GENETICS QUESTIONS 1

1. A number of plant species have a recessive allele for albinism; homozygous albino (white) individuals are unable to synthesize chlorophyll. If a tobacco plant heterozygous for albinism is allowed to self-pollinate and 500 seeds germinate: a/ how many offspring will be the same genotype as the parent? b/ how many seedlings would you expect to be white?

2. In mice colored coat is dominant to albinism. Sniffles, a male mouse with a colored coat is mated to Esmeralda, an alluring albino. The resulting litter of six young all had colored fur. The next time around Esmeralda was mated with Whiskers, who was the same color as Sniffles; some of this litter were white. a/ What are the probable genotypes of Sniffles, Esmeralda, and Whiskers? b/ If a male of the 1st litterwas mated to a colored female of the 2nd litter, what phenotypic ratio might be expected among the offspring? c/ What would be the expected results if a male of the 1st litter was mated to an albino from the 2nd?

3. In Drosophila the allele for dachs (short-legged = d) is recessive to the allele for normal leg length (D), and the allele for hairy body (h) is recessive to the allele for normal body (H). Make a Punnett square for the following crosses: a/ DdHh x DdHh b/ DDHh x Ddhh

4. In humans, freckles are dominant to no freckles. A man with freckles is married to a woman with freckles, but the children have no freckles. What's the deal (assuming no indiscretions have occurred).

5. In horses, B = black, b = brown, T = trotter, t = pacer. A black pacer mated to a brown trotter produces a black trotter offspring year after year. What are the probable genotypes?

6. For each of the following genotypes, give all possible gametes:
a/ ttGG b/ TtGG c/ TtGg d/ TTGg

7. For each of the following, state whether it is a gamete or a genotype of an individual: a/ TT b/ Tg c/ IcCC d/ TW

8. In human beings, brown eyes are usually dominant over blue eyes. Suppose a blue-eyed man marries a brown-eyed woman whose father was blue-eyed. What proportion of their children would you predict to have blue eyes?

9. A brown-eyed man whose father was brown-eyed and whose mother was blue-eyed married a blue-eyed woman whose mother and father were both brown-eyed. The couple has a blue-eyed son. What are the genotypes of all individuals?

10. In hogs a gene that produces a white belt around the animal's body is dominant over its allele for a uniform body. Another independent dominant gene produces fusion of the hoof (syndactyly). Suppose a uniformly colored hog homozygous for syndactyly is mated with a normal footed hog homozygous for the belted character. What would be the phenotype of the F1? If the F1's interbreed, what would be the phenotypic ratio of the F2?