Which does not occur in thallus of Marchantia

Options

A. Nostoc
B. Oil cells
C. Starch grains
D. Reticulate thickenings.

Answer

To determine which option does not occur in the thallus of Marchantia, we can analyze each option provided in the question:

1. **Understanding Marchantia**:
- Marchantia is a genus of liverworts, which are non-vascular plants belonging to the phylum Bryophyta. The thallus of Marchantia is a flat, green, and dorsiventral structure that is not differentiated into true stems and leaves.

2. **Analyzing the options**:
- **Option A: Nostoc**:
- Nostoc is a genus of blue-green algae (cyanobacteria) known for its ability to fix nitrogen. It is not a part of the Marchantia thallus and does not form a symbiotic relationship with it. Therefore, this option is a strong candidate for the answer.
- **Option B: Oil cells**:
- Oil cells are present in the thallus of Marchantia. They are specialized cells that produce oils.
- **Option C: Starch grains**:
- Starch grains are also found in the thallus of Marchantia. They serve as storage for starch, which is a carbohydrate.
- **Option D: Reticulate thickenings**:
- Reticulate thickenings are present in the cell walls of Marchantia, contributing to the structural integrity of the thallus.

3. **Conclusion**:
- After analyzing all the options, it is clear that **Nostoc (Option A)** does not occur in the thallus of Marchantia. The other options (oil cells, starch grains, and reticulate thickenings) are indeed present in the thallus.

**Final Answer**: Option A: Nostoc does not occur in the thallus of Marchantia.

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