Chlorophyll structure: Which long-chain alcohol is esterified to plant chlorophyll molecules as the hydrophobic tail?

Introduction / Context:
Chlorophylls are tetrapyrrole pigments with a porphyrin-like ring (chlorin) chelating Mg2+ and a long hydrophobic tail that anchors the molecule in thylakoid membranes. Identifying that tail is fundamental biochemistry.

Given Data / Assumptions:

• Plant chlorophylls a and b share a common hydrophobic tail.
• The tail is an esterified, long-chain isoprenoid alcohol.
• The name of this alcohol is asked.

Concept / Approach:
The hydrophobic tail is phytol, a C20 diterpenoid alcohol. It anchors chlorophyll in lipid bilayers and helps orient the light-harvesting complex within photosystems.

Step-by-Step Solution:

Verification / Alternative check:
Structural depictions of chlorophyll a/b consistently label the esterified phytol chain at the ring’s propionic acid side chain.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing general isoprenoids with the specific phytol tail of chlorophyll.

Final Answer:
Phytol.