Geography: UPSC Previous Year Questions (Prelims)

Explanation

Statement 1 is correct: The lower stratosphere is mostly free from clouds and water vapor, as most weather phenomena occur in the troposphere below. This impacts the clear air conditions, making it ideal for jet aircraft to fly smoothly.

Statement 2 is correct: The stratosphere is a stable layer with no vertical air movements like convection currents. In contrast, the troposphere experiences turbulence due to rising and falling air masses. The absence of vertical winds in the lower stratosphere ensures a steady flight for jet aircraft.

Explanation

Mangroves function as a safety hedge due to their extensive root systems. These roots act as a natural barrier, protecting coastlines from erosion and the impact of strong waves during storms, cyclones, and tsunamis. The dense network of roots helps to dissipate the energy of waves, reducing their im-pact on the shoreline.

Explanation

Statement 1 is incorrect: La Niña is characterized by unusually cold ocean temperatures in the Equatorial Pacific (not the Indian Ocean). In contrast, El Niño is associated with unusually warm ocean temperatures in the Equatorial Pacific Ocean.

Statement 2 is incorrect: El Niño events are associated with a weakening of the Indian monsoon leading to reduced rainfall and drought conditions in India. This occurs because the warming of the central and eastern Pacific Ocean alters atmospheric circulation patterns, which can suppress the monsoon rains over the Indian subcontinent. La Niña events typically have the opposite effect, strengthening the Indian monsoon and often resulting in above-average rainfall. The cooling of the central and eastern Pacific Ocean during La Niña enhances the monsoon circulation, leading to increased precipitation over India.

Explanation

The crop suitable to be grown in the lower Gangetic plain, which is characterized by a humid climate with high temperature throughout the year, is Paddy and Jute. Paddy: It grows well in the plains of north and north-eastern India, coastal areas and the deltaic regions, where there is an abundance of alluvial clayey soil. A high temperature (above 25°C) and significant humidity are necessary for this kharif crop. Jute: Its cultivation is mainly concentrated in eastern India because of the rich alluvial soil of Ganga-Brahmaputra delta. Jute crops need humid conditions with temperature swings between 24 and 38 degrees Celsius.

Explanation

Salinization refers to the accumulation of soluble salts in the soil resulting from irrigation practices where water evaporates, leaving salts behind. This process adversely affects soil structure and fertility.

Option (a) is incorrect: Salinization reduces crop yields as excess salts in the soil create osmotic stress on plants which hin-ders their ability to absorb water and nutrients. This leads to stunted growth and lower productivity.

Option (b) is correct: Salinization causes soil particles to disperse and clog pores which makes the soil impermeable. This is known as sodic soil degradation. This dispersion leads to the clogging of soil pores, reducing permeability and making the soil less capable of absorbing water. Thus water infiltration decreases and the soil becomes impermeable.

Option (c) is incorrect: Salinization generally occurs due to poor drainage but it does not necessarily raise the water table. On the contrary, a high water table can exacerbate salinization by bringing saline groundwater closer to the root zone through capillary action.

Option (d) is incorrect: Salinization does not directly fill air spaces in the soil with water. It can lead to waterlogging due to reduced soil permeability which indirectly affects soil aeration. Waterlogging displaces air from soil pores which deprives plant roots of oxygen.

Explanation

Arunachal Pradesh, often referred to as the "Orchid Paradise of India,". It boasts over 600 orchid species, accounting for approximately 40% of the country’s orchid diversity. The state’s sub-alpine and sub-tropical climates provide ideal conditions for orchid cultivation which makes it highly suitable for developing an export-oriented industry with minimal production costs.

Explanation

Brahmaputra makes a "U" turn in its course to flow into India due to the Syntaxial bending of geologically young Himalayas. The Himalayan mountains’ gently arching ranges on their western and eastern extremities are abruptly bent southward in deep knee bends known as syntaxial bends. The massive mountains seem to bend around a pivotal point on both the ends. The westernmost point is located where the Hindu Kush joins the Karakoram south of the Pamir. Arunachal Pradesh’s eastern border features a similarly abrupt, almost hairpin curve when the mountain’s strike abruptly shifts from an easterly to a southerly tendency.

Explanation

The above characteristics clearly define Gujarat.

The northern region of Gujarat comprises the Kutch and Banaskantha districts, which are characterized by arid and semi-arid conditions due to low annual rainfall (less than 500 mm). The Thar Desert extends into parts of Gujarat, contributing to the dry climate. Gujarat is the largest producer of cotton in India (~30% of national production). The central districts, such as Ahmedabad, Surendranagar, Rajkot, and Bhavnagar, have ideal black soil (Regur soil) that supports cotton cultivation. Gujarat is highly commercialized in agriculture, focusing on cotton, groundnut, tobacco, and castor rather than food crops. The Saurashtra and Kutch regions specialize in cash crops due to their soil type and climatic conditions.

Explanation

The river originating in Jharkhand referred to here is the Brahmani River. It originates as the Koel River in Jharkhand and is later called the Brahmani in Odisha. River originating in Odishas is the Baitarani River which originates in the Ke-onjhar district of Odisha. The Brahmani and Baitarani rivers merge at a place called Dhamra, near the Bay of Bengal forming a large delta before flowing into the sea. Bhitarkanika National Park is located in the estuarine region formed by the merging of the Brahmani and Baitarani rivers. It is located in the Kendrapara district of Odisha. It is a unique ecosystem of mangroves, wetlands, and tidal rivers. It is one of India’s most important wildlife sanctuaries and a Ramsar site (a wetland of international importance). It is home to saltwater crocodiles, Olive Ridley sea turtles, and a variety of bird species.

Explanation

Statement 1 is incorrect: The broadening (not Deepening) of the Malacca straits between Malaysia and Indonesia will reduce the navigation time and distance. The Malacca Strait is situated between Malaysia and Indonesia and is one of the main shipping lanes. The narrow waterway creates a chokepoint between the Indian Ocean and the Pacific Ocean.

Statement 2 is correct: Opening a new canal across the Kra isthmus between the Gulf of Siam and the Andaman Sea can reduce the navigation time and distance. Kra isthmus is the narrowest part of the Malay Peninsula. It is bordered to the west by the Andaman Sea and to the east by the Gulf of Thailand.