Comparative flagellation: Considering motile reproductive cells, how does the number of flagella in members of Phaeophyta compare with that in members of the Oomycota?

Introduction / Context:
Flagellar form and number are classic characters for distinguishing algal and protist groups. Both brown algae and oomycetes produce motile stages with characteristic heterokont flagella, useful in comparative biology questions.

Given Data / Assumptions:

• Phaeophyta refers to brown algae with motile gametes in many taxa.
• Oomycota produce biflagellate zoospores in their life cycles.
• We compare the number of flagella on their motile cells.

Concept / Approach:
Heterokont organisms typically bear two unequal flagella: one tinsel type with tripartite hairs and one smooth whiplash type. Brown algal sperm cells are usually biflagellate. Oomycete zoospores are also biflagellate with the same heterokont pattern. Therefore, the number is approximately equal, even though life stages and positions of the flagella can differ.

Step-by-Step Solution:
Identify heterokont lineage traits: two unequal flagella.Confirm Phaeophyta sperm are biflagellate in many groups.Confirm Oomycota zoospores are biflagellate.Conclude the number is approximately equal between the two divisions.

Verification / Alternative check:
Electron microscopy reveals the tinsel flagellum with mastigonemes and a smooth flagellum in both groups, supporting the heterokont designation.

Why Other Options Are Wrong:

• Greater or lesser statements are incorrect because both groups commonly show two flagella.
• None of the above is incorrect because equality is the accepted comparison.

Common Pitfalls:
Confusing number with orientation; some oomycete zoospores exhibit anterior and posterior flagella positions, but the count remains two.

Final Answer:
members of the Phaeophyta is approximately equal to members of the Oomycota