Question

Diplontic life cycle is shown by:

• A. Volvox
• B. Polysiphonia
• C. Laminaria
• D. Fucus

Hint:

Life Cycle Exceptions in Algae:

• {Fucus} $\rightarrow$ Diplontic.
• {Ectocarpus, Polysiphonia, Kelps} $\rightarrow$ Haplo-diplontic.

Answer 1

The Correct Option is D

Step 1: Understanding Algal Life Cycles:
Most algae are Haplontic (e.g., \textit{Volvox}, \textit{Spirogyra}, \textit{Chlamydomonas}). Some are Haplo-diplontic (e.g., \textit{Ectocarpus}, \textit{Polysiphonia}, Kelps like \textit{Laminaria}). A few are Diplontic.
Step 2: Identifying the Exception:
\textit{Fucus}, a brown alga, is a notable exception among algae as it follows a Diplontic life cycle, similar to gymnosperms and angiosperms. The dominant phase is diploid (2n), and meiosis leads directly to gamete formation.
Step 3: Evaluating Options:
Volvox: Haplontic.
Polysiphonia: Haplo-diplontic.
Laminaria: Haplo-diplontic.
Fucus: Diplontic.
Therefore, the correct answer is Fucus.