UPSC 2021 Environment and Ecology Questions with Answers

Explanation

Lichens and Mosses do not need soil to grow and survive. Lichens are generally found on rock, tree bark, soil (but can survive without soil as well), houses, tombstones, cars, old farm equipment, etc. Thus, lichen can be found surviving on surfaces without soil. Mosses are non-vascular plants. They do not need soil to survive. They have a rhizoid multi-cell anchoring structure that is used to climb and grip over rocky surfaces. Moss thrives in moist and shady areas. Ferns and Mushrooms generally need soil to grow. Ferns are vascular plants and typically require soil for anchorage and to absorb water and nutrients. While they can grow in places like cracks in rocks, they usually still need some form of substrate (soil or organic material) to thrive. A mushroom is the fleshy, spore-bearing fruiting body of a fungus. They typically require organic matter to decompose as a source of nutrients. Mushrooms are unlikely to grow on a surface without soil unless there is some decaying organic material available.

Explanation

Primary Producers are organisms like plants and algae that produce their own food through photosynthesis or chemo-synthesis. They form the base of the food chain in marine eco-systems. Cyanobacteria and Diatoms are primary producers. Cyanobacteria (also known as blue-green algae) are photosynthetic bacteria that play a significant role in marine ecosystems by converting sunlight into energy and producing oxygen. They are particularly important in nutrient-poor (oligotrophic) oceanic regions. Diatoms are a type of phytoplankton that perform photosynthesis. They are among the most important primary producers in the oceans which contribute significantly to global carbon fixation. They are a key food source for zooplankton and other marine organisms. Copepods and Foraminifera are consumers. Copepods are small crustaceans that are not primary producers. They are zooplankton that feed on phytoplankton (primary producers) and other small organisms. They play a crucial role in marine food webs as a link between primary producers and higher trophic levels. Foraminifera are not primary producers. They are single-celled protists that belong to the zooplankton group. They feed on phytoplankton, detritus, and other small organisms. They are important in marine ecosystems as indicators of environmental conditions.

Explanation

Detritivores also known as detritivores, detritophag-es, detritus feeders, or detritus eaters are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). By doing so, all these detritivores contribute to decomposition and the nutrient cycles.

Option (c) is correct: Earthworms, Millipedes and Woodlice are Detritivores. Detritivores are an important aspect of many ecosystems. They can live on any type of soil with an organic component, including marine ecosystems, where they are termed interchangeably with bottom feeders. Typical detritivorous animals include earth-worm, millipedes, springtails, woodlice, dung flies, slugs, many terrestrial worms, sea stars, sea cucumbers, fiddler crabs, and some sedentary polychaetes such as worms of the family Terebellidae.

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.