Question

what evidence suggests that the large amount of excess \junk\ dna in a genome may serve an important function? choose one: a. all organisms have excess \junk\ dna. b. the nucleotide sequence of \junk\ dna is very similar to that of genes involved in important cell functions. c. the sheer quantity of \junk\ dna suggests it must have some function in the life of the organism. d. a portion of \junk\ dna is highly conserved in its dna sequence among many different eukaryotic species. e. deletions or mutations that fall within \junk\ dna tend to always be harmful to the organism.

Explanation:

Conservation of DNA sequences across different species often implies functional importance. If a portion of "junk" DNA is highly conserved among many eukaryotic species, it is likely to have an important function as non - functional DNA would not be under such selective pressure to remain unchanged. Option A just states presence, not function. Option B similarity doesn't prove function. Option C quantity alone is not strong evidence. Option E is incorrect as not all changes in "junk" DNA are harmful.

Answer:

D. A portion of "junk" DNA is highly conserved in its DNA sequence among many different eukaryotic species