Final Flashcards
Genetic variation leads to genetic diversity in populations and is the raw material for evolution. Biological systems have multiple processes, such as reproduction, that affect genetic variation. They are evolutionarily conserved and shared by various organisms. Which of the following statements best represents the connection between reproduction and evolution?
A) In order to increase genetic diversity for evolution in sexually reproducing organisms, mutations must occur in the zygote after fertilization.
B) Since prokaryotic organisms reproduce asexually, there is no mechanism for them to add genetic diversity for evolution.
C) Plants that use sexual reproduction are rare since this type of reproduction in plants does not contribute to genetic diversity.
D) Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms.
Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms.
Which of the following individuals will inherit an X-linked allele from a man who carries it?
A) all of his children
B) all of his daughters
C) all of his sons
D) half of his daughters
all of his daughters
How does natural selection apply to sexual reproduction as opposed to asexual reproduction?
A) Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction.
B) Sexual reproduction allows the greatest number of offspring to be produced.
C) Sexual reproduction utilizes far less energy than asexual reproduction.
D) Sexual reproduction results in the greatest number of new mutations.
Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction.
When taken up by a cell, which of the following molecules binds to a repressor so that the repressor no longer binds to the operator?
A) promoter
B) corepressor
C) repressor
D) inducer
inducer
Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers, and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. Among the F2 offspring, what is the probability of producing plants with white axial flowers?
A) 3/16
B) 9/16
C) 1/16
D) 1/4
3/16
When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?
A) The gene involved is located on the X chromosome.
B) Other male-specific factors influence eye color in flies.
C) The gene involved is located on the Y chromosome.
D) The gene involved is located on an autosome, but only in males.
A) The gene involved is located on the X chromosome.
A homozygous tomato plant with red fruit and yellow flowers was crossed with a homozygous tomato plant with golden fruit and white flowers. The F1 all had red fruit and yellow flowers. The F1 were testcrossed by crossing them to homozygous recessive individuals, and the following offspring were obtained:
Red fruit and yellow flowers—41
Red fruit and white flowers—7
Golden fruit and yellow flowers—8
Golden fruit and white flowers—44
How many map units separate these genes?
A) 15
B) 18.1
C) 17.1
D) 17.6
A) 15
Which of the following statements regarding gene linkage is correct?
A) All of the traits that Mendel studied—seed color, pod shape, flower color, and others—are due to genes linked on the same chromosome.
B) The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%.
C) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.
D) Linked genes are found on different chromosomes.
C) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.
The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following correctly describes why this situation is possible?
A) different possible assortment of chromosomes into gametes occurs
B) recurrent mutations form new alleles
C) there is a tendency for dominant alleles to segregate together
D) crossing over during prophase I leads to genetic variety
A) different possible assortment of chromosomes into gametes occurs
Which of the following processes would result from a mutation that deactivates a regulatory gene of a repressible operon in an E. coli cell?
A) continuous transcription of the structural gene controlled by that regulator
B) complete inhibition of transcription of the structural gene controlled by that regulator
C) continuous translation of the mRNA because of alteration of its structure
D) irreversible binding of the repressor to the operator
A) continuous transcription of the structural gene controlled by that regulator
Which of the following statements defines a genome?
A) the complete set of an organism’s genes and other DNA sequences
B) a karyotype
C) the complete set of an organism’s polypeptides
D) the complete set of a species’ polypeptides
A) the complete set of an organism’s genes and other DNA sequences
Imagine that there are 25 different species of protists living in a tide pool. Some of these species reproduce both sexually and asexually, and some of them can reproduce only asexually. The pool gradually becomes infested with disease-causing viruses and bacteria. Which species are more likely to thrive in the changing environment?
A) The asexually reproducing species is likely to thrive.
B) The sexually reproducing species is likely to thrive.
C) Sexually and asexually reproducing species are equally likely to thrive.
D) Neither species will be able to thrive.
B) The sexually reproducing species is likely to thrive.
Mendel’s observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?
A) anaphase I of meiosis
B) anaphase II of meiosis
C) metaphase II of meiosis
D) prophase I of meiosis
A) anaphase I of meiosis
Which of the following scenarios describes an example of epistasis?
A) Recessive genotypes for each of two genes (aabb) results in an albino corn snake.
B) In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing.
C) In Drosophila (fruit flies), white eyes can be due to an X-linked gene or to a combination of other genes.
D) In cacti, there are several genes for the type of spines.
B) In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing.
What does a recombination frequency of 50% indicate?
A) The two genes are likely to be located on different chromosomes.
B) Abnormal meiosis has occurred.
C) The genes are located on sex chromosomes.
D) All of the offspring have combinations of traits that match one of the two parents.
A) The two genes are likely to be located on different chromosomes.
A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments, she succeeded in increasing acetylation of histone tails in the chromatin of the cells. Which of the following results would she most likely see in these cells?
A) decreased binding of transcription factors
B) decreased chromatin condensation
C) increased chromatin condensation
D) inactivation of the selected genes
B) decreased chromatin condensation
Asexual reproduction occurs during which of the following processes?
A) the exchange of chromosomes between organisms of different species
B) meiosis
C) fertilization
D) mitosis
D) mitosis
Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?
A) environmental factors such as soil pH affect the phenotype
B) the knowledge that multiple alleles are involved
C) the alleles are codominant
D) the allele for blue hydrangea is completely dominant over the allele for pink hydrangea
A) environmental factors such as soil pH affect the phenotype
What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?
A) Genes are composed of DNA.
B) Traits are inherited in discrete units and are not the result of “blending.”
C) Recessive genes occur more frequently in the F1 generation than do dominant ones.
D) There is considerable genetic variation in garden peas.
B) Traits are inherited in discrete units and are not the result of “blending.”
Cinnabar eye color is a sex-linked, recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes?
A) 100%
B) 50%
C) 25%
D) 0%
A) 100%
Sex determination in mammals is due to the SRY gene found on the Y chromosome. Which of the following situations could allow a person with an XX karyotype to develop a male phenotype?
A) translocation of SRY to an X chromosome
B) the loss of the SRY gene from an autosome
C) the presence of one normal and one shortened (deleted) X
D) the presence of an extra autosomal chromosome
A) translocation of SRY to an X chromosome
During meiosis, a defect occurs in a cell that results in the failure of spindle microtubules binding at the kinetochores. Which of the following statements describes the most likely result of such a defect?
A) Excessive cell divisions will occur resulting in cancerous tumors and an increase in the chromosome numbers known as polyploidy.
B) The resulting cells will not receive the correct number of chromosomes in the gametes, a condition known as aneuploidy.
C) New microtubules with more effective binding capabilities to kinetochores will be synthesized to compensate for the defect.
D) The defect will be bypassed in order to ensure normal chromosome distribution in the new cells.
B) The resulting cells will not receive the correct number of chromosomes in the gametes, a condition known as aneuploidy.
Which of the following statements correctly describes the meaning of the chromosome theory of inheritance as expressed in the early 20th century?
A) Mendelian genes are at specific loci on the chromosome and, in turn, segregate during meiosis.
B) Natural selection acts on certain chromosome combinations rather than on genes.
C) Individuals inherit particular chromosomes attached to genes.
D) No more than a single pair of chromosomes can be found in a healthy normal cell.
A) Mendelian genes are at specific loci on the chromosome and, in turn, segregate during meiosis.
Which of the following statements correctly describes how Mendel accounted for the observation that traits had disappeared in the F1 generation and then reappeared in the F2 generation?
A) New mutations were frequently generated in the F2 progeny, causing traits that had been lost in the F1 to reappear in the F2.
B) Traits can be dominant or recessive, and the recessive traits were “hidden” by the dominant ones in the F1.
C) Members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait.
D) The mechanism controlling the appearance of traits was different between the F1 and the F2 plants.
A) Traits can be dominant or recessive, and the recessive traits were “hidden” by the dominant ones in the F1.
Imagine that you’ve isolated a yeast mutant that contains histones resistant to acetylation. What phenotype would you predict for this mutant?
A) The mutant will grow rapidly.
B) The mutant will require galactose for growth.
C) The mutant will show increased levels of gene expression.
D) The mutant will show decreased levels of gene expression.
D) The mutant will show decreased levels of gene expression.
Which of the following statements is a correct explanation for the observation that all offspring exhibit a phenotype for a particular trait that appears to be a blend of the two parental varieties?
A) The genes are linked and do not separate during meiosis.
B) The genes for the trait are dominant in both of the parents.
C) Neither of the parental genes is dominant over the other.
D) The genes for the trait are recessive in both of the parents.
C) Neither of the parental genes is dominant over the other.
Feather color in budgies is determined by two different genes, Y for pigment on the outside of the feather, and B for pigment on the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. Two blue budgies were crossed. Over the years, they produced 22 offspring, five of which were white. What are the most likely genotypes for the two blue budgies?
A) yyBb and yyBb
B) yyBb and yybb
C) yyBB and yyBB
D) yyBB and yyBb
A) yyBb and yyBb
Which of the following statements would explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced?
A) Recombination did not occur in the cell during meiosis.
B) Both of the characters are controlled by more than one gene.
C) The two genes are closely linked on the same chromosome.
D) The two genes are linked but on different chromosomes.
C) The two genes are closely linked on the same chromosome.
During which of the following processes does independent assortment of chromosomes occur?
A) in mitosis and meiosis II
B) in meiosis II only
C) in meiosis I only
D) in mitosis and meiosis I
C) in meiosis I only
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?
A) 3/8
B) 9/16
C) 1/2
D) 1/16
C) 1/2
Which of the following statements describes the chromosomal makeup of each daughter cell after telophase of meiosis I?
A) The cells are haploid, and the chromosomes are each composed of two chromatids.
B) The cells are diploid, and the chromosomes are each composed of two chromatids.
C) The cells are diploid, and the chromosomes are each composed of a single chromatid.
D) The cells are haploid, and the chromosomes are each composed of a single chromatid.
A) The cells are haploid, and the chromosomes are each composed of two chromatids.
DNA methylation and histone acetylation are examples of which of the following processes?
A) chromosomal rearrangements
B) genetic mutation
C) translocation
D) epigenetic phenomena
D) epigenetic phenomena
During which of the following processes do sister chromatids separate from each other?
A) during both mitosis and meiosis II
B) during meiosis II only
C) during meiosis I only
D) during both mitosis and meiosis I
A) during both mitosis and meiosis II
Red-green color blindness is a sex-linked recessive (Xn) trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?
A) XNXN and XnY
B) XNXN and XNY
C) XnXn and XnY
D) XNXn and XNY
D) XNXn and XNY
Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes eye problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information?
A) It is pleiotropic.
B) It is dominant.
C) It is recessive.
D) It is epistatic.
A) It is pleiotropic.
Mendel crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F2 generation. The results were as follows: 6,022 yellow and 2,001 green (8,023 total). Which of the following statements correctly describes the relationship of the allele for green seeds to the allele for yellow seeds?
A) The green allele is recessive to the yellow allele.
B) The two alleles are codominant.
C) The green allele is dominant to the yellow allele.
D) The two alleles exhibit incomplete dominance.
A) The green allele is recessive to the yellow allele.
In cats, black fur color is determined by an X-linked allele; the other allele at this locus determines orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?
A) tortoiseshell females; tortoiseshell males
B) black females; orange males
C) tortoiseshell females; black males
D) orange females; black males
C) tortoiseshell females; black males
Drosophila melanogaster, the common fruit fly, has 4 chromosomes in each of its gametes. How many chromosomes are in each somatic cell?
8
Saccharomyces cerevisiae, the yeast used to make bread and beer, has 18 chromosomes. How many chromatids are in a cell in G2?
36
The number of chromosomes present in a germ cell of an organism is:
A) half the number of chromosomes present in the somatic cells.
B) double the number of chromosomes present in the somatic cells.
C) one quarter the number of chromosomes present in the somatic cells.
D) the same of chromosomes present in somatic cells.
A) half the number of chromosomes present in the somatic cells.
Which of the following is not a source of genetic variation?
A) Crossing over between sister chromatids
B) Independent assortment of chromosomes
C) Engulfing DNA from other organisms
D) Crossing over between homologous chromosomes
A) Crossing over between sister chromatids
The zygote of an organism has 10 pairs of homologous chromosomes. The total number of chromosomes in the germ cell of the organism is _____________.
20
In Drosophila, red-eye color is dominant over white-eye color. A female Drosophila with red eyes and unknown genotype was crossed to a male with red eyes. Half of the male progeny have red eyes. The following may be true about the female with unknown genotype.
A) She is heterozygous for red eyes.
B) She is homozygous for red eyes.
C) She is hemizygous for red eyes.
D) None of these
A) She is heterozygous for red eyes.
A tall plant has been found, but its zygosity is unknown. Tall is dominant over short height. The following can be done to determine its zygosity:
A) Cross to a true breeding short plant
B) Cross to a true breeding tall plant
C) Cross to a heterozygous tall plant
D) Let it self fertilize then analyze the progeny
A) Cross to a true breeding short plant
A plant homozygous for the unlinked dominant alleles A, B and G is crossed with another plant that is homozygous for the recessive alleles a, b and g. How many different genotypes in the F2 population will give rise to the ABg phenotype?
4
In an asexually reproducing organism it is expected that the offspring will be genetically identical to the parent. However, in one particular event of asexual reproduction the offspring was found to be differing from the parent. The reason behind this could be __________________.
A) mutation
B) crossing over of non-sister chromatids
C) independent assortment of alleles
D) cross over of sister chromatids
Mutation
In a genetic cross between AaBbCcDdEe and Aabbccddee what fraction of the offspring will be homozygous dominant for all five genetic loci?
A) None
B) 1/32
C) 1/64
D) 1/128
A) None
A white mouse (bb) mates with a black (BB) mouse and all the babies are gray in color. Which of the following is true for the alleles responsible for coat color of the mice?
A) The alleles have incomplete dominance.
B) One allele is entirely dominant.
C) Both alleles are codominant.
D) The alleles are influenced by epistasis.
A) The alleles have incomplete dominance.
Two species of organisms A and B inhabit a particular geographic location. Organism A reproduces asexually while Organism B undergoes sexual reproduction. Due to natural calamities, there have been major changes in the biogeography of the habitat. Which of the following is true?
A) Species A has more chances to become extinct.
B) Species B has more chances of becoming extinct.
C) Species A and B have equal chances of becoming extinct.
D) Species A and B do not become extinct, as they were original inhabitants of the region.
A) Species A has more chances to become extinct.
A father with blood type O and a mother with blood type AB have 2 children. One child has blood type A. Which of the following is a possible blood type of the other child?
A) B
B) O
C) AB
D) None of these
A) B
Phoebe’s mother is red-green colorblind and her father is not. Phoebe’s husband is not colorblind. The probability that Phoebe’s daughter is red-green colorblind is _______%.
0%
In a genetic cross between a homozygous tall plant with homozygous purple flowers and a homozygous short plant with heterozygous purple flowers, how many short plants will you expect in the F2 generation if you sample 100 individuals? Both tall and purple are dominant.
25
How many different types of gametes can be produced by a plant with genotype AaBbCcDDEeFfGg?
64
If two people with ‘sickle-cell trait’ have offspring what would be the predicted ratio of phenotypically normal to affected (sickle-cell disease) offspring? (Sickle-cell trait means they have one copy of the sickle-cell allele, but do not have full-blown sickle-cell disease.)
A) Normal: affected = 3:1
B) Normal: affected = 2:1
C) Normal: affected = 1:1
D) Normal: affected = 1:3
A) Normal: affected = 3:1
In a cross between AaBbCcDdEe and Aabbccddee, what fraction of the offspring will be phenotypically dominant for all alleles? Express your answer as a fraction.
3/64
A plant has 4 genes A, B, C and D on chromosome 5. Gene A is very tightly linked to B and gene C is very tightly linked to D. A plant homozygous for alleles A, B, C and D is crossed with another plant homozygous for alleles a, b, c and d. What should be the approximate predicted phenotypic ratio of the F2 population?
A) 9:3:3:1
B) 1:2:2:4:1:2:1:2:1
C) 1:1:1:1
D) 27:9:9:9:3:3:3:1
A) 9:3:3:1
A true breeding, red-eyed, normal-winged female fly is crossed with a true breeding, purple-eyed, vestigial-winged male fly. All of the F1 offspring have red eyes and normal wings. A F1 female fly is mated with a male possessing purple eyes and vestigial wings. Below are the progeny obtained from this cross:
red eyes, normal wings 2,504 flies
purple eyes, vestigial wings 2,374
red eyes, vestigial wings 282
purple eyes, normal wings 272
The percent recombination between the purple eye locus and vestigial wing locus is _________%?
Between 9.9-10.5
Fruit fly gene stubble(sb) is on the second chromosome and curly-O (cyo) is on the third chromosome.
What is the recombination frequency(%) between sb and cyo?
50%
In the lac operon, lactose is a/an __________ and in trp operon tryptophan is a/an __________.
A) repressor; activator
B) co-repressor; inducer
C) product; substrate
D) inducer; co-repressor
D) inducer; co-repressor
A pancreatic cell and a liver cell differ because
A) All of them
B) they have different number of genes.
C) they have different sets of genes.
D) they express different sets of genes.
D) they express different sets of genes.
Histone acetylation ________ transcription; whereas histone methylation _________ transcription.
A) promotes; reduces
B) reduces; promotes
C) slows down; speeds up
D) None of the options
A) promotes; reduces
Which of the following is/are true for enhancer elements?
A) All of the options
B) They maybe located thousands of nucleotides upstream or downstream of a gene.
C) They maybe located within an intron.
D) There maybe multiple enhancers for a given gene.
E) They maybe located thousands of nucleotides upstream or downstream of a gene, and there maybe multiple enhancers for a given gene.
A) All of the options
Which of the following scenarios would violate Mendelian Genetics?
A) the alleles for a particular trait have equal opportunity to segregate into the gametes
B) a trait has 4 alleles exhibiting an order of dominance over one another
C) two separate traits are located on different chromosomes
D) an organism has 2 different alleles for a trait
B) a trait has 4 alleles exhibiting an order of dominance over one another
Which of the following is an example of pleiotropy in genetics?
A) when 2 different alleles of a gene are inherited, the organism will exhibit a blending of the phenotypes of the alleles
B) the presence of the dominant allele for Gene 2 determines whether Gene 1 will produce a phenotype at all
C) environmental factors can influence the expression of particular alleles for a given trait
D) an allele for a gene, when inherited, disrupts metabolic, reproductive and muscular processes in an organism
D) an allele for a gene, when inherited, disrupts metabolic, reproductive and muscular processes in an organism
True-breeding parents (QQRRSSTTUU) x (qqrrssttuu) produce a heterozygous F1. In the F2 generation, what is the probability of a genotype of QqrrssTtUU?
A) 1/64
B) 4/256
C) 1/1024
D) 1/256
D) 1/256
Why might lethal alleles skew the expected results from a monohybrid or dihybrid cross thought to be following Mendelian principles?
A) these alleles may result in death of an organism before they contribute those alleles to the subsequent generation
B) the presence of a lethal allele can mask another allele for a different trait
C) they increase the likelihood of heterozygotes surviving into the subsequent generation
D) lethal alleles always increase the frequency of dominant alleles for a trait
A) these alleles may result in death of an organism before they contribute those alleles to the subsequent generation
In mole rats hairy (H) is dominant to hairless (h). In a test cross between a hairy mole rat and a naked (hairless) mole rat, the offspring in the F1 generation were 50% hairy and 50% naked. What is the genotype of the hairy parent?
A) hh
B) HH
C) Hh
D) HhHh
C) Hh
In terms of gene regulation in eukaryotes, which of the following are related to transcription of genes?
A) enhancers
B) all choices apply to transcription
C) repressors
D) feedback repression
E) promoters
B) all choices apply to transcription
Which of the following is a potential post-translational strategy for gene regulation in eukaryotes?
A) acetylation
B) ubiquitination
C) alternative splicing
D) polyadenylation
B) ubiquitination
A key characteristic of recombinant offspring is
A) their chromosomes lack linked traits
B) they will resemble one parent but not the other
C) they display unique phenotypes compared to either parent
D) they will always follow Mendelian Genetic expectations
C) they display unique phenotypes compared to either parent
