Phycology concept check: Chrysolaminarin is an intracellular energy-storage polysaccharide. In modern algal classification, this reserve material is characteristic of which algal group?

Introduction / Context:
Understanding algal reserve products is a classic way to differentiate major algal divisions. Just as animals store glycogen and higher plants store starch, many algae synthesize distinct storage polysaccharides. This question focuses on chrysolaminarin, a beta-linked glucose polymer that is diagnostic for specific chromalveolate lineages in traditional curricula.

Given Data / Assumptions:

• Chrysolaminarin is the named storage product.
• Answer choices are traditional divisions: Chlorophyta, Chrysophyta, Phaeophyta, Rhodophyta.
• We use standard teaching-level taxonomy and biochemical markers.

Concept / Approach:
Chrysolaminarin is a soluble beta-1,3-linked glucan (with some beta-1,6 branches) stored in vacuoles of golden algae and diatoms. Historically these groups were placed within Chrysophyta in many teaching texts. In contrast, brown algae (Phaeophyta) store laminarin, a related beta-1,3 glucan but referred to as laminarin rather than chrysolaminarin. Green algae (Chlorophyta) and red algae (Rhodophyta) primarily store starch-like polysaccharides in plastids rather than the chrysolaminarin type.

Step-by-Step Solution:
Identify the biochemical marker: chrysolaminarin = beta-glucan reserve of golden-brown lineages.Map to group usage: golden algae and diatoms are classically placed in Chrysophyta for didactic purposes.Differentiate from laminarin of brown algae and starch of green and red algae.Select the division that is characteristically linked to chrysolaminarin: Chrysophyta.

Verification / Alternative check:
Microscopy combined with biochemical assays shows vacuolar chrysolaminarin granules in diatoms and many golden algae. Comparative biochemistry distinguishes chrysolaminarin from plant starch and from laminarin in brown seaweeds.

Why Other Options Are Wrong:

• Chlorophyta: store starch in plastids, not chrysolaminarin.
• Phaeophyta: store laminarin, not chrysolaminarin.
• Rhodophyta: store floridean starch, not chrysolaminarin.

Common Pitfalls:
Lumping all beta-glucans together. Although laminarin is closely related, terminology and taxonomic association matter in exam questions.

Final Answer:
chrysophyta