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During a long-term ecological study, students examined organisms collected from three different environments — a freshwater pond, damp soil near decaying logs and the digestive tract of animals. Instead of naming organisms directly, scientists recorded only structural, cellular and nutritional features.
P:
Microscopic; no true nucleus; rigid cell covering; survives high salinity and temperature.
Q:
Multicellular; filamentous body; cell wall present; no chlorophyll; grows on dead organic matter.
R:
Unicellular; true nucleus; contractile vacuole present; moves using flagella; shows photosynthesis in light but heterotrophic in the absence of light.
S:
Multicellular; well-differentiated tissues; backbone present; aquatic respiration during early life stage.
T:
Acellular; contains genetic material; remains inactive outside a host cell. (i) Identify one organism that clearly belongs to the Kingdom Fungi. State one observation that supports your answer. (ii) Which organism would be placed in the Kingdom Monera? Mention one characteristic that justifies this placement. (iii) Organisms R and Q are both eukaryotic, yet they are placed in different kingdoms. Analyse the criteria that separate them. (iv) Explain why organism S cannot be classified using the mode of nutrition alone. (v) Organism T does not fit into any of the five kingdoms. Which fundamental characteristic used in classification does it lack and what does this reveal about the limitations of classification systems? (vi) If classification were based only on habitat, which organisms might be incorrectly grouped together? Explain the scientific consequences of such a classification. (vii) Imagine scientists discover a new organism that is multicellular, eukaryotic, lacks chlorophyll and absorbs nutrients from a host externally. Should it be placed under fungi or animalia? Justify your reasoning using classification criteria.
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- (i) Q — Fungi (filamentous, cell wall, no chlorophyll, grows on dead matter). (ii) P — Monera (no true nucleus).
- (iii) R and Q differ by level of organisation — R is unicellular (Protista), Q is multicellular (Fungi). (iv) S (with a backbone) is defined by structure, not nutrition alone.
- (v) T is acellular (a virus) — it lacks cellular organisation, so no kingdom fits, showing the system’s limits. (vi) Habitat-only grouping would wrongly club unrelated organisms sharing a habitat. (vii) The new organism (multicellular, absorbs nutrients externally) fits Fungi , not Animalia (which ingest food).
