Prelim GS I 2024 Solution

Prelim GS I 2024 Solution

Q. 1 Consider the following statements: 

Statement I: The atmosphere is heated more by incoming solar radiation than by terrestrial radiation.
Statement II: Carbon dioxide and other greenhouse gases in the atmosphere are good absorbers of long-wave radiation.

Which one of the following is correct in respect of the above statements?

(a) Both Statement I and Statement II are correct and Statement II explains Statement I
(b) Both Statement I and Statement II are correct, but Statement II does not explain Statement I
(c) Statement I is correct, but Statement II is incorrect
(d) Statement I is incorrect, but Statement II is correct

Correct Answer: (d) Statement I is incorrect, but Statement II is correct

Explanation

Statement I:
The atmosphere is heated more by incoming solar radiation than by terrestrial radiation.

– This statement is incorrect. The atmosphere is primarily heated by terrestrial radiation, which is the long-wave radiation emitted by the Earth’s surface after absorbing solar energy. While incoming solar radiation does warm the atmosphere, a significant portion of this energy is absorbed by the Earth’s surface and then re-radiated as long-wave radiation, which in turn heats the atmosphere.

Statement II:
Carbon dioxide and other greenhouse gases in the atmosphere are good absorbers of long-wave radiation.

– This statement is correct. Greenhouse gases, including carbon dioxide, methane, and water vapor, effectively absorb and re-radiate long-wave (infrared) radiation emitted by the Earth. This process is crucial for maintaining the Earth’s temperature and is a fundamental aspect of the greenhouse effect.

Thus, the correct answer is:

(d) Statement I is incorrect, but Statement II is correct.

Q.2 Consider the following statements:

Statement I: Thickness of the troposphere at the equator is much greater as compared to poles.
Statement II: At the equator, heat is transported to great heights by strong convectional currents.

Which one of the following is correct in respect of the above statements?

(a) Both Statement I and Statement II are correct and Statement II explains Statement I
(b) Both Statement I and Statement II are correct, but Statement II does not explain Statement I
(c) Statement I is correct, but Statement II is incorrect
(d) Statement I is incorrect, but Statement II is correct

Correct Answer: (a) Both Statement I and Statement II are correct and Statement II explains Statement I

– Statement I: The thickness of the troposphere at the equator is much greater compared to the poles. This is accurate; the troposphere can reach about 18 km in thickness at the equator, while it is only about 8 km thick at the poles due to temperature variations and air density differences.

– Statement II: At the equator, heat is transported to great heights by strong convectional currents. This statement is also correct. The intense solar heating at the equator leads to significant warming of the air, which causes it to rise and creates strong convection currents that transport heat upwards, contributing to the greater thickness of the troposphere in this region.

Conclusion

Since both statements are correct and Statement II provides an explanation for Statement I, the correct answer is:

(a) Both Statement I and Statement II are correct and Statement II explains Statement I.

Q. 3 Consider the following:

1. Pyroclastic debris
2. Ash and dust
3. Nitrogen compounds
4. Sulphur compounds

How many of the above are products of volcanic eruptions?

(a) Only one
(b) Only two
(c) Only three
(d) All four

Answer: (d) All four

Explanation: 

1. Pyroclastic Debris
– Definition: Pyroclastic debris refers to a variety of volcanic materials ejected during explosive eruptions, including volcanic ash, pumice, and volcanic rock fragments.
– Volcanic Origin: This is a direct product of volcanic activity, formed when magma is explosively fragmented during an eruption.

2. Ash and Dust
– Definition: Volcanic ash consists of tiny fragments of rock and glass that are formed when magma is explosively erupted. Dust can refer to finer particles that are carried high into the atmosphere.
– Volcanic Origin: Ash and dust are clearly products of volcanic eruptions, often resulting from the explosive disintegration of magma.

3. Nitrogen Compounds
– Definition: Volcanic eruptions can release various nitrogen compounds, including nitrogen oxides (NOx), which can contribute to atmospheric reactions.
– Volcanic Origin: While nitrogen is a major component of the atmosphere and not directly derived from magma, its compounds can be released during eruptions due to high-temperature reactions in the volcanic gases.

4. Sulphur Compounds
– Definition: Sulphur compounds, such as sulfur dioxide (SO₂), are commonly emitted during volcanic eruptions. They can lead to acid rain and contribute to atmospheric phenomena.
– Volcanic Origin: These compounds are indeed produced by the melting and degassing of Sulphur-rich minerals in the magma.

Q.4 Which of the following is/are correct inference/inferences from isothermal maps in the month of January?

1. The isotherms deviate to the north over the continent.
2. The presence of cold ocean currents, Gulf Stream and North Atlantic Ocean colder and the isotherms bend toward the north.

Select the answer using the code given below:

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 or 2

Correct Answer: 1 only

Explanation:

In analyzing the inferences from isothermal maps for January, we can evaluate the two statements provided:

isotherm, line drawn on a map or chart joining points with the same temperature.

1. The isotherms deviate to the north over the continent.
– This statement is correct. In January, isotherms tend to shift northward over land areas due to the warmer temperatures of the land compared to the surrounding ocean, which retains heat more effectively. This results in a noticeable deviation of isotherms towards the north over continental regions.

2. The presence of cold ocean currents, Gulf Stream and North Atlantic Ocean colder and the isotherms bend toward the north.
– This statement is incorrect. The Gulf Stream actually warms the North Atlantic Ocean, leading to warmer temperatures in that area. Consequently, isotherms do not bend toward the north due to colder conditions; instead, they can bend southward in response to cooler ocean currents but not as a direct result of the Gulf Stream.

Given this analysis, only the first statement is accurate.

Q.5 Which of the following countries are well known as the two largest cocoa producers in the world?
(a) Algeria and Morocco
(b) Botswana and Namibia
(c) Cote d’Ivoire and Ghana
(d) Madagascar and Mozambique
Correct Answer: C.  Cote d’Ivoire and Ghana

Côte d’Ivoire and Ghana are indeed the two largest cocoa producers in the world.

Cocoa Production Overview
– Côte d’Ivoire:
– It is the largest cocoa producer, with an annual production of approximately 2.2 million tonnes, accounting for about one-third of the global cocoa supply.

– Ghana:
– Following Côte d’Ivoire, Ghana is the second-largest producer, with an annual production of around 1.1 million tonnes, contributing significantly to global cocoa production as well.

Q.6 With reference to the Himalayan rivers joining the Ganga downstream of Prayagraj from West to East, which one of the following sequences is correct?

1. Ghaghara – Gomati – Gandak – Kosi
2. Gomati – Ghaghara – Gandak – Kosi
3. Ghaghara – Gomati – Kosi – Gandak
4. Gomati – Ghaghara – Kosi – Gandak

Answer:- Option 2 : Gomati – Ghaghara – Gandak – Kosi

1. Gomati River
   • Joins the Ganga near Saidpur, Kaithi, close to Varanasi.
2. Ghaghara River
   • Joins the Ganga near Chhapra, Bihar, before Patna.
3. Gandak River
   • Joins the Ganga near Patna at Sonpur.
4. Kosi River
   • Joins the Ganga further downstream near Kursela in Katihar district.

Q.7 Consider the following statements:
Statement I: Rainfall is one of the reasons for the weathering of rocks.
Statement II: Rainwater contains carbon dioxide in solution.
Statement III: Rainwater contains atmospheric oxygen.

Which one of the following is correct in respect of the above statements?
(a) Both Statement II and Statement III are correct and both of them explain Statement I
(b) Both Statement II and Statement III are correct, but only one of them explains Statement I
(c) Only one of the Statements II and III is correct and that explains Statement I
(d) Neither Statement II nor Statement III is correct
Correct Answer: (a) Both Statement II and Statement III are correct and both of them explain Statement I
Explanation:

1. Statement I: Rainfall is one of the reasons for the weathering of rocks.
   • Explanation: This statement is correct. Rainfall contributes to both physical and chemical weathering processes. Water can physically break down rocks through processes like freeze-thaw cycles, and it also facilitates chemical reactions that alter rock minerals.
2. Statement II: Rainwater contains carbon dioxide in solution.
   • Explanation: This statement is also correct. Rainwater absorbs carbon dioxide (CO₂) from the atmosphere as it falls, forming a weak carbonic acid (H₂CO₃) when dissolved. This acid can enhance chemical weathering by reacting with minerals in rocks, particularly those containing calcium carbonate.
3. Statement III: Rainwater contains atmospheric oxygen.
   • Explanation: This statement is correct as well. Rainwater does contain dissolved oxygen from the atmosphere, which can participate in oxidation reactions that contribute to the weathering of certain minerals within rocks.

Q.8 Consider the following countries:
1. Finland
2. Germany
3. Norway
4. Russia
How many of the above countries have a border with the North Sea?
(a) Only one
(b) Only two
(c) Only three
(d) All four

Correct Answer: Only two

1. It is a gas, the amount of which decreases with altitude.
2. Its percentage is maximum at the poles.

Select the answer using the code given below:

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Correct Answer: (a) 1 only

Explanation:

• Correct: Water vapor is indeed a gas, and its concentration generally decreases with altitude in the atmosphere. This is because warmer air can hold more moisture, and as altitude increases, the temperature typically decreases, leading to lower humidity levels.
• Incorrect: Water vapor content is actually lowest at the poles. The polar regions are cold and have lower temperatures, which means they cannot hold as much moisture compared to warmer areas near the equator. The maximum percentage of water vapor is usually found in tropical regions. 

Q.13 Consider the following description:

1. Annual and daily range of temperatures is low.
2. Precipitation occurs throughout the year.
3. Precipitation varies between 50 cm – 250 cm.

What is this type of climate?

(a) Equatorial climate
(b) China type climate
(c) Humid subtropical climate
(d) Marine west coast climate

Correct Answer: (d) Marine west coast climate

Explanation:

• Climate Characteristics

  1. Annual and Daily Range of Temperatures is Low:
     • This suggests a climate with relatively stable temperatures throughout the year, which is typical of regions influenced by large bodies of water.
  2. Precipitation Occurs Throughout the Year:
     • This indicates a climate where rainfall is distributed evenly across all seasons, rather than concentrated in a specific wet season.
  3. Precipitation Varies Between 50 cm – 250 cm:
     • This range of precipitation is significant and can be found in several climate types, but it aligns well with certain temperate climates.

  Climate Types

  Now, let’s consider the options:
  • (a) Equatorial Climate:
    • Characterized by high temperatures and heavy rainfall throughout the year, but typically has a higher annual temperature range.
  • (b) China Type Climate:
    • Generally refers to a monsoon-influenced climate with distinct wet and dry seasons, which does not fit the criteria of consistent precipitation throughout the year.
  • (c) Humid Subtropical Climate:
    • Features hot summers and mild winters with significant rainfall, but often has a more pronounced seasonal variation in temperature.
  • (d) Marine West Coast Climate:
    • Characterized by mild temperatures with low annual and daily temperature ranges, and consistent precipitation throughout the year. This climate typically has rainfall between 50 cm to 250 cm annually.

  Based on the characteristics described:

  • The correct answer is indeed (d) Marine west coast climate.

Q. 14 With reference to “Coriolis force”, which of the following statements is/are correct?

1. It increases with increase in wind velocity.
2. It is maximum at the poles and is absent at the equator.

Select the answer using the code given below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer: (c) Both 1 and 2

Explanation: 

Statement 1: “It increases with increase in wind velocity.”

• Correct: The Coriolis force is proportional to the wind velocity. As the speed of the wind increases, the effect of the Coriolis force also increases. This means that faster winds experience a greater deflection due to the Coriolis effect.

Statement 2: “It is maximum at the poles and is absent at the equator.”

• Correct: The Coriolis force is indeed strongest at the poles and diminishes to zero at the equator. This is because the Coriolis effect arises from the rotation of the Earth, and at the equator, there is no lateral deflection caused by this rotation.

Q.15 On June 21 every year, which of the following latitude(s) experience(s) a sunlight of more than 12 hours?

1. Equator
2. Tropic of Cancer
3. Tropic of Capricorn
4. Arctic Circle

Select the correct answer using the code given below:

(a) 1 only
(b) 2 only
(c) 3 and 4
(d) 2 and 4

Correct Answer: (d) 2 and 4

Explanation:

• June 21 marks the summer solstice in the Northern Hemisphere, when the North Pole is tilted closest to the Sun. This results in the longest day of the year for locations in the Northern Hemisphere.

Sunlight Duration by Latitude

1. Equator (0° Latitude):
   • The equator experiences approximately 12 hours of sunlight year-round. Therefore, it does not exceed 12 hours on June 21.
2. Tropic of Cancer (23.5° N Latitude):
   • On June 21, the Tropic of Cancer receives direct sunlight, resulting in more than 12 hours of daylight. This latitude is significant because it marks the northernmost point where the Sun can be directly overhead.
3. Tropic of Capricorn (23.5° S Latitude):
   • On June 21, this latitude is tilted away from the Sun, resulting in less than 12 hours of sunlight.
4. Arctic Circle (66.5° N Latitude):
   • On June 21, locations within the Arctic Circle experience 24 hours of daylight due to the tilt of the Earth, as they are continuously illuminated by the Sun during this time.

Q.16 One of the following regions has the world’s largest tropical peatland, which holds about three years worth of global carbon emissions from fossil fuels; and the possible destruction of which can exert a detrimental effect on the global climate. Which one of the following denotes that region?

(a) Amazon Basin
(b) Congo Basin
(c) Kikori Basin
(d) Rio de la Plata Basin

Correct Answer: (b) Congo Basin

Explanation: 

Peatlands are wetlands that are made up of layers of peat, an organic material formed from the remains of decaying plants. They are found in almost every country and cover around 3% of the Earth’s surface

• The Congo Basin has been identified as home to extensive peatlands that cover approximately 16.7 million hectares.
• These peatlands store between 26 and 32 billion tonnes of carbon, equivalent to roughly three years’ worth of global fossil fuel emissions.
• The preservation of these peatlands is crucial for combating climate change, as their destruction could release significant amounts of stored carbon into the atmosphere.

The Kikori Basin, located in Papua New Guinea, is a significant ecological area characterized by diverse landscapes and rich biodiversity.

The Rio de la Plata Basin covers parts of southeastern Bolivia, southern and central Brazil, the entire country of Paraguay, most of Uruguay, and northern Argentina. It spans an area of approximately 3.1 million square kilometers (about one-fifth of South America)

Q.17 With reference to perfluoroalkyl and polyfluoroalkyl substances (PFAS) that are used in making many consumer products, consider the following statements:

1. PFAS are found to be widespread in drinking water, food, and food packaging materials.
2. PFAS are not easily degraded in the environment.
3. Persistent exposure to PFAS can lead to bioaccumulation in animal bodies.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (d) 1, 2 and 3

1. PFAS are found to be widespread in drinking water, food, and food packaging materials.
   • Correct: PFAS have been detected in various environmental media, including drinking water and food products. They are commonly used in food packaging and have been found in seafood and other biota due to environmental contamination
2. PFAS are not easily degraded in the environment.
   • Correct: PFAS are known for their high persistence and resistance to degradation. They do not readily break down in the environment, leading to long-lasting contamination . This characteristic has earned them the nickname “forever chemicals” due to their potential to remain in the environment for thousands of years.
3. Persistent exposure to PFAS can lead to bioaccumulation in animal bodies.
   • Correct: PFAS can bioaccumulate in living organisms, meaning that they can build up in the tissues of animals over time, especially as they move up the food chain. This bioaccumulation poses risks not only to wildlife but also to human health through consumption of contaminated food.

Q.18 Consider the following:

1. Carabid beetles
2. Centipedes
3. Flies
4. Termites
5. Wasps

Parasitoid species are found in how many of the above kinds of organisms?

(a) Only two
(b) Only three
(c) Only four
(d) All five

Answer: (b) Only three
Explanation:
Parasitoid species are typically found in flies (e.g., tachinid flies), beetles (some carabid beetles), and wasps (e.g., many wasp species
are parasitoids). However, centipedes and termites are not commonly known to have parasitoid species.

Organisms and Their Associations with Parasitoids

1. Carabid Beetles:
   • Some carabid beetles are known to have parasitoid species. Specifically, certain genera of carabid beetles act as ectoparasitoids, particularly on pupae of other beetles or immature millipedes. This indicates that there are parasitoid species within this group.
2. Centipedes:
   • Centipedes are not commonly associated with parasitoid species. They are primarily predators and do not typically have parasitoids.
3. Flies:
   • Flies, particularly certain families such as tachinid flies, include many species that are known to be parasitoids. This group is well-documented for its parasitoid behavior.
4. Termites:
   • Termites do not have known parasitoid species associated with them. They are social insects primarily involved in decomposition and do not serve as hosts for parasitoids.
5. Wasps:
   • Many wasp species are well-known parasitoids, including various families that lay their eggs in or on other insects, leading to the host’s eventual demise.

Q.19 Consider the following plants:

1. Groundnut
2. Horse-gram
3. Soybean

How many of the above belong to the pea family?

(a) Only one
(b) Only two
(c) Only three
(d) None

Correct Answer: (c) Only three

Explanation:
All three plants, groundnut (peanut), horse-gram, and soybean, belong to the pea family (Fabaceae or Leguminosae).
The pea family, scientifically known as Fabaceae (also referred to as Leguminosae), is a large and diverse family of flowering plants. Here’s a detailed overview based on the search results:

General Characteristics

• Diversity: The Fabaceae family is one of the largest plant families, comprising over 20,000 species across approximately 765 genera. It includes a wide range of plants such as herbs, shrubs, and trees.
• Distribution: Members of this family are found worldwide, thriving in various habitats, including tropical and temperate regions.

Key Features

1. Root Nodules:
   • A distinctive characteristic of Fabaceae plants is the presence of root nodules, which house symbiotic nitrogen-fixing bacteria (such as Rhizobium). This allows legumes to convert atmospheric nitrogen into a form usable by plants, enriching soil fertility.
2. Leaf Structure:
   • Leaves are typically alternate, and can be either simple or compound (often pinnately compound). They usually have stipules and exhibit reticulate venation.
3. Flower Structure:
   • Flowers in the Fabaceae family are generally zygomorphic (bilaterally symmetrical) and often exhibit a characteristic structure with five petals (papilionaceous flowers).
   • The flowers are usually bisexual, containing both male and female reproductive parts.
4. Fruit Type:
   • The fruit produced by members of this family is typically a legume, which is a pod-like structure that contains seeds.

Q.20 Consider the following statements:

Statement I: The Indian Flying Fox is placed under the “vermin” category in the Wild Life (Protection) Act, 1972.
Statement II: The Indian Flying Fox feeds on the blood of other animals.

Which one of the following is correct in respect of the above statements?

(a) Both Statement I and Statement II are correct and Statement II explains Statement I
(b) Both Statement I and Statement II are correct, but Statement II does not explain Statement I
(c) Statement I is correct, but Statement II is incorrect
(d) Statement I is incorrect, but Statement II is correct

Correct Answer: (c) Statement I is correct, but Statement II is incorrect

Statement I:

“The Indian Flying Fox is placed under the ‘vermin’ category in the Wild Life (Protection) Act, 1972.”

• Correct: The Indian Flying Fox is indeed considered vermin due to its destructive tendencies towards fruit farms. It is categorized under Schedule II of the Wildlife (Protection) Act, 1972, which allows for certain management practices in response to its impact on agriculture.

Statement II:

“The Indian Flying Fox feeds on the blood of other animals.”

• Incorrect: The Indian Flying Fox primarily feeds on fruits, nectar, and flowers. It does not feed on the blood of other animals; instead, it plays a crucial role in pollination and seed dispersal within its ecosystem.

Q.21 The organisms “Cicada, Froghopper, and Pond skater” are:

(a) Birds
(b) Fish
(c) Insects
(d) Reptiles

Correct Answer: (c) Insects

1. Cicada:
   • Cicadas are well-known insects belonging to the order Hemiptera. They are famous for their loud mating calls produced by males and have a distinctive life cycle that includes long periods of development underground.
2. Froghopper:
   • Froghoppers, also known as spittlebugs, belong to the family Cercopidae within the order Hemiptera. They are named for their ability to produce a frothy substance (spittle) that protects their nymphs. Froghoppers are known for their jumping ability.
3. Pond Skater:
   • Pond skaters, or water striders, belong to the family Gerridae within the order Hemiptera. They are characterized by their long legs, which allow them to walk on the surface of water. They are predatory insects that feed on small insects that fall onto the water’s surface.