UPSC NDA-2 Archives

31. The loudness of sound is related to:

The loudness of sound is related to:

[amp_mcq option1=”its frequency” option2=”its amplitude” option3=”its speed” option4=”its pitch” correct=”option2″]

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UPSC NDA-2 – 2015

The loudness of a sound is related to its intensity, which in turn is proportional to the square of the amplitude of the sound wave. A sound wave with a larger amplitude carries more energy and is perceived as louder.

Loudness is the perceptual attribute of sound that is most closely related to the intensity of the sound wave, which depends on its amplitude.

Frequency is related to pitch (how high or low a sound is). The speed of sound depends on the medium through which it travels, not its loudness. Pitch is determined by frequency. While frequency and waveform also contribute to the overall perception of sound, amplitude is the primary determinant of loudness. Loudness is typically measured in decibels (dB).

32. Which one of the following is not a site of action in the human body f

Which one of the following is not a site of action in the human body for the malarial parasite Plasmodium?

[amp_mcq option1=”Liver” option2=”Kidney” option3=”Red blood cell” option4=”Brain” correct=”option2″]

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The malarial parasite Plasmodium primarily infects the liver and red blood cells in the human body. It can also affect the brain, causing cerebral malaria. The kidneys are not a primary site of replication or development for the parasite’s lifecycle stages, although malaria can lead to significant kidney complications.

The main sites of Plasmodium infection in humans are the liver (exo-erythrocytic stage) and red blood cells (erythrocytic stage).

Malaria is a mosquito-borne infectious disease caused by Plasmodium parasites. Different species of Plasmodium (e.g., Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, Plasmodium knowlesi) have slightly different lifecycles and disease manifestations, but the general pattern of liver and red blood cell invasion is common. Cerebral malaria is a severe complication of Plasmodium falciparum infection where parasites sequester in the capillaries of the brain. While malaria can cause kidney damage (e.g., malarial nephropathy), the kidney itself is not a host organ for the parasite’s developmental stages.

33. Match List I with List II and select the correct answer using the code

Match List I with List II and select the correct answer using the code given below the Lists:

List I (Element)	List II (Use)
A. Li	1. Time keeper in atomic clocks
B. Na	2. Batteries
C. K	3. Transfer of nerve impulses
D. Cs	4. Control of the water content in the blood

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

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The correct option is C, 2 4 3 1.

Let’s match the elements with their uses:
A. Li (Lithium): Lithium is a highly reactive alkali metal widely used in batteries, particularly rechargeable lithium-ion batteries that power portable electronic devices, electric vehicles, etc. This matches characteristic 2. (A-2)
B. Na (Sodium): Sodium ions (Na+) are essential electrolytes in the body. They play a critical role in regulating blood pressure and the control of water balance in the blood and body tissues through osmosis. This matches characteristic 4. (B-4)
C. K (Potassium): Potassium ions (K+) are also essential electrolytes involved in various bodily functions, including the transmission of nerve impulses and muscle contractions (along with sodium ions). This matches characteristic 3. (C-3)
D. Cs (Cesium): Cesium is an alkali metal, and the isotope Cesium-133 is famously used in atomic clocks due to the highly stable frequency of radiation emitted during electron transitions in its atom, which defines the length of a second. This matches characteristic 1. (D-1)
Thus, the correct matching is A-2, B-4, C-3, D-1, which corresponds to option C (2 4 3 1).

Elements have a wide range of applications based on their unique chemical and physical properties. Lithium, sodium, and potassium are alkali metals known for their reactivity. Cesium is the heaviest stable alkali metal and is known for its very low ionization energy, making it useful in applications like atomic clocks and photocells.

34. Match List I with List II and select the correct answer using the code

Match List I with List II and select the correct answer using the code given below the Lists:

List I (Low-Latitude Climate)	List II (Characteristic)
A. Wet Equatorial	1. Uniform temperatures, mean near 27 °C
B. Monsoon and trade wind coastal	2. Marked temperature cycle with very high temperature before the rainy season
C. Wet-dry tropical	3. Temperatures show an annual cycle with high temperature in the high-Sun season
D. Dry tropical	4. Strong temperature cycle, with intense temperature during high-Sun season

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

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The correct option is D, 1 3 2 4.

Let’s match the low-latitude climate types with their characteristics:
A. Wet Equatorial (e.g., Amazon Basin, Congo Basin): Characterized by uniformly high temperatures throughout the year, typically averaging around 27 °C, and high rainfall year-round. This matches characteristic 1. (A-1)
B. Monsoon and trade wind coastal (e.g., Indian subcontinent, Southeast Asia): Influenced by seasonal wind shifts bringing heavy rainfall (monsoons) or consistent rainfall from trade winds. Temperatures show an annual cycle, with warmer temperatures during the high-Sun season, but moderated by humidity and rainfall. This matches characteristic 3. (B-3)
C. Wet-dry tropical (Savanna, e.g., East Africa, parts of Brazil): Features distinct wet and dry seasons. Temperatures have a marked annual cycle, with the highest temperatures often occurring just before the onset of the rainy season, when it is hottest and driest. This matches characteristic 2. (C-2)
D. Dry tropical (Desert, e.g., Sahara Desert, Arabian Desert): Characterized by extremely low rainfall and high temperatures. Temperatures exhibit a strong annual and diurnal cycle, with intense heat during the high-Sun season. This matches characteristic 4. (D-4)
Thus, the correct matching is A-1, B-3, C-2, D-4, which corresponds to option D (1 3 2 4).

These climate types are typically found between the Tropics of Cancer and Capricorn. They are differentiated based primarily on their annual rainfall distribution and the resulting vegetation patterns, which in turn influence temperature characteristics. The Köppen climate classification system provides a more detailed framework for defining these climate types.

35. The acceleration due to gravity ‘g’ for objects on or near the surface

The acceleration due to gravity ‘g’ for objects on or near the surface of earth is related to the universal gravitational constant ‘G’ as (‘M’ is the mass of the earth and ‘R’ is its radius):

[amp_mcq option1=”G = g $\frac{\text{M}}{\text{R}^2}$” option2=”g = G $\frac{\text{M}}{\text{R}^2}$” option3=”M = $\frac{\text{gG}}{\text{R}^2}$” option4=”R = $\frac{\text{gG}}{\text{M}^2}$” correct=”option2″]

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UPSC NDA-2 – 2015

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The correct option is B, g = G $\frac{\text{M}}{\text{R}^2}$.

The acceleration due to gravity ‘g’ on the surface of the Earth is caused by the gravitational force exerted by the Earth on an object. According to Newton’s Law of Universal Gravitation, the force (F) between the Earth (mass M) and an object (mass m) on its surface (distance R from the center, where R is the Earth’s radius) is given by F = G $\frac{\text{Mm}}{\text{R}^2}$, where G is the universal gravitational constant. This gravitational force is also the object’s weight, W, which is given by W = mg (by Newton’s second law, where ‘g’ is the acceleration due to this force). Equating the two expressions for the force (F = W), we get mg = G $\frac{\text{Mm}}{\text{R}^2}$. Dividing both sides by the mass of the object ‘m’ gives the relationship for the acceleration due to gravity: g = G $\frac{\text{M}}{\text{R}^2}$.

This formula shows that the acceleration due to gravity ‘g’ is independent of the mass of the object itself and depends only on the mass and radius of the planet (or celestial body) and the universal gravitational constant G. The value of ‘g’ varies slightly across the Earth’s surface due to factors like altitude, latitude, and local geological variations.

36. In SI unit of force ‘Newton’ (N) is given by (where m stands for metre

In SI unit of force ‘Newton’ (N) is given by (where m stands for metre and s stands for second):

[amp_mcq option1=”1 N = 1 kg/ms²” option2=”1 N = 1 kgm/s²” option3=”1 N = 1 kg s²/m” option4=”1 N = 1 kg m s²” correct=”option2″]

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The correct option is B, 1 N = 1 kgm/s².

The SI unit of force, the Newton (N), is defined based on Newton’s second law of motion, which states that force (F) equals mass (m) multiplied by acceleration (a): F = ma. The SI unit of mass is the kilogram (kg), and the SI unit of acceleration is meters per second squared (m/s²). Therefore, 1 Newton is defined as the force required to accelerate a mass of 1 kilogram at a rate of 1 meter per second squared. This gives the relationship 1 N = 1 kg * (m/s²), or 1 N = 1 kgm/s².

The Newton is a derived unit in the SI system. It is named after Sir Isaac Newton in recognition of his work on classical mechanics. Other units of force exist, such as the dyne (in the CGS system) or the pound-force (in imperial units), but the Newton is the standard unit in SI.

37. In blood, platelets are required for:

In blood, platelets are required for:

[amp_mcq option1=”transporting oxygen” option2=”transporting carbon dioxide” option3=”initiating blood clotting” option4=”initiating degradation of urea” correct=”option3″]

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The correct option is C, initiating blood clotting.

Platelets, also known as thrombocytes, are small, anucleated cell fragments in the blood that play a crucial role in hemostasis, the process by which bleeding is stopped. When a blood vessel is injured, platelets aggregate at the site of injury, forming a platelet plug. They also release factors that activate the coagulation cascade, a complex series of reactions leading to the formation of a fibrin clot, which reinforces the platelet plug and seals the damaged vessel. Red blood cells (erythrocytes) are responsible for transporting oxygen. Carbon dioxide is transported in the blood in various forms (dissolved in plasma, bound to hemoglobin, or as bicarbonate ions). Urea is a waste product transported by the blood to the kidneys for excretion; its degradation primarily occurs in the liver during its formation from ammonia.

Deficiency or dysfunction of platelets can lead to bleeding disorders, such as thrombocytopenia. Conversely, excessive platelet activation can contribute to the formation of blood clots (thrombosis) within blood vessels, which can lead to serious conditions like heart attacks or strokes.

38. Which one of the following gases is found in highest quantity in

Which one of the following gases is found in highest quantity in Exosphere?

[amp_mcq option1=”Hydrogen” option2=”Helium” option3=”Nitrogen” option4=”Oxygen” correct=”option1″]

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The correct option is A, Hydrogen.

The exosphere is the outermost layer of the Earth’s atmosphere, extending upwards from the thermosphere and gradually thinning into space. The gases in this region are extremely sparse. Due to their very low atomic mass, hydrogen and helium are the most abundant constituents, as they are light enough to reach these high altitudes and potentially escape Earth’s gravity. Hydrogen is generally considered the dominant gas in the outermost reaches of the exosphere. Heavier gases like nitrogen and oxygen are much more concentrated in the lower atmospheric layers.

The exosphere is characterized by extremely low density and consists primarily of hydrogen, helium, and some heavier atoms and molecules near its base. This region marks the transition between Earth’s atmosphere and the vacuum of outer space. Temperature in the exosphere is highly variable and not representative of heat content due to the low particle density.

39. An up fold in rock is:

An up fold in rock is:

[amp_mcq option1=”graben” option2=”horse” option3=”anticline” option4=”syncline” correct=”option3″]

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The correct option is C, anticline.

In structural geology, an up fold in rock layers, where the limbs dip away from the hinge and the oldest strata are typically in the core, is called an anticline. Conversely, a down fold, where the limbs dip towards the hinge and the youngest strata are in the core, is called a syncline. Graben and horst are fault-related structures; a graben is a down-dropped block bounded by normal faults, and a horst is an uplifted block bounded by normal faults.

Folds in rock strata result from compressional forces acting on the Earth’s crust. Anticlines and synclines often occur together in fold belts. The shape of the fold can vary from gentle waves to tight, overturned folds.

40. Magnetic meridian is an imaginary:

Magnetic meridian is an imaginary:

[amp_mcq option1=”line along north-south” option2=”point” option3=”vertical plane” option4=”horizontal plane” correct=”option3″]

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The correct option is C, vertical plane.

The magnetic meridian at any point on the Earth’s surface is an imaginary vertical plane that passes through the geographic location and the Earth’s magnetic poles (or more precisely, along the local direction of the Earth’s magnetic field lines). The angle between the magnetic meridian and the geographic meridian (the vertical plane containing the geographic North and South poles) is called magnetic declination.

A compass needle, free to rotate in a horizontal plane, aligns itself with the horizontal component of the Earth’s magnetic field, pointing towards the magnetic north pole along the magnetic meridian. If the needle is free to rotate vertically as well, it dips, aligning with the full magnetic field vector within the magnetic meridian plane.