Question 83
(Multiple Choice)
The next questions refer to the following table,which compares the percent sequence homology of four different parts (two introns and two exons)of a gene that is found in five different eukaryotic species.Each part is numbered to indicate its distance from the promoter (e.g.,Intron I is the one closest to the promoter).The data reported for species A were obtained by comparing DNA from one member of species A to another member of species A.
% Sequence Homology
-Which of the following is the best explanation for the high degree of sequence homology observed in Exon I among these five species?
A)It is the most-upstream exon of this gene.
B)Due to alternative gene splicing, this exon is often treated as an intron.
C)It codes for a polypeptide domain that has a crucial function.
D)These five species must actually constitute a single species.
E)This exon is rich in G-C base pairs; thus, it is more stable.
Answer