Monohybrid Cross Problems 2012/13- directions



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Monohybrid Cross Problems 2012/13- Directions: Complete on a separate piece of paper & staple this 1/2 sheet to it on the front. For each of the described situations below, answer the question and show your work (punnett sq etc.)


  1. In chimpanzees, straight fingers (S) are dominant to bent fingers. Complete a punnett sq to show the genotypes and phenotypes expected for the following cross: heterozygous straight x homozygous bent.




  1. In humans, tongue rolling is a dominant trait (T), those who are homozygous recessive cannot roll their tongues. Bob can roll his tongue, but his mother cannot. He is married to Sally who cannot roll her tongue. What is the probability that their first born child will not be able to roll his/her tongue? Show the cross to prove it.




  1. In goats, a recessive gene causes the goats to faint (f) when they are startled. A farmer breeds 2 goats (that have never fainted) and their first offspring faints 2 days after its birth. What must the parents genotypes have been? Show the cross to prove it.




  1. In mice, spinning (S) behavior is caused by a dominant gene that effects the mouse's equilibrium and they spin around & around. This gene is lethal to newborn mice if 2 dominant alleles are present. Show the cross. What are the phenotypes of the offspring and in what proportion? Be sure to eliminate any offspring that do not survive.




  1. In pea plants, tallness is dominant (T). A tall plant of unknown genotype is test crosses (this means it was bread with a short plant b/c a short plant must be "tt"). Of the offspring, 890 are short and 910 are tall. What is the genotype of the unknown parent? Show the cross to prove it and explain how you know.




  1. In sheep, white wool color is due to a dominant gene (W), black wool color to its recessive allele (w). A white female mated to a white male produces a black lamb. If they produce another offspring, could it be white? If so, what are the chances of it being white?




  1. A black guinea pig (B) crossed with an albino guinea pig produced 12 black offspring. When the albino was crossed with another black guinea pig, 7 black and 5 albino offspring were obtained. What is the best explanation for this genetic situation? Show proof with a punnett sq

Monohybrid Cross Problems 2012/13- Directions: Complete on a separate piece of paper & staple this 1/2 sheet to it on the front. For each of the described situations below, answer the question and show your work (punnett sq etc.)


  1. In chimpanzees, straight fingers (S) are dominant to bent fingers. Complete a punnett sq to show the genotypes and phenotypes expected for the following cross: heterozygous straight x homozygous bent.




  1. In humans, tongue rolling is a dominant trait (T), those who are homozygous recessive cannot roll their tongues. Bob can roll his tongue, but his mother cannot. He is married to Sally who cannot roll her tongue. What is the probability that their first born child will not be able to roll his/her tongue? Show the cross to prove it.




  1. In goats, a recessive gene causes the goats to faint (f) when they are startled. A farmer breeds 2 goats (that have never fainted) and their first offspring faints 2 days after its birth. What must the parents genotypes have been? Show the cross to prove it.




  1. In mice, spinning (S) behavior is caused by a dominant gene that effects the mouse's equilibrium and they spin around & around. This gene is lethal to newborn mice if 2 dominant alleles are present. Show the cross. What are the phenotypes of the offspring and in what proportion? Be sure to eliminate any offspring that do not survive.




  1. In pea plants, tallness is dominant (T). A tall plant of unknown genotype is test crosses (this means it was bread with a short plant b/c a short plant must be "tt"). Of the offspring, 890 are short and 910 are tall. What is the genotype of the unknown parent? Show the cross to prove it and explain how you know.




  1. In sheep, white wool color is due to a dominant gene (W), black wool color to its recessive allele (w). A white female mated to a white male produces a black lamb. If they produce another offspring, could it be white? If so, what are the chances of it being white?




  1. A black guinea pig (B) crossed with an albino guinea pig produced 12 black offspring. When the albino was crossed with another black guinea pig, 7 black and 5 albino offspring were obtained. What is the best explanation for this genetic situation? Show proof with a punnett sq



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