UPSC IAS Archives

31. The efforts to detect the existence of Higgs boson particle have becom

The efforts to detect the existence of Higgs boson particle have become frequent news in the recent past. What is/are the importance/importances of discovering this particle?

1. It will enable us to understand as to why elementary particles have mass.
2. It will enable us in the near future to develop the technology of transferring matter from one point to another without traversing the physical space between them.
3. It will enable us to create better fuels for nuclear fission.

Select the correct answer using the codes given below.

1 only

2 and 3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2013

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Statement 1 is correct because the Higgs boson is fundamentally linked to the mechanism by which elementary particles acquire mass through their interaction with the Higgs field. Statements 2 and 3 are incorrect; the discovery of the Higgs boson is not related to matter transfer technology (teleportation) or nuclear fission fuel development.

The Standard Model of particle physics describes the fundamental particles and forces. The Higgs field and its associated particle, the Higgs boson, were proposed to explain why some elementary particles have mass while others (like photons) do not. The detection of the Higgs boson in 2012 by the ATLAS and CMS experiments at CERN’s Large Hadron Collider confirmed this mechanism.

Statement 2 describes a speculative concept (teleportation) not related to the properties or applications of the Higgs boson. Statement 3 is irrelevant to the field of nuclear energy; nuclear fission involves the splitting of atomic nuclei, a process governed by the strong nuclear force and properties of isotopes, not the Higgs mechanism.

32. The known forces of nature can be divided into four classes, viz., gra

The known forces of nature can be divided into four classes, viz., gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?

Gravity is the strongest of the four

Electromagnetism acts only on particles with an electric charge

Weak nuclear force causes radioactivity

Strong nuclear force holds protons and neutrons inside the nucleus of an atom

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UPSC IAS – 2013

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The statement that Gravity is the strongest of the four fundamental forces is not correct.

The four fundamental forces of nature are, in order of decreasing strength: Strong Nuclear Force, Electromagnetic Force, Weak Nuclear Force, and Gravity. Gravity is by far the weakest of the four forces. The Strong Nuclear Force holds the nucleus together, Electromagnetism governs interactions between charges, and the Weak Nuclear Force is involved in radioactive decay.

Although gravity is the weakest force at the particle level, its effects are cumulative and always attractive. This makes it the dominant force on large astronomical scales (planets, stars, galaxies). The relative strengths of the forces are approximately: Strong Nuclear Force ~ 1, Electromagnetic Force ~ 10⁻², Weak Nuclear Force ~ 10⁻⁶, Gravity ~ 10⁻³⁹ (relative to the strong force at typical nuclear scales).

33. Which of the following leaf modifications occurs/occur in desert areas

Which of the following leaf modifications occurs/occur in desert areas to inhibit water loss?

1. Hard and waxy leaves
2. Tiny leaves or no leaves
3. Thorns instead of leaves

Select the correct answer using the codes given below.

1 and 2 only

2 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2013

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All the listed leaf modifications occur in desert areas to inhibit water loss: hard and waxy leaves, tiny leaves or no leaves, and thorns instead of leaves.

Desert plants (xerophytes) have evolved various adaptations to survive in arid environments with limited water availability. 1. Hard and waxy leaves (with thick cuticles) reduce cuticular transpiration. 2. Having tiny leaves or shedding leaves during dry periods minimizes the surface area for transpiration. Some plants have modified stems that photosynthesize instead of leaves. 3. Thorns are often modified leaves or stipules; they drastically reduce the surface area for transpiration and also deter herbivores, preventing tissue damage that could lead to water loss.

Other adaptations in desert plants include sunken stomata, fleshy stems or leaves for water storage (succulence), extensive root systems, and C4 or CAM photosynthesis pathways which are more water-efficient.

34. Which of the following statements is/are correct? 1. Viruses lack en

Which of the following statements is/are correct?

1. Viruses lack enzymes necessary for the generation of energy.
2. Viruses can be cultured in any synthetic medium.
3. Viruses are transmitted from one organism to another by biological vectors only.

Select the correct answer using the codes given below.

1 only

2 and 3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2013

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Only statement 1 is correct: Viruses lack enzymes necessary for the generation of energy.

Statement 1 is correct. Viruses are acellular and obligate intracellular parasites. They do not possess their own metabolic machinery, including enzymes for energy production like respiration or fermentation. They hijack the host cell’s metabolic processes to obtain energy and replicate. Statement 2 is incorrect because viruses require living cells to replicate and cannot be cultured in synthetic non-living media. Statement 3 is incorrect because while biological vectors are one mode of transmission for some viruses, many viruses are transmitted through non-vector means such as direct contact, airborne droplets, contaminated surfaces, food, or water.

Viruses consist of genetic material (DNA or RNA) enclosed in a protein coat (capsid), and sometimes an outer envelope derived from the host cell membrane. Their dependence on host cells for replication and metabolism distinguishes them from cellular organisms like bacteria or fungi.

35. Economic growth in country X will necessarily have to occur if

Economic growth in country X will necessarily have to occur if

there is technical progress in the world economy

there is population growth in X

there is capital formation in X

the volume of trade grows in the world economy

This question was previously asked in

UPSC IAS – 2013

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Economic growth in country X will necessarily have to occur if there is capital formation in X.

Capital formation (investment in physical capital like machinery, infrastructure, and human capital like education, skills) increases the productive capacity of an economy. An increase in the stock of capital, combined with labour, directly leads to an increase in the potential output of goods and services, which is the basis of economic growth. While other factors like technology and labor are also crucial, sustained economic growth fundamentally requires investment in increasing the factors of production or improving their productivity.

Technical progress in the world economy and growth in world trade provide opportunities but do not guarantee growth in a specific country X without internal conditions being met (like capital to adopt technology or participate in trade). Population growth increases the labour supply but doesn’t necessarily translate into growth without sufficient capital and technology to employ the additional population productively; it can even lead to a decrease in per capita income if growth in output doesn’t keep pace.

36. Many transplanted seedlings do not grow because

Many transplanted seedlings do not grow because

the new soil does not contain favourable minerals

most of the root hairs grip the new soil too hard

most of the root hairs are lost during transplantation

leaves get damaged during transplantation

This question was previously asked in

UPSC IAS – 2013

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Many transplanted seedlings do not grow because most of their root hairs are lost during the transplantation process.

Root hairs are fine, delicate extensions of root epidermal cells that greatly increase the surface area for absorption of water and mineral nutrients from the soil. When a seedling is dug up for transplantation, the soil around the roots is disturbed, and a large number of these fragile root hairs are broken or stripped off. The plant’s ability to absorb water is severely reduced until new root hairs can grow, leading to ‘transplant shock’, wilting, and potentially death if sufficient water uptake cannot be re-established quickly.

While factors like unfavorable soil conditions or leaf damage can also affect transplant success, the primary and most immediate challenge for a transplanted seedling is the drastic reduction in its water absorption capacity due to root hair loss. Proper watering and minimizing root disturbance during transplantation are crucial for survival.

37. Rainbow is produced when sunlight falls on drops of rain. Which of the

Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena are responsible for this?

1. Dispersion
2. Refraction
3. Internal reflection

Select the correct answer using the codes given below.

1 and 2 only

2 and 3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2013

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Rainbow is produced when sunlight falls on drops of rain, and the phenomena responsible are dispersion, refraction, and internal reflection.

When sunlight enters a raindrop, it is refracted (bent). As the light enters, it also undergoes dispersion, splitting into its constituent colours because different wavelengths of light are refracted at slightly different angles. The dispersed light then reflects off the back inner surface of the raindrop (internal reflection). Finally, the light is refracted again as it exits the raindrop towards the observer. All three processes are essential for the formation of a rainbow.

Primary rainbows are formed by light undergoing one internal reflection. Secondary rainbows, which are fainter and appear above the primary rainbow with the colours reversed, are formed by light undergoing two internal reflections. In both cases, refraction and dispersion occur at the air-water interfaces.

38. Consider the following phenomena : 1. Size of the sun at dusk 2. Co

Consider the following phenomena :

1. Size of the sun at dusk
2. Colour of the sun at dawn
3. Moon being visible at dawn
4. Twinkle of stars in the sky
5. Polestar being visible in the sky

Which of the above are optical illusions?

1, 2 and 3

3, 4 and 5

1, 2 and 4

2, 3 and 5

This question was previously asked in

UPSC IAS – 2013

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The size of the sun at dusk, the colour of the sun at dawn, and the twinkle of stars in the sky are considered optical phenomena or illusions.

1. The apparent increase in the size of the sun (or moon) near the horizon (dusk) is an optical illusion known as the Moon illusion. 2. The reddish/orange colour of the sun at dawn is due to atmospheric scattering (Rayleigh scattering), where shorter wavelengths (blue/green) are scattered away more than longer wavelengths (red/orange) when light travels a longer path through the atmosphere. This phenomenon leads to a perceived colour change. 4. The twinkling of stars is caused by atmospheric refraction due to turbulence in the air, which makes the light from distant stars appear to fluctuate in brightness and position.

Phenomena 3 (Moon being visible at dawn) and 5 (Polestar being visible in the sky) are real astronomical occurrences related to the celestial positions of these bodies and are not optical illusions in the sense of being perceptual distortions or atmospheric effects causing altered appearance. Therefore, 1, 2, and 4 fit the description of optical illusions or related atmospheric optical phenomena causing altered visual perception.

39. Ball bearings are used in bicycles, cars, etc., because

Ball bearings are used in bicycles, cars, etc., because

the actual area of contact between the wheel and axle is increased

the effective area of contact between the wheel and axle is increased

the effective area of contact between the wheel and axle is reduced

None of the above statements is correct

This question was previously asked in

UPSC IAS – 2013

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Ball bearings are used in bicycles, cars, etc., because they significantly reduce the effective area of contact between the moving parts (like the wheel and axle), thereby reducing friction.

Ball bearings replace sliding friction with rolling friction. Sliding friction occurs over a larger contact area between the axle and its housing. Ball bearings consist of spherical balls rolling between two races. The contact between the balls and the races is nearly point contact (in theory, or a very small ellipse in practice). This reduces the area experiencing friction and, crucially, replaces high sliding friction with much lower rolling friction.

Rolling friction is generally much less than sliding friction for the same load. By allowing parts to roll over each other via the balls, the overall frictional force opposing motion is greatly reduced, making movement easier and more efficient, and reducing wear and tear.

40. Consider the following fauna of India : 1. Gharial 2. Leatherback t

Consider the following fauna of India :

1. Gharial
2. Leatherback turtle
3. Swamp deer

Which of the above is/are endangered?

1 and 2 only

3 only

1, 2 and 3

None

This question was previously asked in

UPSC IAS – 2013

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All three fauna mentioned – Gharial, Leatherback turtle, and Swamp deer – are considered endangered or critically endangered in the context of India.

The Gharial (Gavialis gangeticus) is listed as Critically Endangered by the IUCN. The Leatherback Sea Turtle (Dermochelys coriacea), while globally Vulnerable, has populations in the Indian Ocean region that are highly threatened, including the Southwest Indian Ocean subpopulation listed as Critically Endangered. The Swamp Deer (Rucervus duvaucelii) species is listed as Vulnerable, but the Sangai (Rucervus eldii), a subspecies of swamp deer found in Manipur, India, is listed as Endangered.

Conservation efforts are underway in India for all three species. The status ‘endangered’ often refers to the species level, but for questions pertaining to ‘fauna of India’, the status of specific populations or subspecies within India is relevant. Given the status of the Gharial, the critically endangered Leatherback population in the region, and the endangered Sangai subspecies of Swamp deer, all three can be considered endangered in the Indian context.