Flagella comparison across algal divisions: Considering motile stages, how does the number of flagella in members of Rhodophyta compare with that in members of Phaeophyta?

Introduction / Context:
Flagellated stages are important life cycle features in algae. Red algae and brown algae show striking differences in motility that can be used for rapid division-level identification in exams and practicals.

Given Data / Assumptions:

• Rhodophyta refers to red algae.
• Phaeophyta refers to brown algae.
• We compare the presence and number of flagella in motile cells.

Concept / Approach:
Rhodophyta are unique among the major algal divisions in lacking flagellated stages entirely. Their gametes and spores are nonmotile. In contrast, many brown algae produce biflagellate sperm or spores with heterokont flagella. Therefore, Phaeophyta have more flagella than Rhodophyta because the latter have none.

Step-by-Step Solution:
Recall that red algae do not produce flagellated cells.Recall that brown algae produce biflagellate motile stages.Compare counts: any positive number is greater than zero.Select the statement that Phaeophyta have greater flagellar number than Rhodophyta.

Verification / Alternative check:
Textbook life cycle diagrams for Fucus, Ectocarpus, and other brown algae show motile sperm or spores. Red algal life cycles consistently lack flagella at all stages.

Why Other Options Are Wrong:

• Rhodophyta greater: impossible because they have zero flagella.
• Equal: incorrect for the same reason.
• None of the above: incorrect because option indicating greater number in Phaeophyta is correct.

Common Pitfalls:
Assuming every alga has a motile phase. Red algae are the key exception at the division level.

Final Answer:
members of the Phaeophyta is greater than members of the Rhodophyta