1. You observe that two traits – aroma and disease resistance – are always
inherited together in a doubled haploid population of 100 plants. That is,
plants are either aromatic/disease susceptible or non-aromatic/disease
resistant. You would like to breed a plant that is aromatic and disease
resistant. What could you do to determine if this association is due to linkage
or pleiotropy?
2. In a testcross population of 100 plants you obtain the following data. Are the
loci controlling height and color linked? If yes, what is the percent
recombination?
Tall and red
Tall and white Short and red
Short and
white
40
10
10
40
3. A linkage map is 150 cM long. Locus “A” is at one end of the linkage group
(cM position 0) and locus “Z” is at the other end of the linkage map (cM
position 150). What will be the percentage of recombination between the
two loci?
4. On the board, show why a two-strand double crossover gives parental
combinations of alleles.
5. In theory, every pair of homologous chromosomes has at least one crossover
at meiosis. Given the graphical haplotypes shown on the screen, explain why
there is no evidence of recombination in some of the DH lines.