Spirogyra reproduces by fragmentation, but a complex animal like a frog cannot. What is the fundamental difference in body organisation between these two organisms that makes fragmentation a viable reproductive strategy for one but not the other?
Generated by claude-sonnet-4-6 · 2026-06-26 01:04 · grounding rag
Model Answer
Spirogyra has a simple body organisation — its cells are not highly specialised and are not organised into distinct tissues or organs. So when it breaks into fragments, each piece contains all the cell types needed to grow into a new individual.
A frog, however, has specialised cells organised into tissues, tissues into organs, and organs placed at definite positions in the body. In such an organism, cell-by-cell division through fragmentation is impractical, as no random fragment would contain the full, organised set of structures required to sustain life and develop into a complete individual.
Source: Chapter 7, Section 7.2.2 – Fragmentation
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Explanation
What examiners look for:
- The key contrast: simple body organisation (Spirogyra) vs. specialised cells → tissues → organs (frog).
- The reason fragmentation fails in complex organisms: organs must be at definite positions; a random fragment cannot provide this.
- Avoid vague answers like "frog is more complex" — you must explain why complexity prevents fragmentation. The textbook phrase "not simply a random collection of cells" is worth referencing.
- 3 marks = 3 distinct points: (1) Spirogyra's simplicity, (2) frog's organised structure, (3) why fragmentation is impractical for the frog.