Guide Questions for TrEl
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Long Test 1
Solve problems involving codominance, incomplete dominance, and multiple alleles and explain why these are considered as non-Mendelian inheritance.
1. A cross between a blue blahblah bird & a white blahblah bird produces silver blahblah birds.
a. What are the genotypes of the parent blahblah birds in the original cross?
b. What is the genotype of the silver offspring?
c. What would be the phenotypic ratios of offspring produced by two silver blahblah birds?
2. The color of fruit for plant “X” is determined by two alleles. When two plants with orange fruits are crossed the following phenotypic ratios are present in the offspring: 25% red fruit, 50% orange fruit, 25% yellow fruit. What are the genotypes of the parent orange-fruited plants?
3. Predict the phenotypic ratios of offspring when a homozygous white cow is crossed with a roan bull.
4. What should the genotypes & phenotypes for parent cattle be if a farmer wanted only cattle with red fur?
5. A cross between a black cat & a tan cat produces a tabby pattern (black & tan fur together).
a. What pattern of inheritance does this illustrate?
b. What percent of kittens would have tan fur if a tabby cat is crossed with a black cat?
6. A woman with Type O blood and a man who is Type AB are expecting a child. What are the possible blood types of the kid?
7. What are the possible blood types of a child whose parents are both heterozygous for “B” blood type?
8. What are the chances of a woman with Type AB and a man with Type A having a child with Type O?
9. Determine the possible genotypes & phenotypes with respect to blood type of the offspring of a couple whose blood types are A and B. Both sets of grandparents have the AB blood type.
Solve problems involving polygenic inheritance involving determining any of the following: number of alleles or genes, total number of phenotypes or genotypes, probability of a certain phenotype appearing in the F2 population using either Pascal’s Triangle or the combination formula.
Ladybugs (aka Lady beetles) can have zero to nine spots on each side of their carapace. One spotted beetles have one spot on each side of their carapace for a total of 2. Nine spotted beetles have a total of 18. Let’s assume these beetles are diploid and that this is a polygenic trait with 5 genes responsible for the number of spots. No spots will be recessive for all alleles. The addition of one dominant allele will add one spot to each side. An 18 spot beetle is possible with 9 or 10 dominant alleles.
a. List the possible phenotypes and their probabilities of occurrence.
b. Give a sample genotype for each of the possible phenotypes.
State the different methods of sex-determination in animals.
Solve problems involving sex-related inheritance and explain why these are considered as non-Mendelian modes of inheritance.
1. Red-green colorblindness is a recessive x-linked trait. If a man and a woman with normal color vision, but whose fathers are affected with the trait marry, what is the probability that they will give rise to
a. A color-blind girl?
b. A color-blind boy?
c. A child with normal vision?
2. Pattern baldness is a sex-influenced trait that is dominant in men and recessive in women. A heterozygous bald man marries a bald woman, what is the probability that they will give rise to
a. An affected girl?
b. An affected boy?
c. A child who is unaffected?
3. Rooster feathering in chickens is a trait limited in expression only in males and determined by the autosomal recessive genotype hh. The dominant allele (H) produces hen-feathered males. All females are hen-feathered regardless of genotype.
A rooster-feathered male is mated to a hen and they have twelve offspring: six males and six females. Three of the six males have rooster feathers. Determine the possible genotypes of the six female offspring.