• Option A is correct.
• There are many plants and animal species in Oligotrophic lakes. Thus Oligotrophic lakes are rich in diversity.Hence,statement 1 is correct.
• Oxygen is present in the hypolimnion (bottom layer) of Oligotrophic lakes as the sunlight reaches to the bottom of the lake for plants to perform photosynthesis. Hence statement 2 is incorrect.
• On the basis of their nutrient content, they are categorized as Oligotrophic (very low nutrients), Mesotrophic (moderate nutrients) and Eutrophic (highly nutrient rich). Hence statement 3 is incorrect.

• Option B is correct.
• Statement 1 is incorrect.Algae produce oxygen, but only when there is enough light. Eutrophication reduces the clarity of water and underwater light. In eutrophic lakes, algae are starved for light. When algae don’t have enough light they stop producing oxygen and in turn begin consuming oxygen.
• Statement 2 is correct.The oxygen level is already low because of the population explosion and further oxygen is taken up by microorganisms which feed off the dead algae during the decomposition process.
• Statement 3 is correct.As consequence of Eutrophication some algae and blue-green bacteria thrive on the excess ions and a population explosion covers almost the entire surface layer is known as algal bloom. This growth is unsustainable, however. As algal bloom covers the surface layer, it restricts the penetration of sunlight.This further reduces the photosynthesis carried out by phytoplankton thus reducing the dissolved oxygen.

• Option C is correct
• Mangroves are the characteristic littoral plant formation of tropical and subtropical sheltered coastlines. Mangroves are trees and bushes growing below the high water level of spring tides which exhibits remarkable capacity for salt water tolerance.
It produces pneumatophores (blind roots) to overcome respiratory problems in the anaerobic soil conditions.Mangroves send vertical “Pneumatophores” or air roots up from the mud. Hence,statement 1 is correct.
• Some secrete excess salt through their leaves as if you look closely, you can see crystals of salt on the back of the leaves; others block absorption of salt at their roots..Leaves are thick and contain salt secreting glands. Hence,statement 2 is incorrect.
• Mangroves exhibit Viviparity mode of reproduction i.e. seeds germinate in the tree itself (before falling to the ground). This is an adaptive mechanism to overcome the problem of germination in saline water.Hence,statement 3 is correct.

• Option A is correct.
• The Bharat Stage (BS) are emission standards instituted by the Government of India to regulate the output of air pollutants from motor vehicles.The Environment Ministry is responsible for deciding the fuel standard in the country. The Central Pollution Control Board implements these standards. The BS regulations are based on the European emission standards.
BS-VI Diesel will bring down sulphur content by 5 times from the current BS-IV levels. It has 10 ppm of sulphur as against 50 ppm in BS-IV.Sulphur in the Diesel contributes to fine particulate matter emissions. Hence, statement 1 is correct.
• The new standard requires that the use of sulphur in diesel should come down to 10 PPM, whereas according to the BS -II, it was up to 500 PPM. This change will affect the density of diesel oil. The usual density of BS IV fuel diesel ranges from 820 to 845 kg/ cubic metre but now it has to be increased to 860 kg/ cubic metre.The change in density will help improve the quality of oil as well as help reduce air pollution.Hence, statement 2 is incorrect.
• In BS-VI fuel, the volume of PM 2.5 ranges from 20 to 40 micrograms per cubic metre whereas in BS-IV fuel it is up to 120 micrograms per cubic metre. With BS-VI fuel, for every one kilometre, a car will emit 80% less particulate matter and nearly 70% less nitrogen oxide.Hence, statement 3 is incorrect.

• Option D is correct.
• An ecological niche refers to the interrelationship of a species with all the biotic and abiotic factors affecting it. Hence, statement 1 is incorrect.
• No two species can have the exact same niche, otherwise they would be in direct competition for resources with one another. If this occurs, then one species will outcompete the other. If the losing species then does not adapt, it would lead to its extinction. Hence, statement 2 is incorrect.
• In a symbiotic relation, both organisms are deriving benefits from each other. Hence there is no niche overlap between them with respect to food resources and/or habitat.Thus both have different ecological niche. Hence, statement 3 is correct.

• Option A is correct, Only statement 2 is correct. Statements 1 and 3 are incorrect.
• Minister of State for Petroleum and Natural Gas is nodal ministry for Pradhan Mantri JI-VAN (Jaiv Indhan- Vatavaran Anukool fasal awashesh Nivaran) Yojana.
• The main objective of this scheme is to provide financial support to integrated bio-ethanol projects for setting up Second Generation (2G) ethanol projects in the country using lignocellulosic biomass and other renewable feedstock. Hence, statement 3 is incorrect.
• Some other objectives of scheme are:
1) Improving farmer income by providing them remunerative income for their otherwise waste agriculture residues. (Hence, statement 2 is correct while statement 1 is incorrect)
2) Creating rural & urban employment opportunities in 2G Ethanol projects and Biomass supply chain
3) Contributing to Swacch Bharat Mission by supporting the aggregation of nonfood biofuel feedstocks such as waste biomass and urban waste
4) Indigenizing of Second Generation Biomass to Ethanol technologies
5) The ethanol produced by the scheme beneficiaries will be mandatorily supplied to Oil Marketing Companies (OMCs) to further enhance the blending percentage under EBP Programme.

• Option A is correct.
• 2G bioethanol can be produced using inedible farm waste left over after harvest. Corn cobs, rice husks, wheat straw, sugarcane bagasse and Bamboo can be used as feedstock for second generation bioethanol. Hence, statement 1 is correct.
• Feedstock can all be transformed into cellulose and fermented into ethanol that can then be mixed with conventional fuels. Starch in cereals and sugarcane is fermented and converted into 1G bioethanol. Hence,statements 2 and 3 are incorrect.
• Setting up a 2G Bioethanol plant will help reduce air pollution from the Delhi and the NCR region along with generating additional income and green fuel. Reduction in burning of rice straw, the project will contribute to a reduction of greenhouse gasses equivalent to about 3 lakh tonnes of carbon dioxide equivalent emissions per annum, which can be understood as equivalent to replacing nearly 63,000 cars annually on the country’s roads.

• Option A is correct.
• Of these 12.6% of mammals, 4.5% of birds, 45.8% of reptiles, 55.8% of amphibians and 33% of Indian plants are endemic, being found nowhere else in the world.Hence, statement 1 is correct.
• One of seventeen megadiverse countries, it is home to 7.6% of all mammalian, 12.6% of all avian, 6.2% of all reptilian, 4.4% of all amphibian and 11.7% of all fish.Hence, statement 2 is incorrect.
• Just 17 of the world’s 190 or so countries contain 70 percent of its biodiversity, earning them the title “megadiverse.” India is one of these megadiverse countries with 2.4% of the land area, accounting for 7-8% of the species of the world, including about 91,000 species of animals and 45,500 species of plants, that have been documented in its ten bio-geographic regions. Hence, statement 3 is incorrect.

• Option C is correct. Passenger Pigeon, Pyrenean Ibex and Dodo are extinct. Sunda Island Tiger is critically endangered.
• Native to North America, the Passenger or Wild Pigeon has been extinct since the early 20th century. It is estimated that between 3 and 5 billion Passenger Pigeons inhabited the US when Europeans arrived in North America, but their settlement led to mass deforestation resulting in habitat loss and a reduction in the bird population.The Passenger Pigeon died out in the wild by around 1900, with the last known individual dying in captivity in 1914.
• Dodo is an extinct flightless bird that inhabited Mauritius, the Dodo was about one metre tall and may have weighed 10–18 kg. The only account we have of the Dodo’s appearance is through varied illustrations and written accounts from the 17th century so its exact appearance remains unresolved. It is presumed the bird became flightless due to the availability of abundant food sources (seeds, roots and fallen fruits) and a relative absence of predators.
• The Sunda Island tiger, or the Sumatran tiger, is the smallest tiger subspecies in the world, weighing up to 140kg. For reference, the tigers that live in the Amur region are the biggest of all the big cats where males can weigh up to twice as much as Sunda Island tigers. They are also very rare – there are estimated to be around 600 in the wild, and are only found on the Indonesian island of Sumatra.
• Pyrenean Ibex is one of four subspecies of the Spanish Ibex or Iberian Goat that was found in the Iberian Peninsula. The Ibex would grow to a height of 60-76cm at the shoulder and weigh 24-80 kg and fed mainly on grasses and herbs. They were thought to have numbered 50,000 historically, but by the early 1900s its numbers had fallen to fewer than 100. The exact cause of the Pyrenean Ibex’s extinction is unknown; scientists believe factors included poaching and the inability to compete with other mammals for food and habitat. The last Pyrenean Ibex was killed by a falling tree in northern Spain in 2000.

• Option D is correct
• Shannon Index, Simpson Index, and Berger Parker Index are measures of biodiversity in a country.
• These index are quantitative measure that reflects how many different types (such as species) there are in a dataset (a community), and that can simultaneously take into account the phylogenetic relations among the individuals distributed among those types, such as richness, divergence or evenness.These indices are statistical representations of biodiversity in different aspects (richness, evenness, and dominance).