Answer: The question is incomplete,below is the complete question.
What are the terms describes the dna–protein complexes that look like beads on a string?
A) Chromatin
B) 30-nanometer fibre
C) Histones
D) Nucleosome
The correct answer is option D
Explanation: A Nucleosome is the basic fundamental unit of a DNA, and the fundamental sub-unit of a Chromatin.
The Nucleosome is the basic packing unit of DNA,it is built from histone proteins. A nucleosome is made up of 8 histones proteins resembling a thread wrapped round a spool.
The smallest bundle of DNA is known as a Nucleosome,a Nucleosome is produced through interaction between DNA and histone proteins.
Because, photoautotrophs serves as their carbon sources.
Chemoheterotrophic bacteria are those bacteria that are incapable of producing their own food, they depend on photoautotrophs, which are capable of making their own food by trapping energy from the sun. Thus, photoautotrophs serves as source of food for the chemoheterotrophic bacteria.