Download GENETICS PROBLEMS For each of the following questions, it is

GENETICS PROBLEMS
For each of the following questions, it is expected that you will show a complete solution, identifying the genotypes,
phenotypes and ratios where required. Marks are indicated in the square brackets.
1. A homozygous dominant black mouse is mated with a heterozygous black mouse (brown is the other colour).
a. State the genotype of each parent
b. Use a Punnett square to predict the genotypes of the offspring
c. State the phenotypic ratio of these offspring
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2. In daisies, yellow flowers are dominant over white flowers. If a heterozygous yellow daisy is crossed with a white daisy:
a. State the genotype of each parent
b. Use a Punnett square to predict the genotypes of the offspring
c. State the phenotypic ratio of these offspring
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3. a) Explain in a sentence, how you would use a Test Cross to determine the genotype of a guinea pig showing the
dominant trait of grey fur. The recessive trait is white fur.
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b) Show, using the Punnett Squares, all possible outcomes of the Test Cross, and explain how you would interpret the
results.
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4. a) A male rabbit is heterozygous for dwarf ears and has blue eyes. The female has long ears and is heterozygous for
brown eyes.
I.
State the genotype of each parent
II.
Use a Punnett square to predict the genotypes of the offspring
III.
State the phenotypic ratio of these offspring
b) Repeat the above instructions for the same male mated with a female who is heterozygous for both traits
[2]
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[1]
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5. A fruit fly that is homozygous for red eyes is crossed with a fruit fly that is homozygous for white eyes. For each type of
dominance, that the genotype of each parent, use a Punnett Square to predict the genotypes of the offspring, then state
the phenotypic ration of the offspring:
a. Complete dominance (assume ref eyes is dominant to white eyes)
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b. Incomplete dominance
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c. Co-dominance
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6. Use a Punnett Square to predict the probability that a male and female will have a boy or a girl.
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7. Recall that in humans, blood types A and B are co-dominant, while Type O blood is recessive. What blood types can be
expected in the offspring of a Type A male and a Type B female, if both parents are heterozygous for this trait?
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8. In some cats the gene for tail length shows incomplete dominance. Cats with long tails and cats with no tails are
homozygous for their respective alleles. Cats with one long tail allele and one no tail allele have short tails. For each of
the following construct a Punnett Square and give phenotypic and genotype ratios of the offspring.
a) a long tail cat and a cat with no tail
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b) a long tail cat and a short tail cat
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c) a short tail cat and a cat with no tail
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d) two short tail cats.
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