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GENETICS PRACTICE 2 BEYOND THE BASICS

Solve these genetics problems Be sure to complete the Punnett square to show how you derived your solution

INCOMPLETE DOMINANCE

1 In radishes the gene that controls color exhibits incomplete dominance Pure-breeding red radishes crossed with pure-breeding white radishes make purple radishes What are the genotypic and phenotypic ratios when you cross a purple radish with a white radish

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R Zl R R~ 2 Certain breeds of cattle show incomplete dominance in coat color When pure breeding red

cows are bred with pure breeding white cows the offspring are roan (a pinkish coat color) Summarize the genotypes amp phenotypes of the possible offspring when a roan cow is mated with a roan bull

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3 A man with type AB blood marries a woman with type B blood Her mother has type 0 blood List the expected phenotype amp genotype frequencies of their children

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4 The father of a child has type AB blood The mother has type A oWhich blood types can their children NOT have

5 A woman with type A blood and a man with type B blood D 6 h 0 D could potentially have offspring with what blood types n I P I

6 The mother has type A blood Her husband has type B blood

Their child has type 0 blood The father claims the child cant _Ot l+ ~nf)S~1olR be his Is he right ~ ~ 1rshy

7 The mother has type B blood Her husband has type AS blood Their child has type 0 blood The father claims the child cant be his Is he right

16 aJ3 The mother has type AS blood The father has type B blood

t V l-9 His mother has type 0 blood What are all the possibilities of ~ blood type for their children

LETHAL DOMINANT

9 Achondroplasia (dwarfism) is caused by a dominant gene A woman and a man both with dwarfism marry If homozygous achondroplasia results in death of embryos list the genotypes and phenotypes of all potential live-birth offspring

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SEX-LINKED

10 The genes for hemophilia are located on the X chromosome It is a recessive disorder List the possible genotypes and phenotypes of the children from a man normal for blood clotting and a woman who is a carrier (HINT You have to keep track of what sex the children are)

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EXTRA CREDIT Remember those roan cows from question 2 They also have a second gene for horn vs hornless cattle The allele for horns dominates the allele for hornless If a bull and

o 0 I 1J _ cow are heterozygous for both genes what are the probabilities for e pOa~i Ie p type 11 n r X R~ Hn ~1 ~ttit yen-~~ 2-~~ ~~H bull

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