Question

Read the passage and answer the following question.

Restriction enzyme digestion with HindIII of genomic DNA from three toad species (A,B, and C) revealed that species A and B each produced unique fragment patterns, whereas species C shared fragments with both species A and species B.

What is the conclusion of these results?

• A. Species C served as an outgroup for the study.
• B. Restriction enzyme analysis should not be used in the comparison of more than two species simultaneously.
• C. Species C is the most recent living ancestor of both species A and species B.
• D. The DNA sample from species C must have been contaminated.
• E. Species C is a hybrid between species A and species B.

Answer 1

The correct option is E Species C is a hybrid between species A and species B.

Restriction digestion of genome uses RFLP based on highly repetitive sequences or simple-sequence DNA which are less than 10 bp long short sequences and are repeated in multiples per cell. Simple sequence DNA shows relative uniformity within species and great variability between closely related species. This results in restriction fragments of different length based on the position and frequency of restriction sites in repetitive DNA. Since species C shared fragments with both species A and B, it is hybrid of A and B species wherein both of parental species have contributed genome. Thus, the correct answer is option E.