Free response 11 - Punnett Square Practice Problems

Free response 11 - Punnett Square Practice Problems -...

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Punnett Square Practice Problems 1. Cross a homozygous dominant tall pea plant with a heterozygous pea plant. T= tall and t = short a. What percentage will be short? b. What percentage will be tall? c. What are the genotypes and phenotypes? Check your work. Answers: a. 0% b. 100% c. 1 homozygous dominant: 1 heterozygous; 100% tall 2. If Mendel wanted to determine the genotype of a yellow round pea, what would be the best plant to cross it? a. GgWw b. GGWW c. ggWW d. GGww e. ggww Check your work. Answer is e. If the genotype of an individual is to be tested, the best cross to perform is the testcross, to a homozygous recessive. All of the other crosses will allow potential recessive alleles in the yellow round plant to remain masked. 3. What phenotypic ratio of offspring should be expected from the cross AaBb x AAbb? Check your work. Answer is d. Consider each gene separately. Aa x AA will only produce progeny with the A phenotype. Bb x bb is the testcross of a monhybrid, so will produce a 1:1 ratio. One class will have genotype AABb and AaBb and the other class will be composed of AAbb and Aabb individuals. 4. In hogs, a gene that produces a white belt (B) around the animal's body is dominant over its allele for a uniformly colored body (b). Another gene produces a fusion of the two hoofs on each foot, a condition known as syndactyly is mated with a female hog that is normal-footed and homozygous for the belted character. a. What are the genotypes of the male and female hog? b. What would be the phenotype ration? Check your work: Answers: a. male hot is bbTT b. female hog is BBtt c. phenotype is 16:0 all white belt syndactyly 5. Lauren, who has blood type AB, marries Sal who has type B blood but whose mother has type O. a. List the genotypes of Lauren, Sal and Sal's mother. b. What are the percent possibilities for the blood type of their offspring. Check your work: Answers: a. Lauren - I A I B , Sal - I B i, Sal's mother - ii b. 25% type AB, 25% type B, 25% type A, 25 % type B 6. In hamsters, rough coat (R) is dominant over smooth coat (r) and brown coat (B) is dominant over white coat(b). If you cross a homozygous rough, homozygous brown guinea pig with a smooth white one: a. What will be the genotypes of the parents? Check your work: Answer: a. RRBB x rrbb
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More Punnett Square Problems 1. What is the maximum number of different phenotypes that could be produced by the mating of a blood type AB individual to a type B individual? a. 1 b. 2 c. 3 d. 4 2. One breed of cattle can be red, white, or roan. The cross between 2 roans produces equal number of red and white progeny and twice as many roans., If a farmer wanted to breed an all roan herd, what animals should be the parents? a. roan x roan
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This note was uploaded on 12/15/2010 for the course PSYC 1338 taught by Professor Anderson during the Fall '10 term at HCCS.

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Free response 11 - Punnett Square Practice Problems -...

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