Homework #3 Genetics Practice Problems: Name:______

Homework #3 Genetics practice problems: Name:______****Remember to ALWAYS: 1. list alleles and traits for each problem ex: B=Black b=brown 2. list parental genotype 4. Write genotypic ratio 3. list possible gametes 5. Write phenotypic ratio ANSWER THE QUESTION  Part : 5 Incomplete Dominance heterozygotes are a BLEND!!

1. In radishes, red and white are pure-breeding colors, while hybrids are purple. If a red radish is crossed with a white radish, what will be the phenotype of the F2 generation (assuming the F1 generation self-pollinates)? Show the Punnett Square.

F1 generation

F2 generation

2. In snapdragons, flower color is controlled by incomplete dominance. The two alleles are red (R) and white (W). The heterozygous genotype is expressed as pink. a) What is the phenotype of a plant with the genotype RR? ______b) What is the phenotype of a plant with the genotype WW? ______c) What is the phenotype of a plant with the genotype RW? ______

3. A pink-flowered plant is crossed with a white-flowered plant. Show the Punnett Square. What is the probability of producing a pink-flowered plant? ____%

4. What cross will produce the most pink-flowered plants? Show a punnett square to support your answer.

5. In Andalusian fowls, black individuals (B) and white individuals (W) are homozygous. A homozygous black bird is crossed with a homozygous white bird. The offspring are all bluish- gray. Show the cross as well as the genotypes and phenotypes of the parents and offspring.

6. What are the genotypic and phenotypic ratios if a black individual is crossed with a bluish-gray individual? Show the Punnett Square.

7. If two bluish-gray individuals were crossed, what would be the ratios for both phenotype and genotype of the offspring? Show the Punnett Square.

Co-Dominance Heterozygous have BOTH TRAITS!! 8. In some chickens, the gene for feather color is controlled by codominance. The allele for black is B and the allele for white is W. The heterozygous phenotype is known as erminette (black and white spotted). a) What is the genotype for black chickens? ____ b) What is the genotype for white chickens? ____ c) What is the genotype for erminette chickens? ____

9. Two erminette chickens were crossed. Show the Punnett square. a) What’s the probability they would have a black chick? ____% b) What’s the probability they would have a white chick? ____%

10.A black chicken and a white chicken are crossed. Show the Punnett Square. What is the probability that they will have erminette chicks? ____% Part 6 Multiple Alleles

This problem has multiple alleles AND they are co-dominant. 11. Two parents think their baby was switched at the hospital. Its 1968, so DNA fingerprinting technology does not exist yet. The mother has blood type “O,” the father has blood type “AB,” and the baby has blood type “B.” a. Mother’s genotype: ______b. Father’s genotype: ______c. Baby’s genotype: ______or ______d. Punnett square showing all possible genotypes for children produced by this couple e. Was the baby switched?

12. Based on the information in this table, which men could not be the father of the baby? Justify your answer with a Punnett square.

Name Blood Type Mother Type A Baby Type B Sammy the Type O player George the Type AB sleeze The waiter Type A The cable guy Type B

13. A woman with type A blood (genotype AO) is married to a type B person (genotype BO). What proportion of their children will have: 1 A blood? ______

B blood? ______

O blood _____

14. Coat color in rabbits is inherited as a series of multiple alleles. In the case of rabbits, there are four alleles and each one is expressed with a different phenotype. Look over the summary table below:

phenotype allele pattern of inheritance dark gray C dominant to all other alleles coat chinchilla cch dominant to Himilayan and to white Himilayan ch dominant to white white c recessive

Suppose you cross a chinchilla rabbit (cchch) with a dark gray rabbit (Cch). What are the possible offspring?

Part 7 Sex-Linked

15. In humans, hemophilia is a sex linked trait. Females can be normal, carriers, or have the disease. Males will either have the disease or not (but they won’t ever be carriers) X H X H = female, normal X H Y = male, normal X H X h = female, carrier X h X h = female, hemophiliac X h Y= male, hemophiliac Show the cross of a man who has hemophilia with a woman who is a carrier.

What is the probability that their children will have the disease?______7. A woman who is a carrier marries a normal man. Show the cross. What is the probability that their children will have hemophilia? What sex will a child in the family with hemophilia be? 8. A woman who has hemophilia marries a normal man. How many of their children will have hemophilia, and what is their sex?

Calico Cat Genetics 16. In cats, the gene for calico (multicolored) cats is codominant. Females that receive a B and an R gene have black and oRange splotches on white coats. Males can only be black or orange, but never calico. Here’s what a calico female’s genotype would look like: X B X R Show the cross of a female calico cat with a black male? What percentage of the kittens will be black and male? _____ What percentage of the kittens will be calico and male? ______What percentage of the kittens will be calico and female? ______

16. Show the cross of a female black cat, with a male orange cat. What percentage of the kittens will be calico and female? ______What color will all the male cats be? ______

17. What is a sex-linked trait?

18. Why must males inherit colorblindness or hemophilia from their mothers?

19. Why is colorblindness or hemophilia more common in males than in females?

Part 8 Pedigree Analysis