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Probability and Genetics quiz #1

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  • How is probability used in predicting genetic inheritance?
    Probability helps geneticists predict the likelihood of specific genetic outcomes, such as the inheritance of certain alleles, phenotypes, or mutations, by applying mathematical laws like the product law, sum law, and binomial theorem.
  • What is the chance, expressed as a percentage, that Irene is a carrier for a genetic trait?
    The chance that Irene is a carrier depends on the specific genetic scenario, but if the probability is 1/2, then expressed as a percentage, it is 50%.
  • What is the probability that Mary and Justin will have a child affected by a genetic disorder?
    The probability depends on the inheritance pattern of the disorder and the parents' genotypes; for autosomal recessive disorders with both parents as carriers, the chance is typically 25%.
  • What is the chance, expressed as a percentage, that Irene is a carrier for a genetic trait?
    If the probability is 1/2, then Irene has a 50% chance of being a carrier.
  • What proportion of children will have either PKU or CF, but not both?
    The proportion is calculated by adding the probabilities of having PKU only and CF only, excluding those with both; this requires knowing the individual probabilities for each condition.
  • What is the percent probability that four out of seven children will have Huntington's disease?
    Use the binomial theorem: P = C(7,4) × (p)^4 × (1-p)^3, where p is the probability of inheriting Huntington's; if p = 0.5, then P = 35 × (0.5)^4 × (0.5)^3 = 35 × (0.5)^7 ≈ 27.34%.
  • A couple has two female children. What is the probability that their next child will be male?
    The probability is 1/2, or 50%, since each child's sex is an independent event.
  • What is the probability that a female child of Charles and Marie would suffer from hemophilia?
    For X-linked recessive hemophilia, a female must inherit two affected alleles; if both parents are carriers, the probability is typically 0.25 or 25%.
  • What is the probability that individual III-1 has the genotype ww?
    The probability depends on the parental genotypes and inheritance pattern; if both parents are heterozygous (Ww), the chance is 1/4 or 25%.
  • What is the frequency of cats that are homozygous dominant in the population?
    The frequency of homozygous dominant cats is p^2, where p is the frequency of the dominant allele.
  • What is the frequency of cats with short tails in the population?
    The frequency of cats with short tails depends on the genotype responsible; if short tails are dominant, the frequency is p^2 + 2pq, where p is the dominant allele frequency and q is the recessive.
  • What are the odds that a person will inherit the dominant gene for Alzheimer disease?
    If one parent is heterozygous and the other is homozygous recessive, the odds are 1/2 or 50%.
  • With four distinct nucleotides, how many combinations are possible in a sequence of six nucleotides?
    There are 4^6 = 4096 possible combinations.
  • What is the probability that the genotype aa will be produced by parents with genotypes aa x aa?
    The probability is 100%, since both parents can only pass on the 'a' allele.
  • What is the frequency of cats with long tails in the population?
    If long tails are recessive, the frequency is q^2, where q is the frequency of the recessive allele.
  • What is the frequency of the heterozygous genotype in this population of butterflies?
    The frequency of heterozygotes is 2pq, where p and q are the frequencies of the two alleles.
  • What is the expected frequency of the cc genotype?
    The expected frequency is q^2, where q is the frequency of the c allele.
  • In a population of wildflowers where the frequency of the red allele (Cr) is p = 0.7, what is the expected frequency of homozygous red individuals?
    The expected frequency is p^2 = 0.7^2 = 0.49, or 49%.
  • Find the probability that when a couple has a child, the child will be male.
    The probability is 1/2, or 50%, since sex determination is independent for each child.
  • What is a Punnett square used for in genetics?
    A Punnett square is used to predict the possible genetic outcomes of a cross between two individuals by showing the combinations of alleles that offspring can inherit.
  • What can a Punnett square help determine in genetic crosses?
    A Punnett square can help determine the probability of offspring inheriting specific genotypes and phenotypes based on the alleles contributed by each parent.
  • How does a Punnett square assist in understanding inheritance patterns?
    A Punnett square assists in understanding inheritance patterns by visually organizing the possible allele combinations from parental gametes, allowing calculation of the likelihood of each genotype and phenotype in the offspring.
  • What is the purpose of using a Punnett square in genetic studies?
    The purpose of using a Punnett square in genetic studies is to predict and analyze the probability of different genetic outcomes, such as the distribution of alleles and traits among offspring.
  • How is probability related to inheritance in genetics?
    Probability is related to inheritance in genetics because it allows geneticists to predict the likelihood of specific genetic outcomes, such as the appearance of certain phenotypes or alleles, using probability laws like the product law, sum law, and binomial theorem.