Yeast
Explanation
Budding is a mode of asexual reproduction where a new individual develops from a small outgrowth or "bud" on the parent organism's body. This process involves nuclear division and cytoplasmic separation. While common in simple multicellular organisms like Hydra, it is also the primary mode of reproduction for certain unicellular eukaryotes.
Option Analysis
- Spirogyra: Incorrect. Spirogyra is a multicellular, filamentous green alga. It reproduces asexually primarily through fragmentation, where the filament breaks into distinct pieces, each growing into a new organism.
- Yeast: Correct. Yeast is a unicellular fungus. It reproduces asexually via budding. During this process, a small protuberance (bud) appears on the parent cell, the nucleus divides, and one daughter nucleus migrates into the bud. The bud eventually detaches to become an independent cell.
- Fern: Incorrect. Ferns are multicellular vascular plants (Pteridophytes). They reproduce sexually and asexually involving the production of spores, not by budding.
- Moss: Incorrect. Mosses are multicellular non-vascular plants (Bryophytes). They reproduce through spore formation and fragmentation.
Key Takeaway: Yeast is a classic example of a single-celled organism that reproduces by budding, distinguishing it from filamentous algae like Spirogyra which use fragmentation.