Sexual reproduction is absent in

Options

A. Chlorophyceae
B. Phenophyceae
C. Rhodophyceae
D. Cyanophyceae

Answer

To determine which group lacks sexual reproduction among Chlorophyse, Phenophyse, Rhodophyse, and Cyanophyse, we can analyze each group based on their reproductive methods.

### Step-by-Step Solution:

1. **Understand Sexual Reproduction**:
- Sexual reproduction involves the formation of gametes (male and female reproductive cells) and the fusion of these gametes to form a zygote. This process typically requires specialized structures (like stamen and pistil in flowering plants) and motile reproductive bodies.

2. **Identify the Groups**:
- **Chlorophyse**: This group includes green algae, which can reproduce sexually and asexually.
- **Phenophyse**: This group includes brown algae, which also have the capability for sexual reproduction.
- **Rhodophyse**: This group includes red algae, which can reproduce both sexually and asexually.
- **Cyanophyse**: This group refers to blue-green algae (cyanobacteria), which primarily reproduce asexually.

3. **Analyze Cyanophyse**:
- Cyanophyse, or cyanobacteria, do not have specialized sexual organs and do not produce gametes. They reproduce mainly through asexual methods such as binary fission, fragmentation, and spore formation.

4. **Conclusion**:
- Since Cyanophyse lacks sexual reproduction mechanisms and relies on asexual reproduction methods, the answer to the question is **Cyanophyse**.

### Final Answer:
Sexual reproduction is absent in **Cyanophyse**.

---