UPSC Prelims 2012 Analysis

Explanation

All three crops listed (Groundnut, Sesamum, and Pearl millet) are predominantly rainfed crops in India.

Rainfed Agriculture This refers to agricultural practices that rely primarily on rainfall for irrigation. It's a common practice in India, especially for crops grown in areas with limited access to irrigation facilities.

Groundnut, Sesamum, and Pearl millet These crops are known for their drought tolerance and ability to adapt to varying rainfall patterns. They are well-suited for rainfed agriculture and are extensively cultivated in different parts of India.

Explanation

The origin of life on Earth is believed to have been initiated by the formation of complex organic molecules, which are primarily composed of carbon, hydrogen, and nitrogen.

These elements are essential for the development of the fundamental building blocks of life, such as amino acids, nucleic acids (DNA and RNA), and other biomolecules.

Carbon is the central element in organic chemistry and is the backbone of all living organisms, forming the complex structures of biomolecules. Hydrogen and nitrogen are also crucial elements that participate in the formation of these organic molecules, providing the necessary bonds and functional groups.

The other sets of elements mentioned in the options are not the primary elements responsible for the origin of life. Oxygen, sodium, calcium, and phosphorus are important for other aspects of life, such as energy production and signal transduction, but they are not the key elements that initiated the formation of the first living organisms.

Explanation

The rotation of the Earth, also known as the Coriolis effect, influences the direction of ocean currents. In the Northern Hemisphere, currents are deflected to the right, while in the Southern Hemisphere, they are deflected to the left.

Wind-driven currents, which are caused by the wind blowing across the surface of the ocean, are one of the primary types of ocean currents. Changes in air pressure can also affect ocean currents.

Density-driven currents, also known as thermohaline currents, are caused by differences in the density of ocean water. The density of ocean water is influenced by temperature and salinity.

The revolution of the Earth refers to the Earth's orbit around the Sun, which causes the change of seasons. However, it does not directly influence the ocean currents.

Therefore, the factors that influence the ocean currents are the rotation of the Earth, air pressure and wind, and the density of ocean water.

Explanation

The pole star, also known as Polaris, always lies in the northern direction. If the person is standing in the desert and wants to go east, he should keep the pole star to his left. This is because when we face towards the east, the north is on our left.

Therefore, the person should walk in the direction keeping the polestar to his left.

Explanation

The temperature decreases with the increase in height from the Earth's surface due to several reasons.

The Earth's surface absorbs heat from the Sun and then radiates it back into the atmosphere. The lower layers of the atmosphere are thus warmer because they are closer to the heated surface of the Earth. Hence, statement 1 is correct.

There is less moisture in the upper atmosphere. The amount of water vapour decreases with altitude. The majority of the Earth's atmospheric moisture is in the lower atmosphere. Hence, statement 2 is incorrect.

As we move higher from the Earth's surface, the air becomes less dense. This is because the gravitational pull, which pulls everything towards the Earth, decreases with height. Therefore, the air molecules are more spread out and less dense in the upper atmosphere. Hence, statement 3 is correct.

Explanation

The Tropical Savannah Region is characterised by a distinct wet and dry season.

This region experiences a hot climate as it lies within the tropical latitudes. The wet season is usually warmer with temperatures ranging from 25 to 30 degrees Celsius, while the dry season is slightly cooler. The rainfall is not evenly distributed throughout the year, with a definite period of heavy rainfall (wet season) followed by a period of little to no rainfall (dry season).

Explanation

Arunachal Pradesh

Latitude Arunachal Pradesh is located in the northeastern part of India, roughly on the same latitude as northern Rajasthan. Forest Cover Arunachal Pradesh boasts over 80% forest cover, one of the highest in the country. Protected Area Network A significant portion of Arunachal Pradesh's forest area falls under protected areas like national parks and wildlife sanctuaries. Estimates suggest over 12% of the state's forest cover is part of this network.

Explanation

Mixed farming is a type of agriculture which involves both crops and livestock. This is not to be confused with mixed cultivation, implying merely a series of different crops.

Mixed farming is essentially associated with densely populated, urbanized, and industrialized societies, dependent upon high incomes for the sale of its products and the manufacturing industry for the provision of its inputs.

Explanation

The Himalayas are young fold mountains, which are still rising under the influence of the earth's tectonic forces. This continuous vertical growth and the tectonic activity in the region result in certain characteristic features.

Deep gorges are formed due to the erosional activity of rivers flowing through these mountains. The Kali Gandaki Gorge in the Himalayas is one of the deepest in the world.

The rivers in the Himalayas often take sharp turns or U-turns due to the rugged and uneven topography.

The Himalayas consist of a series of parallel mountain ranges such as the Greater Himalayas, Lesser Himalayas, and the Outer Himalayas.

The steep slopes of the Himalayas, combined with the unstable nature of the young rocks, often result in landslides.

Therefore, all of the given features can be said to be evidence for the Himalayas being young fold mountains.

Explanation

All three crops listed (Cowpea, Green gram, Pigeon pea) can be used as pulse, fodder, and green manure.

Pulse These are the dried edible seeds of legumes, which are a good source of protein and dietary fiber for humans.

Fodder These are plants or plant parts used as food for livestock. All three crops are rich in nutrients and can be used as animal feed.

Green manure These are plants grown specifically to be plowed back into the soil to improve its fertility. Legumes like cowpea, green gram, and pigeon pea are nitrogen-fixing plants, meaning they can add nitrogen to the soil, which is a crucial nutrient for plant growth.