Mastering 10 – Flashcards
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The condition that exists when an organism gains or loses one or more chromosomes but not a complete haploid set is known as
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aneuploidy
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True or false? Nondisjunction is viewed as a major case of aneuploidy.
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True
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The incidence of Down syndrome, also known as trisomy 21, increases with increasing maternal age. Which of the following errors most likely produces this condition?
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Nondisjunction during either meiosis I or II in female gamete
Nondisjunction during either meiosis I or II can produce a gamete that will result in a trisomic zygote. Since the incidence of Down syndrome increases with maternal age, it is likely that this error occurs in the female gamete.
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True or False? Females with only one X chromosome do not develop. This condition is lethal
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False
Females with only one X chromosome are viable but have Turner syndrome, which is characterized by underdeveloped ovaries. Males that lack an X chromosome do not develop; this condition is lethal.
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Which of the following statements about the products produced when nondisjunction occurs during meiosis I is true?
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2 products of the second meiotic division have both the maternal and paternal chromosomes of a set and the other 2 products have none for that set
Nondisjunction during meiosis I yields two gametes that are missing a particular chromosome after meiosis II.
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Which of the following accurately describes a possible meiotic nondisjunction event?
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Homologs fail to separate during meiosis I
Ordinarily, homologs separate during meiosis I. Failure of this separation is one of the ways which nondisjunction occurs
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Events during normal meisois
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Homologs separate during meiosis I
One diploid cell produces 4 haploid cells
Sister chromatids separate from each other during meiosis II
NOT: 2 haploid gametes fuse to form a diploid cell
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True or False? In order to create the possibility of generating trisomy, nondisjunction must occur during meiosis II?
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False
Nondisjunction during either meiosis I or meiosis II creates gametes that will generate trisomies if fertilized.
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True or false? Assume that a species has a diploid chromosome number of 24. The term applied to an individual with 25 chromosomes would be triploid.
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False.
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Nondisjunction true statements
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It occurs more frequently in human females over the age of 35
It may fail to separate maternal from paternal chromosomes
It may fail to separate maternal chromatids from one another and paternal chromatids from one another
