UPSC Geoscientist Archives

31. Which of the following statements about river valleys is/are correct?

Which of the following statements about river valleys is/are correct?

1. Kullu Valley is an example of strike valley.
2. Kangra Valley is a transverse valley.
3. Narmada flows in a rift valley.

Select the correct answer using the code given below.

1 and 2

2 and 3

2 only

3 only

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Statement 3 is correct because the Narmada river flows through a classic example of a rift valley, which is a graben structure formed by faulting between the Vindhyan and Satpura ranges. Statement 1 is debatable; while the Kullu Valley is a structural valley shaped by tectonic forces, calling it purely a “strike valley” might not be the most precise geological classification. Statement 2 is incorrect; the Kangra Valley is a longitudinal valley running parallel to the Dhauladhar range, not a transverse valley which cuts across ranges.

– Narmada River flows through a well-known rift valley in India.
– Kullu Valley is primarily a structural valley influenced by faulting.
– Kangra Valley is a longitudinal valley, parallel to the Dhauladhar range.

A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift or fault. Strike valleys are typically formed by erosion along the strike of weak rock layers in folded or tilted strata. Transverse valleys cut across geological structures like mountain ranges.

32. Which one among the following States is the largest producer of natura

Which one among the following States is the largest producer of natural gas in India?

Madhya Pradesh

Jharkhand

Bihar

Rajasthan

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Rajasthan is among the leading states in India for the production of natural gas, particularly onshore. While offshore fields and states like Assam and Tripura are also major producers, among the given options, Rajasthan has emerged as a significant contributor to India’s natural gas output, unlike Madhya Pradesh, Jharkhand, or Bihar which have minimal or no significant natural gas production.

– Rajasthan has substantial natural gas reserves, including Coal Bed Methane (CBM) and tight gas, being actively explored and produced.
– States like Madhya Pradesh, Jharkhand, and Bihar are not known for significant natural gas production.

India’s natural gas production comes from onshore and offshore fields. Major producing regions include the Krishna-Godavari Basin (offshore), Assam, Tripura, Gujarat, and Rajasthan (onshore). The rankings among onshore states can vary slightly year-to-year based on production data, but Rajasthan is consistently listed among the significant producers.

33. Which one of the following is a ‘false fruit’?

Which one of the following is a ‘false fruit’?

Peach

Banana

Apple

Apricot

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A true fruit develops exclusively from the ovary of a flower after fertilization. A false fruit, or accessory fruit, develops from the ovary along with other parts of the flower, such as the thalamus (receptacle), petals, sepals, or calyx. In the case of an apple, the main edible, fleshy part is derived from the greatly enlarged and fleshy thalamus, which surrounds the core (developed from the ovary). Peach, banana, and apricot are considered true fruits as their fleshy, edible parts develop directly from the ovary wall.

– True fruit develops from the ovary.
– False fruit develops from the ovary plus other floral parts (like thalamus).
– Apple’s edible part is derived from the thalamus.
– Peach, Banana, and Apricot develop primarily from the ovary.

Other examples of false fruits include strawberries (fleshy receptacle) and figs (inverted inflorescence/syconium). The concept of “true” vs. “false” fruit is primarily a botanical classification based on floral origin, and all are commonly referred to as fruits in everyday language. Bananas are parthenocarpic fruits, meaning they develop without fertilization, but they are derived solely from the ovary, classifying them as true fruits botanically.

34. “Athlete’s foot” is a skin disease caused by

“Athlete’s foot” is a skin disease caused by

virus

fungus

alga

bacterium

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“Athlete’s foot” is a common name for tinea pedis, which is a fungal infection affecting the skin of the feet. It is typically caused by dermatophyte fungi, such as *Trichophyton*, *Epidermophyton*, and *Microsporum*. These fungi thrive in warm, moist environments, making feet enclosed in shoes and socks susceptible.

– Athlete’s foot is a skin infection.
– Caused by a type of fungus.
– Medically known as tinea pedis.
– Fungi that cause it are called dermatophytes.

Fungal infections are distinct from those caused by viruses (like warts or herpes), algae (which don’t typically cause human skin diseases), or bacteria (like impetigo or cellulitis). Antifungal medications are used to treat athlete’s foot.

35. Quadrat is generally used to enumerate the number of

Quadrat is generally used to enumerate the number of

animals breeding in a pond

burrows present in an anthill

plants present in a unit area

epiphytes on a tree

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A quadrat is a standard frame, typically square or rectangular, used in ecological surveys to sample a specific area. Quadrats are primarily used for studying sessile or slow-moving organisms, most commonly plants. By placing quadrats in multiple locations within a habitat and counting the number of plants (or other organisms like fungi or invertebrates) of interest within each quadrat, ecologists can estimate population density, frequency, and distribution for the entire area. While quadrats can sometimes be adapted for studying other organisms, their fundamental use is to define a unit area for sampling, making them most suitable for enumerating stationary populations like plants.

– A quadrat is a sampling frame defining a unit area.
– Used in ecological surveys.
– Most commonly applied to enumerate sessile or slow-moving organisms.
– Ideal for sampling plant populations in a defined area.

Sampling methods for animals vary depending on the species and habitat and might involve trapping, observation transects, or counting signs like burrows or tracks. While a quadrat could theoretically be used to count burrows in a defined area, its standard application is primarily for vegetation surveys or similar studies of organisms within a fixed plot.

36. Which one of the following would be a suitable plant to test that chlo

Which one of the following would be a suitable plant to test that chlorophyll is necessary for photosynthesis?

Lady Plymouth

Cactus

Cuscuta

Oleander

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To test if chlorophyll is necessary for photosynthesis, you need a plant that has some parts with chlorophyll and some parts without chlorophyll. Variegated leaves, which have green (chlorophyll present) and non-green (chlorophyll absent) patches, are ideal for this experiment. After exposing the plant to light and testing for starch (a product of photosynthesis) using iodine solution, the green parts will test positive (turn blue-black), while the non-green parts will test negative (remain brownish), demonstrating that chlorophyll is required for starch production during photosynthesis. Lady Plymouth (Pelargonium zonale) is a common plant species with variegated leaves often used for this demonstration.

– Experiment requires comparison between parts of a plant with and without chlorophyll.
– Variegated leaves are suitable for this purpose.
– Green parts contain chlorophyll, non-green parts do not.
– Testing for starch after photosynthesis reveals which parts photosynthesized.

Cactus leaves are modified into spines (though the stem is photosynthetic); Cuscuta is a parasitic plant that lacks chlorophyll and obtains nutrients from a host; Oleander has uniformly green leaves. None of these are typically used for a simple experiment demonstrating the necessity of chlorophyll using variegation.

37. Reverberation of sound ensures

Reverberation of sound ensures

a single refraction

a single reflection

multiple reflections

multiple refractions

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Reverberation is the phenomenon where a sound persists in an enclosed space after the original sound source has stopped. This happens because sound waves reflect off the surfaces (walls, ceiling, floor, objects) in the room and these reflections reach the listener’s ear shortly after the initial sound and continue to arrive as they bounce multiple times. It is the collection of these multiple, closely spaced reflections that creates reverberation, not a single reflection (which would be a distinct echo if the delay is long enough) or refraction.

– Reverberation is the persistence of sound.
– It occurs in enclosed spaces.
– It is caused by multiple reflections of sound waves.
– Contrast with echo, which is a single, delayed reflection.

The degree of reverberation depends on the size and shape of the space and the acoustic properties of the surfaces. Highly reflective surfaces (like concrete or glass) lead to strong reverberation, while sound-absorbing materials reduce it. Reverberation time is the time it takes for the sound intensity to decrease by 60 dB after the source stops.

38. The magnitude of work done in moving an electron across two points hav

The magnitude of work done in moving an electron across two points having a potential difference 6 V is (electronic charge = 1.6 × 10⁻¹⁹ C)

1.2 × 10⁻¹⁹ J

9.6 × 10⁻¹⁹ J

4.8 × 10⁻¹⁹ J

1.6 × 10⁻¹⁹ J

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The work done (W) in moving a charge (q) across a potential difference (V) is given by the formula W = qV. In this case, the charge of the electron (q) is given as 1.6 × 10⁻¹⁹ C, and the potential difference (V) is 6 V.
Work done W = (1.6 × 10⁻¹⁹ C) × (6 V) = 9.6 × 10⁻¹⁹ Joules (J).

– Work done (W) = charge (q) × potential difference (V).
– Charge of an electron = 1.6 × 10⁻¹⁹ C.
– Units: Work done in Joules (J), charge in Coulombs (C), potential difference in Volts (V).

This work done represents the energy gained or lost by the charge as it moves through the potential difference. If an electron moves from a point of lower potential to a point of higher potential, positive work is done on it by the external field, and its potential energy increases. If it moves from higher to lower potential, the field does positive work, and its potential energy decreases. In this problem, the sign of work depends on the direction of movement relative to the potential difference, but the magnitude calculation remains W = |qV|.

39. Which one of the following statements about X-rays is not correct?

Which one of the following statements about X-rays is not correct?

X-rays are longitudinal waves.

X-rays are transverse waves.

X-rays are electromagnetic waves.

X-rays do not require a medium to propagate.

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X-rays are a form of electromagnetic radiation. Electromagnetic waves consist of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of wave propagation. This characteristic defines them as transverse waves. Longitudinal waves, such as sound waves, are waves in which the oscillations are parallel to the direction of wave propagation. Therefore, the statement that X-rays are longitudinal waves is incorrect.

– X-rays are electromagnetic waves.
– Electromagnetic waves are transverse waves.
– Transverse waves have oscillations perpendicular to the direction of propagation.
– Longitudinal waves have oscillations parallel to the direction of propagation.
– X-rays, being electromagnetic, do not require a medium to travel.

The electromagnetic spectrum includes, in order of increasing frequency (decreasing wavelength): radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. All waves in the electromagnetic spectrum share the fundamental property of being transverse waves and propagating at the speed of light in a vacuum.

40. The angular acceleration of a simple pendulum at an angle α from the v

The angular acceleration of a simple pendulum at an angle α from the vertical is proportional to

tan α

sin² α

sin α

sin 2α

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For a simple pendulum at an angle α from the vertical, the restoring torque about the point of suspension is given by τ = -mgl sin α, where m is the mass of the bob, g is the acceleration due to gravity, l is the length of the pendulum, and α is the angular displacement. According to Newton’s second law for rotation, the torque is also equal to Iβ, where I is the moment of inertia and β is the angular acceleration. For a simple pendulum, I = ml². Thus, ml²β = -mgl sin α. This gives β = -(g/l) sin α. The magnitude of the angular acceleration is |β| = (g/l) sin α. Since g and l are constants, the angular acceleration is proportional to sin α.

– Restoring torque τ = -mgl sin α.
– Torque τ = Iβ.
– Moment of inertia of a simple pendulum I = ml².
– Angular acceleration β = τ/I = -(g/l) sin α.
– Magnitude of angular acceleration is proportional to sin α.

For small angles (α << 1 radian), sin α ≈ α, and the equation of motion becomes β ≈ -(g/l)α. In this small angle approximation, the motion is Simple Harmonic Motion (SHM), and the angular acceleration is proportional to the angular displacement α. However, for any angle α, the angular acceleration is strictly proportional to sin α.