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Ch. 9 Bio Test

30 Questions
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Questions and Answers
  • 1. 
    How did Mendel's studies in genetics differ from earlier studies of breeding and inheritance?
    • A. 

      Mendel worked with plants; earlier studies used animals

    • B. 

      Mendel was able to explain the blending hypothesis

    • C. 

      Mendel's work was more quantitive

    • D. 

      Mendel worked with wild species, not domesticated ones

    • E. 

      Mendel found that offspring inherit characteristics from both parents

  • 2. 
    A true breeding fruit fly would be ___ for a certain characteristic.
    • A. 

      Homozygous dominant

    • B. 

      Homozygous recessive

    • C. 

      Heterozygous recessive

    • D. 

      Heterozygous

    • E. 

      A or b

  • 3. 
    When looking at the inheritance of a single characteristic, Mendel found that a cross between two- true breeding peas (between purple and white, for example) always yielded a ___ in the F2 generation.
    • A. 

      1:1 phenotypic ratio

    • B. 

      3:1 genpotypic ratio

    • C. 

      1:2:1 phenotypic ratio

    • D. 

      3:1 phenotypic ratio

    • E. 

      1:1 genotypic ratio

  • 4. 
    Alternative forms of genes for a particular characteristic are called
    • A. 

      Homologous chromosomes

    • B. 

      Alleles

    • C. 

      Linked genes

    • D. 

      Genotypes

    • E. 

      Phenotypes

  • 5. 
    A fruit fly has two genes for eye color, but each of its sperm cells has one. This illustrates
    • A. 

      Independent assortment

    • B. 

      Linked genes

    • C. 

      Pleiotropy

    • D. 

      Polygenic inheritence

    • E. 

      Segregation

  • 6. 
    Mendel made some crosses where he looked at two characterisitcs at onece- round yellow peas crossed with wrinkled green peas, for example. He did this because he wanted to find out
    • A. 

      How new characteristics originated

    • B. 

      Whether different characteristics were inherited together or separately

    • C. 

      How plants and animals adapt to their environments

    • D. 

      Whether the characteristics influence each other--whether color affects degree of roundness, for example.

    • E. 

      Actually, Mendel never had a clear purpose in mind

  • 7. 
    A pea plant with purple flowers is heterozygous for flower color. Its genotype is Pp. The P and p alleles in the pea plant's cells are located
    • A. 

      Next to each other on the same chromosome

    • B. 

      At corresponding locations on homologous chromosomes

    • C. 

      On the X and Y chromosomes

    • D. 

      Some distance apart on the same chromosome

    • E. 

      At different locations on homologous chromosomes

  • 8. 
    When an indididual has both Ia and Ib blood group alleles, both genes are expressed and the individual has group AB blood. This is an example of 
    • A. 

      Codominance

    • B. 

      A dihybrid

    • C. 

      Pleiotropy

    • D. 

      Incomplete dominance

    • E. 

      Linked genes

  • 9. 
    How many genes are there on one chromosome?
    • A. 

      One

    • B. 

      Two

    • C. 

      Hundreds

    • D. 

      Thousands

    • E. 

      Millions

  • 10. 
    Which of the following is not true of linked genes?
    • A. 

      They tend to be inherited together

    • B. 

      They tend to violate Mendel's principle of independent assortment

    • C. 

      They are on the same chromosome

    • D. 

      They can form new combinations via crossing over

    • E. 

      They are relatively rare; most genes are unlinked.

  • 11. 
    Morgan and his students were able to map the relative positions of genes on fruit-fly chomosomes by
    • A. 

      Coloring chromosomes with dyes and observing them under a microscope

    • B. 

      Scrambling the chromosomes and observing how the flies changed

    • C. 

      Crossing various flies and looking at the proportions of offspring

    • D. 

      Transplanting chromosomes from one fly to another

    • E. 

      Looking at crosses that showed independent assortment

  • 12. 
    Most sex-linked traits in humans are carried on the __ chromosome, and the recessive phenotypes are seen most often in 
    • A. 

      X...women

    • B. 

      X...men

    • C. 

      Y....women

    • D. 

      Y...men

  • 13. 
    The most lethal genetic disease in the USA is 
    • A. 

      Sickle-cell disease

    • B. 

      Cystic fibrosis

    • C. 

      Huntington's disease

    • D. 

      Hemophilia

    • E. 

      PKU

  • 14. 
    Which of the following human genetic disorders is sex-linked?
    • A. 

      Hemophilia

    • B. 

      PKU

    • C. 

      Cystic fibrosis

    • D. 

      Sickle-cell disease

    • E. 

      All of the above

  • 15. 
    A brown mouse is mated with a white mouse. All of their offspring are brown. If two of these brown offspring are mated, which fraction of these offspring will be white?
    • A. 

      All

    • B. 

      None

    • C. 

      1/4

    • D. 

      1/2

    • E. 

      3/4

  • 16. 
    Suppose you wanted to know the genotype of one of the brown F2 mice in the previous question. The easiest way to do it would be to
    • A. 

      Keep careful records of the parent mice

    • B. 

      Mate it with a brown mouse

    • C. 

      Mate it with a mouse of its own genotype

    • D. 

      Mate it with a white mouse

    • E. 

      It can't be done

  • 17. 
    Some dogs bark while trailing; others are slient. The barker gene is dominant, the silent gene recessive. The gene for normal tail is dominant over the gene for screw (curly) tail. A barker dog with a normal tail who is heterozygous for both characteristics is mated to another dog of the same genotype. Which fraction of their offspring will be barkers with screw tails?
    • A. 

      3/4

    • B. 

      9/16

    • C. 

      3/16

    • D. 

      1/4

    • E. 

      1/16

  • 18. 
    Two heterozygous tall pea plants with purple flowers are crossed. The probability that one of their offspring will have white flowers is 1/4. The probability that one of their offspring will be short is 1/4. What is the probability that one of their offspring will be short with white flowers?
    • A. 

      0

    • B. 

      1/16

    • C. 

      1/8

    • D. 

      1/4

    • E. 

      1/2

  • 19. 
    A young unmarried woman had a baby and wished to collect child support from the father. Her blood group is AB. The baby's blood group is A. There are two possible fathers: Jim is group A, and Michael is group O. Which man could be the father?
    • A. 

      Either

    • B. 

      Jim

    • C. 

      Michael

    • D. 

      Neither

    • E. 

      Impossible to tell given this evidence

  • 20. 
    Which of the following illustrates pleiotropy?
    • A. 

      In fruit flies, the genes for scarlet eyes and hairy body are located on the same chromosome.

    • B. 

      Matings between earless sheep and long-eared sheep always result in short-eared offspring.

    • C. 

      Wheat kernels can range from white to red in color, a trait controlled by several genes.

    • D. 

      The human cystic fibrosis gene causes many symptoms, from respiratory distress to digestive problems.

    • E. 

      An individual with both IA and IB alleles has blood group AB.

  • 21. 
    When two gray-bodied fruit flies are mated, their offspring total 86 gray-bodied males, 81 yellow-bodied males, and 165 gray-bodied females. The allele for yellow body is
    • A. 

      Sex-linked and dominant.

    • B. 

      Not sex-linked and dominant.

    • C. 

      Sex-linked and recessive.

    • D. 

      Not sex-linked and recessive.

    • E. 

      Impossible to say on the basis of this information.

  • 22. 
    Red-green color blindness is a human recessive sex-linked trait. A man and a woman with normal vision have a color-blind son. What is the probability that their next child will also be a color-blind son?
    • A. 

      0

    • B. 

      1/8

    • C. 

      1/4

    • D. 

      1/2

    • E. 

      3/4

  • 23. 
    On a pedigree tracking the inheritance of PKU, a horizontal line joins a black square and a hlaf black circle. What fraction of this couple's children would you expect to suffer from PKU?
    • A. 

      None

    • B. 

      1/4

    • C. 

      1/2

    • D. 

      3/4

    • E. 

      All

  • 24. 
    Duchenne muscular dystrophy (DMD) is caused by a sex-linked recessive. Its victims are invariably boys, who usually die before the age of 20. Why is this disorder almost never seen in girls?
    • A. 

      Sex-linked traits are never seen in girls

    • B. 

      The allele is carried on the Y chromosome.

    • C. 

      Nondisjunction occurs in males but not in females.

    • D. 

      Males carrying the alleles don't live long enough to be fathers.

    • E. 

      A sex-linked allele cannot be passed from mother to daughter.

  • 25. 
    Which of the following would be most useful for preventing a particular genetic disease?
    • A. 

      Knowing how the allele causes phenotypic effects

    • B. 

      Being able to identify carriers

    • C. 

      A test that can determine whether a fetus suffers from a disorder

    • D. 

      Knowing which chromosome bears the allele that causes the disorder

    • E. 

      Tracing the trait back through parents and grandparents

  • 26. 
    Edward was found to be heterozygous (Ss) for sickle-cell trait. The alleles represented by S and s are
    • A. 

      On the X and Y chromosomes

    • B. 

      Linked

    • C. 

      On homologous chromosomes

    • D. 

      Both present in each of Edward's sperm cells

    • E. 

      On the same chromosome but far apart

  • 27. 
    Whether an allele is dominant or recessive depends on
    • A. 

      How common the allele is, relative to other alleles

    • B. 

      Whether it is inherited from the mother or the father

    • C. 

      Which chromosome it is on

    • D. 

      Whether it or another allele determines the phenotype when both are present

    • E. 

      Whether or not it is linked to other genes

  • 28. 
    Two fruit flies with eyes of the usual red color are crossed, and their offspring are as follows: 77 red-eyed males, 71 ruby-eyed females, 152 red-eyed females. The allele for ruby color is 
    • A. 

      Autosomal and dominant

    • B. 

      Autosomal and recessive

    • C. 

      Sex-linked and dominant

    • D. 

      Sex-linked and recessive

    • E. 

      Impossible to determine without further information

  • 29. 
    In some of his experiments, Mendel studied the inheritance patterns of two characteristics at once-folower color and pod color, for example. He did this to find out
    • A. 

      Whether genes for the two characteristics are inherited together or separately

    • B. 

      How many genes are responsible for determining a characteristic

    • C. 

      Whether genes are on chromosomes

    • D. 

      The distance between genes on a chromosome

    • E. 

      How many different genes a pea plant has

  • 30. 
    A man who has B blood type and a woman who has A blood type could have children of which of the following phenotypes?
    • A. 

      A or B only

    • B. 

      AB only

    • C. 

      AB or O

    • D. 

      A, B, or O

    • E. 

      A, B, AB, or O