What Are The Genotype And Phenotype? Quiz

36 Questions

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Botany Quizzes & Trivia

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Questions and Answers
  • 1. 
    Pea plants were particularly well suited for use in Mendel's breeding experiments for all of the following reasons except that
    • A. 

      Peas show easily observed variations in a number of characters, such as pea shape and flower color.

    • B. 

      Many of the observable characters that vary in pea plants are controlled by single genes.

    • C. 

      Peas have an unusually long generation time.

    • D. 

      It is possible to control matings between different pea plants.

    • E. 

      It is possible to obtain large numbers of progeny from any given cross.

  • 2. 
    What is the difference between a monohybrid cross and a dihybrid cross?
    • A. 

      A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations

    • B. 

      A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents.

    • C. 

      A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio.

    • D. 

      A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid only for one.

  • 3. 
     A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates:
    • A. 

      Dominance

    • B. 

      The blending model of genetics

    • C. 

      The mistakes made by Mendel

    • D. 

      True-breeding

    • E. 

      A dihybrid cross

  • 4. 
    The F1 offspring of Mendel;s classic pea cross alwaus looked like one of the two parental varieties because:
    • A. 

      No genes interacted to produce the parental phenotype

    • B. 

      One phenotype was completely dominant over another

    • C. 

      Different genes interacted to produce the parental phenotype

    • D. 

      Each allele affected phenotypic expression

    • E. 

      The traits blended together during fertilisation

  • 5. 
    • A. 

      Genes are composed of DNA

    • B. 

      Traits are inherited in discrete units, and are not the results of blending

    • C. 

      An organism that is homozygous for many recessive traitsis at a disadvantage

    • D. 

      There is considerable genetic variation in garen peas

    • E. 

      Recessive genes occur more frequently in the F1 than do dominant ones.

  • 6. 
    How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?
    • A. 

      16

    • B. 

      64

    • C. 

      8

    • D. 

      4

    • E. 

      32

  • 7. 
    Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This suggests
    • A. 

      Incomplete dominance.

    • B. 

      That the parents were both heterozygous.

    • C. 

      That each offspring has the same alleles.

    • D. 

      That the parents were true-breeding for contrasting traits.

    • E. 

      That a blending of traits has occurred.

  • 8. 
    Two characters that appear in a 9:3:3:1 ratio in the F2 generation should have which of the following properties?
    • A. 

      Each of the traits is controlled by single genes.

    • B. 

      The genes controlling the characters obey the law of independent assortment.

    • C. 

      Four genes are involved.

    • D. 

      Sixteen different phenotypes are possible.

    • E. 

      Each of the genes controlling the characters has two alleles.

  • 9. 
    A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
    • A. 

      HhTt

    • B. 

      Tt

    • C. 

      Hh

    • D. 

      T

    • E. 

      HT

  • 10. 
    It was important that Mendel examined not just the F1 generation in his breeding experiments, but the F2 generation as well, because
    • A. 

      Parental traits that were not observed in the F1 reappeared in the F2.

    • B. 

      He obtained very few F1 progeny, making statistical analysis difficult.

    • C. 

      Analysis of the F1 progeny would have allowed him to discover the law of segregation, but in the law of independent assortment.

    • D. 

      The dominant phenotypes were visible in the F2 generation, but not in the F1.

    • E. 

      Many of the F1 progeny died.

  • 11. 
    When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype?
    • A. 

      0%

    • B. 

      25%

    • C. 

      50%

    • D. 

      75%

    • E. 

      100%

  • 12. 
    Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that
    • A. 

      Traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1.

    • B. 

      The traits were lost in the F1 due to blending of the parental traits.

    • C. 

      Members of the F1 generation had only one allele for each character, but members of the F2 had two alleles for each character.

    • D. 

      New mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1.

    • E. 

      The mechanism controlling the appearance of traits was different between the F1 and the F2 plants.

  • 13. 
    Which of the following about the law of segregation is false?
    • A. 

      It is a method that can be used to determine the number of chromosomes in a plant.

    • B. 

      It states that each of two alleles for a given trait segregate into different gametes.

    • C. 

      It can account for the 3:1 ratio seen in the F2 generation of Mendel's crosses.

    • D. 

      It can be used to predict the likelihood of transmission of certain genetic diseases within families.

    • E. 

      It can be explained by the segregation of homologous chromosomes during meiosis.

  • 14. 
    The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment most probably indicates which of the following? 
    • A. 

      The diploid number of chromosomes in the pea plants was 7.

    • B. 

      None of the traits obeyed the law of segregation.

    • C. 

      All of the genes controlling the traits were located on the same chromosome.

    • D. 

      All of the genes controlling the traits behaved as if they were on different chromosomes.

    • E. 

      The formation of gametes in plants occurs by mitosis only.

  • 15. 
    Mendel was able to draw his ideas of segregation and independent assortment because of the influence of which of the following? 
    • A. 

      His experiments with the breeding of plants such as peas

    • B. 

      The understanding of particulate inheritance he learned from renowned scientists of his time

    • C. 

      His discussions of heredity with his colleagues at major universities

    • D. 

      His reading of the scientific literature current in the field

    • E. 

      His reading and discussion of Darwin's Origin of Species

  • 16. 
    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 of mitosis

    • B. 

      Prophase I of meiosis

    • C. 

      Anaphase I of meiosis

    • D. 

      Metaphase I of meiosis

    • E. 

      Prophase II of meiosis

  • 17. 
    Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?
    • A. 

      Alignment of tetrads at the equator

    • B. 

      Crossing over

    • C. 

      Synapsis of homologous chromosomes

    • D. 

      Separation of cells at telophase

    • E. 

      separation of homologs at anaphase

  • 18. 
    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 the cross BbTt × BBtt will have black fur and long tails?  
    • A. 

      1/2

    • B. 

      1/16

    • C. 

      3/16

    • D. 

      3/8

    • E. 

      9/16

  • 19. 
    In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? 
    • A. 

      1/6

    • B. 

      1/2

    • C. 

      1

    • D. 

      1/4

    • E. 

      0

  • 20. 
    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. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers?
    • A. 

      750

    • B. 

      65

    • C. 

      565

    • D. 

      190

    • E. 

      250

  • 21. 
    In a cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC?
    • A. 

      1/64

    • B. 

      1/4

    • C. 

      1/16

    • D. 

      1/8

    • E. 

      1/32

  • 22. 
    Given the parents AABBCc × AabbCc, assume simple dominance and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent?
    • A. 

      3/4

    • B. 

      1/4

    • C. 

      3/8

    • D. 

      1

    • E. 

      1/8

  • 23. 
    In snapdragons, heterozygotes for one of the genes have pink flowers, whereas homozygotes have red or white flowers. When plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers?
    • A. 

      0%

    • B. 

      100%

    • C. 

      50%

    • D. 

      75%

    • E. 

      25%

  • 24. 
    Tallness (T) in snapdragons is dominant to dwarfness (t), while red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. A dwarf, red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F1 individuals?
    • A. 

      TtRr–dwarf and pink

    • B. 

      TTRR–tall and red

    • C. 

      Ttrr–dwarf and white

    • D. 

      TtRr–tall and red

    • E. 

      TtRr–tall and pink

  • 25. 
    Skin color in a certain species of fish is inherited via a single gene with four different alleles. How many different types of gametes would be possible in this system?
    • A. 

      4

    • B. 

      16

    • C. 

      8

    • D. 

      2

    • E. 

      1

  • 26. 
    When a disease is said to have a multifactorial basis, it means that
    • A. 

      Both genetic and environmental factors contribute to the disease.

    • B. 

      It has many different symptoms.

    • C. 

      It is caused by a gene with a large number of alleles.

    • D. 

      It tends to skip a generation.

    • E. 

      It affects a large number of people.

  • 27. 
    People with sickle-cell trait
    • A. 

      Have increased resistance to malaria.

    • B. 

      Produce normal and abnormal hemoglobin.

    • C. 

      Are usually healthy.

    • D. 

      Are heterozygous for the sickle-cell allele.

    • E. 

      All of the above

  • 28. 
    An ideal procedure for foetal testing in humans would have which of the following features?
    • A. 

      A procedure that could test for the carrier status of the foetus

    • B. 

      Lowest risk procedure that would provide the most reliable information

    • C. 

      The procedure that can test for the greatest number of traits at once

    • D. 

      A procedure that provides a 3D image of the foetus

    • E. 

      The procedure that can be performed at the earliest time in the pregnancy

  • 29. 
    A scientist discovers a DNA-based test for the allele of a particular gene. This and only this allele, if homozygous, produces an effect that results in death at or about the time of birth. Of the following, which is the best use of this discovery?
    • A. 

      To follow the segregation of the allele during meiosis

    • B. 

      To introduce a normal allele into deficient newborns

    • C. 

      To design a test for identifying heterozygous carriers of the allele

    • D. 

      To test school-age children for the disorder

    • E. 

      To screen all newborns of an at-risk population

  • 30. 
    An obstetrician knows that one of her patients is a pregnant woman whose fetus is at risk for a serious disorder that is detectable biochemically in foetal cells. The obstetrician would most reasonably offer which of the following procedures to her patient?
    • A. 

      Amniocentesis

    • B. 

      Ultrasound imaging

    • C. 

      X-ray

    • D. 

      Foetoscopy

    • E. 

      CVS

  • 31. 
    The frequency of heterozygosity for the sickle cell anemia allele is unusually high, presumably because this reduces the frequency of malaria. Such a relationship is related to which of the following?
    • A. 

      The malarial parasite changing the allele

    • B. 

      Mendel's law of segregation

    • C. 

      Darwin's observations of competition

    • D. 

      Mendel's law of independent assortment

    • E. 

      Darwin's explanation of natural selection

  • 32. 
    Cystic fibrosis (CF) is a Mendelian disorder in the human population that is inherited as a recessive. Two normal parents have two children with CF. The probability of their next child being normal for this characteristic is which of the following?
    • A. 

      1/2

    • B. 

      1/4

    • C. 

      3/4

    • D. 

      0

    • E. 

      1/8

  • 33. 
    Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolise a particular amino acid. This amino acid is not otherwise produced by humans. Therefore the most efficient and effective treatment is which of the following?
    • A. 

      Feed them the substrate that can be metabolised into this amino acid.

    • B. 

      Transfuse the patients with blood from unaffected donors.

    • C. 

      Feed the patients the missing enzymes in a regular cycle, i.e., twice per week.

    • D. 

      Regulate the diet of the affected persons to severely limit the uptake of the amino acid.

  • 34. 
    Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which there is very early senility, and death, usually of coronary artery disease, at an average age of approximately 13. Patients, who look very old even as children, do not live to reproduce. Which of the following represents the most likely assumption?
    • A. 

      All cases must occur in relatives; therefore, there must be only one mutant allele.

    • B. 

      Each patient will have had at least one affected family member in a previous generation.

    • C. 

      Successive generations of a family will continue to have more and more cases over time.

    • D. 

      The disorder may be due to mutation in a single protein-coding gene.

    • E. 

      The disease is autosomal dominant.

  • 35. 
    A pedigree analysis for a given disorder's occurrence in a family shows that, although both parents of an affected child are normal, each of the parents has had affected relatives with the same condition. The disorder is then which of the following?
    • A. 

      Maternally inherited

    • B. 

      Cominant

    • C. 

      Incompletely dominant

    • D. 

      Recessive

    • E. 

      A new mutation

  • 36. 
    One of two major forms of a human condition called neurofibromatosis (NF 1) is inherited as a dominant, although it may be either mildly to very severely expressed. If a young child is the first in her family to be diagnosed, which of the following is the best explanation?
    • A. 

      The child has a different allele of the gene than the parents.

    • B. 

      The condition skipped a generation in the family.

    • C. 

      One of the parents has very mild expression of the gene.

    • D. 

      The mother carries the gene but does not express it at all.