Previous Year UPSC Questions

Explanation

Upwelling is a process in which deep, cold water of the ocean rises toward the surface. Winds blowing across the ocean surface push water away. Water then rises up from beneath the surface to replace the water that was pushed away. This process is known as "upwelling."

Statement 1 is incorrect: Decomposer microorganisms primarily reside in the deep ocean and play a role in breaking down organic matter. Upwelling does not bring decomposers to the surface. Most decomposition occurs at depth and decomposer microbes are not significantly transported to the surface by upwelling.

Statement 2 is correct: Upwelling regions bring nutrients like nitrogen, phosphorus, and iron from deep waters to the surface. These nutrients enhance phytoplankton growth which supports higher trophic levels such as fish and marine mammals. Major upwelling zones include the coasts of Peru, California, and West Africa. These regions contribute to high fishery productivity (Ex: Peru-vian anchovy fishery).

Statement 3 is incorrect: Bottom-dwelling (benthic) organisms such as crustaceans and mollusks are not brought to the surface by upwelling. Upwelling affects water movement but does not displace benthic creatures from the ocean floor.

Explanation

DNA Sequencing means determining the order of the four chemical building blocks - called "bases" - that make up the DNA molecule. This sequence informs scientists the kind of genetic information that is carried in a particular DNA segment.

Statement 1 is correct: Pedigree analysis is the examination of a particular trait that is inherited from generation to generation. It helps in understanding the inheritance pattern of that trait and determining whether it is dominant or recessive. A thorough pedigree analysis using pedigree files received via DNA sequencing from the relevant breed organisations will certainly help in interpreting the pattern of inheritance of a livestock.

Statement 2 is correct: Mapping genes allows researchers to identify genetic variations associated with diseases. This understanding facilitates the development of targeted therapies and personalized medicine approaches.

Statement 3 is incorrect: Knowledge of gene positions enables the identification of genes responsible for disease resistance. This information can be utilized to breed or genetically engineer animals that are more resilient to specific diseases. However UPSC has not recognised it as completely true as if this application of DNA sequencing is still under development.

Explanation

Tropical rainforests and tropical deciduous forests differ in their nutrient cycles, soil composition, and regeneration capacity. When a tropical rainforest is removed, it does not regenerate quickly because of the nutrient-poor soil. In tropical rainforests, the warm and humid conditions promote rapid decomposition of organic matter by bacteria and fungi. But due to the high density of plant life the nutrients released are immediately absorbed by plants leaving the soil infertile. In contrast the tropical deciduous forests have richer soils be-cause the leaf litter decomposes and replenishes soil nutrients more effectively. Options (b), (c) and (d) are incorrect:

Propagules (seeds, spores, or other reproductive structures) of rainforest trees generally have high viability. However, the regeneration of rainforests is hindered more by soil nutrient deficiencies than by the viability of propagules. Many rainforest species are fast-growing especially pioneer species that colonize disturbed areas. However, the lack of nutrients in the soil limits their growth and the overall regeneration of the forest. In rainforests slow regeneration is due to nutrient loss and not exotic/invasive species. If soils were fertile, native plants would recover quickly but rainforest soils are typically nutrient-poor which limits their regrowth.

Explanation

Tribal revolts in 19th-century India were driven by the disruption of traditional tribal life, which centered on shifting cultivation, hunting, and forest produce during colonial rule.

Option (d) is correct:

The influx of non-tribals and the imposition of settled agriculture led to land loss for tribals. Restrictions on forest resources and shifting agriculture, along with the introduction of moneylenders, reduced tribals to landless laborers and bonded peasants. The establishment of government monopolies on forests (1865-1878) further exploited tribes. Tribal egalitarianism was replaced by caste-based inequalities, and the influence of Christian missionaries also fueled resentment leading to uprisings like the Kol Rebellion (1832), Santhal Rebellion (1855-56), and Munda Rebellion (1899-1900).

Explanation

The IUCN Red List of "threatened species" is the world’s most comprehensive inventory of the global conservation status of plant and animal species, which is a grouping of three categories: Critically Endangered, Endangered, and Vulnerable.

Statement 1 is incorrect: The Red Data Books primary purpose is not to catalog endemic species in biodiversity hotspots. Its focus is on the conservation status of species, particularly those that are threatened (vulnerable, endangered, or critically endangered).

Statement 2 is correct: The purpose of the Red Data Books is to provide a detailed list of threatened species, including plants and animals. These species are categorized based on their risk of extinction, using criteria such as population size, rate of decline, and geographic range.

Statement 3 is incorrect: The Red Data Books do not focus on listing protected sites or conservation areas. Information about protected sites (such as national parks, wildlife sanctuaries, or biosphere reserves) is typically found in other publications or databases, such as the World Database on Protected Areas (WDPA) or national-level conservation reports.

Explanation

Ex Situ Conservation In Situ Conservation Ex situ conservation is the preservation of biodiversity away from their natural habitats. Here, zoological or botanical parks are places where animals and plants are raised or grown. In situ conservation refers to the preservation of plants and animals in their natural environments. Another method of ex situ conservation is the reintroduction of an animal or plant into its former environment. For instance, This includes the establishment of:

1. National parks and sanctuaries

2. Biosphere reserves the extinct Gangetic Gharial has been brought back into the rivers of Uttar Pradesh, Madhya Pradesh, and Rajasthan.

3. Nature reserves

4. Reserved and protected forests

5. Preservation plots

6. Reserved forests Important locations for ex situ conservation include seed banks, botanical, horticultural, and recreational gardens.

Explanation

Biodiversity Hotspot are regions with high species richness and a high degree of endemism. In 1988, the British bi-ologist Norman Myers coined the term "biodiversity hotspot" as a biogeographic region characterized both by exceptional levels of plant endemism and by serious levels of habitat loss and provided certain qualifications for a hotspot. Options 1, 3 and 5 are correct: In 1989, Conservation Inter-national (CI) adopted Myers’ hotspots as its institutional model. Western Ghats-Sri Lanka and Indo-Burma Region meets the Myers’ criterion to qualify as Biodiversity Hotspot:

Species richness and endemism is one of the major criteria which must contain at least 1,500 species of vascular plants (> 0.5% of the world’s total) as endemics. ‘Degree of Threat’ is also a major criteria for the recognition of biological hotspots. It has to have lost at least 70% of its original habitat. (It must have 30% or less of its original natural vegetation). In other words, it must be threatened. Options 2, 4 and 6 are incorrect: Vegetation density, ethno-bo-tanical importance and adaptation of flora and fauna to warm and humid conditions are not part of the criteria for the recognition of Biodiversity Hotspots.

Explanation

The diversity of plants and animals varies widely over the world. The tropics are home to more species than temperate or polar regions.

Statement 1 is correct: Species diversity decreases as we move away from the equator towards the pole. This is due to several reasons:

Lower latitudes experience warmer temperatures and more stable climates, which support a greater variety of life forms. The equatorial regions receive more consistent and intense sunlight throughout the year, leading to higher primary productivity (photosynthesis) and thus more diverse ecosystems. Tropical regions, such as rainforests, have complex habitats with multiple layers (canopy, understory, forest floor) which support a wide range of species. Tropical regions have remained relatively stable over geological time, allowing species to diversify over millions of years.

Statement 2 is correct: Elevational diversity gradient (EDG) is an ecological pattern where biodiversity changes with elevation. The EDG states that species richness tends to increase as elevation increases, up to a certain point, creating a "diversity bulge" at middle elevations, after which it decreases with altitude. Therefore, it is true that along the mountain gradients, biodiversity is normally greater in the lower altitudes as compared to the higher altitudes.

Explanation

Biodiversity provides a number of natural services for human beings which are listed in the table below:

Ecosystem Services Protection of water resources Soil formation and protection Nutrient storage and recycling Pollution breakdown and absorption Contribution to climate stability Maintenance of ecosystems Recovery from unpredictable events Biological Services Food Medicinal resources and pharmaceutical drugs Wood products Ornamental plants Pollination of crops Breeding stocks Diversity in genes, species and ecosystems Social Services Research, education and monitoring Recreation and tourism Cultural values

Explanation

Statement 1 is correct: The primary reason the westerlies in the Southern Hemisphere are stronger and more persistent than in the Northern Hemisphere is because the Southern Hemisphere has significantly less landmass (about 20% land and 80% water), whereas the Northern Hemisphere has 40% land and 60% water. The vast oceans in the Southern Hemisphere allow westerly winds to move with minimal obstruction, making them stronger and more persistent. In contrast, larger landmasses in the Northern Hemisphere create friction and disrupt wind flow.

Statement 2 is incorrect: The Coriolis force acts equally in both hemispheres at the same latitude as it depends on the Earth’s rotation and the latitude. It does not make the westerlies stronger in one hemisphere over the other. The main reason for the difference is the land-sea distribution. The Coriolis force is stronger near the poles and weaker at the equator, but it does not explain the difference in strength of the westerlies between the two hemispheres.