Every free question on Environment & Ecology (General Science) from past WBCS Preliminary Examination and WBCS Main Examination papers, newest first, each with its answer and a short explanation. Free to read.
Answer: (B) 1972
The National Committee on Environmental Planning and Coordination (NCEPC) was set up in 1972, the year of the Stockholm Conference, as India's first apex environmental body. It was later succeeded by the Department of Environment (1980), so 1980 is the wrong date, as are 1970 and 1974.
Answer: (B) Lindemann
Raymond Lindeman (1942) proposed the ten per cent law: only about 10% of the energy at one trophic level passes to the next. Odum is known for ecosystem ecology generally, Tansley coined the term 'ecosystem', and Darwin proposed natural selection.
Answer: (A) Turtles
Gahirmatha Marine Sanctuary on the Odisha coast protects one of the world's largest mass-nesting (arribada) sites of Olive Ridley sea turtles. Crocodiles are protected at nearby Bhitarkanika, and elephants and deer are not the sanctuary's purpose.
Answer: (C) Acid Rain
'Stone cancer' is the corrosion and pitting of marble and limestone monuments, such as the Taj Mahal, by acid rain: sulphuric acid reacts with calcium carbonate. SPM causes yellowing or blackening rather than this decay, and frost or VOCs are not the cause named by the term.
Answer: (B) Mercury
Minamata disease, first seen in Minamata, Japan, is methylmercury poisoning from eating contaminated fish. Cadmium causes itai-itai disease, arsenic causes arsenicosis (blackfoot disease), and lead causes plumbism.
Answer: (C) New Delhi
The Central Pollution Control Board, set up in 1974 under the Water Act, has its headquarters in New Delhi. Kolkata, Bangalore and Mumbai host only zonal or regional offices.
Answer: (D) Thermosphere
In the thermosphere, absorption of high-energy solar radiation raises temperatures to well over 1000 °C, so it is called the hot layer. Temperature falls with height in the troposphere and mesosphere, and the stratosphere warms only moderately because of ozone.
Answer: (D) Kerala
The Silent Valley Movement (1970s–80s) stopped a hydroelectric dam on the Kunthipuzha river in Palakkad district, Kerala, saving its evergreen forest, now Silent Valley National Park. It did not take place in the other states.
Answer: (D) SF$_6$
Sulphur hexafluoride has a 100-year global warming potential of about 23,500 times that of CO$_2$, the highest of any gas assessed by the IPCC. CFCs have GWPs in the thousands, while CO$_2$ is the reference value of 1.
Answer: (A) SO$_2$
Lichens absorb water and gases directly through their surface and are killed by even low levels of sulphur dioxide, so they are used as indicators of SO$_2$ pollution. CO$_2$ and N$_2$ are normal air components, and CO is not what lichens indicate.
Answer: (C) Sewage
Biochemical oxygen demand measures how much oxygen microbes need to decompose organic matter, so adding organic sewage raises BOD sharply. Heavy metals are toxic but not biodegradable organic load, and plankton are not the main driver named here.
Answer: (C) Mesosphere
Temperature falls with height through the mesosphere to about −90 °C at the mesopause, the coldest part of the atmosphere. The thermosphere above is the hottest layer, and the troposphere and stratosphere are never that cold.
Answer: (D) Japan
Minamata Bay is in Kumamoto Prefecture on Kyushu, Japan, where mercury waste from the Chisso factory caused Minamata disease. It is not in Korea or China.
Answer: (B) Gause
G. F. Gause (1934) showed with Paramecium cultures that two species competing for the same limiting resource cannot coexist indefinitely, which is the competitive exclusion (Gause's) principle. Darwin and Lamarck proposed theories of evolution, and Odum is known for ecosystem ecology.
Answer: (B) Uttarakhand
The Valley of Flowers National Park, a UNESCO World Heritage Site, is in Chamoli district of Uttarakhand. It was part of Uttar Pradesh before Uttarakhand was formed in 2000, which makes (A) the tempting wrong option.
Answer: (B) 2011
The Fukushima Daiichi nuclear disaster followed the earthquake and tsunami of 11 March 2011 in Japan. The other years are wrong.
Answer: (C) Both
Peroxyacetyl nitrate, a component of photochemical smog, is a strong eye irritant, and it is also listed as a mutagen linked to skin cancer. Since both effects are attributed to it, (C) is the answer; liver cancer is not a recognised PAN effect.
Answer: (B) Indoor Air pollution
An electrostatic precipitator charges dust particles in air passed through it and collects them on plates, so it can only clean air drawn through an enclosed unit, as in electronic indoor air cleaners. It does not treat water or remove odorous gases. Note: the best-known use of electrostatic precipitators is in power-plant and factory chimneys, removing fly ash before the gas reaches the open air, so (A) outdoor air pollution is the usual textbook answer.
Answer: (C) Asphalt
Fresh asphalt reflects only about 4–12% of sunlight, the lowest albedo among these surfaces. Forests reflect slightly more, bare soil more still, and fresh snow reflects up to about 90%.
Answer: (C) Urn-shaped
A declining population has fewer young than middle-aged people, giving a narrow base and an urn shape. A triangular pyramid shows an expanding population and a bell shape a stable one.
