Physical properties of triacylglycerols (TAGs) In aqueous systems relevant to human biology, triacylglycerols are best described as:

Introduction / Context:Triacylglycerols (TAGs) are the predominant storage lipids in animals and plants. Their solubility characteristics determine how they are digested, transported, and stored. Understanding that TAGs are hydrophobic neutral lipids explains the need for emulsification and lipoprotein transport systems.

Given Data / Assumptions:

• TAGs consist of glycerol esterified to three fatty acids.
• No charged headgroup is present at physiological pH.
• Biological fluids are aqueous and require specialized carriers for hydrophobes.

Concept / Approach:

The extensive hydrocarbon chains of fatty acyl groups confer strong hydrophobicity, while the ester linkages are neutral. Consequently, TAGs are effectively insoluble in water and segregate into oil droplets. Digestion in the intestine relies on bile salts that emulsify TAGs, and lipoproteins (e.g., chylomicrons, VLDL) transport them through blood and lymph.

Step-by-Step Solution:

Verification / Alternative check:

Experimental partitioning shows TAGs have negligible aqueous solubility; droplet formation and creamy layers in un-emulsified systems visually demonstrate hydrophobicity.

Why Other Options Are Wrong:

Water solubility (Options B and D) contradicts chemical nature; partial solubility (C) is incorrect because the glycerol core is masked by nonpolar chains. Option E describes amphipathic detergents (e.g., bile salts), not neutral TAGs.

Common Pitfalls:

Confusing TAGs with phospholipids; the latter have charged headgroups and amphipathic behavior.

Final Answer:

Insoluble in water (hydrophobic neutral lipids)