UPSC CDS-1

21. Which one of the following is the reason due to which the wind in the

Which one of the following is the reason due to which the wind in the southern hemisphere is deflected towards its left ?

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Difference in the water masses of northern and southern hemisphere
Temperature and pressure variations
Inclined axis of the Earth
Rotation of the Earth
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The wind in the southern hemisphere is deflected towards its left due to the rotation of the Earth.
The apparent force that causes moving objects (like wind and ocean currents) to be deflected from a straight path on a rotating planet is called the Coriolis effect. The Coriolis force acts perpendicular to the direction of motion. Due to the Earth’s rotation, this deflection is to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
The Coriolis effect is zero at the Equator and maximum at the poles. It significantly influences large-scale weather patterns, ocean currents, and the direction of cyclones. Temperature and pressure variations drive the movement of air (wind), but the deflection of that movement is caused by the Earth’s rotation.

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22. Consider the following tributaries of river Brahmaputra : 1. Lohit

Consider the following tributaries of river Brahmaputra :

  • 1. Lohit
  • 2. Tista
  • 3. Subansiri
  • 4. Sankosh

Arrange the above rivers from west to east:

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2-4-3-1
2-3-4-1
4-2-3-1
3-1-2-4
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The correct arrangement of the Brahmaputra tributaries from west to east is Teesta, Sankosh, Subansiri, Lohit.
Arranging tributaries of a river from west to east requires knowledge of their geographical locations and where they join the main river channel. Teesta (2) joins the Brahmaputra (Jamuna) in Bangladesh, west of the confluence point of the main Brahmaputra entering Bangladesh. Sankosh (4) forms part of the border between Assam and West Bengal, joining the Brahmaputra in Assam. Subansiri (3) is a major northern tributary joining the Brahmaputra further east in Assam. Lohit (1) is an eastern tributary that joins the Brahmaputra near Sadiya, marking the easternmost extent of the Brahmaputra in India before it turns south.
The Brahmaputra river, known as Yarlung Tsangpo in Tibet, flows through Arunachal Pradesh (where it’s called Siang), then Assam, and finally enters Bangladesh as Jamuna. Major tributaries include the Dibang, Lohit, Subansiri, Kameng, Manas, Sankosh, and Teesta. The Manas river joins the Brahmaputra between Sankosh and Subansiri. The order from west to east is roughly Teesta, Sankosh, Manas, Subansiri, Dibang, Lohit. Among the given options, 2-4-3-1 (Teesta, Sankosh, Subansiri, Lohit) follows the correct relative west-to-east sequence.

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23. Which one of the following is the cause of long-term sea-level change?

Which one of the following is the cause of long-term sea-level change?

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Atmospheric disturbance
Change in marine water density
Melting of icebergs
Melting of ice sheets
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The correct answer is the melting of ice sheets.
Long-term sea-level change is primarily driven by factors that significantly alter the total volume of water in the oceans or the size of the ocean basins over geological timescales. Melting of large ice sheets (like Greenland and Antarctic ice sheets) adds substantial mass of water to the ocean, directly contributing to long-term sea-level rise. Thermal expansion of seawater due to warming is another significant long-term factor.
Atmospheric disturbances cause short-term, localized changes in sea level (storm surges). Changes in marine water density can contribute to steric sea-level change (thermal expansion or contraction), which is a long-term factor, but melting of ice sheets represents a direct mass addition. Melting of floating icebergs does not significantly alter sea level, as the ice displaces a volume of water equal to its mass (Archimedes’ principle).

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24. Which one of the following is an example of chemical change ?

Which one of the following is an example of chemical change ?

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Burning of paper
Magnetization of soft iron
Dissolution of cane sugar in water
Preparation of ice cubes from water
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Burning of paper is an example of a chemical change.
– A chemical change involves a chemical reaction where one or more substances are transformed into different substances with different properties.
– Burning is a combustion reaction where paper reacts with oxygen, producing ash, carbon dioxide, water vapor, and other substances. This process forms new chemical compounds and is not easily reversible.
– Physical changes alter the form or appearance of a substance but not its chemical composition. Magnetization, dissolution, and phase changes (like freezing water) are physical changes, as the original substances retain their chemical identity and the process is often reversible.
Key indicators of a chemical change include changes in color, temperature, formation of gas or precipitate, and difficulty in reversing the process.

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25. Which one of the following hormones contains peptide chain?

Which one of the following hormones contains peptide chain?

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Oxytocin
Corticotropin
Insulin
Cortisone
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Insulin is a hormone that contains peptide chains.
– Hormones can be classified based on their chemical structure, including peptide/protein hormones, steroid hormones, and amino acid derivatives.
– Oxytocin is a peptide hormone (specifically, a nonapeptide).
– Corticotropin (ACTH) is a peptide hormone (a polypeptide of 39 amino acids).
– Insulin is a protein hormone composed of two polypeptide chains linked by disulfide bonds.
– Cortisone is a steroid hormone, derived from cholesterol.
While Oxytocin and Corticotropin are also peptide hormones, Insulin is a very prominent example of a protein hormone with peptide chains and is often used as a representative example in biochemistry. Given that the question asks for “Which *one* of the following”, and options A, B, and C are all peptide/protein hormones while D is a steroid, it suggests the question intends to identify one among the choices that fits the description, distinguishing it from non-peptide types. All A, B, C fit, making the question potentially flawed if only one answer is strictly correct. However, in such a context, selecting a well-known example of a larger protein hormone like Insulin is a common pattern.

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26. A piece of ice, 100 g in mass is kept at 0 °C. The amount of heat it r

A piece of ice, 100 g in mass is kept at 0 °C. The amount of heat it requires to melt at 0 °C is (take latent heat of melting of ice to be 333.6 J/g):

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750.6 J
83.4 J
33360 J
3.336 J
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The amount of heat required to melt 100 g of ice at 0°C is 33360 J.
– The heat required for a substance to change phase (like melting) at a constant temperature is given by the formula Q = m * L, where Q is the heat energy, m is the mass, and L is the latent heat of fusion (for melting) or vaporization (for boiling).
– Given mass of ice m = 100 g.
– Given latent heat of melting of ice L = 333.6 J/g.
– Heat required Q = 100 g * 333.6 J/g = 33360 J.
Latent heat is the energy absorbed or released during a phase transition at constant temperature and pressure.

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27. A myopic person has a power of -1.25 Dioptre. What is the focal length

A myopic person has a power of -1.25 Dioptre. What is the focal length and nature of his lens ?

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50 cm and convex lens
80 cm and convex lens
50 cm and concave lens
80 cm and concave lens
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The focal length is 80 cm and the nature of the lens is concave.
– The power of a lens (P) is related to its focal length (f) by the formula P = 1/f, where f is in meters and P is in Dioptres.
– Given P = -1.25 D.
– Focal length f = 1 / P = 1 / (-1.25) meters = -0.8 meters.
– Converting to centimeters: -0.8 meters * 100 cm/meter = -80 cm.
– A negative focal length indicates a concave lens. Myopia (nearsightedness) is corrected using concave lenses to diverge light rays before they reach the eye’s lens.
A convex lens has a positive focal length and is used to correct hyperopia (farsightedness).

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28. Norman Borlaug won Nobel Peace Prize for his contributions in : 1. d

Norman Borlaug won Nobel Peace Prize for his contributions in :

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  • 1. development of high-yielding crops.
  • 2. modernization of irrigation infrastructure.
  • 3. introduction of synthetic fertilizers and pesticides.

Select the correct answer using the code given below:

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1 only
2 only
2 and 3 only
1, 2 and 3
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Norman Borlaug won the Nobel Peace Prize for his contributions in the development of high-yielding crops (Statement 1).
– Norman Borlaug is considered the “father of the Green Revolution”.
– His Nobel Peace Prize in 1970 was specifically awarded for his work in developing high-yielding, disease-resistant varieties of wheat, which significantly increased food production, particularly in developing countries.
– While the Green Revolution involved other aspects like irrigation and fertilizers, Borlaug’s direct and Nobel-recognized contribution was primarily in the genetic improvement of crops.
The Nobel committee cited his work for having “done so much to feed the world and create a new basis for the prospects of peace in the world”. This highlights the humanitarian impact of his agricultural innovations.

29. The living content of a cell is called protoplasm. It is composed of :

The living content of a cell is called protoplasm. It is composed of :

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Cytoplasm only
Cytoplasm and nucleoplasm
Nucleoplasm only
Cytoplasm, nucleoplasm and other organelles
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The living content of a cell (protoplasm) is composed of cytoplasm and nucleoplasm.
– Protoplasm refers to all the living substance within a cell membrane.
– In eukaryotic cells, protoplasm includes the cytoplasm (the material within the cell membrane but outside the nucleus) and the nucleoplasm (the substance within the nucleus).
– Cytoplasm itself consists of the cytosol (the jelly-like substance) and the organelles suspended within it. Nucleoplasm contains the genetic material (DNA) and other components of the nucleus.
Option D is redundant because “other organelles” are already included within the definition of cytoplasm. The standard biological definition of protoplasm in a eukaryotic cell is cytoplasm plus nucleus (or cytoplasm and nucleoplasm, which constitutes the living content of the nucleus). Option B accurately reflects this fundamental division within the cell.

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30. Glucose is a source of energy. Which one of the following types of mol

Glucose is a source of energy. Which one of the following types of molecule is Glucose ?

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Carbohydrate
Protein
Fat
Nucleic acid
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Glucose is a type of Carbohydrate.
– Glucose (C6H12O6) is a monosaccharide, which is the simplest form of carbohydrate.
– Carbohydrates are organic compounds that serve as a primary source of energy for living organisms.
– Proteins are polymers of amino acids, fats are lipids composed of fatty acids and glycerol, and nucleic acids (like DNA and RNA) are polymers of nucleotides.
Glucose is broken down through cellular respiration to produce ATP, the main energy currency of the cell.

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