Test Bank For An Introduction To Genetic Analysis 11th Edition BY GRIFFITHS
Chapter 3 Independent Assortment of Genes
Sections 3.1 and 3.2. (Mendel’s law of independent assortment, Working with independent assortment)
1. Mendel crossed Y/Y;R/R (yellow wrinkled) peas with y/y;r/r (green smooth) peas and selfed the F1 to obtain an F2. In the F2 what proportion of the yellow wrinkled individuals were pure-breeding?
2. Mendel crossed Y/Y;R/R (yellow wrinkled) peas with y/y;r/r (green smooth) peas and selfed the F1 to obtain an F2. What proportion of the F2 individuals were pure-breeding?
3. If genes assort independently, a testcrossed dihybrid characteristically produces progeny phenotypes in the ratio:
4. A fish of genotype a/a; B/b is crossed to a fish whose genotype is A/a; B/b. What proportion of the progeny will be heterozygous for at least one of the genes? (Assume independent assortment.)
5. In the offspring of a dihybrid self, what percentage of the individuals are themselves dihybrid?
6. A leucine-requiring mutant strain of haploid yeast is crossed to a cysteine-requiring mutant strain. Assuming independent assortment, what proportion of the spores produced will be mutant?
7. In a haploid fungus similar to Neurospora, a red-colored mutant is crossed to an alanine-requiring mutant. Assuming independent assortment, what proportion of the spores produced will be alanine-requiring?
8. Two pure-breeding mutant plants were crossed: One had small leaves (wild-type leaves are large), and the other made pink flowers (wild-type flowers are purple). All F1 individuals had small leaves and purple flowers. Assuming independent assortment, what proportion of the F2 individuals are expected to be phenotypically wild type?
9. Mendel’s Y/y; R/r dihybrid pea plants were the F1 of the cross between a double homozygous dominant and a double homozygous recessive. If we testcrossed these dihybrids, what proportion of the offspring would be recombinant and phenotypically resemble the F1 dihybrid?
Use the following information to answer questions 10 and 11.
The following is known about the inheritance of size and fur color in Holland lop rabbits:
- Crosses between large individuals only produce large individuals.
- Crosses between dwarf individuals produce both large and dwarf rabbits in a ratio of 1:2. Such crosses also produce some very small kits (baby rabbits) that generally die within a few days.
- Crosses between brown rabbits only produce brown kits.
- Some crosses between black rabbits produce only black kits, whereas others produce both black and brown kits.
- The size and fur-color phenotypes segregate independently.
10. What are the expected phenotypes in the F1 of a cross between a dwarf rabbit that breeds true for brown fur color and a large rabbit that breeds true for black fur color?
A) black dwarf only
B) black dwarf and black large only
C) brown dwarf and black dwarf only
D) brown dwarf, brown large, black dwarf, and black large
E) brown large only