1) 20 Important Words & Meanings (Meanings in Hindi)

2) Important Notes (Quick Revision)

• Diversity: Enormous variety exists in plants and animals—unicellular to multicellular, aquatic to desert, vertebrates to invertebrates.
• Adaptation: Gradual, continuous changes in structure/behaviour that help survival in a habitat; not sudden.
• Aquatic plants: Waxy leaf surface, large floating leaves, air spaces for buoyancy, ribbon-like leaves; roots may be short/fibrous or even free-floating.
• Desert plants: Leaves reduced to spines; thick waxy layer; green fleshy stems (photosynthesis); deep/spreading roots to find water.
• Snowy regions (Conifers): Conical shape with sloping branches prevents snow accumulation; thick bark tolerates cold.
• Forests & Grasslands: Tall trees compete for light; climbers use tendrils; grasses have fibrous roots that prevent soil erosion.
• Special nutrition: Cuscuta (dodder) is parasitic with haustorial roots; insectivorous plants (e.g., Venus flytrap, pitcher plant) trap insects to obtain nitrogen.
• Aquatic animals: Streamlined (spindle-shaped) body, scales/fins, gills to breathe, air bladder for floating.
• Amphibians (e.g., frog): Webbed feet, smooth slippery skin, breathe via skin in water and lungs on land; long hind legs for leaping; dorsal colours help camouflage.
• Birds & aerial animals: Feathers, hollow bones, forelimbs → wings, streamlined body reduce air resistance; insects have 2 pairs of wings & 6 legs; bats use patagium.
• Reptiles: Scaly skin; most creep using body muscles; claws/thin soles (e.g., lizards); snakes with scaly ventral plates.
• Forest carnivores: Strong legs, sharp claws & canines; padded paws (tiger) for silent stalking; forward-facing eyes for depth perception.
• Herbivores: Side-placed eyes (wide view), long legs/hooves for running, strong molars; colours blend with surroundings.
• Desert animals: Thick skin, long legs with cushioned soles, nostril flaps, long eyelashes; many are nocturnal or burrow-dwelling.
• Camouflage: Blending with surroundings for protection/hunting (butterflies, grasshoppers, lizards).
• Darwin: Survival of the fittest; natural selection preserves beneficial traits across generations.
• Why classify?: Easier study of vast diversity; organisms grouped by similarities/differences into a hierarchy: Kingdom → Phylum/Division → Class → Order → Family → Genus → Species (often written as $K \\to P \\to C \\to O \\to F \\to G \\to S$).
• Binomial nomenclature: Two-part scientific name—Genus species; e.g., dog = Canis lupus familiaris, cow = Bos taurus, hibiscus = Hibiscus rosa-sinensis, jowar = Sorghum bicolor.
• Key idea: It is our duty to conserve biodiversity.

3) 20 Important “One-Word Answer” Type Questions

1. Which plant has haustorial (sucking) roots?
   Cuscuta — a parasitic plant that absorbs food from its host.
2. Which organ helps fish to breathe?
   Gills — for respiration in water.
3. Name the body shape that reduces water resistance in fish.
   Spindle-shaped (streamlined) — tapering at both ends.
4. Which desert plant has a fleshy, green stem?
   Cactus — stem stores water and does photosynthesis.
5. Which layer on lotus leaves makes water trickle off?
   Waxy layer — prevents wetting/rotting.
6. Who proposed “survival of the fittest”?
   Charles Darwin — first principle of his evolution theory.
7. What is the two-part naming system of organisms called?
   Binomial nomenclature — Genus + species.
8. Give one conifer found in snowy regions.
   Deodar (or Pine) — conical shape with sloping branches.
9. Which roots in grasses help prevent soil erosion?
   Fibrous roots — form a dense mat in soil.
10. Which climbing structure is spring-like in some plants?
    Tendrils — help climbers/vines reach sunlight.
11. Which animal is called the “Ship of the desert”?
    Camel — adapted to move on sand and conserve water.
12. Forelimbs are modified into wings in which group?
    Birds — lightweight, feather-covered bodies.
13. Which internal organ helps fish float?
    Air bladder — provides buoyancy.
14. Animals living on land and in water are called?
    Amphibians — e.g., frog.
15. Animals without a backbone are called?
    Invertebrates — e.g., insects, worms.
16. What is the basic unit of classification?
    Species — organisms that interbreed to produce similar offspring.
17. Human beings belong to which kingdom?
    Animalia — multicellular, heterotrophic.
18. Write the scientific name of dog.
    Canis lupus familiaris.
19. Name one insectivorous plant.
    Venus flytrap — traps insects for nitrogen.
20. Which feature on tiger’s feet aids silent movement?
    Padded paws — help stealthily approach prey.

4) 20 Very Short Answer Questions

1. Why don’t lotus leaves remain wet?
   Because of a waxy coating that repels water and prevents rotting.
2. Why are desert plants often leafless or have needle-like leaves?
   To reduce water loss by evaporation (transpiration).
3. How does a conical shape help conifers in snow?
   Sloping branches shed snow, preventing breakage.
4. Why are cactus stems green?
   They contain chlorophyll and do photosynthesis in absence of leaves.
5. What do frogs use to swim easily?
   Webbed toes act like oars; smooth skin reduces drag.
6. Why are frog’s hind legs long?
   For powerful leaping on land and thrust in water.
7. Why are tiger’s eyes in front?
   Front-facing eyes give depth perception to judge distance of prey.
8. Why are deer’s eyes on the side?
   Side placement gives a wide field of view to spot predators.
9. Why don’t duck’s feathers get soaked?
   Waxy feathers repel water.
10. What is camouflage?
    Blending with surroundings using colour/shape to hide.
11. Which roots of aquatic floaters are not anchored?
    Free-floating roots—not fixed into soil.
12. Why do many desert animals stay in burrows by day?
    To avoid extreme heat and conserve water.
13. Which plant is a parasite with yellow, wire-like stems?
    Cuscuta (dodder).
14. What do insectivorous plants mainly gain from insects?
    Nitrogen for growth in poor soils.
15. Name the body covering common in reptiles.
    Scales on the skin.
16. What helps birds remain lightweight?
    Hollow bones and feathers.
17. Give one reason classification is needed.
    It makes the study of the vast diversity systematic.
18. Write the scientific name of cow.
    Bos taurus.
19. What does the air bladder do in fish?
    Provides buoyancy to float at different depths.
20. State Darwin’s second principle.
    Natural selection—useful variations are preserved.

5) 20 Short Answer Questions (2–3 lines)

1. Differentiate between terrestrial and aquatic plants in one or two points.
   Aquatic plants have waxy surfaces, often air spaces and floating leaves; terrestrial plants usually have strong stems and well-anchored roots suited for land.
2. How are desert plants adapted to scarcity of water?
   Leaves reduced to spines, thick waxy cuticle, fleshy stems to store water, and deep/spreading roots to absorb water.
3. Explain adaptations of conifers to snowy regions.
   Conical shape with sloping branches sheds snow; thick bark protects from cold; needle-like leaves reduce water loss.
4. How do tendrils help climbers?
   Spring-like tendrils coil around supports, allowing climbers to reach sunlight with minimal woody tissue.
5. Describe two adaptations of frogs for an amphibious life.
   Webbed feet for swimming; cutaneous respiration in water and lungs on land; long hind legs for leaping.
6. What features aid birds in flight?
   Hollow bones, feathers, forelimbs modified as wings, and a streamlined body reduce air resistance.
7. How are carnivores adapted for catching prey?
   Strong legs for speed, sharp claws and canines for tearing, padded paws for stealth, and front-facing eyes for depth.
8. State two adaptations of herbivores for safety.
   Side-placed eyes for wide view, long legs/hooves for fast running; colours often blend with habitat.
9. Why are insectivorous plants found in nitrogen-poor soils?
   They trap insects to obtain nitrogen, compensating for poor soil nutrients.
10. Explain the parasitic mode of nutrition in Cuscuta.
    Cuscuta is leafless with yellow stems and uses haustorial roots to absorb food/water from the host’s conducting tissues.
11. What is camouflage? Give an example.
    Camouflage is blending with surroundings; e.g., a frog’s dorsal colour merges with grasses.
12. State Darwin’s two main ideas in brief.
    Survival of the fittest—best-adapted organisms survive; Natural selection—beneficial traits are preserved across generations.
13. Why do we classify organisms?
    To organise the immense diversity, making description, study, and identification easier and more meaningful.
14. Write the hierarchical ranks used in classification.
    Kingdom → Phylum/Division → Class → Order → Family → Genus → Species (i.e., $K \\to P \\to C \\to O \\to F \\to G \\to S$).
15. What is binomial nomenclature?
    A two-part scientific naming system: Genus species, e.g., Homo sapiens.
16. Give two adaptations of desert animals.
    Thick skin to reduce water loss, flat cushioned feet for sand; nostril flaps and long eyelashes protect from dust.
17. How are aquatic plants kept afloat?
    Air spaces in stems/petioles and broad floating leaves provide buoyancy.
18. Distinguish vertebrates from invertebrates in one point.
    Vertebrates have a backbone; invertebrates do not.
19. Write any two scientific names mentioned in this chapter.
    Canis lupus familiaris (dog), Bos taurus (cow), Hibiscus rosa-sinensis (hibiscus), Sorghum bicolor (jowar).
20. How do sloping branches help plants in rainy/snowy places?
    They shed water/snow quickly, preventing accumulation and damage.

6) Textbook Exercise – Answers

Colour Legend

Questions are in Red   |   Answers are in Green