Environment and Ecology: UPSC Previous Year Questions (Prelims)

Explanation

The phosphorus cycle is unique for not have a significant atmospheric component. Phosphorus is primarily released into the cycle through the weathering of rocks containing phosphate minerals (e.g., apatite). Weathering releases phosphate ions (PO₄³⁻) into soil and water, making it available for uptake by plants and other organisms. Phosphorus is one of the most important nutrients in biological systems since it is a fundamental ingredient of nucleic acids, phospholipids, and several phosphor-ylated compounds.

Explanation

All of the given species can establish a symbiotic relationship with other organisms. Symbiotic Relationship:

A relationship between two (or more) species that may or may not be advantageous to one or both is referred to as symbiotic. Symbiosis typically occurs between different species. Interactions within the same species (intraspecific) are usually not categorized as symbiosis but may involve other forms of cooperation. For eg., Coral has a symbiotic relationship (each gives something to the other and gets something back in return) with ‘zooxanthellae’ microscopic algae which live on coral.

Option 1 is correct: The relationship between cnidarians and dinoflagellate algae is termed "symbiotic" because both the animal host and the algae are benefiting from the association. It is a mutualistic interaction.

Option 2 is correct: Two common mutualistic relationships involving fungi are mycorrhiza (fungi and plant roots) and lichen (fungi and either cyanobacteria or green algae).

Option 3 is correct: Protozoa mostly represent a close mutualistic association between a protozoan and unicellular symbionts such as bacteria, cyanobacteria or/and unicellular algae or protozoans and a multicellular organisms such as ruminants, lower termites, wood-eating cockroaches, plants.

Explanation

Reservoir Volume (Million Cubic km) Percentage of the Total Oceans 1,370 97.25 Ice caps and Glaciers 29 2.05 Groundwater 9.5 0.68 Lakes 0.125 0.01 Soil Moisture 0.065 0.005 Atmosphere 0.013 0.001 Streams and Rivers 0.0017 0.0001 Biosphere 0.0006 0.00004 Water makes up about 71% of the Earth’s surface, while the other 29% consists of continents and islands. Oceans and Seas make up 97% of the Earth’s water and only about 2.5% is in the form of freshwater. 71 % of earth surface constitutes water & only 29 % constitutes a land area of earth. 97 % of water area constitutes Oceans & Seas & 2.5 % as freshwater.

Statement 1 is incorrect: Fresh Water distribution is as given below: Ice Caps and Glaciers > Groundwater >Lakes Ice & Snow > Soil Moisture > Atmosphere > Rivers and Streams.

Statement 2 is correct: While about 69% of earth’s freshwater is in ice caps and glacier, groundwater has about 30% of earth’s freshwater. Kakes, Rivers and swamps etc make up the remaining 1%. While 75 % of freshwater is in glaciers & ice caps, only 7 % of freshwater is groundwater. Saline ground-water 0.93% Saline lakes 0.07% Freshwater 2.5% Surface water and other freshwater 1.3% Atmoshpheric water 0.22% Biological wate 0.22% Rivers 0.46% Swamps and marshes 2.53% Soil moisture 3.52% Ice and snow 73.1% Glaciers and ice caps 68.6% Oceans 96.5% Groundwater 30.1% Lakes 20.1% Surface water and other freshwater Freshwater Total Global water Distribution of Earth’s Water Resources

Explanation

Lemongrass is a tall herb that is widely distributed in tropical and subtropical regions of Asia, Africa, and Australia. Lemongrass is most frequently produced in China and India. The lemongrass herb is well known for its effectiveness at warding off mosquitoes and works as a mosquito repellent. It contains the chemical citronella, which aids in disguising the smells that mosquitoes use to target victims. A 2011 study found that the strong odour of lemongrass oil effectively killed or fully repelled more than 90% of the mosquitoes from a particular range of species.

Explanation

Savanna Biome is a particular kind of grassland biome made up of vast expanses of open grassland with few trees. Tropical and Semi-tropical savannas are two kinds of savannas. All continents excluding Antarctica have grasslands. The largest savannas are found close to the equator in Africa.

Option (c) is correct:

Frequent wildfires both natural (lightning-induced) and human-induced prevent the establishment of dense forests. Fires destroy young tree saplings before they can mature into large trees, thus maintaining grasslands. Savanna fires are a key ecological process that helps maintain the balance between grasslands and scattered trees. Large herbivores like elephants, zebras, and antelopes feed on young tree shoots, preventing forests from expanding. Grazing by animals ensures that tree cover remains sparse which allows grasses to dominate. Studies on African and Indian savannas have shown that herbivory is a critical limiting factor for tree growth. The limited and unpredictable rainfall pattern allows grasses to outcompete trees for available water. Savannas experience distinct wet and dry seasons leading to limited water availability. Trees require consistent moisture to grow into dense forests but in savannas prolonged dry periods hinder tree survival. Burrowing animals such as aardvarks and rodents and termites play a role in soil aeration and nutrient cycling. But they do not significantly prevent tree growth or forest development. Trees can grow in varied soil types and soil properties alone do not explain forest suppression.

Explanation

Permaculture is a totally integrated design system that’s modelled on nature.

Statement 1 is correct: Permaculture farming promotes multi-cropping and integrated farming systems. While chemical farming is more suitable for monoculture cropping due to the use of crop-specific inputs like irrigation, chemical fertiliser and harvesting methods.

Statement 2 is correct: Conventional farming usually alters the natural environment, increases soil salinity, and eliminates biodiversity. Such problems are not seen in permaculture farming as it relies on organic fertilizers.

Statement 3 is incorrect: Chemical farming is based on the intense use of inputs like chemical fertilizers and irrigation that make the soil less fertile over time, thus restricting its practice in semi-arid regions. Thus, conventional farming is not suitable for semi-arid regions. Permaculture involves well-designed systems that don’t produce waste and permaculture tries to imitate well-designed systems. Thus, it can work in arid climates as well.

Statement 4 is correct: Mulching is an important component of Permaculture systems for promoting maximum efficiency.

Explanation

Climate-Smart Agriculture (CSA) is a strategy to assist those in charge of managing agricultural systems in efficiently adapting to climate change. The CSA approach pursues the triple objectives of:

Sustainably increasing productivity and incomes Adapting to climate change Reducing greenhouse gas emissions where possible

Statement 1 is correct: The Climate-Smart Village project in India is a CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS).

Statement 2 is correct: Climate Change, Agriculture and Food Security (CCFAS) is carried out under CGIAR (formerly the Consultative Group for International Agricultural Research).

Statement 3 is correct: ICRISAT is a CGIAR Research Center. It is a non-profit, non-political public international research organization that conducts agricultural research for development in Asia and sub-Saharan Africa with a wide array of partners throughout the world.

Explanation

Copper Smelting is a process of applying heat to ore in order to extract a base metal. Smelting uses heat and a chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving the metal base behind. It is the method of extracting pure elemental copper (Cu) from copper concentrate (CuFeS₂).

Statement 1 is incorrect: Copper smelting generally does not release lethal quantities of carbon monoxide (CO) into the environment.

Statement 2 and 3 are correct: Some smelting processes can also produce large quantities of solid waste, known as slag. This slag may leach heavy metals (arsenic, cadmium, lead or mercury depending on the composition of the ore) into groundwater reservoirs. Smelting processes are known to emit high quantities of air pollutants such as hydrogen fluoride, sulphur dioxide, oxides of nitrogen, offensive and noxious smoke fumes, vapours, gases, and other toxins.

Explanation

Statement 1 is correct: Furnace oil or fuel oil is a dark viscous residual product of crude-oil distillation. It is used as a fuel in different types of combustion equipment.

Statement 2 is correct: Marine engines and slow speed engines use Furnace oil for power generation, they are used for drying tea leaves. Thermic fluid heaters and hot air generators also use Furnace oil.

Statement 3 is correct: The emissions of oxides of sulphur are a direct result of the sulphur content of the fuel oil.

Explanation

Magnetite particles are a highly magnetic mineral form of iron and are known to be present in air pollution. Exposure to airborne particulate matter (PM) is associated with pulmonary, cardiovascular and neurological problems.

Option 1 is correct: Vehicle brake systems are the major source of airborne magnetite at the roadside.

Option 2 is correct: Petrol and diesel-engine exhaust are also a source of airborne magnetite.

Option 4 is correct: Other sources of Magnetite pollution include Power plants. Options 3 and 5 are incorrect: Household microwave stoves and telephone lines not are established as sources of airborne magnetite particles. Other sources of Magnetite pollution include microwave Stoves within homes, As per WHO, Telephone lines produce low frequency, low energy electromagnetic fields which are the potential source of magnetite particles.