Question

How would I work the following problems out? I would like someone to show their work so I could better understand the answers and thought process.

Genetics Problems

For the first couple of problems, you will be working with guinea pigs. Their coat color shows an example of complete dominance - black (B) is dominant over brown (b).

1. A heterozygous black male is crossed with a heterozygous black female. What would be the resulting phenotypic ratio in the offspring?

2. A heterozygous black male is crossed with a brown female. (A) What would be the resulting phenotypic ratio in the offspring? (B) What would be the probability of getting a black offspring?

For the next two problems, you will be working with snapdragons. Flower color in snapdragons shows incomplete dominance.

RR = Red

R'R' = White

RR' = Pink

3. A red flowered plant is crossed with a white flowered plant. What phenotype(s) would the offspring show?

4. A pink flowered plant is crossed with another pink flowered plant. (A) What would be the resulting phenotypic ratio? (B) What would be the probability of getting a pink flowered offspring?

The next genetic problems deal with blood type.

5. - 6. Give the possible genotypes for each of these blood types (these do not require crosses - just write the possible genotypes for each phenotype):

Type A

Type B

Type AB

Type O

7. A type O woman has children with a type AB man. Give the possible phenotypes of their children.

8. Is it possible for an A type woman and a B type man to have children that are type O? Explain your answer.

The final problems deal with the sex-linked trait of color-blindness. Color-blindness is caused by a recessive gene that is found on the X chromosome.

XC = normal vision

Xc = color-blindness

9. A woman with normal vision that is homozygous (XCXC) has children with a color-blind man (XcY). (A) if they have a daughter, what is the probability that she will be a carrier? (hint - only look at the female offspring). (B) What is the probability that they will have a color-blind child?

10. A woman with normal vision that is a carrier (XCXc) has children with a man with normal vision (XCY). (A) If they have a son, what is the probability he will be color-blind? (hint - only look at the male children for this answer). (B) What is the probability that they will have a color-blind child?

Answer 1

(1)(2)(3)(4)(5)-(6)

(7)(8)(9)(10)