UPSC NDA-1 Archives

41. Which one of the following is not a part of nerves ?

Which one of the following is not a part of nerves ?

[amp_mcq option1=”Axons” option2=”Connective tissues” option3=”Schwann cells” option4=”Smooth muscles” correct=”option4″]

This question was previously asked in

UPSC NDA-1 – 2015

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Nerves are bundles of nerve fibers (axons) covered by protective sheaths and supported by connective tissue.

Axons are the main projections of nerve cells that transmit signals. Schwann cells (a type of glial cell) form the myelin sheath around axons in the peripheral nervous system. Connective tissues (epineurium, perineurium, endoneurium) form the outer layers and internal support structure of nerves. Smooth muscles are a type of muscle tissue found in organs and blood vessels; they are not structural components of a nerve. While nerves innervate smooth muscles (control their function), the muscle tissue itself is not part of the nerve structure.

The basic structural unit of a nerve is the neuron, which includes an axon. Axons are bundled together to form nerves. Glial cells like Schwann cells provide support and insulation. Connective tissue provides structure and protection to the nerve bundle.

42. Which endocrine gland requires iodine to synthesize a particular hormo

Which endocrine gland requires iodine to synthesize a particular hormone whose deficiency may cause goitre disease ?

[amp_mcq option1=”Hypothalamus” option2=”Pancreas” option3=”Thymus” option4=”Thyroid gland” correct=”option4″]

This question was previously asked in

UPSC NDA-1 – 2015

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The thyroid gland is an endocrine gland located in the neck that produces thyroid hormones.

Thyroid hormones (thyroxine and triiodothyronine) contain iodine atoms. Iodine is an essential micronutrient required for the synthesis of these hormones. A deficiency of iodine leads to insufficient production of thyroid hormones, which in turn causes the thyroid gland to enlarge, a condition known as goitre, in an attempt to compensate and produce more hormones.

The hypothalamus is part of the brain and controls the pituitary gland, which in turn regulates the thyroid. The pancreas produces insulin and glucagon (regulating blood sugar). The thymus is involved in immune system development. Only the thyroid gland directly synthesizes hormones requiring iodine, whose deficiency causes goitre.

43. The luxuriant growth of natural vegetation in tropical rainforest is d

The luxuriant growth of natural vegetation in tropical rainforest is due to

1. fertile soil.
2. hot and wet climate throughout the year.
3. intense sunlight for photosynthesis.
4. seasonal change to facilitate nutrient absorption.

Select the correct answer using the code given below :

[amp_mcq option1=”1 and 4 only” option2=”2 and 3 only” option3=”1, 2 and 3 only” option4=”1, 2, 3 and 4″ correct=”option2″]

This question was previously asked in

UPSC NDA-1 – 2015

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Tropical rainforests are characterized by consistently high temperatures and abundant rainfall throughout the year.

Statement 2 (hot and wet climate throughout the year) provides the ideal temperature and moisture conditions for rapid plant growth. Statement 3 (intense sunlight for photosynthesis), due to their location near the equator, ensures high energy input for primary production. Statement 1 (fertile soil) is generally incorrect; rainforest soils are often poor in nutrients as rapid decomposition and uptake mean most nutrients are stored in the biomass, not the soil. Statement 4 (seasonal change) is incorrect; tropical rainforests exhibit minimal seasonal temperature and rainfall variation compared to other biomes, and nutrient cycling is continuous.

The combination of high temperature, high humidity, and intense sunlight creates a highly productive environment for vegetation growth. The limiting factor is usually not climate or light, but rather nutrient availability, which is compensated for by efficient nutrient cycling within the ecosystem.

44. A farmer in a semi-arid area claims that his farming practice is very

A farmer in a semi-arid area claims that his farming practice is very environment friendly. Which of the following practices on his farm can justify his claim ?

1. Planting a tree belt.
2. Practising crop rotation.
3. Carrying out a large scale irrigation system.
4. Using organic fertilizers.

Select the correct answer using the code given below :

[amp_mcq option1=”3 and 4 only” option2=”1, 2 and 4″ option3=”1, 3 and 4″ option4=”1 and 2 only” correct=”option2″]

This question was previously asked in

UPSC NDA-1 – 2015

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In a semi-arid area, environment-friendly farming practices focus on water conservation, soil preservation, and sustainable resource use.

1. Planting a tree belt acts as a windbreak, reducing wind erosion which is critical in semi-arid areas, and can help conserve soil moisture. This is environment-friendly.
2. Practising crop rotation improves soil structure, fertility, and reduces the build-up of pests and diseases, reducing the need for chemical inputs. This is environment-friendly.
3. Carrying out a large scale irrigation system in semi-arid areas can lead to unsustainable water use, depletion of water sources, and soil salinization, making it generally not environment-friendly.
4. Using organic fertilizers improves soil health, water retention, and fertility without introducing synthetic chemicals, which is environment-friendly.

Practices 1, 2, and 4 are beneficial for sustainability and environmental health in semi-arid regions by promoting soil conservation, water efficiency (indirectly through improved soil health and windbreaks), and reducing reliance on harmful chemicals. Large-scale irrigation without careful management is often detrimental in water-scarce environments.

45. ‘Yakuts’ are the nomadic herders of

‘Yakuts’ are the nomadic herders of

[amp_mcq option1=”Gobi” option2=”Sahara” option3=”Tundra” option4=”Kalahari” correct=”option3″]

This question was previously asked in

UPSC NDA-1 – 2015

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The Yakuts (Sakha people) are an ethnic group native to the Sakha Republic in Northeast Asia, a region characterized by harsh climates and diverse biomes including taiga and tundra.

Traditionally, the Yakuts practiced horse breeding, cattle rearing, and in the northern regions, reindeer herding. Reindeer herding is strongly associated with the Tundra and northern Taiga environments. Gobi, Sahara, and Kalahari are deserts in other continents and are not associated with the Yakuts.

The Sakha Republic (Yakutia) is the largest subnational entity in the world by area and covers vast territories of Siberia, extending into the Arctic regions which include significant Tundra zones. Their traditional lifestyle, particularly reindeer herding, places them in the context of the Tundra biome.

46. Which of the following are the characteristics of organic farming ?

Which of the following are the characteristics of organic farming ?

1. Use of chemical fertilizers to improve soil fertility.
2. Frequent decomposing and fal- lowing.
3. Use of herbs to control pests.
4. Higher productivity per hectare.

Select the correct answer using the code given below :

[amp_mcq option1=”3 and 4 only” option2=”1, 2 and 4″ option3=”1, 3 and 4″ option4=”1 and 2 only” correct=”option1″]

This question was previously asked in

UPSC NDA-1 – 2015

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Organic farming avoids the use of synthetic chemical fertilizers and pesticides. It focuses on natural methods to maintain soil fertility and control pests.

Statement 1 is incorrect as organic farming explicitly prohibits the use of chemical fertilizers. Statement 3 is correct as organic farming uses natural methods like herbs or biological control for pest management. Statement 2, “Frequent decomposing and fallowing”, refers to practices like composting (decomposition of organic matter for fertilizer) and fallowing or crop rotation for soil health, which are characteristic of organic farming. Statement 4, “Higher productivity per hectare”, is generally not a characteristic of organic farming compared to high-input conventional farming; yields are often lower, though soil health and sustainability are improved. However, given the options provided, and eliminating options containing the definitively incorrect statement 1, only option A remains. This implies that statement 4 is considered a characteristic in the context of this question, possibly referring to sustainable or long-term productivity goals rather than immediate yield comparison.

Key characteristics of organic farming include building healthy soil through organic matter, crop rotation, cover crops, natural pest and disease control, and avoidance of synthetic chemicals, GMOs, and synthetic growth regulators. While higher short-term productivity is not a guaranteed characteristic, organic systems aim for sustainable productivity over time.

47. In the reaction ZnO + C → Zn + CO, ‘C’ acts as

In the reaction ZnO + C → Zn + CO, ‘C’ acts as

[amp_mcq option1=”an acid” option2=”a base” option3=”an oxidising agent” option4=”a reducing agent” correct=”option4″]

This question was previously asked in

UPSC NDA-1 – 2015

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In the reaction ZnO + C → Zn + CO, zinc oxide (ZnO) loses oxygen to become zinc (Zn), undergoing reduction. Carbon (C) gains oxygen to become carbon monoxide (CO), undergoing oxidation.

A reducing agent is a substance that causes another substance to be reduced, while it itself is oxidized. In this reaction, carbon (C) removes oxygen from ZnO, thus causing the reduction of ZnO. Carbon itself is oxidized in the process. Therefore, carbon acts as a reducing agent.

Conversely, an oxidising agent is a substance that causes another substance to be oxidized, while it itself is reduced. ZnO acts as the oxidising agent in this reaction because it provides oxygen for the oxidation of carbon and is itself reduced. This is a common method for the extraction of metals from their oxides using carbon as a reducing agent (smelting).

48. Permanent hardness of water is due to the presence of

Permanent hardness of water is due to the presence of

[amp_mcq option1=”sulphates of sodium and potassium” option2=”sulphates of magnesium and calcium” option3=”carbonates of sodium and magnesium” option4=”bicarbonates of magnesium and calcium” correct=”option2″]

This question was previously asked in

UPSC NDA-1 – 2015

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Hardness of water is primarily caused by the presence of dissolved calcium and magnesium ions (Ca$^{2+}$ and Mg$^{2+}$). Temporary hardness is caused by their bicarbonates, which can be removed by boiling. Permanent hardness is caused by the presence of calcium and magnesium sulphates and chlorides, which are not removed by simple boiling.

Permanent hardness of water is due to the dissolved sulphates and chlorides of calcium and magnesium.

Sodium and potassium ions do not cause water hardness. Carbonates and bicarbonates of Ca and Mg cause temporary hardness. Permanent hardness needs chemical methods like ion exchange (using zeolite or synthetic resins) for removal.

49. Which one among the following does not wet the walls of the glass vess

Which one among the following does not wet the walls of the glass vessel in which it is kept ?

[amp_mcq option1=”Water” option2=”Alcohol” option3=”Mercury” option4=”Phenol” correct=”option3″]

This question was previously asked in

UPSC NDA-1 – 2015

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Whether a liquid wets a solid surface depends on the balance between adhesive forces (attraction between liquid molecules and solid surface) and cohesive forces (attraction between liquid molecules). Water, alcohol, and phenol have adhesive forces with glass that are stronger than their internal cohesive forces, causing them to spread out and wet the glass surface. Mercury, on the other hand, has very strong cohesive forces (due to metallic bonding) that are much stronger than the adhesive forces between mercury and glass. Therefore, mercury minimizes its contact area with the glass, forming a convex meniscus and does not wet the glass.

Wetting is determined by the relative strengths of adhesive forces between the liquid and the solid and cohesive forces within the liquid.

A liquid wets a surface if the angle of contact between the liquid and the solid is less than 90 degrees. A liquid does not wet a surface if the angle of contact is greater than 90 degrees (as is the case with mercury on glass, where it is obtuse).

50. When you walk on a woolen carpet and bring your finger near the metall

When you walk on a woolen carpet and bring your finger near the metallic handle of a door an electric shock is produced. This is because

[amp_mcq option1=”charge is transferred from your body to the handle” option2=”a chemical reaction occurs when you touch the handle” option3=”the temperature of the human body is higher than that of the handle” option4=”the human body and the handle arrive at thermal equilibrium by the process” correct=”option1″]

This question was previously asked in

UPSC NDA-1 – 2015

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When you walk on a woolen carpet, friction between your shoes and the carpet causes charge separation, resulting in a build-up of static electric charge on your body (triboelectric effect). When you then touch a conductive object like a metallic door handle, this accumulated charge rapidly transfers from your body to the handle, creating a momentary electric current which you perceive as a shock.

Static electricity build-up due to friction and subsequent sudden discharge is the cause of the electric shock.

The amount of charge built up depends on factors like the materials involved, humidity, and the extent of friction. Metal handles are good conductors, facilitating the rapid discharge.