L11 Numerical Abnormalities of Chromosomes
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Questions and Answers

What is the term used to describe a condition where the chromosome complement is an exact multiple of the haploid number (23)?

  • Structural abnormality
  • Polyploidy (correct)
  • Aneuploidy
  • Numerical abnormality

    • Which of the following conditions involves an abnormal number of chromosomes that is not an exact multiple of the haploid number (23)?

  • Down syndrome (correct)
  • Triploidy
  • Structural abnormality
  • Tetraploidy

    • Approximately what percentage of spontaneous abortions with a chromosomal abnormality involve triploidy?

  • 1%
  • 10%
  • 30%
  • 20% (correct)

    • Which of the following statements about triploids is true?

    <p>Few triploids survive to term, and those that do usually have a quick demise.</p> Signup and view all the answers

    What is the estimated incidence of autosomal aneuploidy in newborns?

    <p>0.2%</p> Signup and view all the answers

    Which of the following is NOT an example of a cytogenetic abnormality?

    <p>Cystic fibrosis</p> Signup and view all the answers

    What is the cause of Turner syndrome?

    <p>Nondisjunction of the X chromosome</p> Signup and view all the answers

    What genetic condition leads to male hypogonadism?

    <p>Klinefelter syndrome (47, XXY)</p> Signup and view all the answers

    What is the key factor determining male sex?

    <p>Single Y chromosome</p> Signup and view all the answers

    Which scenario is most likely to result in mental retardation?

    <p>Higher number of X chromosomes in males and females</p> Signup and view all the answers

    What is a common characteristic of sex chromosome disorders?

    <p>Subtle, chronic problems relating to sexual development and fertility</p> Signup and view all the answers

    How can Turner syndrome be diagnosed?

    <p>Absence of Barr bodies in buccal smear</p> Signup and view all the answers

    What is the main cause of aneuploidy shown in the image?

    <p>Failure of homologous chromosomes to separate during meiosis I</p> Signup and view all the answers

    What is the consequence of a gamete with an abnormal chromosome number fusing with a normal gamete?

    <p>A zygote with monosomy or trisomy</p> Signup and view all the answers

    Which of the following aneuploidies is generally lethal?

    <p>Monosomy of an autosomal chromosome</p> Signup and view all the answers

    Which of the following trisomies is the most common chromosomal disorder in humans?

    <p>Trisomy 21 (Down syndrome)</p> Signup and view all the answers

    What is a major risk factor for having a child with Down syndrome?

    <p>Advanced maternal age</p> Signup and view all the answers

    Which of the following statements about sex chromosome aneuploidies is true?

    <p>They are generally compatible with life</p> Signup and view all the answers

    What is the approximate incidence of Trisomy 18 (Edwards' Syndrome)?

    <p>1 in 8,000 live births</p> Signup and view all the answers

    Which of the following physical abnormalities is characteristic of Edwards' Syndrome?

    <p>Rocker-bottom feet</p> Signup and view all the answers

    What is the most common sex affected by Trisomy 18?

    <p>Females</p> Signup and view all the answers

    Which of the following is a characteristic feature of Patau's Syndrome (Trisomy 13)?

    <p>Cyclopia (single central eye)</p> Signup and view all the answers

    Which statement regarding sex chromosome abnormalities is correct?

    <p>Only one X chromosome is active due to lyonization</p> Signup and view all the answers

    What is the approximate survival rate for infants with Trisomy 18 (Edwards' Syndrome)?

    <p>Few survive beyond 1 year of age</p> Signup and view all the answers

    What is the primary characteristic of Klinefelter's syndrome?

    <p>Having 47 chromosomes (XXY) or 48 (XXXY)</p> Signup and view all the answers

    Which of the following is NOT a symptom of Klinefelter's syndrome?

    <p>Increased muscle mass</p> Signup and view all the answers

    What is the incidence of Klinefelter's syndrome?

    <p>1 in 500 males</p> Signup and view all the answers

    What is the primary characteristic of XXX syndrome (Superfemale)?

    <p>The presence of a third X chromosome in a female</p> Signup and view all the answers

    What is the primary characteristic of XYY syndrome?

    <p>The presence of an extra Y chromosome in a male</p> Signup and view all the answers

    What is the cause of Fragile X syndrome?

    <p>An unusually large number of repeat nucleotide triplets near the tip of the X chromosome</p> Signup and view all the answers

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