Required_Homework_2_key-1

Required_Homework_2_key-1 - 1 If two animals heterozygous...

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1. If two animals heterozygous for a single pair of genes are mated and have 200 offspring, about how many will have the dominant phenotype? a. 200 *b. 150 c. 100 d. 50 e. cannot be determined from the information below A/a x A/a = ¾ will have at least one A allele. SO, ¾ of 200 = 150 2. Long tails (T) are dominant to short tails (t) in mice. A long- tailed mouse is mated with a short-tailed mouse: 7 of the offspring had long tails and 6 had short tails. What is the genotype of the long- tailed mouse? a. T/T *b. T/t c. T/T or T/t, cannot be distinguished from the information given d. t/t We know the short tailed mouse is genotype t/t. If this mouse was crossed to a T/t mouse about half would have long and half would have short tails. So, answer b is correct. (If the mouse was T/T—all the offspring would be long-tailed.) 3. Whether an allele is dominant or recessive depends on a. how common it is b. whether it was inherited from the mother or father c. which chromosome it is on *d. whether it or another allele determines the phenotype when both are present e. choices a and d 4. Your mother’s brother has cystic fibrosis but their parents (your maternal grandparents) and your mother are all normal. Your father comes from a family in which the disease was never seen and we assume he is normal and NOT a carrier. You are about to start a family of your own and you wonder if there is a chance that you could be a CARRIER. What is the probability that you are a CARRIER (Hint: carefully draw a pedigree!) a. 0; there is no chance of me being a carrier b. 2/3 c. 1/4 *d. 1/3 e. none of the above choices are the correct probability Your mother has a 2/3 chance of being a carrier (remember this is just like the example form powerpoint in class.) If your mother turns out to be a carrier, you would have a 1/2 chance of inheriting the allele. SO, multiply 2/3 x 1/2 = 2/6 = 1/3 (*Note- because we are not told otherwise, we assume your father is entirely normal and has no associations with the disease allele.)
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5. If a man who was deaf (this form of deafness is an autosomal recessive disease) and a woman who had sickle-cell disease had a child, what would be the probability that the child would be a carrier of both diseases? (For those of you overthinking this. ..the deaf man is not a carrier for sickle cell and the woman is not a carrier of the deafness trait) a. 0 b. 1/2 c. 1/4 d. 2/3 *e. 1 ( the child will definitely be a carrier of both diseases)
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Required_Homework_2_key-1 - 1 If two animals heterozygous...

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