Final answer:
Amino acids are the monomers used to build proteins, which are crucial polymers in living organisms. DNA and cellulose are polymers themselves, while triglycerides are a type of lipid. Therefore, the correct answer is option d. amino acids.
Step-by-step explanation:
Monomers are the basic building blocks of polymers, which are large, complex molecules that play critical roles in living organisms. When considering the options provided, we are looking for a class of monomers that are used in the formation of polymers within biological systems.
DNA and cellulose are both polymers, with DNA being a polymer of nucleotides and cellulose being a polymer of glucose units. Triglycerides are a form of lipid, rather than a polymer made from monomers. Proteins are indeed polymers, but they are made up of amino acids, hence amino acids are the actual monomers.
Amino acids contain both an amine functional group and a carboxylic acid functional group. These groups participate in condensation reactions to form peptide bonds, creating the primary structure of proteins. Amino acids are therefore the correct answer to this question. They are monomers that make up the proteins, which are necessary for a multitude of functions in living organisms, including enzymatic catalysis, structure, transport, and signaling.
Option d. amino acids is the correct choice as they are the monomer building blocks in the polymers (proteins) of living organisms.