Ecosystem, environment and ecology
In a village pond, small plants make food, small fish eat them, a heron eats the fish, and bacteria clean up whatever dies. If any one of them vanishes, the pond slowly goes out of balance. That working whole is an ecosystem.
An ecosystem (परिसंस्था) is made of biotic and abiotic factors and their interactions.
Rule 1: Ecosystem — Producers, herbivores, predators and decomposers (even organisms of filthy places) are all important for the balance. The saying "Jivo Jivasya Jivanam" means life lives on life.
In the figure : In the figure each member of an ecosystem is important.
- Easy : Grass (producer) → grasshopper (herbivore) → frog (predator) → snake → bacteria that decompose dead bodies.
- Medium : If frogs disappear, grasshoppers increase and eat too many plants; the whole chain is disturbed.
- Exam-type : Even vultures and bacteria that live on dead matter are useful: they remove dead bodies and return minerals to the soil.
Rule 2: Environment and ecology — The environment is all the physical, chemical and biological factors, natural and artificial, that affect living organisms. Ecology studies the interactions between biotic and abiotic factors. The ecosystem is its basic functional unit: a pond is a small ecosystem, the Earth is the largest. Balance is kept by the water, carbon, nitrogen and oxygen cycles and by food chains.
- Easy : Abiotic factors: sunlight, water, air, soil. Biotic factors: plants, animals, microbes.
- Medium : A fish tank at home is a tiny ecosystem, while a forest is a larger one.
- Exam-type : Classify the pond ecosystem: water, sunlight and mud are abiotic; algae, fish, frogs and bacteria are biotic; together they form the ecosystem.
Ecosystem, environment and ecology
In the app you can move this figure with your finger.
Open in the appEcosystem = biotic + abiotic + interactions. Cycles and food chains keep the balance.
Thinking only big animals matter. Producers and decomposers are equally essential.
Memory clue: "Make, eat, hunt, clean: producer, herbivore, predator, decomposer".
Spot the difference
| Factor | Examples |
|---|---|
| Biotic | Plants, animals, microbes |
| Abiotic | Sunlight, water, air, soil |
Practice questions
- 1What is an ecosystem?
- 2What does ecology study?
- 3Name the largest ecosystem.
- 4Name two abiotic factors.
- 5Which cycles help to keep the balance of nature?
- 6In the chain grass → rabbit → fox, name the producer and the predator.
- 7Why are decomposers important?
- 8What may happen if all the snakes in a field are killed?
Show answers (try them yourself first)
- 1Biotic and abiotic factors with their interactions.
- 2Interactions between biotic and abiotic factors.
- 3The Earth.
- 4Sunlight and water.
- 5Water, carbon, nitrogen and oxygen cycles.
- 6Producer: grass; predator: fox.
- 7They break down dead matter and return minerals to the soil.
- 8Rats increase and damage crops, upsetting the balance.
Pollution and need of conservation
Smoke from chimneys, plastic bags in drains and oil on water look different, but they have one thing in common: something unwanted has been added to air, water or soil, and living things suffer.
Environmental pollution (पर्यावरण प्रदूषण) is an unwanted change in the physical, chemical or biological properties of air, water or soil that harms living beings.
Rule 1: Causes of pollution — Population explosion, rapid industrialisation, deforestation, unplanned urbanisation and indiscriminate use of resources.
In the figure : In the figure main kinds of environmental pollution.
- Easy : Cutting trees reduces oxygen and increases carbon dioxide: deforestation.
- Medium : More vehicles in a growing city mean more smoke, so air pollution increases with population and urbanisation.
- Exam-type : A factory releases untreated water into a river: fish die and people downstream fall ill. This links industrialisation with water pollution and health.
Rule 2: Radioactive pollution and conservation — Radioactive pollution comes from X-rays and atomic plants (Chernobyl, Windscale, Three Mile Island). It causes cancer, tissue damage, genetic changes and vision problems. Conservation (संवर्धन) maintains the balance, solves natural and man-made problems, and needs public awareness through education.
- Easy : A hospital must shield X-ray rooms to protect people from radiation.
- Medium : Radiation can change genes, so its harm may pass to future generations.
- Exam-type : Conservation is not "keeping things untouched" but using resources wisely so that they last for children and grandchildren.
Pollution = harmful unwanted change in air, water, soil. Causes: population, industry, deforestation.
Thinking pollution is only smoke. Water, soil, noise and radioactive pollution also exist.
Memory clue: "More people, more factories, fewer trees = more pollution".
Spot the difference
| Cause | Effect |
|---|---|
| Deforestation | Less oxygen, more CO₂ |
| Industrialisation | Air and water pollution |
| Atomic plants | Radioactive pollution |
Practice questions
- 1Define environmental pollution.
- 2Give three causes of pollution.
- 3Name two places linked with radioactive accidents.
- 4Name two harmful effects of radioactive pollution.
- 5What is conservation?
- 6Why does deforestation increase air pollution?
- 7How does unplanned urbanisation lead to pollution?
- 8Why must people be educated for conservation to succeed?
Show answers (try them yourself first)
- 1An unwanted harmful change in the properties of air, water or soil.
- 2Population explosion, industrialisation, deforestation.
- 3Chernobyl and Three Mile Island.
- 4Cancer and genetic changes.
- 5Wise use and protection of resources to maintain the balance of nature.
- 6Fewer trees take in less CO₂ and give out less oxygen.
- 7More vehicles, waste and crowded living without proper drains or waste disposal.
- 8Conservation needs everyone's cooperation, which comes from awareness.
Laws and institutions for conservation
To stop people from throwing garbage in the river, a notice is not enough. We need a rule and a punishment, and a group that checks. Environmental laws and organisations do this job at the national and world level.
UNEP (United Nations Environment Programme) was established in 1972.
Rule 1: Laws in India — Wildlife Protection Act 1972 (clauses 49A, 49B, 49C); Forest (Conservation) Act 1980; Environmental (Protection) Act 1986 (up to 5 years' imprisonment or a fine up to ₹1 lakh); National Green Tribunal 2010. Rules: sound pollution (2000), bio-medical waste (1998), e-waste (2011).
In the figure : In the figure important environmental laws in order.
- Easy : Chronological order: Wildlife Protection Act (1972), Forest Act (1980), Environmental Protection Act (1986), National Green Tribunal (2010).
- Medium : The gap between the Environmental Protection Act (1986) and the NGT (2010) is 2010 − 1986 = 24 years.
- Exam-type : Disposing old mobile phones by throwing them in garbage is wrong; e-waste rules (2011) ask that they be given to authorised recyclers.
Rule 2: Organisations — Bombay Natural History Society, IUCN, IPCC, WWF, BirdLife International, Green Climate Fund and Greenpeace (the largest). Jadav Molai Payeng of Assam created the "Molai Jungle" by planting trees on a sandbank and received the Padma Shri.
- Easy : WWF works for protecting wildlife; Greenpeace is the largest environmental organisation.
- Medium : IPCC studies climate change and IUCN keeps the Red List of threatened species.
- Exam-type : One person can make a big difference: Payeng's tree planting grew into a forest, which shows personal effort can help conservation.
UNEP 1972; WPA 1972; Forest Act 1980; EPA 1986; NGT 2010. Greenpeace is largest.
Mixing up 1972 events. Both UNEP and the Wildlife Protection Act date from 1972.
Memory clue: "72 wildlife, 80 forest, 86 environment, 2010 green court".
Spot the difference
| Law or body | Year |
|---|---|
| UNEP | 1972 |
| Wildlife Protection Act | 1972 |
| Forest (Conservation) Act | 1980 |
| Environmental (Protection) Act | 1986 |
| National Green Tribunal | 2010 |
Practice questions
- 1In which year was UNEP established?
- 2What is the punishment under the Environmental (Protection) Act 1986?
- 3Which is the largest environmental organisation?
- 4Who created the Molai Jungle?
- 5In which year were e-waste rules made?
- 6Arrange in order: NGT, Forest Act, Wildlife Protection Act.
- 7How many years passed between the Wildlife Protection Act and the NGT?
- 8Why do we need both laws and public awareness?
Show answers (try them yourself first)
- 11972.
- 2Up to 5 years' imprisonment or a fine up to ₹1 lakh.
- 3Greenpeace.
- 4Jadav Molai Payeng of Assam.
- 52011.
- 6Wildlife Protection Act (1972), Forest Act (1980), NGT (2010).
- 72010 − 1972 = 38 years.
- 8Laws set rules and punishment, but people must understand and follow them for real change.
Biodiversity and its conservation
A forest has tall trees, shrubs, many insects and birds, while a lawn has only one kind of grass. Which would survive a disease better? The forest, because its variety gives many backups. That variety of life is biodiversity.
Biodiversity (जैवविविधता) is the variety of living things at three levels: genetic, species and ecosystem.
Rule 1: Three levels of biodiversity — Genetic diversity: variety within a species. Species diversity: the number of different species. Ecosystem diversity: the variety of habitats such as forests, ponds and deserts. Sacred groves (देवराई), over 13,000 in India, are forests conserved in the name of God.
In the figure : In the figure biodiversity has three levels.
- Easy : Different varieties of mango in India show genetic diversity within one species.
- Medium : A forest with 200 species of plants and birds has more species diversity than a garden with 10 species.
- Exam-type : A country that has forests, deserts, mountains, wetlands and sea coasts has high ecosystem diversity.
Rule 2: Conserving biodiversity — Protect rare species; set up national parks, sanctuaries and bioreserves; run special projects for particular species; follow the rules; and record traditional knowledge.
- Easy : A national park protects both the animals and the habitat where they live.
- Medium : Sacred groves protect trees and animals because people believe it is wrong to harm them.
- Exam-type : Recording traditional knowledge, such as which plant a village healer uses for a cough, protects both plants and knowledge.
Biodiversity: genetic, species, ecosystem. Sacred groves: over 13,000 in India.
Thinking biodiversity means only the number of animals. It covers genes, species and habitats.
Memory clue: "Gene, Species, Ecosystem: G-S-E".
Spot the difference
| Level | Meaning |
|---|---|
| Genetic | Variety within a species |
| Species | Number of different species |
| Ecosystem | Variety of habitats |
Practice questions
- 1What is biodiversity?
- 2Name the three levels of biodiversity.
- 3What are sacred groves?
- 4Give two ways of conserving biodiversity.
- 5Which level of diversity do different breeds of cattle show?
- 6A forest has 120 species and a plantation has 4. Which has greater species diversity, and by how many times?
- 7Why is a forest with many species more stable than a single-crop field?
- 8How do sacred groves help conservation?
Show answers (try them yourself first)
- 1The variety of life at genetic, species and ecosystem levels.
- 2Genetic, species and ecosystem diversity.
- 3Forests conserved in the name of God.
- 4National parks and sanctuaries.
- 5Genetic diversity.
- 6The forest, 120 ÷ 4 = 30 times.
- 7If one species is hit by disease, others fill the gap; a single crop can be wiped out.
- 8Religious belief protects the trees and animals from being cut or hunted.
Hotspots and threatened species
Imagine a library where a big fire has burned 86 out of every 100 books, and the remaining few hold half of the world's most valuable knowledge. Those places on Earth are called biodiversity hotspots.
A biodiversity hotspot (जैवविविधता केंद्र) is a region rich in species that has lost most of its natural area.
Rule 1: Hotspots — There are 34 biodiversity hotspots. They once covered 15.7% of the Earth; 86% of that is destroyed and only 2.3% remains, yet it holds 1,50,000 plant species, 50% of the world's plants. Endangered heritage places: Western Ghats, Manas and Sundarbans.
In the figure : In the figure hotspots have lost most of their area.
- Easy : If a hotspot forest was 200 hectares and 86% is destroyed, 200 × 14 ÷ 100 = 28 hectares remain.
- Medium : Western Ghats, Manas and Sundarbans are heritage places in India that are in danger.
- Exam-type : Hotspots hold 50% of the world's plant species in only 2.3% of the land, so protecting small areas saves a huge number of species.
Rule 2: Threatened species — Endangered (lion-tailed monkey, lesser florican), rare (red panda, musk deer), vulnerable (tiger, lion), indeterminate (giant squirrel). The IUCN publishes the Red List (लाल यादी). World Biodiversity Day is on 22 May.
In the figure : In the figure categories of threatened species.
- Easy : The lion-tailed monkey is endangered; the tiger is vulnerable.
- Medium : The red panda and musk deer are rare; the giant squirrel is indeterminate.
- Exam-type : The Red List tells governments which species need protection first, so conservation money goes where it is most needed.
34 hotspots; 15.7% once, 2.3% now. Categories: endangered, rare, vulnerable, indeterminate. 22 May.
Thinking endangered and vulnerable mean the same. Endangered species are in more immediate danger.
Memory clue: "Endangered, Rare, Vulnerable, Indeterminate: E-R-V-I".
Spot the difference
| Category | Example |
|---|---|
| Endangered | Lion-tailed monkey |
| Rare | Red panda |
| Vulnerable | Tiger |
| Indeterminate | Giant squirrel |
Practice questions
- 1How many biodiversity hotspots are mentioned?
- 2What percent of the Earth did hotspots once cover?
- 3Who publishes the Red List?
- 4When is World Biodiversity Day?
- 5Give an example of a vulnerable species.
- 6300 hectares of a hotspot forest lose 86% of the area. How many hectares remain?
- 7Name three heritage places in danger.
- 8Why do conservationists focus on hotspots?
Show answers (try them yourself first)
- 134.
- 215.7%.
- 3IUCN.
- 422 May.
- 5Tiger (or lion).
- 6300 × 14 ÷ 100 = 42 hectares.
- 7Western Ghats, Manas, Sundarbans.
- 8A small area holds a huge number of species that exist nowhere else, so protecting it saves many species.
Quick revision
- UNEP 1972; EPA 1986; NGT 2010.
- Biodiversity: genetic, species, ecosystem.
- 34 hotspots; Red List by IUCN.