Heredity -- Exam 4

28 Questions

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Heredity -- Exam 4

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Questions and Answers
  • 1. 
    Two alleles expressing exactly the same information for a trait are designated as _______________________.
    • A. 

      Heterozygous

    • B. 

      Monogamous

    • C. 

      Hemizygous

    • D. 

      Homozygous

  • 2. 
    Dominant alleles are so called because under most circumstances they _____________________________.
    • A. 

      Code for genes that are never considered lethal

    • B. 

      Suppress the expression of other alleles

    • C. 

      Code only for tallness and dark skin

    • D. 

      Code for most phenotypic and genotypic expressions of a trait

  • 3. 
    Recessive genes are usually expressed in humans only when ____________________________.
    • A. 

      Both alleles are exactly the same, or homozygous

    • B. 

      The organism is in the embryonic stage

    • C. 

      They are coding the skin color

    • D. 

      They are coding for genetic diseases

  • 4. 
    These characteristics that can be determined on superficial inspection of an individual are known as _____________________.
    • A. 

      Polygenic

    • B. 

      Phenotypic

    • C. 

      Genotypic

    • D. 

      Polyspermic

  • 5. 
    Is genetic diversity due entirely to inherited genes on the sex chromosomes?
    • A. 

      Yes, because genetic diversity is due to the Y influence on the autosomoes

    • B. 

      No, because genetic diversity have nothing to do with the sex chromosomes but is due to crossing-over of chromosomes, independent assortment of chromosomes, and segregation of chromosomes

    • C. 

      Yes, because the male has a Y chromosomes

    • D. 

      Yes, because the female has two X chromosomes and the male has only one X chromosome

  • 6. 
    A female infant is born with several hundred oocytes, each one genetically unique. This is due to _______________________________.
    • A. 

      Chromosome deletion

    • B. 

      Recessive inheritance

    • C. 

      Independent assortment and random crossover

    • D. 

      Mutation

  • 7. 
    In meiosis the spermatozoa that are produced are genetically unlike each other and unlike the cell that produces them. This is one reason for the great variation among humans. What causes this effect?
    • A. 

      Crossing-over and chromosome segregation only

    • B. 

      Crossing-over, chromosome segregation, and independent assortment

    • C. 

      Chromosome segregation and independent assortment only

    • D. 

      Crossing-over and independent assortment only

  • 8. 
    The reason recessive genetic disorders are more frequent than disorders inherited as dominant is that ________________________________.
    • A. 

      Recessive genetic disorders are limited to persons of the same ethnicity

    • B. 

      Carriers may pass them on to their offspring, unaware that they are carriers

    • C. 

      Dominant genetic disorders are never expressed in males

    • D. 

      People carrying dominant genetic disorders always die before birth

  • 9. 
    The gene responsible for the condition known as sickle-cell anemia demonstrates _________________________.
    • A. 

      A sex-linked genetic disorder

    • B. 

      A recessive genetic disorder

    • C. 

      Incomplete dominance

    • D. 

      A dominant genetic disorder

  • 10. 
    An example of multiple-allele inheritance is _____________________.
    • A. 

      The ABO blood group

    • B. 

      Hair that seems to have several shades of a color

    • C. 

      The appearance of freckles on the skin

    • D. 

      The appearance of birthmarks on the skin

  • 11. 
    Which of the following is true concerning environmental influence on genetic expression?
    • A. 

      Drugs and nutrition can alter normal gene expression

    • B. 

      Environmental factors determine the way in which 90 percent of our genes are expressed

    • C. 

      It is impossible to alter in any way the expression of a gene in humans

    • D. 

      The only time a gene can be influenced by environmental factors is in the second trimester of pregnancy

  • 12. 
    Sex chromosomes of a normal male are ____________________.
    • A. 

      YY

    • B. 

      XX

    • C. 

      XY

    • D. 

      Any of these, depending on the father

  • 13. 
    A woman has blond hair and brown eyes. This statement is best described as indicating _______________________.
    • A. 

      Recessive traits

    • B. 

      Phenotype

    • C. 

      Genotype

    • D. 

      Allelic pairs

  • 14. 
    A chromosomal aberration in which part of a chromosome is lost is known as ____________________________.
    • A. 

      Translocation

    • B. 

      Crossing-over

    • C. 

      Inversion

    • D. 

      Deletion

  • 15. 
    Inheritance of stature (height) in humans is probably due to ____________________.
    • A. 

      Incomplete dominance

    • B. 

      Polygene inheritance

    • C. 

      Polymorphism

    • D. 

      Polyploidy

  • 16. 
    An individual who is heterozygous for a particular trait, yet expresses both alleles of that trait, is an example of ______________________.
    • A. 

      Dominance

    • B. 

      Recessive inheritance

    • C. 

      Incomplete dominance

    • D. 

      Sex-linked inheritance

  • 17. 
    Given the information in Figure 29.1, what would be the genotype of the offspring designated by the blank square?
    • A. 

      Gg

    • B. 

      Dg

    • C. 

      Gg

    • D. 

      GG

  • 18. 
    Given the information in Figure 29.1, what would the genotype ratio be for the offspring?
    • A. 

      1:2:1

    • B. 

      1:1:1:1

    • C. 

      1:3

    • D. 

      4:0

  • 19. 
    Given the information in Figure 29.1, what is the phenotype ratio (assuming C is dominant and there is no incomplete dominance)?
    • A. 

      1:3

    • B. 

      1:2:1

    • C. 

      1:1:1:1

    • D. 

      4:0

  • 20. 
    Given the information in Figure 29.1, if C were an incomplete dominant trait, what would be the phenotype ratio be for the offspring?
    • A. 

      1:3

    • B. 

      1:2:1

    • C. 

      1:1:1:1

    • D. 

      4:0

  • 21. 
    __________________________ is the most common type of fetal testing.
    • A. 

      CVS

    • B. 

      Blood chemistry

    • C. 

      Amniocentesis

    • D. 

      A DNA probe

  • 22. 
    Huntington's disease involves ____________________________.
    • A. 

      The presence of an extra chromosome

    • B. 

      Hypo secretion of thyroxine

    • C. 

      Hyper secretion of growth hormone

    • D. 

      Degeneration of the basal nuclei of the brain

  • 23. 
    Which of the following statements is true concerning genetic screening?
    • A. 

      Screening is illegal in over half of the world

    • B. 

      Genetic screening is rarely done because it yields very little accurate information

    • C. 

      Screening can be done before conception by carrier recognition or during fetal testing

    • D. 

      Screening can be done only in the first trimester of pregnancy

  • 24. 
    Amy's hand was exposed to X rays. A gene in a skin cell of her hand mutated. This mutant gene will _____________________.
    • A. 

      Replicate itself when the cell divides but will not be passed on to Amy's offspring

    • B. 

      Replicate itself and be passed on to Amy's children

    • C. 

      Definitely cause skin cancer

    • D. 

      Not form an exact duplicate of itself when the cell divides

  • 25. 
    The main way a recessive allele would be expressed even when only one copy is present would be _________________________.
    • A. 

      Recessive inheritance

    • B. 

      Dominance

    • C. 

      Incomplete dominance

    • D. 

      Sex-linked inheritance

  • 26. 
    A couple whose blood types are A and B may have a child with which of the following blood types?
    • A. 

      AB or O only

    • B. 

      A or B only

    • C. 

      AB only

    • D. 

      A, B, AB, or O

  • 27. 
    Gene mutations in the sex chromosomes of the human would tend to become visibly expressed ___________________________
    • A. 

      Equally frequently in both sexes

    • B. 

      More frequently in females

    • C. 

      More frequently in males

    • D. 

      In neither males or females

  • 28. 
    For which of the following are newborn infants not routinely screened at birth?
    • A. 

      Color blindness

    • B. 

      Imperforate anus

    • C. 

      PKU

    • D. 

      Congenital hip dysplasia