Genetics Chapter: Sex Determination and Traits
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Questions and Answers

What is the genotype of a typical female human?

  • XX (correct)
  • YY
  • XY
  • Xy
  • Which parent determines the sex of the offspring?

  • The mother only
  • The father only (correct)
  • Both parents equally
  • It is random
  • Which characteristic is true about X-linked traits?

  • They are more commonly expressed in females.
  • They can appear in both males and females. (correct)
  • Only males can be carriers.
  • They can only appear in females.
  • What happens to one of the X chromosomes in females?

    <p>It is inactivated.</p> Signup and view all the answers

    Which of the following describes a Y-linked trait?

    <p>It is never expressed in females.</p> Signup and view all the answers

    What genetic combination represents a male fruit fly?

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

    How many sex chromosomes do humans have in total?

    <p>23</p> Signup and view all the answers

    What is a characteristic of hemizygous genes?

    <p>There is one copy of each gene.</p> Signup and view all the answers

    Based on Charlie Chaplin's blood type (AB) and the mother's blood type (A), what are the possible blood types of their child?

    <p>AB and O</p> Signup and view all the answers

    What is the reason for immunizing Rh-negative mothers after their first pregnancy?

    <p>To prevent Rh incompatibility in subsequent pregnancies</p> Signup and view all the answers

    In mallard ducks, what is the dominant allele that determines plumage pattern?

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

    What genotypes could the offspring from a restricted (MR) and dusky (md) duck cross exhibit?

    <p>50% restricted, 50% mallard</p> Signup and view all the answers

    Which coat color is the most dominant in rabbits?

    <p>Full Color</p> Signup and view all the answers

    If a full color rabbit with the genotype Ccch is bred with a Himalayan rabbit with genotype chc, what types of offspring can be produced?

    <p>Full color, chinchilla, and Himalayan</p> Signup and view all the answers

    Why did the judge rule in favor of the mother regarding child support?

    <p>Based on the blood type evidence</p> Signup and view all the answers

    What is the expected phenotype ratio from a cross of a mallard and dusky duck?

    <p>100% mallard</p> Signup and view all the answers

    What phenotypic ratio is seen in the offspring of a cross between two tabby cats?

    <p>1 black : 2 tabbies : 1 tan</p> Signup and view all the answers

    Which of the following represents the genotype for a roan shorthorn cow?

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

    Which of the following statements about codominance is true?

    <p>Two alleles are expressed simultaneously without blending.</p> Signup and view all the answers

    What are the alleles responsible for blood types A and B?

    <p>IA and IB</p> Signup and view all the answers

    What would be the parental genotypes of two cats that produced 36 tabbies and 40 black cats?

    <p>One tabby and one black</p> Signup and view all the answers

    Which of the following exemplifies codominance?

    <p>A red and white cow producing a roan cow</p> Signup and view all the answers

    What does multiple alleles mean in the context of blood typing?

    <p>More than two alleles exist for a single gene.</p> Signup and view all the answers

    Which notation is used to denote the alleles for the coat color of a shorthorn cow?

    <p>C, R, W</p> Signup and view all the answers

    What phenotype is expected for a rabbit with the genotype c h cch?

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

    What would be the possible offspring colors if a white rabbit is mated with a chinchilla rabbit?

    <p>White and chinchilla</p> Signup and view all the answers

    Which of the following alleles is known as a lethal gene when present in homozygous condition?

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

    What is the expected phenotypic ratio from a cross between two yellow mice Yy x Yy when considering the lethal YY genotype?

    <p>2 yellow : 1 grey</p> Signup and view all the answers

    In the context of lethality, which of the following conditions describes Huntington's disease?

    <p>Dominant lethal</p> Signup and view all the answers

    If a chinchilla rabbit produces some white offspring, what can be inferred about the genotypes of the parents?

    <p>One parent is white, the other is chinchilla</p> Signup and view all the answers

    Which phenotype is not possible from a cross between a Himalayan rabbit and a white rabbit?

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

    Which of the following statements about allelic dominance is correct?

    <p>C is more dominant than cch</p> Signup and view all the answers

    What is true about sex-linked traits that are found on the X chromosome?

    <p>They are predominantly recessive traits.</p> Signup and view all the answers

    In the case of red-green colorblindness, which statement is correct?

    <p>Males have only one X chromosome, increasing their chance of colorblindness.</p> Signup and view all the answers

    What genetic pattern is displayed in the human pedigree for color-blindness?

    <p>X-linked recessive inheritance.</p> Signup and view all the answers

    What is the likely family genotype pattern for Serena, who has two normal daughters and one hemophiliac son?

    <p>Serena is heterozygous for hemophilia.</p> Signup and view all the answers

    What does congenital generalized hypertrichosis (CGH) signify?

    <p>A rare X-linked dominant trait.</p> Signup and view all the answers

    Which phenotype would be expected from a mating between a black female cat and an orange male cat?

    <p>Both male and female kittens may show tortoiseshell patterns.</p> Signup and view all the answers

    How is red-green colorblindness specifically identified in individuals?

    <p>With a visual test using an Ishihara chart.</p> Signup and view all the answers

    What genotype would be necessary for a female to be colorblind?

    <p>Homozygous recessive.</p> Signup and view all the answers

    Study Notes

    Genotype of Sexes

    • XX for females
    • XY for males

    Sex Determination

    • Humans have 46 chromosomes
    • 2 of these chromosomes determine sex
    • The father determines the sex of an offspring

    Sex-Linked Traits

    • The gene that determines a character is located on the sex chromosomes
    • X-linked trait: The gene for the trait is found on the X chromosome
    • Y-linked trait: The gene for the trait is found on the Y chromosome

    Eye Color in Fruit Flies

    • Eye color is a sex-linked trait
    • Red eyes are dominant to white eyes

    Codominance

    • Both alleles of a gene pair are expressed in the heterozygote
    • Phenotypes of both parents are combined in the offspring

    Codominance Notation

    • Choose a letter to represent the gene
    • Use different letters to represent each allele
    • Turn the letters into superscripts
    • Combine the two letters, using capital letters

    Codominance Examples

    • Shorthorn cows
    • Blue roosters
    • Human blood typing
    • Tabby cats

    Lethal Genes

    • Some genes are lethal when present in a homozygous condition
    • Achondroplasia, cystic fibrosis, and sickle cell anemia are examples of recessive lethal conditions
    • Huntington's disease is an example of a dominant lethal condition

    Creeper Allele in Chickens

    • An embryo with two copies of the creeper gene will not survive

    Manx Cat

    • Manx cats are heterozygous for a dominant lethal allele
    • The dominant lethal allele causes the cat to lack a tail
    • A cross between a manx cat and a normal cat will result in a 50% chance of the offspring being manx

    Mouse Coat Color

    • Yellow fur is dominant to grey fur
    • The genotype "YY" is a lethal gene, which causes a 2: 1 ratio of yellow to grey offspring

    Sex-Linked Traits

    • Genes are located on the sex chromosomes
    • The color vision gene is located on the X chromosome, not the Y chromosome
    • Sex-linked traits are usually recessive

    Red-Green Colorblindness

    • Recessive sex-linked trait
    • The gene is found on the X chromosome, not the Y chromosome
    • Males are more likely to have red-green colorblindness
    • Females must be homozygous recessive to have red-green colorblindness

    Calico Cats

    • Calico cats are female
    • Their fur color is determined by the random inactivation of one of their X chromosomes
    • They have a combination of black and orange fur

    Human X-Linked Traits

    • Hemophilia is a recessive sex-linked trait
    • The gene for hemophilia is located on the X chromosome
    • Females are carriers of hemophilia

    Writing Sex-Linked Genotypes

    • Use X to represent the X chromosome
    • Use Y to represent the Y chromosome
    • Use superscripts to represent the alleles
    • Write the X chromosome first, followed by the Y chromosome

    Hemophilia Genotypes

    • Normal female: XHXH
    • Carrier female: XHXh
    • Hemophiliac female: XhXh
    • Normal male: XHY
    • Hemophiliac male: XhY

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    Description

    Explore the foundational concepts of genetics, including sex determination, sex-linked traits, and codominance. This quiz covers essential topics such as eye color in fruit flies and lethal genes, providing an in-depth understanding of genetic inheritance patterns. Test your knowledge of how traits are inherited and expressed in various organisms.

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