Question

What are the subunits of protein, starch, and DNA

Answer 1

The name of the DNA subunit is a nucleotide. There are three parts, there is a sugar, a base, and a phosphate group. The sugar is the pentose sugar known as deoxyribose (the D in DNA). The "deoxy" just means that it is "missing" an oxygen group compared ribose. The base is what makes up the "language" of DNA. There are four possible bases, adenine, thymine, cytosine, and guanine. The phosphate and the sugar form the backbone of the DNA and are the same in every nucleotide.

Answer 2

well, basically, everything is made of atoms and cells. Those are youre building blocks for every life unit. The subunits of proteins are amino acids. These acids combine (in different combinations) to form different proteins.
The subunits of starch are carbohydrates. They build to form molecules of starch.
The subunits of DNA are nucleic acids. These mix with other things to form DNA. It is like the protein where different combinations create different DNA strands/molecules.