One can easily differentiate between a protonera of moss and a multicellular, filamentous green alga as the former does not contain chloroplast in the rhizoids and bears buds which give rise to erect, leafy gametophores.

Answer

To differentiate between the protonema of moss and a multicellular, filamentous green alga, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Protonema**:
- Protonema is the initial stage of moss development that occurs after a haploid spore germinates. It forms a filamentous structure that is typically branched.
- This structure is crucial for the moss lifecycle and serves as a precursor to the gametophore.

2. **Characteristics of Protonema**:
- Protonema does not contain chloroplasts in its rhizoids. Rhizoids are root-like structures that anchor the moss but do not perform photosynthesis.
- The protonema is usually a simple, filamentous structure that can spread out and absorb water and nutrients.

3. **Development into Gametophore**:
- As the protonema matures and receives adequate nutrition, it develops into a gametophore.
- The gametophore is the leafy structure that is recognizable as the adult form of the moss gametophyte.

4. **Comparison with Multicellular Green Alga**:
- In contrast, multicellular filamentous green algae typically possess chloroplasts throughout their structure, including their rhizoids.
- Algae do not have a distinct protonema stage and do not develop into gametophores in the same way that moss does.

5. **Conclusion**:
- The key differences lie in the presence of chloroplasts in the rhizoids and the developmental stages. Protonema does not have chloroplasts in its rhizoids and develops into leafy gametophores, while multicellular green algae have chloroplasts and do not undergo this specific developmental process.