UPSC CDS-2 Archives

11. Which one of the following is the correct ascending sequence of States

Which one of the following is the correct ascending sequence of States with regard to percentage of urban population (2011)?

[amp_mcq option1=”Tamil Nadu—Mizoram—Goa—Maharashtra” option2=”Goa—Mizoram—Maharashtra—Kerala” option3=”Maharashtra—Kerala—Mizoram—Goa” option4=”Mizoram—Goa—Maharashtra—Kerala” correct=”option3″]

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The correct answer is C) Maharashtra—Kerala—Mizoram—Goa.

Based on the 2011 Census of India data for the percentage of urban population, the approximate percentages for the states listed are: Maharashtra (45.2%), Kerala (47.7%), Tamil Nadu (48.4%), Mizoram (52.1%), and Goa (62.2%). Arranging the states given in option C in ascending order of urban population percentage gives Maharashtra (45.2%) < Kerala (47.7%) < Mizoram (52.1%) < Goa (62.2%). This is a correct ascending sequence among the options provided.

Urbanization levels vary significantly across Indian states. States like Goa and Mizoram, despite their smaller populations, have relatively high percentages of urban residents compared to many larger states. Maharashtra and Tamil Nadu are among the most urbanized large states. The ascending sequence in option C correctly reflects the relative positions of these states in terms of urban population percentage according to the 2011 census.

12. Which one of the following statements explains higher mutation rate an

Which one of the following statements explains higher mutation rate and faster evolution found in RNA virus?

[amp_mcq option1=”RNA is relatively unstable compared to DNA.” option2=”Virus can multiply only within the living cell of a host.” option3=”Metabolic processes are absent in virus.” option4=”Virus can remain latent for a long period.” correct=”option1″]

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The correct answer is A) RNA is relatively unstable compared to DNA.

RNA molecules are generally less stable than DNA molecules primarily because of the presence of a hydroxyl group at the 2′ carbon of the ribose sugar, which makes the phosphodiester bond more susceptible to hydrolysis. Additionally, RNA viruses typically lack the proofreading mechanisms that DNA polymerases have, leading to a much higher error rate during replication. These factors result in a higher mutation rate.

Higher mutation rates in RNA viruses contribute to faster evolution, allowing them to adapt quickly to changing environments, evade host immune responses, and develop resistance to antiviral drugs. Options B, C, and D describe general characteristics of viruses but do not specifically explain the higher mutation rate or faster evolution relative to DNA viruses or other life forms.

13. Which one of the following is the special type of milk produced by a l

Which one of the following is the special type of milk produced by a lactating mother, essential for the development of immune response of newborn baby in human?

[amp_mcq option1=”Breast milk produced after a month of childbirth” option2=”Transitional milk” option3=”Colostrum” option4=”Mineralized milk” correct=”option3″]

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Colostrum is the special type of milk produced immediately after childbirth that is essential for the development of the immune response of the newborn baby in human.

Colostrum is the first milk produced by the mother, typically in the first few days after birth. It is often described as “liquid gold” due to its yellowish color and immense nutritional and immunological value. It is significantly different from mature breast milk. Colostrum is particularly rich in immunoglobulins (antibodies), especially IgA, which provides passive immunity to the newborn, protecting them against various infections. It also contains leukocytes (white blood cells), growth factors, and nutrients highly suited for the newborn’s initial needs.

After colostrum, the composition of breast milk changes over approximately two weeks, becoming transitional milk, and then settles into mature milk. While mature milk continues to provide antibodies and nutritional support, colostrum has the highest concentration of immune components, making it uniquely crucial for establishing the newborn’s early immune defenses and gut health.

14. Which of the following roles is/are played by epididymis, vas deferens

Which of the following roles is/are played by epididymis, vas deferens, seminal vesicles and prostate in male reproductive system of human?

[amp_mcq option1=”Spermatogenesis and maturation of sperms” option2=”Maturation and motility of sperms” option3=”Spermatogenesis and motility of sperms” option4=”Motility of sperms only” correct=”option2″]

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The roles played by epididymis, vas deferens, seminal vesicles and prostate in the male reproductive system primarily include maturation and motility of sperms.

Spermatogenesis, the production of sperm, occurs in the seminiferous tubules within the testes. The structures listed play subsequent roles:
– Epididymis: Sperm produced in the testes are immature and non-motile. They mature and gain motility (the ability to swim) in the epididymis during their passage through this coiled tube. It also stores sperm.
– Vas deferens: This duct transports mature sperm from the epididymis to the ejaculatory duct during ejaculation. It does not play a significant role in maturation or production.
– Seminal vesicles and Prostate: These are accessory glands that produce the seminal fluid, which mixes with sperm to form semen. This fluid contains substances (like fructose from seminal vesicles and enzymes from the prostate) that provide nutrients and support for sperm motility, survival, and function within the female reproductive tract.
Therefore, maturation (epididymis) and facilitating motility (epididymis and the fluid contributions from seminal vesicles/prostate) are key roles of these structures.

The complete path of sperm from production to ejaculation involves testes (spermatogenesis) -> epididymis (maturation, storage) -> vas deferens (transport) -> ejaculatory duct (formed by vas deferens and seminal vesicle duct) -> urethra. Bulbourethral glands (Cowper’s glands) also contribute fluid to the semen.

15. Which one of the following features is an indication for modification

Which one of the following features is an indication for modification of stem of a plant?

[amp_mcq option1=”Presence of ‘eye’ on potato” option2=”‘Scale’ found in onion” option3=”‘Tendril’ found in pea” option4=”‘Hair’ present in carrot” correct=”option1″]

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The presence of ‘eye’ on potato is an indication for modification of stem of a plant.

Modifications are adaptations of plant parts for specific functions. To identify a modification, we look for features characteristic of the original plant part.
A) ‘Eye’ on potato: An ‘eye’ on a potato is an axillary bud, located at a node. The presence of nodes and internodes is a characteristic feature of stems. Potato tubers are modified underground stems used for storage and vegetative propagation.
B) ‘Scale’ found in onion: Onion bulbs consist of a reduced stem base and fleshy modified leaves (scales) that store food. While the bulb includes a stem component, the ‘scales’ themselves are modified leaves.
C) ‘Tendril’ found in pea: Tendrils in peas are modified leaves or leaflets used for support.
D) ‘Hair’ present in carrot: Carrots are modified taproots. Root hairs are extensions of epidermal cells of roots, not stems.
Thus, the presence of buds (eyes) on a potato directly indicates its stem nature, even though it’s modified into a tuber.

Other examples of stem modifications include rhizomes (ginger), corms (colocasia), bulbs (onion, garlic), runners/stolons (grasses, strawberry), thorns (Bougainvillea, citrus), and cladodes (Opuntia). Root modifications include taproots for storage (carrot, radish), adventitious roots for support (banyan), and pneumatophores for respiration (mangroves).

16. In which of the following, heat loss is primarily not due to

In which of the following, heat loss is primarily not due to convection?

[amp_mcq option1=”Boiling water” option2=”Land and sea breeze” option3=”Circulation of air around blast furnace” option4=”Heating of glass surface of a bulb due to current in filament” correct=”option4″]

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In the heating of the glass surface of a bulb due to current in the filament, heat loss is primarily not due to convection.

Heat transfer occurs through conduction, convection, and radiation. Convection involves heat transfer through the movement of fluids (liquids or gases).
A) Boiling water: Heat is transferred throughout the water by convection currents.
B) Land and sea breeze: These are atmospheric movements caused by differential heating, a classic example of convection.
C) Circulation of air around blast furnace: Hot air rises and cooler air sinks, setting up convection currents around the furnace.
D) Heating of glass surface of a bulb due to current in filament: The filament of an incandescent bulb gets extremely hot due to the electric current. Heat is transferred from the filament to the surrounding space (including the glass envelope). If the bulb is evacuated, there is no medium for convection inside. Even if filled with an inert gas, the primary mode of heat transfer from the very hot filament across the gap to the glass envelope is thermal radiation. The glass surface then heats up by absorbing this radiation. While there might be some conduction through the support wires and subsequent convection/radiation from the outer glass surface, the initial transfer from the filament to the glass inside the bulb is significantly by radiation, not primarily convection.

Modern energy-efficient bulbs like LEDs produce less heat compared to incandescent bulbs. Incandescent bulbs convert only about 5-10% of electrical energy into light, with the rest being dissipated as heat, largely through radiation from the filament.

17. Which one of the following can extinguish fire more quickly?

Which one of the following can extinguish fire more quickly?

[amp_mcq option1=”Cold water” option2=”Boiling water” option3=”Hot water” option4=”Ice” correct=”option1″]

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Cold water can extinguish fire more quickly.

Water extinguishes fire primarily by cooling the burning material below its ignition temperature and by smothering (displacing oxygen) as it turns into steam. The cooling effect is due to water’s high specific heat capacity and high latent heat of vaporization. Cold water, compared to hot or boiling water, needs to absorb more heat to reach its boiling point (100°C) and then vaporize. This means a given mass of cold water can absorb a greater amount of heat from the fire, leading to more efficient cooling and quicker extinguishment. Boiling water is already at its boiling point and only absorbs heat through vaporization, while hot water requires less energy to reach boiling and vaporize compared to cold water. Ice must first absorb heat to melt before it can absorb further heat as liquid water and then vaporize, making its action potentially slower initially compared to liquid water directly applied.

Water is effective against fires involving solid materials (Class A fires), but it is not suitable for fires involving flammable liquids, gases, or electrical equipment, where it can spread the fire or pose an electrical hazard. Different types of fire extinguishers (e.g., foam, dry chemical, CO₂) are used for these other types of fires.

18. A circuit has a fuse having a rating of 5 A. What is the maximum numbe

A circuit has a fuse having a rating of 5 A. What is the maximum number of 100 W-220 V bulbs that can be safely connected in parallel in the circuit?

[amp_mcq option1=”20″ option2=”15″ option3=”11″ option4=”10″ correct=”option4″]

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A maximum of 11 bulbs can be safely connected in parallel in the circuit.

The circuit has a fuse rating of 5 A, which means the total current drawn by all connected devices must not exceed 5 A to prevent the fuse from blowing. Each bulb is rated at 100 W at 220 V. The current drawn by a single bulb is calculated using the formula P = V * I, so I = P/V.
Current per bulb = 100 W / 220 V = 10/22 A = 5/11 A.
When bulbs are connected in parallel, the voltage across each bulb is the same (220 V), and the total current drawn from the source is the sum of the currents drawn by each bulb. Let N be the number of bulbs connected. The total current is N * (5/11) A.
For safe operation, the total current must be less than or equal to the fuse rating: N * (5/11) A ≤ 5 A.
N * 5 ≤ 5 * 11
N ≤ 11.
Since the number of bulbs must be a whole number, the maximum number of bulbs that can be safely connected in parallel is 11.

Fuses are safety devices designed to protect electrical circuits from excessive current that could cause overheating and potentially fire. They are intentionally the weakest point in the circuit and melt, breaking the connection, if the current exceeds their rated value. Parallel connections are common for household appliances like lights, allowing each device to operate independently at the full circuit voltage.

19. The direction of magnetic field at any location on the earth’s surface

The direction of magnetic field at any location on the earth’s surface is commonly specified in terms of

[amp_mcq option1=”field declination” option2=”field inclination” option3=”both field declination and field inclination” option4=”horizontal component of the field” correct=”option3″]

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The direction of the Earth’s magnetic field at any location is specified in terms of both field declination and field inclination.

The Earth’s magnetic field at a given point is a vector quantity with both magnitude and direction. To fully describe the direction of this vector in three-dimensional space relative to the Earth’s surface and geographic north, two angles are needed.
Magnetic Declination is the angle in the horizontal plane between magnetic north (the direction a compass needle points) and true geographic north.
Magnetic Inclination (or Dip angle) is the angle between the magnetic field vector and the horizontal plane. This angle measures how steeply the field lines dip into the Earth.
Together, declination specifies the horizontal direction (azimuth), and inclination specifies the vertical angle (dip), thus defining the orientation of the magnetic field vector.

The magnitude of the Earth’s magnetic field is also important, along with its direction. The horizontal component of the field is related to both the total field strength and the inclination (Horizontal Component = Total Field * cos(Inclination)). While the horizontal component is a part of the description, specifying the *direction* requires both declination and inclination.

20. When a convex lens produces a real image of an object, the minimum dis

When a convex lens produces a real image of an object, the minimum distance between the object and image is equal to

[amp_mcq option1=”the focal length of the convex lens” option2=”twice the focal length of the convex lens” option3=”four times the focal length of the convex lens” option4=”one half of the focal length of the convex lens” correct=”option3″]

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The minimum distance between an object and its real image formed by a convex lens is four times the focal length (4f).

For a convex lens, a real image is formed when the object is placed outside the focal point (object distance |u| > f). The image formed is real and inverted. The lens formula is 1/v – 1/u = 1/f. Using distances as positive values, 1/v + 1/|u| = 1/f. Let D be the distance between the object and the image, D = |u| + v. To minimize D, we can express v in terms of |u| and f: 1/v = 1/f – 1/|u| = (|u|-f)/(f|u|), so v = f|u|/(|u|-f). Thus, D = |u| + f|u|/(|u|-f) = (|u|(|u|-f) + f|u|)/(|u|-f) = (|u|² – f|u| + f|u|)/(|u|-f) = |u|²/(|u|-f). Let x = |u|-f, so |u| = x+f. D = (x+f)²/x = (x² + 2xf + f²)/x = x + 2f + f²/x. For a real image, |u| must be greater than f, so x > 0. By AM-GM inequality, x + f²/x ≥ 2√(x * f²/x) = 2f. The minimum value occurs when x = f²/x, i.e., x² = f², so x = f (since x>0). This means |u|-f = f, so |u| = 2f. When |u|=2f, v = f(2f)/(2f-f) = 2f²/f = 2f. The minimum distance D = |u| + v = 2f + 2f = 4f. This happens when the object is placed at 2f, forming a real image at 2f.

If the object is placed closer than the focal length (|u| < f), a virtual image is formed. As the object approaches the focal point from outside (from |u| > f), the real image moves further away from the lens towards infinity. As the object moves away from the lens, the real image moves towards the focal point. The minimum separation between object and a real image occurs specifically when the object is placed at 2f.