An alga which exhibits diplontic life cycle is

Options

A. Spirogyra
B. Fucus
C. Polysiphonia
D. Ulothrix

Answer

To determine which alga exhibits a diplontic life cycle, we can follow these steps:

### Step 1: Understand the Types of Life Cycles in Algae
Algae can exhibit different types of life cycles, primarily:
- **Haplontic**: The dominant phase is haploid, and the zygote undergoes meiosis to produce spores.
- **Diplontic**: The dominant phase is diploid, and the gametes are produced by meiosis from the diploid sporophyte.
- **Haplodiplontic**: This is an intermediate condition where both haploid and diploid phases are present.

### Step 2: Identify the Algae in the Question
The options given are:
1. Spirogyra
2. Fucus
3. Polysiphonia
4. Eulothrix

### Step 3: Analyze Each Option
- **Spirogyra**: Exhibits a haplontic life cycle.
- **Fucus**: Exhibits a diplontic life cycle, where the sporophyte is the dominant phase.
- **Polysiphonia**: Exhibits a haplodiplontic life cycle.
- **Eulothrix**: Also does not exhibit a diplontic life cycle.

### Step 4: Conclusion
Based on the analysis, the alga that exhibits a diplontic life cycle is **Fucus**.

### Final Answer:
**Fucus** is the alga that exhibits a diplontic life cycle.

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