1. Bio 130 – Quiz April 4

2. Q. 1 – T.H. Morgan and his colleagues worked out a set of symbols to represent fly genotypes. Which of the following are representative?
AaBb × AaBb
46, XY or 46, XX
vg+vgse+se × vgvgsese
+2 × +3
IAIB × IAIA
Answer: c

3. Q. 2 - In some Drosophila species there are genes on the Y chromosome that do not occur on the X chromosome. Imagine that a mutation of one gene on the Y chromosome reduces the size by half of individuals with the mutation. Which of the following statements is accurate with regard to this situation?
This mutation occurs in all offspring of a male with the mutation.
This mutation occurs in all male but no female offspring of a male with the mutation.
This mutation occurs in all offspring of a female with the mutation.
This mutation occurs in all male but no female offspring of a female with the mutation.
This mutation occurs in all offspring of both males and females with the mutation.
Answer: B
The point of this question is to help students understand sex-linkage by looking at the effect of genes on the Y chromosome. Answer a is incorrect because half of the sperm of the mutant male will contain an X chromosome and produce normal size daughters. Answer c is incorrect because females do not have a Y chromosome and cannot carry the mutation. Answer d is incorrect because, again, females do not have a Y chromosome and thus cannot carry the mutation. Answer e is incorrect because females cannot carry the mutation (no Y chromosome) and only the half of the eggs that are fertilized by a Y-bearing sperm will receive the mutation (i.e., only half of the male offspring). Answer b is correct because all the sons of the mutant male receive his Y chromosome.

4. Q. 3 - In cocker spaniels solid coat color is dominant over spotted coat color. If two heterozygous dogs were crossed to each other, what would be the probability of having a litter of 3 pups, 2 with solid coats and one with a spotted coat?
3/8
9/16
9/32
9/64

5. Q. 4 – Two human parents with normal skin pigmentation have an albino child. What is the probability that their next child will be an albino too?
1/8
1/16 1