Evaluate the statement: DNA is a long chain made of repeating units called amino acids. How should this statement be classified?

Introduction / Context:
Deoxyribonucleic acid, or DNA, is the hereditary material in most organisms. Understanding its chemical nature is essential in biology. Many exam questions ask students to distinguish between nucleic acids and proteins, because confusing their building blocks can lead to serious misunderstandings about how genes and enzymes work.

Given Data / Assumptions:

• The statement claims that DNA is a long chain of repeating units called amino acids.
• We must judge whether this description is correct or incorrect.
• We assume standard definitions of DNA, nucleotides, and amino acids.
• No numerical calculation is required, only conceptual knowledge.

Concept / Approach:
DNA is a nucleic acid made of repeating subunits called nucleotides. Each nucleotide consists of three parts: a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, guanine, or cytosine). Amino acids, on the other hand, are the building blocks of proteins, not nucleic acids. Proteins are polypeptide chains formed by linking amino acids, whereas DNA is a polynucleotide chain formed by linking nucleotides. Therefore, the statement that DNA is composed of amino acids is incorrect.

Step-by-Step Solution:
Step 1: Recall the basic structure of DNA as a double helix made of two polynucleotide strands.Step 2: Identify the repeating unit in each strand, which is the nucleotide, not the amino acid.Step 3: Recognise that amino acids belong to proteins and are joined by peptide bonds to form polypeptides.Step 4: Compare this knowledge with the statement given. It confuses nucleotides with amino acids.Step 5: Conclude that the statement is incorrect and select the option that explicitly states that DNA is made of nucleotide units.

Verification / Alternative check:
Any standard biology diagram of DNA labelling shows sugars, phosphates, and bases as components of nucleotides. In contrast, diagrams of proteins show amino acid residues linked in a chain. Genetics and molecular biology textbooks repeatedly emphasise that genes are segments of DNA composed of nucleotides, while the products of many genes are proteins composed of amino acids. This confirms that the correct building blocks of DNA are nucleotides.

Why Other Options Are Wrong:
Option B incorrectly accepts the statement and reinforces the confusion between proteins and nucleic acids. Options C and D try to restrict the statement to particular kinds of DNA, but the chemical nature of DNA is the same in bacteria, plants, and animals, so these options are also incorrect. Option E denies that DNA is a long chain polymer, which contradicts the very definition of DNA as a polynucleotide molecule. Only option A correctly identifies the error and gives the right description of DNA structure.

Common Pitfalls:
Students often learn the terms nucleotide and amino acid at the same time and may mix them up, especially when thinking quickly in an exam. Another common error is to remember that both DNA and proteins are long chains and assume their building blocks are the same. To avoid confusion, it helps to link nucleotides with nucleic acids and amino acids with proteins and to repeat that genes are nucleotide sequences that encode amino acid sequences in proteins.

Final Answer:
The correct evaluation is that The statement is incorrect; DNA is made of repeating nucleotide units rather than amino acids.