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8.E: Patterns of Inheritance (Exercises)

  • Page ID
    8086
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    8.1: Mendel’s Experiments

    Multiple Choice

    Imagine that you are performing a cross involving seed color in garden pea plants. What traits would you expect to observe in the F1 offspring if you cross true-breeding parents with green seeds and yellow seeds? Yellow seed color is dominant over green.

    A. only yellow-green seeds
    B. only yellow seeds
    C. 1:1 yellow seeds:green seeds
    D. 1:3 green seeds:yellow seeds

    Answer

    B

    Imagine that you are performing a cross involving seed texture in garden pea plants. You cross true-breeding round and wrinkled parents to obtain F1 offspring. Which of the following experimental results in terms of numbers of plants are closest to what you expect in the F2 progeny?

    A. 810 round seeds
    B. 810 wrinkled seeds
    C. 405:395 round seeds:wrinkled seeds
    D. 610:190 round seeds:wrinkled seeds

    Answer

    D

    Free Response

    Describe one of the reasons that made the garden pea an excellent choice of model system for studying inheritance.

    Answer

    The garden pea has flowers that close tightly during self-pollination. This helps to prevent accidental or unintentional fertilizations that could have diminished the accuracy of Mendel’s data.

    8.2: Laws of Inheritance

    Multiple Choice

    The observable traits expressed by an organism are described as its ________.

    A. phenotype
    B. genotype
    C. alleles
    D. zygote

    Answer

    A

    A recessive trait will be observed in individuals that are ________ for that trait.

    A. heterozygous
    B. homozygous or heterozygous
    C. homozygousdiploid

    Answer

    C

    What are the types of gametes that can be produced by an individual with the genotype AaBb?

    A. Aa, Bb
    B. AA, aa, BB, bb
    C. AB, Ab, aB, ab
    D. AB, ab

    Answer

    C

    What is the reason for doing a test cross?

    A. to identify heterozygous individuals with the dominant phenotype
    B. to determine which allele is dominant and which is recessive
    C. to identify homozygous recessive individuals in the F2
    D. to determine if two genes assort independently

    Answer

    A

    Free Response

    Use a Punnett square to predict the offspring in a cross between a dwarf pea plant (homozygous recessive) and a tall pea plant (heterozygous). What is the phenotypic ratio of the offspring?

    Answer

    The Punnett square would be 2 × 2 and will have T and T along the top and T and t along the left side. Clockwise from the top left, the genotypes listed within the boxes will be Tt, Tt, tt, and tt. The phenotypic ratio will be 1 tall:1 dwarf.

    Use a Punnett square to predict the offspring in a cross between a tall pea plant (heterozygous) and a tall pea plant (heterozygous). What is the genotypic ratio of the offspring?

    Answer

    The Punnett square will be 2 × 2 and will have T and t along the top and T and t along the left side. Clockwise from the top left, the genotypes listed within the boxes will be TT, Tt, Tt, and tt. The genotypic ratio will be 1TT:2Tt:1tt.

    8.3: Extensions of the Laws of Inheritance

    Multiple Choice

    If black and white true-breeding mice are mated and the result is all gray offspring, what inheritance pattern would this be indicative of?

    A. dominance
    B. codominance
    C. multiple alleles
    D. incomplete dominance

    Answer

    D

    The ABO blood groups in humans are expressed as the IA, IB, and i alleles. The IA allele encodes the A blood group antigen, IB encodes B, and i encodes O. Both A and B are dominant to O. If a heterozygous blood type A parent (IAi) and a heterozygous blood type B parent (IBi) mate, one quarter of their offspring are expected to have the AB blood type (IAIB) in which both antigens are expressed equally. Therefore, ABO blood groups are an example of:

    A. multiple alleles and incomplete dominance
    B. codominance and incomplete dominance
    C. incomplete dominance only
    D. multiple alleles and codominance

    Answer

    D

    In a cross between a homozygous red-eyed female fruit fly and a white-eyed male fruit fly, what is the expected outcome?

    A. all white-eyed male offspring
    B. all white-eyed female offspring
    C. all red-eyed offspring
    D. half white-eyed make offspring

    Answer

    C

    When a population has a gene with four alleles circulating, how many possible genotypes are there?

    A. 3
    B. 6
    C. 10
    D. 16

    Answer

    C

    Free Response

    Can a male be a carrier of red-green color blindness?

    Answer

    No, males can only express color blindness and cannot carry it because an individual needs two X chromosomes to be a carrier.

    Could an individual with blood type O (genotype ii) be a legitimate child of parents in which one parent had blood type A and the other parent had blood type B?

    Answer

    Yes this child could have come from these parents. The child would have inherited an i allele from each parent and for this to happen the type A parent had to have genotype IAi and the type b parent had to have genotype IBi.


    This page titled 8.E: Patterns of Inheritance (Exercises) is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by OpenStax.

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