Which one of the two multicellular organisms Spirogyra and Planaria reproduces by regeneration and why ? Give an example of any other organism which can also reproduce by the same process.
Generated by claude-sonnet-4-6 · 2026-06-15 06:44 · grounding rag
Model Answer
Planaria reproduces by regeneration. Planaria has a simple body organisation with specialised cells that can proliferate and develop into all body parts, allowing each cut piece to grow into a complete organism.
Spirogyra, however, reproduces by fragmentation, not regeneration.
Another example: Hydra can also reproduce by regeneration.
Source: How do Organisms Reproduce?, Section 7.2.3 Regeneration
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Explanation
- The question tests whether students can distinguish between fragmentation (Spirogyra) and regeneration (Planaria) — two different processes often confused.
- Key reason to mention: Planaria has specialised cells that proliferate and undergo organised development, making regeneration possible.
- Hydra is the go-to textbook example for the "other organism" — it is explicitly mentioned alongside Planaria in the regeneration section.
- Do not say Spirogyra reproduces by regeneration — the passage clearly states Spirogyra uses fragmentation (breaking into pieces upon maturation).