Alkanoates are naturally found in

Analysis

The question asks for the natural occurrence of alkanoates (also known as esters). To answer this, we need to identify which of the listed biological compounds is chemically composed of ester linkages.

Concept Explanation

Alkanoates (Esters) are organic compounds formed by the reaction between an alkanol (alcohol) and an alkanoic acid (carboxylic acid). This process is known as esterification.

In nature, the most common form of alkanoates are fats and oils. Chemically, fats and oils are triglycerides, which are esters derived from glycerol (a trihydric alcohol) and three fatty acids (long-chain carboxylic acids). These substances are collectively classified as lipids.

Let's look at the other options:

• Vitamins: These are complex organic compounds required in small quantities for metabolism; they do not have a single functional group classification like alkanoates.
• Proteins: These are polymers of amino acids linked by peptide bonds (amide linkages), not ester linkages.
• Rubbers: Natural rubber is a polymer of isoprene (2-methyl-1,3-butadiene), which is a hydrocarbon.

Step-by-Step Solution

1. Identify the functional group: Alkanoates contain the ester functional group (-COO-).
2. Relate to biological molecules: Fats and oils are formed when glycerol reacts with fatty acids. The bond formed between the hydroxyl group of the glycerol and the carboxyl group of the fatty acid is an ester bond.
3. Categorize: Fats and oils belong to the class of biomolecules known as lipids.
4. Conclusion: Since lipids are essentially esters of fatty acids and glycerol, alkanoates are naturally found in lipids.

Correct Option

The correct option is A.

Exam Tip

When you see the word "Alkanoate," immediately think "Ester." Remember the mnemonic "Fats are Esters" to quickly link lipids to alkanoates in your exams. Also, remember that proteins are linked by peptide (amide) bonds, not ester bonds—this is a very common distractor in JAMB Chemistry!