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Unformatted text preview: EEMB 129 Midterm I Name____________________________ 2010 Perm #___________________________ Read each question carefully before you answer it. Make sure that you show your work. 1. (12 pts) Based on Mendels observations, give the genotypes, phenotypes & expected frequencies for the following crosses: a) a tall (dominant and homozygous) variety crossed with the dwarf variety Tt (1), tall (1) b) the progeny of (a) self-fertilized TT, Tt, tt (1:2:1); tall, dwarf (3:1) c) the progeny from (a) crossed with the original tall parent TT, Tt (1:1); tall (1) d) the progeny from (a) crossed with the dwarf variety Tt, tt (1:1); tall, dwarf (1:1) 2. (8 pts) When mapping three linked genes, why do geneticists prefer to do one three-point cross rather than three two-point crosses? Give two reasons. Three-point crosses allow the detection of double-crossover recombinants. It is more efficient to do a single three-point cross than three two-point crosses. 3. (10 pts) In pigeons, the color pattern of feathers is controlled by one locus with a dominant allele D causing a checkered pattern while a recessive allele d causes a plain pattern. An independently assorting gene controls the specific color of feathers, with a dominant allele B producing red feathers and a recessive allele b producing brown feathers. Birds from a true- breeding checkered, red variety are crossed to birds from a true-breeding plain, brown variety. a) Predict the phenotype of their progeny checkered pattern, red color b) If the progeny are intercrossed, what genotypes and phenotypes will appear in the F2 and in what proportions? D_B_ 9 checkered, red D_bb 3 checkered, brown ddB_ 3 plain, red ddbb 1 plain, brown EEMB 129 Midterm I Name____________________________ 2010 Perm #___________________________ 4. (8 pts) Mendel studied seven different traits of the garden pea (flower color, seed shape, seed 4....
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This note was uploaded on 10/16/2010 for the course EEMB 129 taught by Professor Ajnarivera during the Spring '09 term at UCSB.
- Spring '09