Chapter 24 of 24
Chapter 24: Web of Life
Ecological Harmony: Food Webs, Sun, Soil, Water, Air, Plants, Animals, and Human Coexistence | CBSE Session 2026–27
Core Pedagogical Competencies & Concepts
- The interconnectedness of all living and non-living elements: Sun, Air, Water, Soil, Plants, Animals, and Humans.
- Everything in nature is linked in a dynamic 'Web of Life'; removing even one thread affects all other members.
- How non-living abiotic factors (Sun, Water, Soil) provide the foundation for all living biotic organisms.
- Human responsibility: Protecting forests, preventing water pollution, and living in respectful equilibrium with nature.
All Textbook Exercises & In-Text Tasks (17 Questions)
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Q1
Web of Life Concept
What is meant by the 'Web of Life'? How are plants, animals, and non-living elements tied together?
[3 Marks]
✅ Step-by-Step Solution & Working
The Web of Life describes the intricate, interdependent network of relationships connecting all living creatures (plants, animals, microorganisms, humans) with non-living environmental elements (sunlight, air, water, soil).
• The Sun powers plant photosynthesis.
• Plants absorb rainwater and soil minerals to synthesize food and oxygen.
• Herbivores eat plants, and carnivores prey on herbivores.
• When organisms die, decomposers return nutrients back to the soil, sustaining the eternal cycle.
• The Sun powers plant photosynthesis.
• Plants absorb rainwater and soil minerals to synthesize food and oxygen.
• Herbivores eat plants, and carnivores prey on herbivores.
• When organisms die, decomposers return nutrients back to the soil, sustaining the eternal cycle.
CBSE Step-by-Step Marking Scheme
Definition of the ecological web connecting biotic and abiotic elements
1.5 Marks
Cyclical flow: Sun ➔ Plants ➔ Animals ➔ Decomposers ➔ Soil
1.5 Marks
Q2
Impact of Disruption
What would happen to the Web of Life if all green trees on Earth were cut down?
[3 Marks]
✅ Step-by-Step Solution & Working
If all green trees were destroyed:
1. Atmospheric oxygen would plummet while heat-trapping carbon dioxide would soar, causing runaway global heating.
2. Herbivorous animals would starve to death, causing carnivores to die out soon after.
3. Soil would wash away without tree roots to bind it, causing desertification and the total collapse of human civilization.
1. Atmospheric oxygen would plummet while heat-trapping carbon dioxide would soar, causing runaway global heating.
2. Herbivorous animals would starve to death, causing carnivores to die out soon after.
3. Soil would wash away without tree roots to bind it, causing desertification and the total collapse of human civilization.
CBSE Step-by-Step Marking Scheme
Oxygen/carbon dioxide collapse
1 Mark
Food chain starvation
1 Mark
Soil erosion and collapse of life
1 Mark
Q3
Human Role as Stewards
Why are humans not 'owners' of the Earth, but rather 'caretakers' or 'trustees'?
[2 Marks]
✅ Step-by-Step Solution & Working
Humans are simply one thread woven into the vast web of life, completely dependent on clean air, fresh water, and plants for our very survival. As caretakers (custodians), it is our sacred responsibility to protect all species and pass down a healthy, vibrant planet to future generations.
CBSE Step-by-Step Marking Scheme
Humans as dependent threads in the web rather than owners
1 Mark
Stewardship and conservation responsibility
1 Mark
Q4
Ecology & Interconnection • Web of Life
In 'Web of Life':
(a) What does a 'Food Web' show?
(b) Trace a simple 4-link food chain on land: Grass $\rightarrow$ Grasshopper $\rightarrow$ Frog $\rightarrow$ Snake.
[3 Marks]
(a) What does a 'Food Web' show?
(b) Trace a simple 4-link food chain on land: Grass $\rightarrow$ Grasshopper $\rightarrow$ Frog $\rightarrow$ Snake.
✅ Step-by-Step Solution & Working
Food Web Science:
(a) Definition:
• A food web shows how all living organisms (plants, herbivores, carnivores, humans) and non-living elements (sun, water, soil) are connected together in nature for energy and survival.
(b) 4-Link Food Chain:
• Green Grass (uses sunlight to make food) $\rightarrow$
• Grasshopper (eats grass) $\rightarrow$
• Frog (eats grasshopper) $\rightarrow$
• Snake (eats frog).
(a) Definition:
• A food web shows how all living organisms (plants, herbivores, carnivores, humans) and non-living elements (sun, water, soil) are connected together in nature for energy and survival.
(b) 4-Link Food Chain:
• Green Grass (uses sunlight to make food) $\rightarrow$
• Grasshopper (eats grass) $\rightarrow$
• Frog (eats grasshopper) $\rightarrow$
• Snake (eats frog).
CBSE Step-by-Step Marking Scheme
Definition of ecological interdependence
1.5 M
Accurate 4-step linear food chain
1.5 M
Q5
Connecting String Activity • Classroom Ecosystem
In the textbook classroom game with a ball of string:
(a) Each child wears a badge of an animal, plant, sun, or water. How does the string connect them all?
(b) What happens when one child (like 'Forest') lets go of the string?
[3 Marks]
(a) Each child wears a badge of an animal, plant, sun, or water. How does the string connect them all?
(b) What happens when one child (like 'Forest') lets go of the string?
✅ Step-by-Step Solution & Working
String Game Insights:
(a) Interconnection:
• The ball of string is passed from Sun to Grass, Grass to Deer, Deer to Tiger, Tiger to Soil, creating an intricate web of string where everyone is holding a piece.
(b) Breakage of Balance:
• When 'Forest' drops the string, the tension collapses, and all other connected children feel their strings sag. This visually demonstrates that if forests are destroyed, every animal, water source, and human is directly harmed.
(a) Interconnection:
• The ball of string is passed from Sun to Grass, Grass to Deer, Deer to Tiger, Tiger to Soil, creating an intricate web of string where everyone is holding a piece.
(b) Breakage of Balance:
• When 'Forest' drops the string, the tension collapses, and all other connected children feel their strings sag. This visually demonstrates that if forests are destroyed, every animal, water source, and human is directly harmed.
CBSE Step-by-Step Marking Scheme
Passing string creating visual web of life
1.5 M
Ecosystem collapse demonstration explained
1.5 M
Q6
Natural Elements • Non-Living Supporters of Life
Name three non-living elements of nature without which no plant or animal could survive.
[3 Marks]
✅ Step-by-Step Solution & Working
Non-Living Life Supporters:
1. Sunlight (Sun): Ultimate source of heat and energy for plant photosynthesis.
2. Water: Essential for circulation, digestion, and life fluids in all cells.
3. Air (Oxygen): Essential for respiration in animals, humans, and plants.
1. Sunlight (Sun): Ultimate source of heat and energy for plant photosynthesis.
2. Water: Essential for circulation, digestion, and life fluids in all cells.
3. Air (Oxygen): Essential for respiration in animals, humans, and plants.
CBSE Step-by-Step Marking Scheme
Sunlight, Water, and Air named with biological reasons
3.0 M
Q7
Earth Pledge • Global Conservation
Why is human survival directly dependent on preserving wildlife and biodiversity?
[2 Marks]
✅ Step-by-Step Solution & Working
Biosphere Integrity:
• Humans are not separate from nature; we are just one strand in the web of life. Forests provide our rainfall and oxygen, bees pollinate our crops, and rivers provide our drinking water. If nature is degraded, human civilization cannot survive.
• Humans are not separate from nature; we are just one strand in the web of life. Forests provide our rainfall and oxygen, bees pollinate our crops, and rivers provide our drinking water. If nature is degraded, human civilization cannot survive.
CBSE Step-by-Step Marking Scheme
Ecosystem services and human dependence on nature explained
2.0 M
Q8
Observation Time • Animals and Habits
In Chapter 24 ('Web of Life'), what animals did the characters observe, and how do they move from place to place?
[3 Marks]
✅ Step-by-Step Solution & Working
Observations:
Animals move in diverse ways adapted to their bodies:
• Birds (Crow, Pigeon): Fly using wings and hop on two feet.
• Mammals (Cow, Dog): Walk and run on four legs.
• Reptiles (Lizard, Snake): Crawl on walls or slither on the ground.
• Insects (Ant, Grasshopper): Walk on six legs and hop/fly.
Animals move in diverse ways adapted to their bodies:
• Birds (Crow, Pigeon): Fly using wings and hop on two feet.
• Mammals (Cow, Dog): Walk and run on four legs.
• Reptiles (Lizard, Snake): Crawl on walls or slither on the ground.
• Insects (Ant, Grasshopper): Walk on six legs and hop/fly.
CBSE Step-by-Step Marking Scheme
Birds, mammals, reptiles, insects movement
3 M
Q9
Find Out & Write • Animal Habitats
Name two animals that live:
(a) On trees
(b) In water
(c) On land
(d) Underground in burrows.
[2 Marks]
(a) On trees
(b) In water
(c) On land
(d) Underground in burrows.
✅ Step-by-Step Solution & Working
Habitats:
• (a) On trees: Monkey, Squirrel, Owl.
• (b) In water: Fish, Frog, Crocodile.
• (c) On land: Horse, Elephant, Goat.
• (d) In burrows: Rabbit, Earthworm, Snake.
• (a) On trees: Monkey, Squirrel, Owl.
• (b) In water: Fish, Frog, Crocodile.
• (c) On land: Horse, Elephant, Goat.
• (d) In burrows: Rabbit, Earthworm, Snake.
CBSE Step-by-Step Marking Scheme
Correct examples for all 4 habitats
2 M
Q10
Discuss & Share • Our Senses
How do our five sense organs help us understand and navigate our daily environment?
[3 Marks]
✅ Step-by-Step Solution & Working
Five Senses:
1. Eyes: Help us see shapes, colours, and identify hazards.
2. Ears: Help us hear traffic horns, spoken words, and alarm sounds.
3. Nose: Helps us smell food, flowers, and detect smoke or gas leaks.
4. Tongue: Helps us taste sweet, sour, salty, and bitter food.
5. Skin: Helps us feel touch, heat, cold, roughness, and pain.
1. Eyes: Help us see shapes, colours, and identify hazards.
2. Ears: Help us hear traffic horns, spoken words, and alarm sounds.
3. Nose: Helps us smell food, flowers, and detect smoke or gas leaks.
4. Tongue: Helps us taste sweet, sour, salty, and bitter food.
5. Skin: Helps us feel touch, heat, cold, roughness, and pain.
CBSE Step-by-Step Marking Scheme
All 5 sense organs explained with functions
3 M
Q11
Water Cycle & Weather • Rain and Clouds
Where does rainwater come from, and why do plants and trees look fresher and greener after a rain shower?
[3 Marks]
✅ Step-by-Step Solution & Working
Rain and Plant Health:
• Rain comes from water evaporating from rivers, ponds, and seas, forming clouds in the sky that cool and condense into rain droplets.
• Rain washes off thick dust accumulated on leaves, unblocks stomata for breathing, and deeply soaks the roots with fresh mineral-rich moisture.
• Rain comes from water evaporating from rivers, ponds, and seas, forming clouds in the sky that cool and condense into rain droplets.
• Rain washes off thick dust accumulated on leaves, unblocks stomata for breathing, and deeply soaks the roots with fresh mineral-rich moisture.
CBSE Step-by-Step Marking Scheme
Water cycle / cloud formation
1.5 M
Why plants look greener after rain
1.5 M
Q12
Food Diversity • Regional Diets
Why do people living in Kerala eat more rice, fish, and coconut, while people in Punjab eat more wheat chapatis, mustard greens, and lassi?
[3 Marks]
✅ Step-by-Step Solution & Working
Regional Food Factors:
• What people eat depends directly on what grows easily and abundantly in their climate and geography.
• Kerala has coastal climate, abundant rainfall, and coconut groves, making fish and rice staples.
• Punjab has fertile plains ideal for wheat and mustard cultivation, and a strong dairy culture.
• What people eat depends directly on what grows easily and abundantly in their climate and geography.
• Kerala has coastal climate, abundant rainfall, and coconut groves, making fish and rice staples.
• Punjab has fertile plains ideal for wheat and mustard cultivation, and a strong dairy culture.
CBSE Step-by-Step Marking Scheme
Climate and agriculture connection
1.5 M
Kerala and Punjab examples explained
1.5 M
Q13
Cooking Methods • Kitchen Science
Match each food item to its primary method of cooking:
(a) Idli — (1) Frying
(b) Puri — (2) Steaming
(c) Roti — (3) Roasting on Tawa.
[3 Marks]
(a) Idli — (1) Frying
(b) Puri — (2) Steaming
(c) Roti — (3) Roasting on Tawa.
✅ Step-by-Step Solution & Working
Matching:
• (a) Idli — (2) Steaming
• (b) Puri — (1) Frying in oil
• (c) Roti — (3) Roasting on Tawa.
• (a) Idli — (2) Steaming
• (b) Puri — (1) Frying in oil
• (c) Roti — (3) Roasting on Tawa.
CBSE Step-by-Step Marking Scheme
Idli-Steaming, Puri-Frying, Roti-Roasting
3 M
Q14
Shelter & Houses • Diversity in Homes
Why are houses in heavy-rainfall regions like Assam built on bamboo stilts with sloping roofs?
[3 Marks]
✅ Step-by-Step Solution & Working
Stilt Houses:
• Bamboo Stilts: Keep the house 10 to 12 feet above ground level to prevent floodwaters and wild animals from entering.
• Sloping Roofs: Allow torrential rainwater to slide off quickly without accumulating or causing leaks.
• Bamboo Stilts: Keep the house 10 to 12 feet above ground level to prevent floodwaters and wild animals from entering.
• Sloping Roofs: Allow torrential rainwater to slide off quickly without accumulating or causing leaks.
CBSE Step-by-Step Marking Scheme
Reason for bamboo stilts (floods)
1.5 M
Reason for sloping roof (rain runoff)
1.5 M
Q15
Community Helpers • Occupations
Identify the worker who:
(a) Mends our shoes
(b) Delivers letters and parcels
(c) Shapes clay into earthen pots on a wheel
(d) Treats sick people and prescribes medicines.
[2 Marks]
(a) Mends our shoes
(b) Delivers letters and parcels
(c) Shapes clay into earthen pots on a wheel
(d) Treats sick people and prescribes medicines.
✅ Step-by-Step Solution & Working
Community Helpers:
• (a) Mends shoes: Cobbler
• (b) Delivers letters: Postman / Mail carrier
• (c) Shapes clay pots: Potter
• (d) Treats sick people: Doctor.
• (a) Mends shoes: Cobbler
• (b) Delivers letters: Postman / Mail carrier
• (c) Shapes clay pots: Potter
• (d) Treats sick people: Doctor.
CBSE Step-by-Step Marking Scheme
Cobbler, Postman, Potter, Doctor
2 M
Q16
Web of Life • Food Chain
What is the 'Web of Life'? Draw a simple food chain showing how grass, deer, and lion are connected.
[3 Marks]
✅ Step-by-Step Solution & Working
Web of Life & Food Chain:
• The Web of Life shows that every living organism is interconnected and depends on others for survival.
• Food Chain: Sunlight → Grass (Producer) → Deer (Herbivore) → Lion (Carnivore).
If grass disappears, deer starve; if deer disappear, lions cannot survive.
• The Web of Life shows that every living organism is interconnected and depends on others for survival.
• Food Chain: Sunlight → Grass (Producer) → Deer (Herbivore) → Lion (Carnivore).
If grass disappears, deer starve; if deer disappear, lions cannot survive.
CBSE Step-by-Step Marking Scheme
Definition of Web of Life
1.5 M
Grass → Deer → Lion chain explained
1.5 M
Q17
Review Questions • True or False
Write True or False:
(a) Blind people can read books written in Braille script using their fingertips.
(b) Rainwater is the main natural source of fresh water on Earth.
(c) Animals do not have feelings and cannot communicate danger to each other.
[3 Marks]
(a) Blind people can read books written in Braille script using their fingertips.
(b) Rainwater is the main natural source of fresh water on Earth.
(c) Animals do not have feelings and cannot communicate danger to each other.
✅ Step-by-Step Solution & Working
Answers:
• (a) True: Braille uses raised dots felt with fingertips.
• (b) True: Rain replenishes rivers, lakes, and groundwater.
• (c) False: Animals communicate through warning calls, scents, and body language to alert their group of predators.
• (a) True: Braille uses raised dots felt with fingertips.
• (b) True: Rain replenishes rivers, lakes, and groundwater.
• (c) False: Animals communicate through warning calls, scents, and body language to alert their group of predators.
CBSE Step-by-Step Marking Scheme
True, True, False with reasoning
3 M
🌟 NEP 2020 Competency-Based Case Study
Synthesizing EVS Wisdom: Becoming Young Environmental Guardians
Having completed all 24 chapters of Class 3 EVS (exploring animals, plants, water, food, homes, crafts, and the web of life), students take a green pledge.
Analytical Task: Synthesize the core message of Class 3 EVS by proposing four daily lifestyle commitments every young student can follow to protect our Earth's Web of Life.
Evaluation & Model Answer:
Every student can become a guardian of the Web of Life through four simple, daily commitments: (1) Water Conservation: Never let taps run idly; treat every drop as precious nectar. (2) Green Diet & Anti-Waste: Finish all food on the plate, enjoy seasonal nutritious fruits, and avoid single-use plastic wrappers. (3) Plant & Animal Compassion: Adopt a balcony sapling, feed neighborhood birds fresh water during summers, and treat street animals with gentleness. (4) Waste Segregation: Separate wet organic peels for garden composting and recycle scrap paper to save forest trees.
Rubric: Synthesis across water, food, animal compassion, and waste reduction; practical student-led eco-habits (4 Marks).