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A researcher conducted crosses between two different strains of Drosophila. When true-breeding flies with singed bristles (s) and normal wings (L) were crossed to true-breeding flies with normal bristles (S) and vestigial wings (l), all F1 offspring had normal wings and normal bristles. The F1 offspring were crossed to flies with singed bristles and vestigial wings. Which F2 offspring is/are nonrecombinant? 

During the technique of genomic hybridization, DNA from normal cells or cancer cells is hybridized to metaphase chromosomes. Which samples are fluorescently labeled?

The Igf2 gene that is inherited from the mother is silenced due to imprinting. A mutation, which we will call Igf2—, is a loss-of-function mutation. If an Igf2 Igf2— mother is crossed to an Igf2 Igf2  father, what is the predicted outcome?

By conducting testcrosses, researchers have found that the apple has 17 linkage groups. How many chromosomes would you expect to find in pollen cells?

A fruit fly with a diploid set of autosomes has one X chromosome but no Y chromosome. This fly would be

A change in chromosome structure that does not involve a change in the total amount of genetic material is

Which of the following do you think would cause the most detrimental phenotype?

Which of the following events is LEAST likely to occur in a cross involving epistasis by both genes?

In four o’clocks, RR plants have red flowers, Rr have pink flowers, and rr have white flowers. If r allele is a loss-of-function allele, a reasonable molecular explanation for the pink phenotype would be

True-breeding tall plants with white flowers are crossed to true-breeding dwarf plants with purple flowers. The F1 plants were tall with purple flowers. The genes that affect these traits independently assort. If the F1 plants were allowed to self-fertilize, the expected ratio of the F2 generation would be