Final answer:
According to Chargaff's rules, if 30% of the nucleotides of a DNA molecule contain adenine, then 30% would also be thymine. The percentages of cytosine and guanine would need to be determined separately.
Step-by-step explanation:
When studying a new species of deep-sea organism and determining that 30% of the nucleotides in its DNA contain adenine, we can use Chargaff's rules to analyze the genetic makeup of this organism. Chargaff's rules state that in a DNA molecule, the amount of adenine (A) equals the amount of thymine (T), and the amount of cytosine (C) equals the amount of guanine (G). Therefore, if 30% of the bases are adenine, then thymine would also be 30%. To find the percentages of cytosine and guanine, we would need additional data, as those are paired separately according to Chargaff's rules.