BIO1107 Exam 4

Which of the following is not a step in the cloning of a DNA fragment into an E. coli plasmid?

"Transformation" of the ligated plasmid DNA into E. coli cells Selection of cells containing the plasmid by plating onto medium containing an antibiotic Correct Response Transfer of the fragment directly into human cells to assess its function Ligation of a DNA fragment into a plasmid that has been cut with a suitable restriction enzyme

Which statement is not true about chromosome non-disjunction in meiosis?

Chromosome non-disjunction in meiosis occurs at much higher frequencies in 40 year old women relative to 25 year old women Correct Response There is no way to distinguish whether chromosome non-disjunction occurred in meiosis I or in meiosis II Chromosome non-disjunction in meiosis I will lead to a gamete with two different homologs of a chromosome (as opposed to two copies of the same homolog) Chromosome non-disjunction in meiosis is the major cause of Down syndrome

Which feature is not a characteristic of meiosis?

Correct Response Ploidy remains the same from start to end Pairing of homologs Crossovers between homologs occur DNA replication occurring in only one of two cell divisions

Which of the following is not an example of natural selection?

Correct Response A 90% reduction in a population from a tsumani that killed all genotypes with equal efficiency A heritable increase in the resistance of a weed to an herbicide after three seasons of herbicide treatments to a field Reduced seed production from poor insect pollination in a white-flowered mutant plant relative to the wild type yellow-flowered plant A viral pandemic that kills 50% of individuals of a population of an animal that have a specific blood type but does not kill any individuals of the same species that have different blood types

Which of the following is not a normal usage of the term "cloning"

Correct Response Amplification of a single DNA sequence fragment by PCR Producing an organism that is a genetically identical copy of another Inserting a human gene into an E. coli plasmid Isolating a single asexually dividing cell and allowing it to grow into a colony of genetically identical cells

Which definition fits best for a genetically modified organism (GMO)?

Correct Response An organism that has been modified by recombinant DNA technology An organism carrying any known mutation Any organism specifically bred to carry at least two mutations An organism with one or more mutations caused by treatment with a mutagen (mutation causing agent)

Which statement is true about meiotic chromosomes?

Correct Response Crossovers exchange chromosome pieces between homologs Synaptonemal complex holds homologs together at anaphase of meiosis I Chiasmata contribute to holding sister chromatids together at anaphase of meiosis II DNA double strand breaks in meiosis function to allow separation of sister chromatids in meiosis II

Which statement is true about DNA denaturation and/or hybridization?

Correct Response Denatured DNA refers to double stranded DNA that has become single stranded Only two strands of identical sequence can hybridize together DNA denaturation and renaturation occur equally quickly in all circumstance Strong base is the only effective means to denature double stranded DNA

Which of the following is not a step in the detection of a specific DNA fragment in a genomic using Southern blotting and hybridization?

Exposure of a filter with the transferred DNA fragments on it to a radioactively labeled probe made from a specific DNA sequence Correct Response Degradation of DNA on the filter through treatment with DNase Running a gel with restriction enzyme-digested DNA Transfer of DNA from the gel to a membrane

Which one of the following is an inaccurate statement about sexual reproduction

It can both create and destroy particular combinations of gene forms (alleles) Correct Response It can never exist without a fully functional ability to carry out meiosis It produces a very high level of genetic exchange relative to alternative processes It can be an excellent mechanism for the efficient spread of a transposon into the genome of a species

Which description best defines paired-end sequencing?

It obtains sequences of both strands of a DNA region It involves sequencing of very short (~10s of bp) DNA regions It specifically involves sequencing of chromosome ends Correct Response It involves sequencing the two end regions of a relatively large (>1000 bp) genomic DNA fragments in order to link contigs separated by long repeats

Which statement is false about lactase persistence?

Lactase persistence refers to the ability of adult humans to be able to digest the milk sugar lactose Lactase persistence prevents lactose intolerance Lactose persistence is a comparatively recent occurrence among human populations that became widespread only after humans began raising cows and other ruminant animals Correct Response A single mutant allele that has spread worldwide is responsible for all lactase persistence in humans

Which statement is not true about real time quantitative PCR (qPCR)

Measures levels of DNA during exponential stage of DNA amplification Can utilize fluorescently labeled DNA Requires a PCR machine able to measure fluorescence during the PCR reactions Correct Response Achieves ten fold amplification of DNA with each cycle

Which statement is true about human oogenesis?

Meiotic cell divisions in humans occur in many tissues throughout the body Human egg cells are approximately the same size as human sperm One pair of meiotic divsions in women produces four viable haploid oocytes Correct Response The first meiotic division in oogenesis is arrested from before birth until after puberty

Which statement is false about alleles?

Multiple alleles can exist for the same gene Only two alleles of the same gene can normally be present in one diploid individual Correct Response An allele that is recessive to another allele cannot be dominant over a third allele Only one allele of a gene can normally be present in one haploid individual

Which of the following is not a feature of CRISPR-Cas9?

NO IDEA!!!! Cas9 contains an RNA, part of the sequence of which determines what DNA sequence is cleaved A region of the Cas9 RNA can be customized to cut at sequences chosen by a scientist Cleavage by Cas9 can help accomplish targeted gene editing Cas9 primarily aids gene editing by increasing the likelihood that transformed DNA can enter a cell during transformation

A new population established from a small number of individuals that are not representative of the whole population is a description that best fits which one of the following?

Natural selection Bottleneck effect Correct Response Founder effect Directional selection

Which of the following would not be considered a component of sexual reproduction?

Occasional production of diploids through fusions of cells of opposite mating types in a yeast that largely reproduces through clonal mitotic divisions (Most yeast do have a sexual phase) Correct Response Gradual acquisition of multiple mutations in a purely mitotically dividing eukaryotic single celled organism Production of eggs and sperm in separate sexes in an animal species "Alteration of generations" between haploid and diploid organisms in a fern

Which of the following is not a feature of next-generation sequencing?

Overlapping short sequence reads are computer assembled into large "contigs" Most forms of next-gen sequencing have short (10s -low 100s bp) sequence reads It can carries out orders of magnitude more megabases of sequence per unit cost than earlier dideoxy sequencing Correct Response DNA sequence repeats like transposons so not hinder assembly of contigs into a complete genomic sequence

Which of the following represents a test cross as defined in class?

P X F1 cross F1 X F1 cross F2 with a dominant phenotype X F2 with a dominant phenotype Correct Response F2 with a dominant phenotype X P with recessive phenotype (A test cross is to try to figure out what the genotype is)

Which statement is untrue about Mendel's experiments?

Recessive traits would disappear in F1 offspring but reappear in a percentage of F2 offspring The traits he described independently assorted from one another Each trait he described had clear heritably dominant and recessive forms Correct Response Reciprocal crosses, with male and female parents switched, produced different results in the purple/white flower plant crossings (There is no sex linkage in his Pea plants. Made no difference if it was male or female plant.)

Which of the following steps was not involved in generating Dolly the cloned sheep?

Removal of the nucleus from an oocyte cell Fusing a diploid somatic cell to an enucleated oocyte Transplant of an oocyte into a surrogate mother Correct Response Fertilization of an oocyte with sperm from a genetically identical male

Which of the following best approximates Mendel's law of segregation?

Replicated chromosomes segregate into separate daughter cells during mitosis Like alleles preferentially segregate with one another in meiosis Correct Response Gametes from an individual contain only one allele of a particular gene (3 Mendel's Laws-KNOW THESE) Plants with recessive traits should not be outcrossed

Which statement is untrue about restriction enzymes?

Some restriction enzymes produce blunt ends that lack overhangs Many restriction enzymes produce "sticky ends" with single strand overhangs Correct Response Restriction enzymes methylate bases in their target sites prior to cleaving them They commonly cut at 4-8 bp palindromic sequences

The absence of predators on islands often allow small herbivores to heritably reach significantly larger body sizes than mainland populations. This is an example of:

Stabilizing selection Sexual selection Diversifying selection Correct Response Directional selection

Genetic drift refers to which of the following?

The movement of alleles among different populations Non-random differences in the abilities of genetically different members of a population to survive The consequences of sexual reproduction creating individuals with new combinations of alleles Correct Response The role of chance in the survival and reproduction of individuals in a population

Crossing a Parental purple flower pea plant back to an F1 strain that came from a cross between a purple flower and a white flower plant, what would be the expected ratio of genotypes and phenotypes of the offspring?

25% PP purple flowered plants, 50% Pp purple flowered plants and 25% pp white flowered plants 75% PP purple flowered plants and 25% Pp purple flowered plants Correct Response 50% PP purple flowered plants and 50% Pp purple flowered plants 100% PP purple flowered plants

An animal population in Hardy-Weinberg equilibrium has two alleles of a coat color gene. The allele for the dominant black coat color has a frequency of 0.2 (20%) while the recessive white coat color allele has a frequency of 0.8 (80%). What percentage of the population is white?

80% 32% 50% Correct Response 64%

Which example below qualifies as a transgenic organism?

A mouse that has been genetically engineered to lose its only functional copy of a particular native gene in just its liver cells and in just certain specific conditions A human patient with a genetic disorder that has received gene therapy that introduced a functional human copy of the defective gene back into her cells A yeast engineered to have a duplicated copy of one of its native chromosomes Correct Response An E. coli cell carrying a plasmid engineered by scientists to contain an antibiotic resistance gene isolated from another bacterial species

Which one of the following situations is less likely to benefit from the high level of genetic exchange accomplished by obligate sexual reproduction?

A species with a complex life history and a large number of genes A comparatively rare species with a global population never exceeding 10,000 Large animal species like rhinos and elephants Correct Response A single cell organism with a generation time less than a hour (sexual reproduction produces a great deal of genetic exchange, and that isn't needed for something that doesn't live long)

Epistasis refers to which of the following?

A synergistic relationship between two genes such that the phenotype produced by mutation of one gene is enhanced by the phenotype of another gene The dominance of one allele of a gene over other alleles of the same gene The emergence of any unexpected phenotype when mutations in two genes are combined in one organism Correct Response An antagonistic relationship between two genes such that the phenotype produced by mutation of one gene is masked by the phenotype of another gene

Which definition below fits best to describe a genetic chimera?

An organism that is a genetic clone of another A population composed of organisms with particularly diverse genetic backgrounds An organism composed of cells that are not all genetically identical Correct Response A single organism that was generated by fusion of two genetically different fertilized eggs or developing embryos

Which definition below fits best to describe a genetic mosaic?

An organism that is a genetic clone of another A single organism that was generated by fusion of two genetically different fertilized eggs or developing embryos A population composed of organisms with particularly diverse genetic backgrounds Correct Response An organism composed of cells that are not all genetically identical

Which statement is true about Bt toxin?

Bt is a very broad spectrum insecticide Bt is a non-biological chemical compound developed by a chemical company There is only a single form of Bt Correct Response Bt only becomes activated in the guts of its insect targets

Which one of the following is a screen rather than a selection?

Correct Response Growing mutagenized bacterial cells (i.e., cells treated with a chemical causing mutations) and searching through the resulting thousands of colonies on plates for rare colonies that have an abnormal wrinkled morphology Placing a population of bacterial cells on medium containing a carbon source that they can't use (e.g., an unusual type of sugar molecule) and looking for any rare colonies that form from mutants now able to utilize that carbon source Placing yeast cells at a temperature high enough to kill all cells except rare mutants that can survive at the temperature used Selecting for the presence of a plasmid by growing cells on a plate with antibiotics that kill all cells except those that have taken up the plasmid

Which of the following is true of dideoxy sequencing?

Correct Response Having each of the four different dideoxy nucleotides tagged with a different fluorescent dye is often used in dideoxy sequencing Multiple dideoxy nucleotides are typically incorporated in each of the individual DNA molecules that are produced in a given DNA sequencing reaction A dideoxy nucleotide is the first base added onto the primer is a DNA sequencing reaction The 5' ends of the DNA molecules that are produced in a given DNA sequencing reaction are all different

Which statement is true about dihybrid crosses?

Correct Response If A and B are separate genes, dihybid crosses could be represented as AaBb X AaBb If A and B are separate genes, dihybid crosses could be represented as AaBb X aabb They normally yield dominant:recessive offspring ratios of 1:1 They involve breeding between hybrids between different but related species of organisms

A gene for trait A in mouse is found to have 11% linkage to a gene for trait B. The trait A gene in turn shows 20% linkage to a gene for trait C. What is the order of the three genes on a chromosome?

Correct Response It can't be distinguished if it is A, B, C or C, A, B A, C, B C, A, B A, B, C

Which statement is true about linked genes?

Correct Response Linkage is a relative term; some gene pairs are more linked than others Mutations at two linked genes cannot ever be separated in meiosis All genes on the same chromosome will definitely behave as if they are linked They function in the same biochemical pathway

Gene flow refers to which of the following?

Correct Response The movement of alleles among different populations The consequences of sexual reproduction creating individuals with new combinations of alleles The role of chance in the survival and reproduction of individuals in a population Non-random differences in the abilities of genetically different members of a population to survive

A population geneticist's definition of relative fitness would best match which of the following?

Correct Response The number of offspring an organism produces, relative to others of its population The age to which an organism lives, relative to others of its species The relative health of an organism, at the peak of its life The relative social dominance of an individual relative to others of its population

Which statement is untrue about recessive traits?

Correct Response They can only produce a phenotype in haploid organisms They are likely the result of lost or greatly reduced function of a gene They are more likely to be observed in self-fertilizing plants than in outcrossing (non-self-frertilizig) plants They require a homozygous genotype with regard to the gene causing the trait

Which statement about gel electrophoresis is true?

Correct Response UV light is typically used to visualize DNA that has been run on gels All restriction fragments from the same plasmids show up with the same brightness on gels because they each have identical numbers of molecules Larger DNA molecules run more quickly on gels than do small molecules DNA fragments can be directly visualized on gels without any added dye

When A and B are two genes, each with two alleles, an AaBb individual is bred to an aabb individual. Which two (2) of the following represent recombinant types and not parental types?

Correct Response aaBb aabb Correct Answer Aabb aAbB

Which statement is untrue about a eukaryotic species with no documented sexual reproduction?

Correct Response It would be expected to be composed of individuals that were all genetically distinct from one another It could be more capable of horizontal gene transfer than most sexually reproducing species It could be a recent asexual derivative of a species with occasional sexual reproduction It could well be a species with cryptic sexual forms that have not yet been discovered

Which statement is untrue about horizontal gene transfer (HGT)?

Correct Response While HGT is common in prokaryotes and some lower eukaryotes, there is no evidence to support that it has ever occurred bringing new genes into vertebrates Retrovirus endogenization is an example of HGT A horizontally transferred gene can much more closely resemble (in terms of DNA sequence similarity) a gene from a distantly related organism than any gene from closely related species HGT is apt to be easier with single-celled organisms than multicellular organisms

Which kind of event does not characterize the behavior of chromosomes at some point in meiosis I?

DNA double strand breaks occur in chromosomes Synaponemal complex forms Correct Response Sister kinetochores are not held close together but instead all held in opposing positions on opposite sides of sister chromatids (They act like one so they are held close together) Clustering of telomeres of all chromosomes

Which statement is false about Crown Gall disease of plants?

DNA from a bacterial cell is transferred into a chromosome of a plant Correct Response Though a natural example of "genetic engineering", it has not been relevant to technologies of generating genetically modified plants It is caused by infection with the bacterium Agrobacterium tumefaciens It causes tumor-like growths in many species of plants

Which of the following DNA samples would be expected to hybridize together most quickly (assuming all are at equal concentration)?

Denatured bacterial genomic DNA Denatured human genomic DNA Correct Response A denatured 3000 bp plasmid DNA

Which one of the following does not constitute an example of genetic exchange?

Endogenization of a retrovirus into the germline of a mammalian host species Transfer of a plasmid from one bacterial species to another Sexual reproduction producing offspring different from either parent Correct Response Transcriptional activation of genes in the nuclei of root cells of a plant after contact of the roots with a bacterial pathogen in the soil (Change in gene expression).

Which statement best describes 'reverse genetics'?

Genetics experiments that prove to be a failure Starting with a mutant, then working toward identifying the affected gene Doing genetic analysis solely by examining genome sequences Correct Response Starting with a gene's sequence and then constructing a mutation in the organism the gene came from

Which statement is false about glyphosate?

Glyphosate is a broad spectrum herbicide Weeds resistant to glyphosate are already known to exist Correct Response Transgenic plants resistant to glyphosate contain an enzyme activity derived from a mammal Glyphosate acts by blocking a biochemical pathway present in plants but not present in animals

Which of the following terms refers to a diploid carrying two non-identical alleles of the same gene?

Homozygous Recessive Correct Response Heterozygous Aneuploid

Which of the following statements is false about the integration of transformed DNA fragments into chromosomal DNA?

In most organisms, transformed DNA will integrate randomly, not using homology In at least some organisms (such as yeast), transformed DNA will integrate preferentially using homology Random integration is thought to occur at rare and randomly located sites of DNA double strand breaks Correct Response Gene editing can occur with at equal efficiency with either random or homologous integration of DNA sequence

Which statement is false about the use of dideoxy nucleotides in DNA sequencing?

Incorporation of a single dideoxy nucleotide at the 3' end of a DNA chain will block any further nucleotide addition by a DNA polymerase Dideoxy nucleotides often also have fluorescent dye domains added to them to facilitate automated DNA sequencing A dideoxy nucleotide is missing the hydroxyl group on the deoxyribose used for making the sugar-phosphate bond in the DNA backbone Correct Response During a DNA sequencing reaction, DNA synthesis is carried out where a particular dideoxy nucleotide (say ddATP) completely replaces all the normal nucleotide (meaning dATP in this example)

Which statement is not true about the parasexual life cycle of Candida albicans?

Incorrect Response It occurs in the absence of a proper meiosis It produces a wide variety of viable aneuploidy progeny Correct Answer It produces haploid gametes (It does not produce these.) It can feature mating of two diploid cells to produce a tetraploid

Which statement is not true about the law of independent assortment?

Independent assortment of chromosomes helps assure that offspring will not always be identical in phenotype to a parent Two mutations on separate chromosomes should segregate independently from one another Two mutations close together on the same chromosome will not independently assort Correct Response Independent assortment does not occur with recessive alleles

Which form of genetic exchange is absent in prokaryotes?

Integration of virus (phage) genomes into host chromosomes Correct Response Meiosis Uptake of naked DNA from outside the cell Movement of plasmids from one species to another

Which one of the following is not true about PCR?

PCR reactions have high temperature steps and work best with a DNA polymerase from an organism that grows at high temperature Requires DNA primers for the polymerization step Correct Response Requires a DNA ligase to connect amplified fragments Each round in a PCR reaction can double the about of target DNA fragment that is present

Which of the following is not an option to explain complete dominance of one allele over another allele as opposed to incomplete dominance?

Phenotypes from organisms with one or two functional alleles may not be discernably different Correct Response Two alleles that both contribute equally to the final phenotype Disruption of one allele of a gene may not perturb a biochemical pathway if the component encoded by the gene is not rate limiting for the pathway Some genes may have negative feedback regulation that raises the activity of their gene or protein product when one allele is inactivated

Which statement is false about the genetics of blood types?

The O allele is recessive to both the A allele and the B allele An AO genotype will produce the same phenotype as a AA genotype Correct Response An AB genotype will produce the same phenotype as a AA genotype The A allele is co-dominant with the B allele

Which of the following is not an advantage of the pea plant that helped Mendel establish the principle of genetics?

The organism is normally self fertilizing but can manually be cross fertilized Correct Response Unusually for a higher eukaryote, pea plants are haploid Pea plants can be grown in large numbers and reproduce within a single year Pea plants had multiple discontinuously variable heritable traits available that could be studied

Natural selection refers to which of the following?

The role of chance in the survival and reproduction of individuals in a population Correct Response Non-random differences in the abilities of genetically different members of a population to survive The consequences of sexual reproduction creating individuals with new combinations of alleles The movement of alleles among different populations

Which statement is false about complex phenotypic traits in humans?

They are commonly influenced by environmental factors Correct Response They always show little evidence of being heritable Human twins provide an excellent means of studying them They are influenced by many genes

Which statement is true about X-linked traits?

They are due to mutations on any type of sex chromosome Correct Response X-linked traits are less likely to produce phenotypes in women as compared to men A female carrier of an X-linked trait will pass the allele for that trait to 100% of her daughters A father with a genotype from an X-linked trait will pass that trait to 100% of his sons

Which statement is false about DNA oligonucleotides and microarrays?

They are synthetically made single stranded DNAs Oligonucleotides of unique sequences are present on each "spot" on a microarray Microarrays can be used to detect gene expression levels across an entire genome in one experiment Correct Response Microarrays, like Southern blots, are typically hybridized to a single specific DNA sequence at a time

What statement is false about temperature sensitive mutants?

They can be a useful means of studying the function of genes essential to life Correct Response They have never been demonstrated to occur in homeothermic animals such as mammals They are an example of a broader class of mutants known as conditional mutants Their gene products display different activity levels at different temperatures

Which statement about plasmids used in the laboratory is untrue?

They typically contain multiple restriction enzyme cutting sites useful for cloning They often replicate to copy numbers of at least tens of molecules per cell They contain replication origins and selectable marker genes such as antibiotic resistance genes Correct Response Plasmid DNA can't readily be experimentally separated from bacterial chromosomal DNA