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14 Cards in this Set
- Front
- Back
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Why did the improvement of microscopy techniques in the late 1800s set the stage for the emergence of modern genetics?
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It allowed the study of meiosis and mitosis, revealing parallels between behaviors of genes and chromosomes.
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Males are more often affected by sex-linked traits than females because
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males are hemizygous for the X chromosome.
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Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having
cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes |
100%
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Calico cats are female because
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a male inherits only one of the two X-linked genes controlling hair color.
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A Barr body is normally found in the nucleus of which kind of human cell?
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Somatic cells of a female only
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Sex determination in mammals is due to the SRY region of the Y chromosome. An abnormality could allow which of the following to have a male phenotype?
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Translocation of SRY to an autosome of a 46, XX individual
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How would one explain a testcross involving F1dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced
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The two genes are linked.
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What does a frequency of recombination of 50% indicate?
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The two genes are likely to be located on different chromosomes
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What is the reason that linked genes are inherited together
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They are located close together on the same chromosome.
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If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?
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1/4 of the gametes will ben+ 1, one will ben-1, and two will be n.
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One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?
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Translocation
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In humans, male-pattern baldness is controlled by an autosomal gene that occurs in two allelic forms. AlleleHndetermines nonbaldness, and alleleHbdetermines pattern baldness. In males, because of the presence of testosterone, alleleHbis dominant overHn. If a man and woman both with genotype HnHb have a son, what is the chance that he will eventually be bald
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75%
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What is the source of the extra chromosome 21 in an individual with Down syndrome
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Nondisjunction or translocation in either parent
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At which phase(s) is it preferable to obtain chromosomes to prepare a karyotype?
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Late prophase or metaphase
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