Which of the following is correctly matched with its description? a) Nonrepetitive DNA is composed of thousands of copies of many short repeats. b) Moderately repetitive DNA contains transposable elements and genes that are expressed in abundance and thus have many copies. c) Moderately repetitive DNA contains retro elements, such as the Alu sequence. d) Moderately repetitive DNA contains unique sequences, such as genes found in one or a few copies. e) Highly repetitive DNA contains transposable elements and genes that are expressed in abundance and thus have many copies.

c) Moderately repetitive DNA contains retro elements, such as the Alu sequence.

Explanation:

The genetic material (DNA) has been proven to contain segments or sequences that are non-coding regions i.e. do not encode proteins. These non-coding sequences can either be repeated in the genome (repetitive) or not (non-repititive). The repetitive DNA sequences can consist of short sequences that repeat themselves enormous amount of times in the genome. This repetitive DNA sequence is said to be HIGHLY repetitive.

Another one can contain long nucleotide sequences scattered in the genome. They do not repeat as often as the highly repetitive sequences. They contain retro elements like Alu sequences and transposons. These sequence is said to be MODERATELY repetitive.

The non-repititive sequences are the part of the DNA that encodes a protein. They are called unique sequences because they occur in only one or few copies in the genome.