Genetics Problems. Bio 30
Topics: Allele, Plant sexuality, Zygosity, Gene, Dominance, Genetics / Pages: 17 (4145 words) / Published: Dec 18th, 2012

Genetics Practice Problems, book #1

1. In peas, the gene for tallness is dominant to the gene for shortness. What offspring phenotypes and genotypes would be expected from the following crosses, and in what proportions?

a. Heterozygous x heterozygous b. Heterozygous x homozygous tall c. Homozygous tall x homozygous short

2. If blue eye color in man is recessive to all other colors, could:

i. Brown eyed parents have a blue eyed child? ii. Blue eyed parents have a brown eyed child? iii. Explain.

3. The gene for yellow seed coat in peas is dominant to its allele, green. What offspring phenotypic and genotypic ratio would be expected from a cross between a pea plant known to be heterozygous for coat color and one which produced green seeds?

4. From a mating between two normal winged drosophila, 27 dumpy winged and 79 normal winged offspring were produced.

i. What is the nature of the dumpy winged gene? ii. What were the parental genotypes?

5. In a cross between a dumpy winged fly and one of the parents in the previous question, how many normal winged flies would be expected among 120 offspring?

6. Albinism, the inability to synthesize chlorophyll, is a recessive character in a number of green plant species. If a tobacco plant known to be heterozygous for albinism is self-pollinated and 600 of its seeds are subsequently germinated, how many seedlings would be expected to be albino? And how many would be expected to have the parental genotype?

7. A man and his wife can both taste phenylthiourea. They have four children, two of whom are unable to taste. What are the parental genotypes?

8. Construct a pedigree diagram for the following families:

a. A man and his wife are both tasters and they have two taster sons, a taster daughter and a non-taster daughter. One of the sons is

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