UPSC CAPF

41. The electrical device used for converting mechanical energy into elect

The electrical device used for converting mechanical energy into electrical energy is called

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voltmeter
ammeter
motor
generator
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UPSC CAPF – 2022
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The correct answer is D, generator.
A generator is a device that converts mechanical energy into electrical energy. This conversion is based on the principle of electromagnetic induction, where a relative motion between a conductor and a magnetic field induces an electric current in the conductor. Mechanical work is done to cause this relative motion.
A motor is a device that converts electrical energy into mechanical energy.
A voltmeter is an instrument used to measure electric potential difference (voltage).
An ammeter is an instrument used to measure electric current.
Generators are essential components in power plants, converting mechanical energy from sources like turbines (driven by steam, water, or wind) into electrical energy for distribution.

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42. The optical phenomenon responsible for the blue colour of sky is

The optical phenomenon responsible for the blue colour of sky is

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dispersion
reflection
refraction
scattering
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UPSC CAPF – 2022
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The correct answer is D, scattering.
The blue colour of the sky is primarily caused by the scattering of sunlight by molecules and tiny particles in the Earth’s atmosphere.
This phenomenon is explained by Rayleigh scattering, which states that the amount of scattering is inversely proportional to the fourth power of the wavelength. Shorter wavelengths (like blue and violet) are scattered much more effectively than longer wavelengths (like red and orange).
When sunlight enters the atmosphere, the blue light is scattered in all directions by the atmospheric particles, making the sky appear blue. Our eyes are more sensitive to blue light than violet, contributing to the perception of a blue sky.
Dispersion is the splitting of white light into its constituent colours due to different wavelengths having different refractive indices in a medium (like in a prism or rainbow). Reflection is the bouncing of light off a surface. Refraction is the bending of light as it passes from one medium to another. While refraction plays a role in atmospheric phenomena like mirages, it’s scattering that causes the blue sky.

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43. Which one of the following materials *cannot* be used to make a convex

Which one of the following materials *cannot* be used to make a convex lens?

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Aluminium
Glass
Sapphire
Water
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UPSC CAPF – 2022
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The correct answer is A, Aluminium.
A lens works by refracting (bending) light as it passes through the material. For a material to be used to make a lens, it must be transparent or at least translucent to the type of light intended to be used (e.g., visible light for optical lenses).
Glass, Sapphire, and Water are all transparent or translucent materials that can refract light, making them suitable for manufacturing lenses.
Aluminium is a metal that is opaque to visible light. Light does not pass through it but is reflected or absorbed. Therefore, Aluminium cannot be used to make a convex lens for visible light.
Lenses are typically made from materials like glass, plastic, quartz, sapphire, fluorite, or even liquids like water. The choice of material depends on the desired optical properties (like refractive index, dispersion), cost, durability, and the specific wavelength range of light for which the lens is intended.

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44. Which one of the following is *not* the unit of pressure?

Which one of the following is *not* the unit of pressure?

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pascal (Pa)
N/m²
J/m²
bar
This question was previously asked in
UPSC CAPF – 2022
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The correct answer is C, J/m².
Pressure is defined as force per unit area (Pressure = Force/Area).
The SI unit of force is Newton (N) and the SI unit of area is square meter (m²). Therefore, N/m² is a unit of pressure.
Pascal (Pa) is the SI unit of pressure, defined as 1 Pa = 1 N/m².
Bar is a non-SI unit of pressure, widely used (1 bar = 10⁵ Pa).
Joule (J) is the unit of energy or work. J/m² represents energy per unit area. While pressure has the same dimensions as energy density (J/m³), J/m² represents pressure multiplied by distance (since J = N.m, J/m² = (N.m)/m² = N/m * m = Pressure * Distance). Therefore, J/m² is not a unit of pressure.
J/m³ (Joule per cubic meter) represents energy density and has the same units as pressure (N/m² or Pa). This is because Energy = Force × Distance, so J = N.m. Thus, J/m³ = N.m/m³ = N/m², which are units of pressure. However, J/m² is not dimensionally equivalent to pressure.

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45. Two objects, x and y, have equal mass and are moving with speeds u and

Two objects, x and y, have equal mass and are moving with speeds u and 3u respectively. Their kinetic energies k_x and k_y are related as

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k_x = k_y
2k_x = k_y
9k_x = k_y
3k_x = k_y
This question was previously asked in
UPSC CAPF – 2022
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The correct answer is C, 9k_x = k_y.
The kinetic energy (k) of an object with mass (m) and speed (v) is given by the formula k = ½ mv².
For object x, mass is m and speed is u, so k_x = ½ mu².
For object y, mass is m and speed is 3u, so k_y = ½ m(3u)² = ½ m(9u²) = 9 (½ mu²).
Comparing k_y with k_x, we find k_y = 9k_x, or 9k_x = k_y.
Kinetic energy is directly proportional to the mass of the object and the square of its speed. Doubling the speed of an object quadruples its kinetic energy (if mass remains constant). Tripling the speed increases the kinetic energy by a factor of nine.

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46. Phloem tissues are mostly responsible for transport of

Phloem tissues are mostly responsible for transport of

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water
oxygen
minerals
food
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UPSC CAPF – 2022
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The correct answer is D) food.
Plant vascular tissues consist of xylem and phloem. Xylem is primarily responsible for the transport of water and dissolved minerals from the roots to the rest of the plant. Phloem is primarily responsible for the transport of organic nutrients, mainly sugars (food) produced during photosynthesis in the leaves, to other parts of the plant where they are needed for growth or storage.
The transport of food in the phloem is called translocation and can occur in multiple directions (upwards, downwards, or sideways) depending on the source (where food is produced) and sink (where food is needed) areas. Oxygen is primarily exchanged through stomata on the leaves and lenticels on stems, not transported systemically through vascular tissue in this manner.

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47. Buds produced in the notches along the leaf margin of Bryophyllum fall

Buds produced in the notches along the leaf margin of Bryophyllum fall on soil and develop into new plants. This is an example of which one of the following types of reproduction?

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Vegetative propagation
Budding
Spore formation
Regeneration
This question was previously asked in
UPSC CAPF – 2022
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The correct answer is A) Vegetative propagation.
Vegetative propagation is a form of asexual reproduction in plants where new individuals are produced from vegetative parts of the parent plant, such as roots, stems, or leaves, rather than from seeds or spores. In Bryophyllum, adventitious buds develop in the notches along the leaf margin; these buds can detach, fall to the ground, and grow into new plants, which is a classic example of vegetative propagation via leaves.
Budding is a type of asexual reproduction, but it typically involves the formation of a bud that develops into a new individual while attached to the parent (e.g., yeast, Hydra) or as a horticultural technique (bud grafting). Spore formation is a reproductive method found in fungi, bacteria, algae, and some plants like ferns and mosses. Regeneration is the ability of an organism to regrow lost body parts.

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48. Depending on the requirements, plant nutrients are classified as micro

Depending on the requirements, plant nutrients are classified as micronutrients and macronutrients. Which one of the following is an example of a macronutrient?

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Manganese
Copper
Magnesium
Chlorine
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UPSC CAPF – 2022
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The correct answer is C) Magnesium.
Plant nutrients are classified as macronutrients or micronutrients based on the quantity required by the plant. Macronutrients are needed in relatively large amounts, while micronutrients are needed in very small amounts. The primary macronutrients are Nitrogen (N), Phosphorus (P), and Potassium (K). Secondary macronutrients include Calcium (Ca), Magnesium (Mg), and Sulfur (S). Manganese (Mn), Copper (Cu), and Chlorine (Cl) are classified as micronutrients.
Magnesium is a component of chlorophyll, essential for photosynthesis, and activates many enzymes. Its requirement by plants is relatively high compared to micronutrients.

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49. One way of incorporating desired characters into crop varieties is hyb

One way of incorporating desired characters into crop varieties is hybridization. In this process, there is crossing between genetically dissimilar plants. Which one of the following crossings will not refer to hybridization?

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Intervarietal
Interspecific
Intergeneric
Intragenic
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The correct answer is D) Intragenic.
Hybridization refers to the crossing of genetically dissimilar individuals to produce offspring with a combination of traits from both parents. This can occur between different varieties of the same species (intervarietal), between different species (interspecific), or even between different genera (intergeneric). Intragenic refers to genetic changes or events (like mutation or recombination) occurring within a single gene, not involving the crossing of different individuals or groups.
Hybridization is a key technique in plant and animal breeding to introduce desirable traits from one genetic background into another. Intragenic studies focus on the structure, function, and alterations of individual genes.

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50. Which one of the following animals has a four-chambered heart?

Which one of the following animals has a four-chambered heart?

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King cobra
Turtle
Chameleon
Crocodile
This question was previously asked in
UPSC CAPF – 2022
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The correct answer is D) Crocodile.
Most reptiles (snakes like King cobra, turtles, lizards like Chameleon) have a three-chambered heart with two atria and a single ventricle, often partially divided. However, crocodiles are unique among living reptiles in possessing a complete four-chambered heart, similar to birds and mammals, which allows for complete separation of oxygenated and deoxygenated blood.
The four-chambered heart in crocodiles is an evolutionary adaptation that provides more efficient circulation, particularly beneficial for their active lifestyle and diving habits.

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