Diversity in Living World – Case-based Questions with Answers
The following 20 case-based questions are grouped by topic. Each scenario is followed by one or more short questions and clear, NCERT-aligned answers. Use these for classroom practice, revision or as model answers for exams.
Riya has a small backyard garden. She notices a tall mango tree, some coriander plants, a climbing money plant near a fence and a patch of pumpkin spreading on the ground.
- Q: Classify the four plants by habit.
A: Mango — tree; coriander — herb; money plant — climber; pumpkin — creeper. - Q: Why is the money plant growing up the fence while pumpkin spreads on the ground?
A: Money plant is a climber needing support to reach light; pumpkin is a creeper that grows along the ground using runners to access space and resources.
Students visit a nearby pond and observe water lilies floating on the surface and tadpoles swimming below.
- Q: Identify the type of plants and animals seen and one adaptation for each.
A: Water lilies — aquatic plants with floating leaves (adaptation: air spaces for buoyancy); Tadpoles — aquatic animals with tails and gills for swimming and breathing underwater.
A slice of bread left in a closed box develops fuzzy green patches after a few days.
- Q: What has grown on the bread and which group does it belong to?
A: Mould (fungus) has grown; it belongs to the fungi group. - Q: Explain why fungi grow on stale bread.
A: Fungi are decomposers that feed on dead organic matter; bread provides food and moisture favourable for fungal growth.
A farmer plants pea crops and notices healthy soil after rotating with legume crops.
- Q: How do legume crops improve soil? Which organisms are involved?
A: Legumes host nitrogen-fixing bacteria in root nodules which convert atmospheric nitrogen into forms plants can use, enriching soil fertility.
During cooking, the family uses curd and bread often. The science teacher explains microbes are involved.
- Q: Name the microorganisms involved in making curd and bread and give one benefit each.
A: Curd — bacteria (Lactobacillus) turn milk into curd (benefit: preserves milk, provides probiotics); Bread — yeast (a fungus) ferments dough producing CO₂ that makes bread rise.
A teacher draws a food chain: Grass → Deer → Tiger.
- Q: Identify producers, consumers and give one role of decomposers in this chain.
A: Producer: Grass. Consumers: Deer (primary consumer/herbivore), Tiger (secondary/top carnivore). Decomposers (fungi, bacteria) break down dead remains returning nutrients to soil which helps grass grow.
In a city park, students notice sparrows, pigeons and mynas feeding on seeds and leftovers.
- Q: Which dietary group do these birds belong to and how do they help the ecosystem?
A: Mostly omnivores/seed-eaters; they help in seed dispersal and keeping insect populations in check, and some are scavengers helping clean the environment.
A class studies cactus plants and notes thick stems and spines.
- Q: Explain how cactus features are adaptations to their habitat.
A: Thick stems store water to survive drought; spines reduce water loss and protect from herbivores; reduced leaves lower transpiration.
Students observe algae blooms in a pond after nearby waste is dumped into it.
- Q: Why do algae blooms occur and what harm can they cause?
A: Excess nutrients (like nitrates/phosphates) cause rapid algal growth; blooms reduce oxygen in water when algae die and decompose, harming aquatic life.
A school starts composting vegetable waste and notices dark, crumbly compost after weeks.
- Q: Which organisms help make compost and why is compost useful?
A: Decomposers like fungi, bacteria, earthworms break down organic waste into nutrient-rich compost that improves soil structure and fertility for plants.
While studying insects, a student finds an ant and a butterfly and records their features.
- Q: List two observable features that help classify these as insects.
A: Both have six legs and three body parts (head, thorax, abdomen); many insects also have wings and antennae—features used for insect classification.
A student notices seeds stuck to her pet dog's fur after playing in a field.
- Q: What method of seed dispersal is this and why is dispersal important?
A: Seed dispersal by animals (epizoochory) where seeds attach to fur; dispersal prevents overcrowding, allows colonisation of new areas and reduces competition.
A farmer observes many caterpillars on maize leaves causing damage.
- Q: Suggest two eco-friendly control measures and explain why identifying the pest matters.
A: Use biological control (introduce natural predators like birds/parasitoids) or manual removal; crop rotation or planting resistant varieties also help. Identifying the pest helps choose targeted control so beneficial organisms are not harmed.
After heavy rain, mushrooms appear in a shady corner of the playground.
- Q: Why do mushrooms appear after rain and what ecological role do they play?
A: Moist conditions favour fungal growth and spore germination; mushrooms are fruiting bodies of fungi (decomposers) that break down dead organic matter and recycle nutrients.
A school aquarium has goldfish and aquatic plants; sometimes plants cover the surface.
- Q: Explain one benefit and one problem of too many plants in the aquarium.
A: Benefit: plants produce oxygen and provide shelter for fish; Problem: excessive plants can block sunlight, use up nutrients, and cause oxygen depletion at night affecting fish.
Two bins: one with vegetable peels (compost), other with plastic waste. After months, compost reduces to soil-like material while plastic remains.
- Q: Explain why compost decomposes but plastic does not and name organisms involved in decomposition.
A: Organic matter is biodegradable and broken down by microbes (bacteria, fungi) and detritivores (earthworms); plastic is non-biodegradable and resists microbial breakdown, persisting in the environment.
Students note that some animals (bats) are active at night while others (sparrows) are active during day.
- Q: What do these activity patterns tell us about adaptation and niche?
A: Activity patterns (nocturnal/diurnal) are behavioral adaptations to avoid competition and predators, and to exploit different food resources—each species occupies a specific ecological niche.
In a market, many plants are sold for different uses: spinach (leaves), mango (fruit), turmeric (rhizome).
- Q: Explain how different plant parts serve human needs with one example each.
A: Leaves (spinach) — food rich in nutrients; Fruits (mango) — food and vitamins; Rhizomes (turmeric) — used as spice/medicine. Plants provide diverse products from different parts.
Students record various organisms in the neighborhood: ants, grass, mango tree, mushroom on compost, stray dog.
- Q: Propose a simple classification table with columns: Organism, Group (plant/animal/fungus/microbe), Habitat.
A: Example: Ant — animal — ground; Grass — plant — soil/ground; Mango tree — plant — soil/tree canopy; Mushroom — fungus — compost/soil; Dog — animal — human habitations.
A garden has few bees because neighbours spray pesticide frequently.
- Q: Why are bees important and how can the community help protect them?
A: Bees pollinate many crops and flowers essential for food production and biodiversity. Protect them by reducing pesticide use, planting bee-friendly flowers, and creating small water sources and habitats.
How to use these cases: Read the scenario, underline key facts, answer concisely and support explanations with examples or diagrams when required. Practice converting cases into short classroom presentations or posters for deeper learning.