[Campbell Biology P.351] In a testcross for two genes, what is the maximum possible frequenc... | Practice Question

In a testcross for two genes, what is the maximum possible frequency of recombination, and what does it indicate about the two genes?

  • A: 50%; it indicates the genes are on different chromosomes (unlinked).
  • B: 100%; it indicates the genes are on different chromosomes (unlinked).
  • C: 0%; it indicates the genes are completely linked.
  • D: 50%; it indicates the genes are very close together on the same chromosome.

Explanation

The text states, 'A 50% frequency of recombination in such testcrosses is observed for any two genes that are located on different chromosomes and thus cannot be linked.' This occurs because of the independent assortment of homologous chromosomes during meiosis I.