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Genetics Practice Test

  1. Define these words: alleles, chromosome, dominant trait, F1 generation, F2 generation, gamete, genome, genotype, heterozygous, homozygous, hybrid, parent generation, phenotype, recessive trait, somatic cell, trait, pure-bred, incomplete dominance, codominance, multiple alleles, epistasis, pleiotropy.
  2. Give an example using "lettered alleles", i.e. Tt, of these genotypes: homozygous dominant, homozygous recessive and heterozygous.
  3. How do you get a line of purebred plants?
  4. Describe Mendel's three laws.
  5. Describe three hypothetical plant breeding experiments as examples of Mendel's laws.
  6. Use lettered alleles or Punnett squares to illustrate the above experiments.
  7. What are the phenotypic and genotypic ratios for a single trait cross of heterozygous individuals?
  8. What are the phenotypic ratios for a dihybrid cross of heterozygous individuals?
  9. Type AB blood is an example of which Mendelian genetics variation?
  10. In humans, brown eyes are usually dominant over blue eyes. If a blue-eyed man marries a brown-eyed woman, what proportion of their children would you predict will have blue eyes?
  11. In short horn cattle, a red bull (CR) is crossed with a white cow (CW). The offspring are roan, intermingled red and white hairs. What do we call this variation of Mendelian genetics?
  12. Tall tomato plants are produced by the action of a dominant allele (T) and dwarf plants by its recessive allele (t). Hairy stems are produced by a dominant allele (H) and hairless stems by its recessive allele (h). A TtHh plant is crossed with a TThh tomato plant. Describe the phenotypic ratio in this dihybrid cross.
  13. Describe the genotypic ratio in this dihybrid cross.
  14. What are the chances of the above cross producing tall, hair-less plants?