Environment, Pollution and Biodiversity
Environment, Pollution and Biodiversity
Environment is where the science block and the Bihar block overlap, which makes it unusually rewarding. Expect 1 to 2 questions, and be ready for a state-specific one on Bihar's protected areas. Ecosystem vocabulary and conservation categories carry most of the marks.
Ecosystem and Food Chain
An ecosystem has biotic components, meaning living things, and abiotic ones such as light, water, air and soil. Energy moves through it in a food chain.
- Producers — green plants, which make their own food.
- Consumers — herbivores, carnivores and omnivores.
- Decomposers — bacteria and fungi, which break down dead matter.
Energy always flows in one direction through a food chain, and only a small fraction passes to the next level. That is why food chains are short.
Pollution and Climate
| Type | Main causes | Effect |
|---|---|---|
| Air | Vehicle and industrial smoke, stubble burning | Respiratory illness, smog |
| Water | Sewage, industrial effluent, pesticides | Waterborne disease, dead fish |
| Soil | Excess fertiliser, plastic, industrial waste | Loss of fertility |
| Noise | Traffic, loudspeakers, machinery | Hearing loss, stress |
Carbon dioxide, methane and nitrous oxide are greenhouse gases. They trap heat and drive global warming. Ozone depletion is a separate problem caused mainly by chlorofluorocarbons, and the ozone layer sits in the stratosphere where it blocks ultraviolet radiation.
✗ Global warming and ozone depletion are the same problem | ✓ Greenhouse gases cause warming; CFCs deplete the ozone layer
Conservation: In-Situ and Ex-Situ
| Approach | Meaning | Examples |
|---|---|---|
| In-situ | Protected in natural habitat | National park, sanctuary, biosphere reserve |
| Ex-situ | Protected outside habitat | Zoo, botanical garden, seed bank |
Bihar's Protected Areas
- Valmiki National Park, in West Champaran district, is the only national park in Bihar and is counted as the eighteenth tiger reserve of the country. It was declared a wildlife sanctuary in 1978 and a national park in 1990.
- Vikramshila Gangetic Dolphin Sanctuary, in Bhagalpur district, was notified on 7 August 1991 and protects a roughly 60 kilometre stretch of the Ganga from Sultanganj to Kahalgaon. It is home to the Ganges river dolphin, India's national aquatic animal.
वाल्मीकि — बिहार का एकमात्र राष्ट्रीय उद्यान; विक्रमशिला — गंगा डॉल्फिन अभयारण्य।
TRE pointer: The two Bihar names in this topic are among the most predictable state questions in the entire paper, and most candidates prepare only one of them. Learn the district with each: Valmiki with West Champaran, Vikramshila with Bhagalpur. The examiner's usual trick is to attach the right park to the wrong district. Note also that the dolphin links this topic back to the national-symbols question in General Awareness, so one fact earns marks twice.
60-Second Recap
- Biotic means living, abiotic means non-living; energy flows one way through a food chain.
- Producers are green plants; decomposers are bacteria and fungi.
- Greenhouse gases cause global warming; CFCs deplete the ozone layer — two separate problems.
- In-situ conservation is in the natural habitat; ex-situ is outside it.
- Valmiki National Park, West Champaran — the only national park in Bihar, 18th tiger reserve of India.
- Vikramshila Gangetic Dolphin Sanctuary, Bhagalpur, notified 1991, Sultanganj to Kahalgaon.
Frequently Asked Questions
Which is the only national park in Bihar?
Valmiki National Park in West Champaran district. It was declared a wildlife sanctuary in 1978 and a national park in 1990, and it is counted as the eighteenth tiger reserve of the country. Pairing the park with its district is the safest way to store this fact.
Where is the Vikramshila Gangetic Dolphin Sanctuary?
In Bhagalpur district of Bihar. Notified on 7 August 1991, it protects about a sixty kilometre stretch of the Ganga between Sultanganj and Kahalgaon, and it is a key habitat of the Ganges river dolphin, which is India's national aquatic animal.
What is the difference between in-situ and ex-situ conservation?
In-situ conservation protects species where they naturally live, through national parks, wildlife sanctuaries and biosphere reserves. Ex-situ conservation keeps them outside their natural habitat, in zoos, botanical gardens, seed banks and gene banks. Questions usually ask you to sort examples into these two boxes.
Are global warming and ozone depletion the same thing?
No, and treating them as one is a common error. Global warming is caused by greenhouse gases such as carbon dioxide and methane trapping heat. Ozone depletion is caused mainly by chlorofluorocarbons breaking down ozone in the stratosphere, which lets more ultraviolet radiation through.