Chapter 14 Sapling – Flashcards
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Which of the following describes the mechanism by which new alleles are formed?
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Mutations can occur within existing genes, which brings about new allele variations
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Which statements describes recessive alleles?
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Any allele whose presence can be masked by another allele
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What is the offspring of a genetic cross between two true-breeding organisms with different genotypes called?
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hybrid
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How did Mendel use self-pollination and cross-pollination techniques in his experiments with flower color to observe the basic patterns of inheritance?
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By cross-pollinating a parental generation of plants with different colored flowers and allowing the F1 generation to self-pollinate, Mendel observed the basic patterns of inheritance in the F2 generation.
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How is a true breeding yellow-seeded pea plant different from a hybrid yellow-seeded pea plant?
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They have the same phenotype but different genotypes
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Which of the following can be concluded from Gregor Mendel's experiments with pea plants?
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a heterozygous phenotype is the same as a homozygous dominant phenotype
alleles of different genes are inherited independently of each other
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In meiosis, a diploid cell divides into reproductive cells called gametes. The provided diagram shows chromosome separation during gamete production. Using this diagram, select the statements that are true about Mendel's Law of Segregation.
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Each gamete carries one version of each gene
Each parent provides one copy of each chromosome
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Mendel formulated the Law of Independent Assortment to explain the basic rules of inheritance based on his experiments with pea plants. With the modern understanding of chromosomes, alleles, and the process of gamete formation, what is the physical basis for the Law of Independent Assortment?
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Alleles on non homologous chromosomes separate randomly into gametes during meiosis
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In humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation (A) is dominant over albinism (a). For this question, assume it is a single gene with two alleles. If two people have normal pigmentation, what possible phenotypes may be observed in their offspring?
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Normal pigmentation or albinism
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In humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation (A) is dominant over albino characteristics (a). For this question, assume it is a single gene with two alleles. If both parents display the albino phenotype, what are all of the possible genotypes that may be observed in their offspring?
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aa only
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In pea plants, the genes for plant height and flower color are located on different chromosomes and assort independently of one another. According to the law of independent assortment, what are all the possible phenotypes for offspring of a self-pollinated pea plant with a genotype of TtPp? Consider that T=tall, t=short, P=purple flowers, and p=white flowers.
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tall with purple flowers, tall with white flowers, short with purple flowers, short with white flowers
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In fruit flies, gray bodies (G) are dominant over black bodies (g), and brown pigments (N) are dominant over yellow pigments (n). Each individual possesses two alleles for each trait. If a fly that is homozygous dominant for both traits is crossed with a fly that is homozygous recessive for both traits, what is the predicted genotype of the offspring?
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GgNn
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In a hypothetical mouse species, brown fur (B) is completely dominant to white fur (b), and long fur (L) is completely dominant to short fur (l). If two mice heterozygous for both traits mate and produce a litter of pups, what is the probability that an individual pup will have white, short fur?
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1/16
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Which of the following ideas was developed to explain the physical basis of Mendel's finding that hereditary factors undergo segregation and independent assortment?
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The chromosomal theory of inheritance
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Why are linked genes often inherited together?
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Linked genes are close together on the same chromosome
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What determines an individuals sex in humans?
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Females have two of the same sex chromosomes, whereas males have two different sex chromosomes
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True statements about incomplete dominance
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Heterozygous individuals have a phenotype intermediate to the homozygous dominant and homozygous recessive phenotypes.
If homozygous dominant plants have red flowers, and homozygous recessive plants have white flowers, then heterozygous plants have pink flowers.
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In a species of flowers, having long thorns (TT) is incompletely dominant over not having thorns (TN ). What is the genotype of a flower of this species that has long thorns?
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T^t T^t
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Which of the following statements accurately describes both pleiotropy and polygenic inheritance?
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Polygenic inheritance refers to the cumulative effect of two or more genes on a single trait. Pleiotropy refers to a single gene that affects multiple traits.
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Examples of pleitropy
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A defect in a single gene causes a disease in which affected individuals have longer limbs and vision problems.
A single gene determines the size and color of a plant's flowers.
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Ways the environment can affect a genetic trait
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The environment can limit the available resources required by an organism for essential biochemical processes.
Decreased exposure to certain environmental factors can decrease the risk of developing a specific disease.
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What is the defining characteristic of quantitative traits?
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They vary along a continuum
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Describe a gene
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A section of DNA which codes for a protein or RNA product
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Describe an allele
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One variation of the code for a protein or RNA product
