Biomolecule classification check: Which one of the following sets consists entirely of lipids (i.e., members of the same macromolecular class)?
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ARibose, sucrose, glucose, fructose
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BSterols, waxes, fatty acids, amino acids
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COils, sterols, waxes, fats
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DNucleotide, nucleoside, nucleus, DNA
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ECellulose, glycogen, starch, chitin
Answer
Correct Answer: Oils, sterols, waxes, fats
Explanation
Introduction / Context:Accurate classification of biomolecules underpins understanding of structure–function relationships in biochemistry. The question tests whether you can identify a set in which all members belong to the lipid family.
Given Data / Assumptions:
- Lipids include diverse hydrophobic or amphipathic molecules such as triacylglycerols (fats/oils), sterols, waxes, and fatty acids.
- Other classes include carbohydrates, nucleic acids, and proteins.
Concept / Approach:Evaluate each set for internal consistency. A correct set must contain only lipids; any presence of a carbohydrate, nucleic acid component, or protein renders the set mixed and therefore incorrect for the prompt.
Step-by-Step Solution:
Inspect option C: oils (triacylglycerols), sterols (cholesterol), waxes (esters of long-chain alcohols and fatty acids), fats (triacylglycerols) — all lipids.Inspect option A: ribose, sucrose, glucose, fructose — all carbohydrates, not lipids.Inspect option B: includes amino acids, which are proteins’ building blocks; the set is mixed.Inspect option D: nucleotide/nucleoside/DNA are nucleic acid-related; nucleus is an organelle, not a macromolecule class.Inspect option E: all polysaccharides (carbohydrates), not lipids.Verification / Alternative check:Textbook definitions categorize lipids by solubility in nonpolar solvents and amphipathic nature; option C meets this criterion exclusively.
Why Other Options Are Wrong:
- A and E are carbohydrate-only sets.
- B includes a nonlipid (amino acids).
- D mixes nucleic acid components with an organelle.
Common Pitfalls:Equating “oils” with non-lipid substances or assuming “nucleus” is a macromolecule; overlooking that “sterols” (e.g., cholesterol) are a lipid subclass.
Final Answer:Oils, sterols, waxes, fats