1Revise, Reflect, Refine15 questions
Q.1Meena and Hari observed an animal in their garden. Hari called it an insect while Meena said it was an earthworm. Choose the correct option which confirms that it is an insect. (i) Bilateral symmetrical body (ii) Body with jointed legs (iii) Cylindrical body (iv) Body with little segmentationv
Answer:(ii) Body with jointed legs.
Q.2Sponges represent one of the simplest animal body plans. Their bodies lack true tissues and organs. Which feature of sponge cells supports its classification under the animal kingdom? (i) Absence of mitochondria (ii) Ability to photosynthesise (iii) Presence of a cell membrane (iv) Presence of a cell wallv
Answer:(iii) Presence of a cell membrane.
Q.3Observe two different animals in your immediate environment. What features help you distinguish between them? How do these features help place them into different groups?v
Answer:Features such as body segmentation, number of legs, wings, backbone, body covering and movement distinguish animals. For example, an ant has jointed legs and an external skeleton, placing it among arthropods, while a lizard has a backbone and scales, placing it among vertebrates/reptiles.
Q.4How would a scientist justify choosing cellular organisation as a more fundamental characteristic for the basis of classification rather than the presence of xylem and phloem?v
Answer:Cellular organisation is fundamental because it applies to all organisms and separates prokaryotes/eukaryotes and unicellular/multicellular forms. Xylem and phloem occur only in vascular plants, so they are too narrow for broad classification.
Q.5You find an unlabelled slide of a single-celled organism that has a well-defined nucleus and multiple cilia. Which group would it most likely belong to? Give reasons.v
Answer:It most likely belongs to Protista because it is unicellular, eukaryotic, has a well-defined nucleus and uses cilia for movement, as in ciliates such as Paramecium.
Q.6How does the diversity of organisms contribute to the balance and stability of an ecosystem?v
Answer:Diversity supports producers, consumers, decomposers, pollination, food webs and nutrient cycling. It makes ecosystems more stable because different organisms can maintain functions if some species decline.
Q.7If all unicellular organisms were grouped into a single kingdom, what problems would arise?v
Answer:It would group very different organisms together, such as bacteria without a true nucleus and unicellular eukaryotes with a nucleus. This would ignore cellular organisation, nutrition, reproduction and evolutionary relationships.
Q.8Viruses were studied in earlier classes. Why are they not placed in any of the five kingdoms? Give reasons.v
Answer:Viruses are acellular, lack independent metabolism, and reproduce only inside host cells, so they do not fit the cellular basis of five-kingdom classification.
Q.9If you were asked to revise the five kingdom classification, would you create a separate category for viruses or keep them outside the system? Justify your answer and explain what this indicates about the evolving nature of scientific classification.v
Answer:Viruses should be kept outside the five kingdoms or placed in a separate acellular category because they have genetic material but lack cells and independent metabolism. This shows classification systems change as new evidence challenges old criteria.
Q.10Viruses contain genetic material like living organisms but lack cellular organisation. Which features prevent them from fitting into the five kingdom system? What does this tell us about the limitations of classification systems?v
Answer:Viruses lack cellular organisation, cytoplasm, organelles and independent metabolism, and reproduce only in host cells. This shows that systems based on cellular life have limits for acellular entities.
Q.11Both pteridophytes and bryophytes lack flowers and seeds, yet they are placed in different groups. Explain this classification using their key features.v
Answer:Bryophytes are non-vascular and lack true roots, stems and leaves. Pteridophytes have vascular tissues and differentiated roots, stems and leaves. Hence they are placed in different groups even though both lack flowers and seeds.
Q.12In the classification hierarchy, which group — class or genus — has fewer members but more features in common? Explain your answer.v
Answer:Genus has fewer members and more shared features than class because genus is a lower, more specific taxonomic category.
Q.13A scientist discovers a new organism with the characteristic features of locomotion and autotrophic nutrition. Which character(s) would help the scientist identify the organism belonging to Protista according to the five kingdom classification?v
Answer:A unicellular eukaryotic body, locomotory structures such as flagella/cilia, and autotrophic nutrition would point to Protista, since protists can show plant-like and animal-like characters.
Q.14A researcher identified a unicellular eukaryotic organism as fungi. What identification key would you suggest according to the five kingdom classification to keep a unicellular organism in the Kingdom Fungi?v
Answer:Check for eukaryotic cell organisation, absence of chlorophyll, absorptive heterotrophic nutrition, a cell wall, and fungal reproduction such as spores or budding. A unicellular organism with these features may be placed in Fungi, like yeast.
Q.15During 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 as given in the table below. Organisms Key Observations Microscopic; no true nucleus; rigid cell covering; survives high salinity and P temperature Multicellular; filamentous body; cell wall present; no chlorophyll; grows on Q dead organic matter Unicellular; true nucleus; contractile vacuole present; moves using flagella; R shows photosynthesis in light but heterotrophic in the absence of light Multicellular; well-differentiated tissues; backbone present; aquatic S respiration during early life stage T Acellular; contains genetic material; remains inactive outside a host cell The students realised that some organisms fit neatly into Whittaker’s five kingdom classification, while others challenged the very basis of this classification. Based on the case study, answer the following questions — (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? 250 (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.v
Answer:Q belongs to Fungi because it is multicellular, filamentous, lacks chlorophyll and grows on dead organic matter. P belongs to Monera because it has no true nucleus. R and Q are both eukaryotic, but R is unicellular and partly autotrophic while Q is multicellular absorptive heterotroph. S needs body organisation/backbone, not nutrition alone. T lacks cellular organisation, showing a limitation of five-kingdom classification. Habitat-only grouping would wrongly group unrelated pond/soil organisms. A multicellular eukaryote lacking chlorophyll and absorbing nutrients externally belongs to Fungi.