Heredity 2- one gene/two genes

In cats, long hair is recessive to short hair. A true-breeding (homozygous) short-haired male is mated to a long-haired female. What will their kittens look like?

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Two cats are mated. One of the parent cats is long-haired. The litter which results contains two short-haired and three long-haired kittens. What does the second parent look like and what is its genotype?

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Mr. and Mrs. Smith both have widow's peaks (dominant). Their first child has a widow's peak, but their second child doesn't. Mr. Smith accuses Mrs. Smith of being unfaithful to him. Is he necessarily justified? Why or why not? Work the genetics problem predicting the frequencies of the versions of this trait among their prospective children.

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Mr. and Mrs. Jones have six children. Three of them have attached earlobes (recessive) like their father, and the other three have free earlobes like their mother. What are the genotypes of Mr. and Mrs. Jones and their numerous offspring?

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Mr. and Mrs. Anderson both have tightly curled hair. (The hair form gene shows incomplete dominance. There are two alleles, curly and straight. The heterozygote has wavy hair). The Andersons have a child with wavy hair. Mr. Anderson accuses Mrs. Anderson of being unfaithful to him. Is he necessarily justified? Why or why not?

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Two wavy haired people (one male and one female) marry and have eight children. Of these eight, how many would you expect to be curly haired, how many wavy haired and how many straight haired, assuming that the family follows the expected statistically predicted pattern? Suppose you examine the actual children and discover that three of the eight have curly hair. What do you suppose went wrong?

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Basic body color for horses is influenced by several genes, one of which has several different alleles. Two of these alleles - the chestnut (dark brown) allele and a diluting (pale cream) allele (often incorrectly called albino)--- display incomplete dominance. A horse heterozygous for these two alleles is a palomino (golden body color with a flaxen mane and tail). Is it possible to produce a herd of pure-breeding palomino horses? Why or why not. Work the Punnett's square for mating a palomino to a palomino and predict the phenotype ratio among the offspring.

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In certain portions of the Jewish population there is a genetic disease called Tay Sachs disease fatal to infants within their first five years of life. This disease is caused by a recessive allele of a gene. Why does this disease persist, even though it is invariably fatal long before the afflicted individual reaches reproductive age? (Why doesn't the allele for Tay Sachs disease simply disappear?)

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About 80% of the human population can taste the chemical PTC, while the other 20% can't. This characteristic is governed by a single gene with two alleles, a tasting allele and a non-tasting allele. What does this statistic tell us about which allele (tasting or non -tasting ) is dominant?

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In fruit flies, the gene for wing shape has an unusual allele called 'curly' (designated Cy). The normal (wild type) allele is designated 'cy'. A fly homozygous for cy (cy cy) has normal, straight wings. The heterozygote (Cy cy) has wings which curl up on the ends (and, incidentally, can't really fly). The homozygote for the Cy allele (Cy Cy) never hatches out of the egg. In other words, the allele is lethal in the homozygous condition. If two curly winged flies are mated, and the female lays 100 eggs, predict the following showing the appropriate work.

a. How many eggs will produce living offspring?

b. How many straight winged flies do you expect among the living offspring?

c. What percentage of the living offspring do you expect to be curly winged like the parents?

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