA strand with the sequence UUCGAG D) RNA double helix with the sequence UUCGAG for one strand and AAGCUC for the complimentary strand

Q: Transcription is the ________. A) manufacture of a strand of RNA complementary to a strand of DNA B) manufacture of two new DNA double helices that are identical to an old DNA double helix C) modification of a strand of RNA prior to the manufacture of a protein D) manufacture of a protein based on information carried by RNA

Q: The shared genetic code of all life on Earth is evidence that ________. A) the genetic code arose relatively late in the history of life on Earth B) DNA replication is error-free C) all life shares a common ancestry D) bacterial cells arose earlier than eukaryotic cells

Q: How many nucleotides make up a codon? A) two B) three C) four D) five

Q: How many amino acids are common to all living systems? A) 10 B) 20 C) 30 D) 100

Q: What name is given to the collection of traits exhibited by an organism? A) genome B) genotype C) phenotype D) genetic code

Q: DNA replication ________. A) is a slow process that results in virtually no errors B) requires DNA polymerase and RNA polymerase C) is a very fast process that results in numerous errors D) requires the cooperation of over a dozen enzymes and other proteins

Q: After replication, ________. A) each new DNA double helix consists of two old strands B) each new DNA double helix consists of one old strand and one new strand C) each new DNA double helix consists of two new strands D) one new DNA double helix consists of two old strands and the other new DNA double helix consists of two new strands

Q: What type of chemical bond joins the bases of complementary DNA strands? A) ionic B) covalent C) hydrophilic D) hydrogen

Q: Evidence for the spiral nature of DNA came from ________. A) X-ray crystallography studies B) studies of disease-causing bacteria C) base rule studies D) bacteriophage studies

Q: If one strand of a DNA double helix has the sequence GTCCAT, what is the sequence of the other strand? A) ACTTGC B) TGAACG C) CAGGTA D) CAGGUA

Q: In a DNA double helix, adenine pairs with ________ and guanine pairs with ________. A) cytosine... thymine B) guanine... adenine C) thymine... cytosine D) uracil... cytosine

Q: If adenine makes up 20% of the bases in a DNA double helix, what percent of the bases is guanine? A) 60% B) 40% C) 20% D) 30%

Q: RNA contains the nitrogenous base ________ instead of ________, which is found only in DNA. A) a deoxyribose sugar... a ribose sugar B) uracil... thymine C) uracil... guanine D) thymine... uracil

Q: Please read the following scenario to answer the following question. The parents of a child with unusual disease symptoms take the child to a doctor for help. The doctor suspects that the condition might have a genetic basis. She recommends that the child be taken to a specialty clinic where physicians and staff members are trained to diagnose genetic diseases and counsel parents. Ultimately, the child is diagnosed with a rare recessively inherited disease. The parents are tested for the gene, and both are found to be heterozygous. The parents want to have another child but are afraid this child will also be affected. What would genetic counselors say is the probability that the second child will have the disease? A) 1/2 B) 1/4 C) 1/8 D) 1/16

Q: Please read the following scenario to answer the following questions. Widow's peak, a pointed hairline on the forehead, is a genetic trait caused by a dominant allele. It can be traced back through a family's history using pedigree analysis. The pedigree shown here is of three generations of a family. Notice that some individuals (shown in gray) have a widow's peak (W = dominant allele and w = recessive allele). This pedigree supports the fact that widow's peak is due to a dominant allele, because if it were due to a recessive allele and both parents show the recessive phenotype, then ________. A) half of the sons would have a widow's peak B) all of the offspring would have a widow's peak C) none of the daughters would have a widow's peak D) all of the daughters and none of the sons would have a widow's peak

Q: Please read the following scenario to answer the following questions. Widow's peak, a pointed hairline on the forehead, is a genetic trait caused by a dominant allele. It can be traced back through a family's history using pedigree analysis. The pedigree shown here is of three generations of a family. Notice that some individuals (shown in gray) have a widow's peak (W = dominant allele and w = recessive allele). Janice's genotype is ________. A) Ww B) WW C) ww D) WW orWw

Q: Please read the following scenario to answer the following questions. Widow's peak, a pointed hairline on the forehead, is a genetic trait caused by a dominant allele. It can be traced back through a family's history using pedigree analysis. The pedigree shown here is of three generations of a family. Notice that some individuals (shown in gray) have a widow's peak (W = dominant allele and w = recessive allele). Mary has the genotype ________. A) WW B) ww C) Ww D) More information is needed.

Q: This hypothetical pedigree for a disease in humans illustrated inheritance that is A) autosomal recessive. B) autosomal dominant. C) sex-linked dominant. D) carried on the Y chromosome.

Q: Please refer to the following art to answer the following questions. Recombinant offspring were produced by the mating shown in the accompanying art. What is the recombination frequency of purple round and red long offspring? A) 21% B) 381 C) 21 + 21 D) 11%

Q: Please refer to the following art to answer the following questions. In the accompanying art, you see a table with the actual number of offspring that resulted from a dihybrid cross. The numbers do not show the 9:3:3:1 ratio predicted. One phenotype occurred more than predicted; another occurred less. The reason could be because ________. A) of errors in mitosis B) some of the alleles were linked C) some of the alleles were sex-linked D) of polygenic inheritance

Q: Experience with dog breeding has taught geneticists ________. A) that, given enough time, any desired trait can be bred into dogs B) that purebred dogs have offspring with qualities identical to the parents, because all purebred dogs are alike genetically C) that, while physical traits can be molded through artificial selection, behavioral traits cannot D) that geographically isolated groups of dogs may be selected for quite different traits, resulting in a different dog breed

Q: Hypophosphatemia (vitamin Dresistant rickets) is inherited as a sex-linked dominant trait. The relevant gene is found on the X chromosome. What is the expected outcome of a cross between a homozygous recessive woman and a man with hypophosphatemia? A) All of their daughters and none of their sons exhibit hypophosphatemia. B) Fifty percent of their daughters and fifty percent of their sons exhibit hypophosphatemia. C) All of their sons and none of their daughters exhibit hypophosphatemia. D) Twenty-five percent of their offspring exhibit hypophosphatemia.

Q: Red-green color blindness is inherited as a sex-linked recessive trait. The gene is found on the X chromosome. Can a man with normal color vision father a daughter who is red-green color-blind? A) Yes, if the woman with whom he mates is red-green color-blind. B) Yes, if the man is heterozygous for red-green color blindness. C) No, he can't (unless there is a mutation). D) No, the expression of the trait skips a generation.

Q: Assume that having three nostrils is inherited as a sex-linked trait on the Y chromosome. A man with three nostrils has a daughter who has a son with a man who has only two nostrils. What is the probability that the three-nostriled man's grandson has three nostrils? A) 0% B) 25% C) 50% D) 100%

Q: Linked genes are usually ________. A) found on the X chromosome B) found on the Y chromosome C) codominant D) located close together on a chromosome

Q: The recombination frequency between gene B and gene C is 11%. The recombination frequency between gene B and gene D is 5%. The recombination frequency between gene C and gene D is 15%. What would be the arrangement of these genes on a linkage map? A) CDB B) DBC C) BCD D) More information is needed.

Q: A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring. What is the recombination frequency of the two gene pairs? A) 6% B) 3% C) 30% D) 1.5%

Q: What is the best explanation for a BbCc bbcc cross producing offspring in a 5:5:1:1 phenotypic ratio? A) linked genes B) polygenic inheritance C) incomplete dominance D) codominance

Q: ________ genes violate Mendel's principle of independent assortment. A) Codominant B) Linked C) Recessive D) Pleiotropic

Q: What is the basis of Mendel's laws? A) the behavior of chromosomes during prophase I of meiosis only B) the behavior of chromosomes during mitotic anaphase C) the behavior of chromosomes during prophase I and prophase II of meiosis D) the behavior of chromosomes during metaphase I and anaphase I of meiosis

Q: Many human traits, such as our performance on intelligence tests or our susceptibility to heart disease, are ________. A) determined only by our genes B) influenced by both genes and the environment C) determined by genes in some people and by the environment in other people D) not affected by our genes

Q: In humans, the inheritance of ________ is best explained as being polygenic. A) cystic fibrosis B) height C) blood type D) sickle-cell disease

Q: What is key to recognition of a trait whose expression is determined by the effects of two or more genes (polygenic inheritance)? A) A mating between a homozygous and a heterozygous individual produces more than the expected number of offspring expressing the dominant trait. B) All of the alleles of the gene for that trait are equally expressed. C) Pleiotropy occurs. D) The trait varies along a continuum in the population.

Q: Marfan syndrome is the result of inheriting a single allele. Individuals with Marfan syndrome are tall and long-limbed, and have both cardiovascular and eye defects. Of what type of inheritance is the phenotype of Marfan syndrome an example? A) codominance B) homozygous recessive C) pleiotropy D) incomplete dominance

Q: An individual with the blood group genotype LMLN has the phenotype MN. What is the relationship between the LM and LN alleles? A) codominance B) pleiotropy C) LN is dominant D) incomplete dominance

Q: What is the key to the recognition of codominance? A) The phenotype of the heterozygote is intermediate between the phenotypes of the homozygotes. B) The trait exhibits a continuous distribution. C) The alleles affect more than one trait. D) The heterozygote expresses the phenotype of both homozygotes.

Q: An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair. If an individual with wavy hair mates with an individual with straight hair, what is the probability that their child will have curly hair? A) 0% B) 25% C) 50% D) 75%

Q: An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair. What is the relationship between the alleles for hair texture? A) pleiotropy B) incomplete dominance C) wavy hair dominant to both straight and curly hair D) codominance

Q: What is the key to the recognition of incomplete dominance? A) The phenotype of the heterozygote falls between the phenotypes of the homozygotes. B) The trait exhibits a continuous distribution. C) The alleles affect more than one trait. D) The heterozygote expresses the phenotype of both homozygotes.

Q: Which of the following techniques is used to collect fetal cells during pregnancy for genetic testing? A) testcross B) dihybrid cross C) amniocentesis D) pedigree analysis

Q: Achondroplasia is a form of dwarfism caused by a dominant allele. The homozygous dominant genotype causes death, so individuals who have this condition are all heterozygotes. If a person with achondroplasia mates with a person who does not have achondroplasia, what percentage of their children would be expected to have achondroplasia? A) 0% B) 50% C) 75% D) 100%

Q: An individual heterozygous for cystic fibrosis ________. A) cannot have children with cystic fibrosis B) is a carrier C) will have children who are all carriers of cystic fibrosis D) has cystic fibrosis

Q: The ________ is most commonly found in nature. A) recessive trait B) wild-type trait C) parental type D) dominant trait

Q: What data or test would you seek to determine whether or not a trait is sex linked? A) karyotype B) pedigree C) DNA sequence D) blood test

Q: In humans, free earlobes (E) are dominant to attached earlobes (e) and the presence of freckles (F) is dominant to the absence of freckles (f). If an individual heterozygous for both of these traits were to mate with an individual with attached earlobes and no freckles, what is the probability of having a child with attached earlobes and freckles? A) 0% B) 25% C) 50% D) 100%