Cellulose is to carbohydrate as: a. amino acid is to protein. b. lipid is to fat. c. collagen is to protein. d. nucleic acid is to DNA. e. nucleic acid is to RNA.
The correct answer and explanation is:
Correct Answer: a. amino acid is to protein
Explanation (300 words):
The analogy “Cellulose is to carbohydrate as ___ is to ___” tests the relationship between a specific substance and its broader category.
Cellulose is a specific type of carbohydrate. More precisely, cellulose is a polysaccharide made of repeating glucose units and is found in the cell walls of plants. It provides structural support due to its rigid, fibrous nature. Being a polysaccharide, cellulose falls under the larger class of carbohydrates, which also includes monosaccharides (like glucose) and disaccharides (like sucrose).
Let’s examine the options:
- a. Amino acid is to protein: This is the correct answer. Amino acids are the building blocks of proteins, just as glucose units (monosaccharides) are the building blocks of polysaccharides like cellulose. Proteins are large, complex molecules made up of one or more chains of amino acids, folded into specific structures to perform various functions in the body. This relationship mirrors how cellulose, a complex carbohydrate, is composed of repeating monosaccharide units.
- b. Lipid is to fat: This is the reverse of the correct relationship. Fat is a type of lipid, not the other way around. This breaks the pattern.
- c. Collagen is to protein: Collagen is a specific protein, so this is analogous to saying “Cellulose is to carbohydrate as collagen is to protein,” which would compare two specific substances. The relationship doesn’t reflect the structural analogy we’re seeking.
- d. Nucleic acid is to DNA and e. Nucleic acid is to RNA: In these, DNA and RNA are types of nucleic acids, not the other way around. Again, this reverses the hierarchical structure.
Therefore, “amino acid is to protein” correctly mirrors “cellulose is to carbohydrate”, representing a part-to-whole, building block-to-structure relationship.