DNA is often called the blueprint of life. Which statement best explains why DNA is described this way?

Introduction / Context:
In biology, DNA is often described metaphorically as the blueprint or instruction manual of life. This phrase is used in textbooks and popular science writing to help students understand the central role of DNA in heredity and development. The question asks you to choose the explanation that accurately captures why this metaphor is used, based on what DNA actually does in cells.

Given Data / Assumptions:

• The phrase blueprint of life refers to DNA.
• Options offer different reasons for this description, some serious and some clearly incorrect.
• We assume knowledge of DNA as the genetic material that encodes information.
• The correct explanation should refer to instructions or codes that guide organism structure and function.

Concept / Approach:
DNA, or deoxyribonucleic acid, is a long molecule made of nucleotide sequences that store genetic information. Genes are segments of DNA that encode the instructions for building proteins or functional RNA molecules. These proteins and RNAs control the structure, growth, metabolism, and behaviour of cells and organisms. Just as a blueprint in engineering specifies how to construct a building, the DNA sequence specifies how to construct and maintain a living organism. The metaphor does not refer to the color or appearance of DNA but to its informational role.

Step-by-Step Solution:
Step 1: Identify the main idea behind the phrase blueprint of life, which is the idea of a plan or set of instructions. Step 2: Recall that DNA carries genetic information in the sequence of its bases. Step 3: Recognise that genes made from DNA direct the synthesis of proteins that determine traits and regulate processes. Step 4: Compare the given options and look for one that mentions coded instructions and determination of structure and function. Step 5: Eliminate options that mention color, energy supply like ATP, or location only in bones, as these do not reflect the informational role. Step 6: Choose the statement that correctly explains DNA as containing coded instructions for building an organism.

Verification / Alternative check:
Genetics textbooks explain that the sequence of bases in DNA forms a genetic code. This code specifies the order of amino acids in proteins and influences when and where genes are expressed. Diagrams of gene expression show the flow of information from DNA to RNA to protein. These explanations align exactly with the idea that DNA is an instruction set or blueprint for the organism, confirming the correct option.

Why Other Options Are Wrong:
Because DNA molecules are blue in color and shaped like building plans: DNA is not literally blue and building plans are just a comparison, not the reason. Because DNA directly provides energy for every reaction in the cell like ATP: ATP, not DNA, is the main energy currency of the cell. Because DNA is found only in the skeleton and bones of living things: DNA is present in almost all cells, not restricted to bones. Because DNA can be seen easily with the naked eye as a life map: Individual DNA molecules are microscopic and cannot be seen without special techniques.

Common Pitfalls:
Students sometimes take metaphors too literally, thinking that DNA might physically resemble a blueprint or have special visible markings. It is important to remember that the phrase blueprint of life is a symbolic way to express the idea that DNA carries information. Focusing on the informational role of DNA helps keep the metaphor in perspective and leads to the correct explanation.

Final Answer:
DNA is called the blueprint of life because it contains coded instructions that determine the structure and function of an organism.