21. In a portion of a gene, the nitrogenous base sequence is T-C-G-A-A-T. Which nitrogenous base sequence would normally be found bonded to this
section of the gene?
A-C-G-T-A-A
A-C-G-U-U-A
A-G-C-T-T-A
U-G-C-A-A-U

A-G-C-T-T-A

Explanation:

The nitrogenous base-pairs are Adenine (A)—Thymine (T) and Cytosine (C)—Guanine (G).

Adenine on one strand of a DNA molecule means thymine on the complementary strand, and vice versa.

Cytosine on one strand of a DNA molecule means guanine on the complementary strand, and vice versa.

A gene is a specific portion of a DNA molecule that codes for a trait.