Ecosystem and its components
By a pond there are water, sunlight, soil, grass, frogs, fish and birds, and each depends on the others in some way.
Living things are biotic factors (जैविक घटक) and non-living things are abiotic factors (अजैविक घटक). The structure formed by their interactions is an ecosystem (परिसंस्था).
Rule 1: Biotic and abiotic factors — Air, water, soil, sunlight and minerals are abiotic. Plants, animals and microbes are biotic.
- Easy : Stone and water are abiotic; grass and ant are biotic.
- Medium : A rail track and the moss growing on it: track abiotic, moss biotic.
- Exam-type : Sunlight is abiotic yet vital for plants to make food; so abiotic factors affect biotic ones.
Rule 2: Producers, consumers and decomposers — Plants make their own food, so they are producers. Animals eat ready food, so they are consumers (primary, secondary, tertiary). Microbes break down dead bodies, so they are decomposers.
- Easy : Grass is a producer; deer a consumer; fungus a decomposer.
- Medium : Grass → grasshopper → frog: grass producer, grasshopper primary consumer, frog secondary consumer.
- Exam-type : Grass → grasshopper → frog → snake → eagle: the eagle is a fourth-level consumer. Humans eat at many levels.
Man is a consumer in the ecosystem.
Thinking an ecosystem is only plants and animals. Non-living factors are part of it.
Memory clue : "P-C-D: Producer, Consumer, Decomposer" — the three groups of biotic factors.
Spot the difference
| Group | How they get food | Example |
|---|---|---|
| Producers | Make their own food | Grass, trees |
| Consumers | Eat others | Deer, tiger |
| Decomposers | Break down dead bodies | Fungi, bacteria |
Practice questions
- 1What is an ecosystem?
- 2Name two abiotic factors.
- 3Who are producers?
- 4What do decomposers do?
- 5In grass → deer → tiger, who is the primary consumer?
- 6Why is sunlight important though it is abiotic?
- 7What would happen in an ecosystem without decomposers?
- 8Explain "man is a consumer".
Show answers (try them yourself first)
- 1A structure formed by biotic and abiotic factors and their interactions.
- 2Air and water (or soil, sunlight).
- 3Plants that make their own food.
- 4They break down dead plants and animals.
- 5The deer.
- 6Plants use it to make food.
- 7Dead bodies would pile up and minerals would not return.
- 8Man does not make food; he eats plants and animals.
Interactions and niche
A sunflower plant in a garden gives oxygen to the air and food and shelter to ants and bees.
Every living thing in an ecosystem plays a particular role. Its position and role with respect to other living things is its niche (निश).
Rule 1: Abiotic factors act on biotic factors — Air, water, soil, sunlight, temperature and humidity decide which organisms survive and in what numbers. Some plants need more sunshine, others thrive in shade.
- Easy : Cactus grows in a desert but a rice field does not.
- Medium : Some microbes need oxygen and some do not.
- Exam-type : Biotic factors also change abiotic ones: plants add oxygen to air and take in carbon dioxide.
Rule 2: Cycle of nutrients and energy — Producers make food from sunlight and minerals. Consumers eat it. Decomposers break down dead bodies and the minerals go back to soil and water. At each step some energy leaves as heat.
- Easy : Dry leaves rot in the soil and give minerals back to the tree.
- Medium : Without microbes dead bodies would pile up and minerals would not return.
- Exam-type : Energy comes from the Sun and leaves as heat, so an ecosystem needs sunlight all the time.
Interactions and niche
In the app you can move this figure with your finger.
Open in the appMinerals are used again and again; energy has to come fresh from the Sun.
Thinking that only abiotic factors act on biotic ones. Biotic factors also change abiotic ones.
Memory clue : "Sun → producer → consumer → decomposer → minerals" — the order of the cycle.
Spot the difference
| Item | Recycled | Needed all the time |
|---|---|---|
| Minerals | Yes | — |
| Energy | No | From the Sun |
Practice questions
- 1What is a niche?
- 2Who returns minerals to the soil?
- 3Where does an ecosystem get its energy from?
- 4State one effect of abiotic factors on biotic factors.
- 5What change do plants bring in the air?
- 6Explain the niche of a sunflower plant.
- 7Why do we say energy is not recycled?
- 8What may happen if a shade-loving plant is kept in strong sun?
Show answers (try them yourself first)
- 1The position and role of an organism.
- 2Decomposers.
- 3From the Sun.
- 4They decide which organisms survive and in what numbers.
- 5Oxygen increases and carbon dioxide decreases.
- 6It gives oxygen and gives insects food and shelter.
- 7It leaves as heat at each step.
- 8It may wither because it needs less sunlight.
Biomes and land ecosystems
A grassland, a thick forest and a desert each have different plants and animals.
Large regions of the Earth share a climate and abiotic factors, and so share kinds of living things. Such a large ecosystem is a biome (जैवसमूह). Biomes are of two kinds: land (भूचर) and aquatic (जलीय).
Rule 1: Grassland ecosystem — Grasslands form where rain is too little for big trees. Long summers and little rain give dwarf plants. Goats, sheep, deer, zebra, giraffe, tiger, lion, birds, insects and microbes live here.
- Easy : In grassland the grass is the producer and the deer a primary consumer.
- Medium : Grass → rabbit → snake → eagle: here the snake is the secondary consumer.
- Exam-type : The one-horned rhino had vanished from Dudhwa by hunting; it was brought back there in 1984.
Rule 2: Evergreen forests and protected areas — An evergreen forest is a natural ecosystem with many kinds of plants, animals and abiotic factors. About 520 sanctuaries and national parks in India conserve ecosystems.
- Easy : Gir in Gujarat is the only home of the Asiatic lion.
- Medium : Kaziranga (Assam) has two-thirds of the world's one-horned rhinos; Ranthambore is famous for tigers.
- Exam-type : Bharatpur is famed for water birds, so its lakes and marshes matter there.
A large biome holds many small ecosystems; the Earth itself is one huge ecosystem.
Thinking that a single tree is an independent ecosystem. It cannot live alone.
Memory clue : "Biome = big area, same climate" — two kinds: land and aquatic.
Spot the difference
| Point | Grassland | Evergreen forest |
|---|---|---|
| Rain | Less | Plenty |
| Plants | Grass, dwarf plants | Tall varied trees |
| Animals | Deer, lion, tiger | Tiger, leopard, many animals |
Practice questions
- 1What is a biome?
- 2Name the two kinds of biomes.
- 3Which is the only home of the Asiatic lion?
- 4Why are big trees absent in a grassland?
- 5Name one producer and one consumer of a grassland.
- 6What is Bharatpur sanctuary famous for?
- 7Why do we need sanctuaries and national parks?
- 8The rhino was brought back to Dudhwa. What does this show?
Show answers (try them yourself first)
- 1A large ecosystem with a similar climate.
- 2Land and aquatic.
- 3The Gir forest.
- 4Rainfall is low.
- 5Grass - producer; deer - consumer.
- 6Water birds.
- 7To keep ecosystems and rare animals safe.
- 8A lost species can be restored with proper effort.
Aquatic ecosystems
A village pond and the vast sea both hold water, yet life in them differs.
About 71 % of the Earth is covered by water and 29 % is land, so aquatic biomes matter a great deal. The types are the freshwater (गोड्या पाण्याची), the marine (सागरी) and the creek ecosystem.
Rule 1: Freshwater ecosystem — Ponds, lakes and rivers belong here. Decomposers at the bottom break down dead plants and animals. Water plants are producers; insects, snails and frogs are consumers.
- Easy : Algae and water plants of a pond are producers.
- Medium : Small fish are eaten by frogs and large fish by herons: levels of consumers.
- Exam-type : In a river, energy moves on with the flow of water.
Rule 2: Marine ecosystem — Shallow water has small fish and prawns feeding on algae. The middle of the sea has fewer organisms. Large fish are secondary consumers. The sea is rich in nutrients and the bottom has many decomposers.
- Easy : At the sea bottom bacteria break down dead animals.
- Medium : Algae are producers in the marine ecosystem.
- Exam-type : A pond and the sea differ: the sea is huge and salty, a pond is small and fresh.
Aquatic ecosystems also have producers, consumers and decomposers.
Thinking the sea has only fish. It also has plants, algae and bacteria.
Memory clue : "71 water, 29 land" — most of the Earth is water.
Spot the difference
| Point | Freshwater | Marine |
|---|---|---|
| Example | Pond, river, lake | Sea, ocean |
| Water | Fresh | Salty |
Practice questions
- 1What percent of the Earth is covered by water?
- 2Name three types of aquatic ecosystems.
- 3Name one producer of a pond.
- 4Who are the producers in the marine ecosystem?
- 5What do decomposers at the bottom of a water body do?
- 6What type of ecosystem is a river?
- 7Why is the study of aquatic biomes important?
- 8Why does the sea floor have many decomposers?
Show answers (try them yourself first)
- 1About 71 %.
- 2Freshwater, marine and creek.
- 3Algae (or a water plant).
- 4Algae and marine plants.
- 5Break down dead plants and animals.
- 6Freshwater.
- 7Because most of the Earth is water.
- 8Dead organisms and waste settle there and need to be broken down.
Human interference and loss of ecosystems
When a village gets new roads, a dam and a factory, nearby forests and marshes shrink.
Human activities disturb the working of ecosystems and bring about their diminishment (ऱ्हास). An ecosystem may change into another kind or a species may become extinct.
Rule 1: Causes of loss — Growing population and heavier use, urbanisation, industry and traffic, tourism, large dams and wars are the causes.
- Easy : Farmland and marshes are filled up to expand a city.
- Medium : A dam submerges a forest into an aquatic ecosystem and reduces flow downstream.
- Exam-type : Facilities built for tourists put stress on the local ecosystem.
Rule 2: Importance of every organism — If all honey-bees were destroyed because one stung us, flowers would not be pollinated, honey would stop, and crops and food chains would suffer.
- Easy : Without bees on flowers there will be fewer fruits.
- Medium : When one species dwindles, those depending on it dwindle too.
- Exam-type : Natural ecosystems keep the balance of the biosphere, so protecting them is necessary.
Natural disasters such as earthquakes and floods change ecosystems too, but human interference can be more damaging.
Thinking that cutting a little forest does no harm. The effects spread in a chain.
Memory clue : "Growth, city, factory, tourism, dam, war" — six causes of loss.
Spot the difference
| Cause | Effect |
|---|---|
| Urbanisation | Farmland, marshes, forests are destroyed |
| Large dam | Forest submerged, downstream flow falls |
| Tourism | Stress on the local ecosystem |
Practice questions
- 1Give two examples of human interference.
- 2What is diminishment of an ecosystem?
- 3Name one natural disaster.
- 4How does a large dam affect ecosystems?
- 5Which lands shrink due to urbanisation?
- 6What stress does a growing population put on ecosystems?
- 7What will happen if all honey-bees are destroyed?
- 8Suggest two ways to protect ecosystems.
Show answers (try them yourself first)
- 1Cutting forests and mining.
- 2Damage or change in an ecosystem.
- 3Earthquake (or flood, drought).
- 4It submerges forests and lessens flow downstream.
- 5Farmland, marshes, forests and grasslands.
- 6More use of natural resources and more waste.
- 7Pollination falls and fruits and honey decrease.
- 8Plant trees and use resources only as needed.