Biology 303 Midterm, Fall 2007

1. If a family plans to have five children, what is the probability that four of them would be girls?

2. Assume that you have a garden and some pea plants have solid leaves and others have striped leaves. You conduct a series of crosses (a through e) and obtain the results given in the table.

Cross Progeny solid striped

(a) solid X striped 55 60 (b) solid X solid 36 0 (c) striped X striped 0 65 (d) solid X solid 92 30 (e) solid X striped 44 0

Define gene symbols and give the possible genotypes of the parents of each cross.

3. The genes for garnet eyes and forked bristles are 12.5 map units apart on the X chromosome in Drosophila melanogaster. Both genes are recessive. A cross is made between a garnet-eyed female and a forked-bristled male. (a) If 200 offspring from this cross were obtained, present the expected number, sex, genotype, and phenotype in each class of the F1. (b) If the F1 offspring were crossed to produce 800 flies of an F2 generation, present the expected number, sex, and phenotype in each class. Assume 20% recombination occurs between.

4. A corn plant known to be heterozygous at three loci was testcrossed. The following progeny were obtained:

+ + + 455 a b c 470 + b c 36 a + + 33 + + c 36 a b + 35 + b + 460 a + c 475

Determine the gene arrangement, linkage relationships, and map distances. 5. A female fruit fly was mated to a wild type male and the following progeny were obtained:

Female

+ + + 2000

Male + + + 3 a b c 1 + b c 839 a + + 825 + + c 86 a b + 90 + b + 81 a + c 75

Determine the gene arrangement, linkage relationships, map distances, and coefficient of coincidence.

6. The following results are ordered tetrad pairs from a cross between strain p+ and strain +q:

Tetrad Class 1 2 3 4 5 6 7 p + p + p q + q p + p q p + p + p q p q p + + + + + + q + q + + + + p + p q p q p q + q + q + + + q + q + + + + 55 4 3 6 21 5 3

They are summarized by tetrad classes.

a) Calculate the gene-centromere distance for each locus. b) Calculate the distance between the two linked loci. c) Draw a linkage map, including the centromere.

7. Ten female guppies had the following numbers of liveborn offspring in their first litter: 21, 19, 23, 14, 19, 28, 30, 26, 17, and 13. Calculate the mean, variance (s2), and the standard deviation (s) of the litter size for these data.