Download GENETIC TEST REVIEW SHEET… Be able to use basic genetic

GENETIC TEST REVIEW SHEET…
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Be able to use basic genetic terms (differentiate between genotype and phenotype, know the
difference between homozygous and heterozygous)
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Work out monohybrid & dihybrid crosses forward & backwards, determining phenotype and
genotypes.
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Determine gender (XX and XY)
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Distinguish between sex-determined links and autosomnal traits.
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What is meiosis, where does it occur and what is the end result?
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Know other patterns of inheritance: Incomplete inheritance, codominance, multiple alleles,
polygenetic traits, environmental influences, F1, F2 and basic meiosis
Sample problems:
1. A plant that is homozygous for red fruit is crossed with a plant homozygous for yellow fruit. All red fruits are
produced. If these red fruit offspring are crossed with each other, what is the probability of offspring producing
red fruit?
2. In a plant species, the trait for bright yellow flower color is dominant over the trait for white flower color. Two
plants with bright yellow flowers are crossed, and some offspring have white flowers. Two of those white
offspring are then crossed. What color would you expect to see in the offspring of this second cross?
3. In Drosophila (fruit flies) the sex-linked trait of red eye color (XR) is dominant over white (Xr). Which is the
correct genotype for a red-eyed female fruit fly?
4. In cocker spaniels the allele for a black coat color (B) is dominant over the allele for a brown coat color (b). If a
brown cocker spaniel is crossed with a heterozygous black cocker spaniel, which genotype ratio can be expected?
5. Brown eyes are dominant over blue eyes for a particular litter of puppies. What could account for a litter of
puppies that had more blue eyes than brown eyes?
6. In cattle, the allele for short horns (S) is dominant over the allele for long horns (s). Two heterozygous shorthorn cattle are bred and produced four offspring. What percentage would you expect to have long horns?
7. Two traits were observed for hamsters: color and tail length. For color, black (B) is dominant over tan (b). For
tail length, short tails (S) are dominant over long tails (s). What is the genotype for a heterozygous black shorttailed hamster?
8. In guinea pigs, the allele for rough coat (R) is dominant over the allele for smooth coat (r). A homozygous
dominant guinea pig and a homozygous recessive guinea pig are mated. Show the possible genotypes of their
offspring?
9. In humans, the sex-linked trait of normal blood clotting is dominant to hemophilia. Which of the following
shows the genotype for someone who is considered to be a carrier for hemophilia?