Complete Evidence Analysis:
Claim: Potato (Solanum tuberosum) is an underground STEM tuber (NOT a root)
| Evidence | Observation | Conclusion |
|---|---|---|
| "Eyes" visible on potato surface | "Eyes" = axillary buds at nodes | Buds = stem feature (roots never have axillary buds) |
| Nodes and internodes | Slight ridges (nodes) and zones between them (internodes) visible | Nodes/internodes = stem features exclusively |
| Greens when placed in light | Chlorophyll synthesis occurs | Stems can photosynthesize; roots cannot (no chloroplasts in light) |
| Arises from stolons | Stolon (subaerial stem) swells at tip to form tuber | Confirms stem origin |
| Scale leaves at nodes | Tiny cataphylls present at eye (bud) nodes | Leaves/scale leaves = stem feature |
Counter-argument from skeptic: "It grows underground, so it must be a root" Rebuttal: Underground location does NOT determine root vs. stem. Multiple genuine stem modifications (ginger, onion, corm) also grow underground. The PRESENCE of nodes, internodes, axillary buds, and scale leaves is the definitive criterion.
NEET Question Pattern:
- "Potato is a modification of ___" → Stem (stem tuber)
- "What confirms potato is a stem?" → Eyes (axillary buds at nodes)
- "What makes sweet potato a root?" → Absence of nodes, internodes, and buds