Final answer:
The given statement "Nucleosomes are aided in their formation by the high proportion of [acidic/basic/polar] amino acids in histone proteins" is true because nucleosome formation is facilitated by the abundance of basic amino acids in histones. The correct option is a.
Step-by-step explanation:
Nucleosomes are aided in their formation by the high proportion of basic amino acids in histone proteins. This statement is true. Histones are alkaline proteins that are particularly rich in the basic amino acids lysine and arginine.
The positive charges on these amino acids allow them to interact with the acidic and negatively charged phosphodiester backbone of the DNA. Hence, the DNA wraps around an octamer of these histone proteins to form what is known as a nucleosome. This structure resembles "beads on a string" when viewed under an electron microscope, with the beads representing the nucleosomes themselves. Hence, a is the correct option.