Environment and Ecology: UPSC Previous Year Questions (Prelims)

Explanation

Photochemical smog, often referred to as "Los Angeles smog," is most commonly found in urban areas with high numbers of automobiles. It does not require smoke or fog to form. This type of smog is formed from the nitrogen oxides and hydrocarbon (peroxyacetyl nitrate, a hazardous pollutant) vapors released by vehicles and other sources, which then undergo photochemical reactions in the lower atmosphere in the presence of sunlight.

Explanation

Aflatoxins are produced by certain species of fungi (moulds), specifically Aspergillus flavus and Aspergillus parasiticus, which often grow on stored grains and oilseeds under conditions of high humidity and temperature. Exposure to aflatoxins can lead to serious health issues, including liver cancer, especially in children. Beyond health risks, aflatoxins cause significant economic losses, with an estimated 25% of global food crops affected annually.

Explanation

Bagasse and Molasses:

Introduction Uses Bagasse is the remnant left after extracting the juice of the sugarcane or sorghum is known as bagasse. It is a dry pulpy fibrous material. It is used for the generation of heat energy and electricity. Ethanol produced from it is also used as a popular fuel in some countries. It substitutes wood to produce pulp, paper, and board. As a cattle feed when mixed with molasses and enzymes and then fermenting. Molasses is the thick syrup that results from the refining of sugarcane or sugar beets into sugar. It contains a good amount of Vitamin B6 and minerals like calcium, manganese, iron and magnesium. Sweetening and flavouring foods. In the production of fine commercial brown sugar. In baking and cooking. Producing ethanol and is the prime ingredient in the distillation of few alcoholic beverages. As a cattle feed. Statements 1 and 3 are correct: Bagasse can be used for the generation of heat energy and electricity. Molasses can be used for the production of ethanol and it is also used as the ingredient in the distillation of a few alcoholic beverages.

Statement 2 is incorrect: Molasses is not used for the production of chemical fertilizers. Synthetic fertilizers are typically made from chemical compounds like ammonia, urea, and phosphates, which are derived from petrochemicals or mineral sources. Molasses is rich in sugars and organic matter which make it unsuitable for the production of synthetic fertilizers.

Explanation

Option 1 is correct: The Gharial is critically endangered. Once found across the Indian subcontinent, its population has drastically declined due to habitat loss, reduction in prey species, entanglement in fishing nets, and water pollution. It is now confined to a few river systems, especially in the Chambal River. The Gharial is listed as critically endangered by the IUCN Red List.

Option 2 is correct: The Leatherback turtle is the largest species of sea turtle and is listed as vulnerable by the IUCN. The species faces numerous threats, including accidental capture in fishing nets, habitat destruction (especially nesting sites), and illegal hunting. It is found along India’s coasts, particularly in the Andaman and Nicobar Islands and parts of the Tamil Nadu coast. However many subpopulations (such as in the Pacific and Southwest Atlantic) are Critically Endangered.

Option 3 is correct: The Swamp deer (also called the Barasingha) is endangered. It is found in wetland areas in parts of In-dia, such as Uttarakhand and Madhya Pradesh. Habitat destruction, hunting, and the drainage of wetlands have contributed to its population decline. Note: According to UPSC Answer Key Option C is correct

Explanation

Option 1 is correct: Star Tortoise (Geochelone ele-gans) is naturally found in India. It is a species of tortoise that inhabits the dry forests and scrublands of India, particularly in Rajasthan, Gujarat, Madhya Pradesh, and parts of Tamil Nadu. It is easily recognizable due to the star-like patterns on its shell. The species is endangered due to habitat loss and illegal trade. There is a huge international demand for these animals as exotic pets which threatens their survival.

Option 2 is correct: Monitor lizards are found in India and are widespread across the country. Several species, including the Indian monitor lizard (Varanus bengalensis), can be found in forests, grasslands, and even near human settlements. These lizards are known for their size, strength, and scavenging habits.

Option 3 is correct: Pygmy Hog (Porcula salvania) is naturally found in India, specifically in the grasslands of Assam. It is a critically endangered species and is the smallest wild pig in the world. The Pygmy hog’s population has been reduced due to habitat destruction, especially the loss of grasslands in the region.

Statement 4 is incorrect: The Spider monkey is not naturally found in India. It is native to Central and South America, specifically the tropical forests of the Amazon Basin.

Explanation

Mammals are warm-blooded animals with hair and vertebrates, or backbones. Unlike other classes of animals, female mammals produce milk to nourish their young. Almost all mammals give birth to live young (except for the platypus and echidna, which lay eggs). Statements 1 is correct: Dugong belongs to the order Sirenia and is a marine mammal found in warm coastal waters. The Dugong (Dugong dugon) is the sea cow found in Indian waters. They are herbivorous and are known for their gentle nature. They give birth to live young and nurse them with milk, characteristic of mammals. They are found in over 30 countries and in India are seen in the Gulf of Mannar, Gulf of Kutch, Palk Bay, and the Andaman and Nicobar Islands.

Statement 2 is incorrect: The Sea Horse is not a mammal but a fish, part of the genus Hippocampus. Despite its name, the sea horse is a small marine creature, known for its unique horse-like head and upright swimming posture. It is an ectother-mic species (cold-blooded) and lays eggs, unlike mammals which give birth to live young Statements 3 is correct: Sea Lion is a mammal. It belongs to the family Otariidae and is a type of pinniped (a group of fin-foot-ed mammals). Sea lions are marine mammals that live in coastal areas and are known for their external ear flaps and ability to "walk" on land using their front flippers.

Explanation

Bio-fertilizers are living or biologically active products or microbial inoculants of bacteria, algae and fungi (separately or in combination) which are able to enrich the soil with nitrogen, phosphorus, organic matter etc.

Statement 1 is incorrect: Agaricus refers to a genus of fungi, commonly known for species like Agaricus bisporus, the common button mushroom. While it is used in culinary and medicinal contexts, it is not used as a biofertilizer. They are not involved in nitrogen fixation or other activities that promote soil fertility, which are characteristic of biofertilizers.

Statement 2 is correct: Nostoc is a genus of cyanobacteria (blue-green algae) that can fix atmospheric nitrogen. It is often used as a biofertilizer because of its ability to enhance soil fertility by converting atmospheric nitrogen into a form that plants can utilize. Nostoc is commonly found in rice paddies and is used to improve nitrogen content in the soil, especially in organic farming.

Statement 3 is incorrect: Spirogyra is a genus of green algae that primarily plays a role in freshwater ecosystems. While it is important for oxygen production and can contribute to the aquatic environment, it is not used as a biofertilizer. Unlike Nostoc, Spirogyra does not have significant nitrogen-fixing capabilities.

Explanation

Lion-tailed macaques (Macaca silenus) are endemic to India, found only in the Western Ghats. They inhabit evergreen and semi-evergreen rainforests, typically at elevations up to 1,500 meters, and are often associated with broadleaf trees. This species is of conservation importance due to its primitive traits. Despite having a relatively wide range, their habitat is small and highly fragmented. The Lion-tailed Macaque has a distinctive appearance with a dark coat, silver-white mane, long tail, and pink face. It resides in monsoon forests and disturbed habitats across Karnataka, Kerala, and Tamil Nadu, but is absent in Andhra Pradesh.

Explanation

Millennium Ecosystem Assessment (MA) was initiated in 2001 by the United Nations. The objective of the MA was to evaluate how changing ecosystems might affect human well-being as well as the scientific foundation for any necessary action to improve the systems’ conservation and sustainable us-age, as well as their contribution to human well-being. Ecosystem services to the society are in the form of:

1. Provisioning services: food, raw materials, genetic resources, water, etc

2. Regulating services: carbon sequestration and climate regulation

3. Cultural services: tourism and religion

4. Supporting services: that are necessary for the production of all other ecosystem services such as nutrient recycling, crop pollination and soil formation, etc.

Explanation

Phytoplanktons are the primary producers in the marine food chain and hence they are called the ‘grass of the sea’. They contribute more than half of the oxygen in the environment and help in reducing global warming by absorbing human-in-duced carbon dioxide. They are important bioindicators regulating life in oceAns:

Statements 1 is correct: If phytoplankton are destroyed then less CO₂ will be absorbed thereby increasing atmospheric carbon and contributing to global warming. Phytoplankton are responsible for carbon fixation through photosynthesis. They absorb CO₂ from the atmosphere and convert it into organic matter. When phytoplankton die, some of this carbon sinks to the ocean floor, sequestering it for long periods. Statements 2 is correct: Phytoplankton are the primary producers in marine ecosystems forming the base of the food web. They are consumed by zooplankton which in turn are eaten by larger organisms like fish, marine mammals, and seabirds. The destruction of phytoplankton would disrupt the entire marine food chain and can lead to the collapse of fisheries and the decline of marine biodiversity.

Statement 3 is incorrect: The density of ocean water is primarily determined by temperature and salinity and not by the presence of phytoplankton. While phytoplankton can slightly affect water properties through their metabolic activities but their destruction would not cause a drastic decrease in ocean water density.