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Sex-Linked Genes quiz #1

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  • Who will have hemophilia: a male with one X chromosome carrying the hemophilia allele or a female with one X chromosome carrying the hemophilia allele?
    A male with one X chromosome carrying the hemophilia allele will have hemophilia, because males have only one X chromosome and cannot compensate with a normal allele.
  • What is a sex-limited trait?
    A sex-limited trait is a trait that is expressed only in one sex, even though both sexes may carry the genes for it. For example, size differences in orb weaver spiders.
  • What are the chances that a girl will inherit color blindness if her father can see color?
    If her father can see color, he does not carry the color blindness allele on his X chromosome, so the girl cannot inherit color blindness from him.
  • Which chromosome is most commonly affected by sex-linked traits?
    The X chromosome is most likely affected by a sex-linked trait, because it contains many more genes than the Y chromosome.
  • Why is a sex-linked recessive gene on the X chromosome more likely to be expressed in males?
    A sex-linked recessive gene on the X chromosome is more likely to be expressed in males, since they have only one X chromosome.
  • Which types of inheritance are observed in the ABO blood group system of humans?
    The ABO blood group system shows codominance and multiple alleles, but is not sex-linked.
  • What nitrogen base pairs with adenine?
    Thymine pairs with adenine in DNA.
  • Which nitrogen base bonds to cytosine?
    Guanine bonds to cytosine in DNA.
  • If Brian has a son who is color-blind, what does this indicate about Brian's genotype?
    Brian must carry the color blindness allele on his X chromosome and pass it to his son through the mother, since males inherit their X chromosome from their mother.
  • What is true about sex-linked traits regarding their chromosomal location and expression in males and females?
    Sex-linked traits are often found on the X chromosome and affect males and females differently due to their sex chromosome composition.
  • True or false? Most of the cells in a mushroom contain haploid nuclei.
    False. Most cells in a mushroom are dikaryotic (contain two haploid nuclei), not haploid.
  • Is a mutant trait X-linked if it appears more frequently in males than females?
    Yes, if a mutant trait appears more frequently in males, it is likely X-linked.
  • Which syndrome among Turner syndrome, Klinefelter syndrome, Down syndrome, and Sickle cell anemia is not caused by a chromosomal aberration?
    Sickle cell anemia is not caused by a chromosomal aberration, but by a gene mutation on chromosome 11.
  • Which symbol is used to label a male that expresses a sex-linked disorder on a pedigree?
    A filled square is used to label a male expressing a sex-linked disorder on a pedigree.
  • Which allele combination represents a female who is heterozygous for a sex-linked trait?
    A female who is heterozygous for a sex-linked trait has the allele combination X^A X^a (one normal and one mutant allele).
  • How are the alleles for sex-linked traits inherited?
    Alleles for sex-linked traits are inherited through the sex chromosomes, with males inheriting their X from their mother and Y from their father, and females inheriting one X from each parent.
  • Which macromolecule is involved in how hemophilia is passed from parents to their children?
    DNA is the macromolecule involved in passing hemophilia from parents to children.
  • Why aren't there any affected females in the F1 generation under these conditions?
    If the trait is X-linked recessive and the mother is not a carrier, females in the F1 generation will not be affected because they need two mutant alleles to express the trait.
  • In X-linked patterns of inheritance, how are traits passed from parents to offspring?
    In X-linked inheritance, males inherit their X chromosome from their mother and Y from their father, while females inherit one X from each parent.
  • Males are more often affected by X-linked traits than are females because ________.
    Males are more often affected by X-linked traits because they have only one X chromosome, so a single mutant allele will cause the trait.
  • X-linked recessive traits in humans (or in Drosophila) are observed most frequently in which sex?
    X-linked recessive traits are observed most frequently in males.
  • If it is a sex-linked pedigree and females are labeled 'XX', what should males be labeled?
    Males should be labeled 'XY' in a sex-linked pedigree.
  • Since the allele for colorblindness is located on the X chromosome, colorblindness is inherited in what manner?
    Colorblindness is inherited in an X-linked recessive manner.
  • A woman is red-green color-blind. What can we conclude, if anything, about her father?
    Her father must be red-green color-blind, since she must inherit the mutant X chromosome from both parents.
  • How do X-linked genes differ from Y-linked genes in terms of presence and number?
    X-linked genes are present in both sexes and affect many traits, while Y-linked genes are only present in males and are fewer in number.
  • If it is a sex-linked pedigree and females are labeled 'XX', what should males be labeled?
    Males should be labeled 'XY' in a sex-linked pedigree.
  • Which type of mutation occurs only in gametes?
    Germline mutations occur only in gametes.
  • The X-linked recessive vision disorder that affects about 8% of Caucasian males is called red-green color blindness.
    Red-green color blindness is an X-linked recessive vision disorder affecting about 8% of Caucasian males.
  • If it is a sex-linked pedigree and females are labeled 'XX', what should males be labeled?
    Males should be labeled 'XY' in a sex-linked pedigree.
  • Genes that travel on the X chromosome are called what?
    Genes that travel on the X chromosome are called X-linked genes.
  • Video tutor session quiz: What is the pattern of inheritance for sex-linked pedigrees?
    Sex-linked pedigrees show traits that are inherited through the X or Y chromosome, often with males more frequently affected by X-linked recessive traits.
  • Explain why it is unusual for Calix to be a male calico cat.
    It is unusual for Calix to be a male calico cat because calico coloring requires two X chromosomes, and males are typically XY; male calicos usually have an extra X chromosome (XXY).
  • Is Paris Jackson biologically related to Michael Jackson?
    Yes, sons inherit their X chromosome from their mother.
  • Traits that are carried on the X chromosome are said to be what?
    Traits carried on the X chromosome are said to be X-linked.
  • If a trait is X-linked recessive, who would express the trait?
    Males with the mutant allele and females with two mutant alleles would express the trait.
  • The Notch mutation is a deletion on the X chromosome. How would this affect males and females differently?
    Males would express the Notch mutation if they inherit the mutant X, while females would need two mutant X chromosomes to express the trait.
  • Females who have one abnormal copy of a mutated gene on the X chromosome are known as what?
    Females with one abnormal copy of a mutated gene on the X chromosome are known as carriers.
  • Five males with an X-linked trait: what does this suggest about the inheritance pattern?
    If five males express an X-linked trait, it suggests the trait is X-linked recessive and more likely to affect males.