PRE-AP BIOLOGY: GENETICS

PRACTICE QUESTIONS

  1. Which one of the following is false?
    A) The offspring of two different varieties are called hybrids.
    B) Hybridization is also called a cross.
    C) The parental plants of a cross are the P generation.
    D) The hybrid offspring of a cross are the P1 generation.
    E) The hybrid offspring of an F1 cross are the F2 generation.
  1. Varieties of plants in which self-fertilization produces offspring that are identical to the parents are referred to as
    A) hybrids.
    B) the F2 generation.
    C) monohybrid crosses.
    D) independent crosses.
    E) true-breeding.
  1. A monohybrid cross is
    A) the second generation of a self-fertilized plant.
    B) a breeding experiment in which the parental varieties have only one trait in common.
    C) a breeding experiment in which the parental varieties differ in only one trait.
    D) a triploid plant that results from breeding two very different plants.
    E) None of the choices are correct.
  1. Which one of the following is false?
    A) The genetic makeup of an organism constitutes its genotype.
    B) An organism with two different alleles for a single trait is said to be heterozygous.
    C) Alleles are alternate forms of a gene.
    D) An allele that is fully expressed is referred to as recessive.
    E) The expressed physical traits of an organism are called its phenotype.
  1. Mendel's law of independent assortment states that
    A) chromosomes sort independently of each other during mitosis and meiosis.
    B) genes sort independently of each other in animals but not in plants.
    C) independent sorting of genes produces polyploid plants under some circumstances.
    D) each pair of alleles segregates independently of the other pairs of alleles during gamete formation.
    E) None of the choices are correct.
  1. What is a testcross?
    A) a mating between an individual of unknown genotype and an individual homozygous recessive for the trait of interest
    B) a mating between an individual of unknown genotype and an individual heterozygous for the trait of interest
    C) a mating between an individual of unknown genotype and an individual homozygous dominant for the trait of interest
    D) a mating between two individuals heterozygous for the trait of interest
    E) None of the choices are correct.
  1. Assuming that the probability of having a female child is 50% and the probability of having a male child is also 50%, what is the probability that a couple's first-born child is female and second-born child is male?
    A) 25%
    B) 50%
    C) 75%
    D) 100%
    E) None of the choices are correct.
  1. A carrier of a genetic disorder who does not show symptoms is most likely to be ______to transmit it to offspring.
    A) heterozygous for the trait and able
    B) heterozygous for the trait and unable
    C) homozygous for the trait and able
    D) homozygous for the trait and unable
    E) None of the choices are correct.
  1. Many genetic disorders of humans are caused by
    A) multiple alleles.
    B) recessive alleles.
    C) drinking during pregnancy.
    D) a mutation that occurs in the egg, sperm, or zygote that gives rise to the affected individual.
    E) None of the choices are correct.
  1. The vast majority of people afflicted with recessive disorders are born to parents who were
    A) both affected by the disease.
    B) not affected at all by the disease.
    C) slightly affected by the disease, showing some but not all of the symptoms.
    D) subjected to some environmental toxin that caused the disease in their children.
    E) None of the choices are correct.
  1. Which one of the following is an example of incomplete dominance in humans?
    A) sickle-cell disease
    B) hypercholesterolemia
    C) skin color
    D) ABO blood groups
    E) None of the choices are correct.
  1. The expression of both alleles for a trait in a heterozygous individual illustrates
    A) incomplete dominance.
    B) codominance.
    C) pleiotropy.
    D) polygenic inheritance.
    E) blending inheritance.
  1. A person with AB blood illustrates the principle of
    A) incomplete dominance.
    B) codominance.
    C) pleiotropy.
    D) polygenic inheritance.
    E) blending inheritance
  1. Sickle-cell disease represents
    A) codominance and pleiotropy.
    B) codominance and blended inheritance.
    C) multiple alleles, pleiotropy, and blended inheritance.
    D) codominance and multiple alleles.
    E) multiple alleles and pleiotropy.
  1. Which of the following is essentially the converse of pleiotropy?
    A) incomplete dominance
    B) codominance
    C) multiple alleles
    D) polygenic inheritance
    E) blending inheritance
  1. Individual features of all organisms are the result of
    A) genetics.
    B) the environment.
    C) genetics and cytoplasmic determinants.
    D) the environment and individual needs.
    E) genetics and the environment.

Also review:

Monohybrid Punnett squares

Dihybride Punnett squares

Pedigrees

Phenotypic vs Genotypic ratios