UPSC NDA-2 Archives

11. Who among the following popularized the use of embryological character

Who among the following popularized the use of embryological characters in taxonomy ?

[amp_mcq option1=”Carl Linnaeus” option2=”Panchanan Maheshwari” option3=”Birbal Sahni” option4=”Bentham and Hooker” correct=”option2″]

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The correct answer is B) Panchanan Maheshwari.

Panchanan Maheshwari was a renowned Indian botanist who made significant contributions to the study of angiosperm embryology. He extensively studied the embryological features of plants and emphasized their importance in understanding plant relationships and classification (taxonomy).

Carl Linnaeus is known as the father of modern taxonomy and is famous for his binomial nomenclature system. Birbal Sahni was an Indian paleobotanist. Bentham and Hooker developed a widely used system of classification based primarily on morphological characters. Panchanan Maheshwari’s work helped integrate embryological data into taxonomic studies, particularly for flowering plants.

12. Mitochondria are able to produce their own

Mitochondria are able to produce their own

[amp_mcq option1=”Nucleus” option2=”Proteins” option3=”Chloroplasts” option4=”Digestive enzymes” correct=”option2″]

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The correct answer is B) Proteins.

Mitochondria contain their own DNA and ribosomes, enabling them to synthesize some of the proteins they need for their function. This makes them semi-autonomous organelles.

Mitochondria are often called the “powerhouses” of the cell because they generate most of the cell’s supply of adenosine triphosphate (ATP), used as a source of chemical energy. They are believed to have originated from symbiotic bacteria, which is supported by the presence of their own DNA (circular, similar to bacterial DNA) and ribosomes (70S, similar to bacterial ribosomes).

13. Blood is a type of

Blood is a type of

[amp_mcq option1=”Epithelial tissue” option2=”Muscular tissue” option3=”Nervous tissue” option4=”Connective tissue” correct=”option4″]

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Animal tissues are broadly classified into four primary types: epithelial tissue, connective tissue, muscle tissue, and nervous tissue. Each type has distinct structures and functions.
A) Epithelial tissue forms linings and coverings of surfaces and cavities, and constitutes glands.
B) Muscular tissue is responsible for movement through contraction.
C) Nervous tissue transmits electrical and chemical signals throughout the body.
D) Connective tissue supports, connects, or separates different types of tissues and organs. Connective tissues are characterized by having cells dispersed within an extracellular matrix. Blood consists of various cell types (red blood cells, white blood cells, platelets) suspended in a liquid extracellular matrix called plasma. Plasma accounts for a significant portion of blood volume and its components are produced by cells. Due to its structure (cells in an extracellular matrix) and function (connecting different parts of the body through transport), blood is classified as a specialized type of connective tissue.

– There are four main types of animal tissue: epithelial, connective, muscle, and nervous.
– Connective tissue supports and connects other tissues and organs.
– Blood consists of cells suspended in plasma, an extracellular matrix.
– Blood fits the definition and characteristics of connective tissue.

Other examples of connective tissue include bone, cartilage, adipose tissue (fat), and loose connective tissue found under the skin. Blood is sometimes considered a “fluid connective tissue” due to its liquid matrix (plasma).

14. Net movement of water from a dilute to a concentrated solution through

Net movement of water from a dilute to a concentrated solution through a selectively permeable membrane is called

[amp_mcq option1=”Diffusion” option2=”Dispersion” option3=”Osmosis” option4=”Absorption” correct=”option3″]

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The description “Net movement of water from a dilute to a concentrated solution through a selectively permeable membrane” is the definition of osmosis.
A) Diffusion is the net movement of particles (solute or solvent) from a region of higher concentration to lower concentration, which can occur with or without a membrane. It is driven by a concentration gradient.
B) Dispersion refers to the spreading out of particles or substances.
C) Osmosis is specifically the movement of solvent (usually water) across a selectively permeable membrane from an area of higher water potential (dilute solution, lower solute concentration) to an area of lower water potential (concentrated solution, higher solute concentration). This movement occurs down the water potential gradient and fits the description perfectly.
D) Absorption is the process by which one substance is taken into another, either physically or chemically. While osmosis results in the absorption of water by the concentrated solution, “osmosis” is the specific term for the described process of water movement across a membrane due to concentration differences.

– Osmosis is the movement of solvent (water) across a selectively permeable membrane.
– Water moves from a region of higher water concentration (dilute solution) to lower water concentration (concentrated solution).
– Diffusion is the general movement of particles from high to low concentration.

A selectively permeable (or semi-permeable) membrane allows certain molecules or ions to pass through by diffusion, and occasionally specialized facilitated diffusion. The rate of passage depends on the pressure, concentration, and temperature of the molecules or solutes on either side, as well as the permeability of the membrane to each solute. Osmosis is a specific type of diffusion involving the solvent.

15. Which one of the following is termed as ‘Dry ice’ ?

Which one of the following is termed as ‘Dry ice’ ?

[amp_mcq option1=”Ice present in ice-cream” option2=”Solid water at Antarctica” option3=”Solid state of carbon dioxide” option4=”Solid water of ionosphere” correct=”option3″]

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‘Dry ice’ is the common name for solid carbon dioxide ($\text{CO}_2$). At standard atmospheric pressure, solid carbon dioxide does not melt into a liquid but instead undergoes sublimation, transitioning directly from the solid phase to the gaseous phase. This is why it is called “dry ice,” as it appears as ice but doesn’t produce liquid water upon warming.
A) Ice present in ice-cream is frozen water.
B) Solid water at Antarctica is frozen water (H₂O ice).
C) Solid state of carbon dioxide is indeed dry ice.
D) Solid water of ionosphere is not a recognized term for dry ice; the ionosphere is a layer of the atmosphere where water exists primarily as gas or plasma, not solid ice.

– Dry ice is solid $\text{CO}_2$.
– Dry ice sublimes (solid to gas transition) at atmospheric pressure.
– Common ice is frozen water (solid H₂O).

Dry ice is much colder than water ice, with a sublimation temperature of -78.5 °C (-109.3 °F) at atmospheric pressure. It is used for cooling, freezing, and fog effects (by causing water vapor in the air to condense).

16. Which one of the following substances is not a mixture ?

Which one of the following substances is not a mixture ?

[amp_mcq option1=”Tin” option2=”Sea water” option3=”Soil” option4=”Air” correct=”option1″]

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Matter can be classified into pure substances (elements and compounds) and mixtures. A mixture is formed when two or more substances are combined physically but not chemically. The components of a mixture retain their individual properties and can often be separated by physical means.
A) Tin (Sn) is a chemical element, found on the periodic table. Elements are pure substances, consisting only of one type of atom. Therefore, tin is not a mixture.
B) Sea water is a solution of various salts (like sodium chloride, magnesium chloride, etc.), dissolved gases, and other substances in water. It is a homogeneous mixture (a solution).
C) Soil is a complex combination of inorganic mineral particles, organic matter, water, air, and living organisms. It is a heterogeneous mixture.
D) Air is a mixture of gases, primarily nitrogen ($\text{N}_2$), oxygen ($\text{O}_2$), argon (Ar), carbon dioxide ($\text{CO}_2$), and trace gases. It is a homogeneous mixture (a solution of gases).
Since Tin is an element and not a combination of different substances physically mixed, it is not a mixture.

– Pure substances include elements and compounds.
– Mixtures are physical combinations of two or more substances.
– Elements cannot be broken down into simpler substances by chemical means.

Elements are the basic building blocks of matter. Compounds are formed by chemical reactions between elements in fixed proportions. Mixtures can have variable compositions. Identifying whether something is a mixture involves checking if it’s a pure element or compound, or a physical blend of multiple substances.

17. Soaps clean surfaces on the principle based on

Soaps clean surfaces on the principle based on

[amp_mcq option1=”Viscosity” option2=”Floatation” option3=”Elasticity” option4=”Surface tension” correct=”option4″]

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Soaps are surfactants, meaning they reduce the surface tension of water. Water molecules have strong cohesive forces, leading to high surface tension. This makes it difficult for water to spread and penetrate fabrics or surfaces. Soaps interfere with these forces, lowering surface tension and allowing water to wet surfaces more effectively. Additionally, soap molecules have a hydrophilic (water-attracting) head and a hydrophobic (oil-attracting) tail. The hydrophobic tails surround grease and dirt particles, forming tiny structures called micelles. These micelles, with their hydrophilic heads facing outwards, are soluble in water and can be easily washed away, carrying the dirt with them. This cleaning action is primarily based on the reduction of surface tension and the emulsification/dispersion of dirt through micelle formation, both consequences of the surfactant properties related to surface tension effects.

– Soaps are surfactants.
– Surfactants reduce the surface tension of water.
– Reduced surface tension allows water to spread and penetrate effectively.
– Soap molecules emulsify grease and dirt by forming micelles.
– The fundamental principle involves the interaction of soap at surfaces (related to surface tension).

Viscosity is the resistance of a fluid to flow. Floatation is based on buoyancy. Elasticity is the ability of a material to return to its original shape after deformation. While these properties exist, they are not the primary principles behind the cleaning action of soaps. The ability to lower surface tension is key to the wetting and emulsification processes central to how soaps remove dirt.

18. Which one of the following does not represent the salt, Calcium carbon

Which one of the following does not represent the salt, Calcium carbonate ?

[amp_mcq option1=”Lime water” option2=”Limestone” option3=”Chalk” option4=”Marble” correct=”option1″]

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Calcium carbonate ($\text{CaCO}_3$) is a common chemical compound found in various natural forms. Limestone, chalk, and marble are all naturally occurring forms of calcium carbonate. Limestone is a sedimentary rock largely composed of calcium carbonate. Chalk is a type of limestone. Marble is a metamorphic rock formed from limestone.
Lime water, however, is a saturated solution of calcium hydroxide ($\text{Ca(OH)}_2$). It is produced by dissolving calcium oxide (quicklime) in water to form calcium hydroxide (slaked lime), and then dissolving the calcium hydroxide in more water. While calcium carbonate can be *formed* by passing carbon dioxide through lime water (causing precipitation), lime water itself is calcium hydroxide solution, not calcium carbonate.

– Calcium carbonate ($\text{CaCO}_3$) exists in forms like limestone, chalk, and marble.
– Lime water is a solution of calcium hydroxide ($\text{Ca(OH)}_2$).
– Passing $\text{CO}_2$ through lime water produces $\text{CaCO}_3$ precipitate.

Calcium carbonate is a widely used substance, for example, as a building material, as an abrasive, in agriculture to reduce soil acidity, and in medicine as an antacid. Calcium hydroxide (lime water) is also used in various industrial processes and as a test for carbon dioxide.

19. 10 g of ice at $-10^\circ$C is mixed with 10 g of water at $0^\circ$C.

10 g of ice at $-10^\circ$C is mixed with 10 g of water at $0^\circ$C. The amount of heat required to raise the temperature of mixture to $10^\circ$C is

[amp_mcq option1=”400 cal” option2=”550 cal” option3=”1050 cal” option4=”1200 cal” correct=”option3″]

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To calculate the total heat required, we need to consider the heat needed for each stage of the process:
1. Heat required to raise the temperature of 10 g of ice from -10°C to 0°C:
$Q_1 = m_{ice} \times c_{ice} \times \Delta T_1$
Assuming specific heat of ice $c_{ice} = 0.5 \, \text{cal/g}^\circ\text{C}$.
$Q_1 = 10 \, \text{g} \times 0.5 \, \text{cal/g}^\circ\text{C} \times (0^\circ\text{C} – (-10^\circ\text{C})) = 10 \times 0.5 \times 10 = 50 \, \text{cal}$.
2. Heat required to melt 10 g of ice at 0°C into water at 0°C:
$Q_2 = m_{ice} \times L_{fusion}$
Assuming latent heat of fusion of ice $L_{fusion} = 80 \, \text{cal/g}$.
$Q_2 = 10 \, \text{g} \times 80 \, \text{cal/g} = 800 \, \text{cal}$.
After this step, we have 10 g of water at 0°C.
3. Heat required to raise the temperature of the 10 g of water (from melted ice) from 0°C to 10°C:
$Q_3 = m_{water(ice)} \times c_{water} \times \Delta T_2$
Assuming specific heat of water $c_{water} = 1 \, \text{cal/g}^\circ\text{C}$.
$Q_3 = 10 \, \text{g} \times 1 \, \text{cal/g}^\circ\text{C} \times (10^\circ\text{C} – 0^\circ\text{C}) = 10 \times 1 \times 10 = 100 \, \text{cal}$.
4. Heat required to raise the temperature of the initial 10 g of water from 0°C to 10°C:
$Q_4 = m_{water(initial)} \times c_{water} \times \Delta T_3$
$Q_4 = 10 \, \text{g} \times 1 \, \text{cal/g}^\circ\text{C} \times (10^\circ\text{C} – 0^\circ\text{C}) = 10 \times 1 \times 10 = 100 \, \text{cal}$.

Total heat required = $Q_1 + Q_2 + Q_3 + Q_4 = 50 + 800 + 100 + 100 = 1050 \, \text{cal}$.

– Heat transfer during phase change (melting or freezing) involves latent heat ($Q = mL$).
– Heat transfer during temperature change involves specific heat ($Q = mc\Delta T$).
– Need to account for heat required for each component (ice and water) and each process (heating ice, melting ice, heating water).

The problem assumes standard values for specific heat capacities of ice and water and the latent heat of fusion of ice. If the final temperature was, for example, 0°C, we would first check if the initial water had enough heat to raise the ice to 0°C and then melt it completely. In this case, the target temperature is above 0°C, implying all ice must first melt.

20. Which one of the following statements regarding lenses is not correct

Which one of the following statements regarding lenses is not correct ?

[amp_mcq option1=”A convex lens produces both real and virtual images.” option2=”A concave lens produces virtual images.” option3=”A convex lens can produce images equal, greater and smaller than the size of the object.” option4=”A concave lens always produces images smaller than the size of the object.” correct=”option4″]

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Let’s analyze each statement regarding lenses, assuming standard behaviour with real objects, but considering the possibility of virtual objects as the word “always” appears in option D.
A) A convex lens produces both real and virtual images. This is correct. A convex lens produces real images for objects placed beyond its focal point (F) and virtual images for objects placed between F and the optical center (O).
B) A concave lens produces virtual images. This is correct. A concave lens produces virtual, erect, and diminished images for any real object position. It can also produce real images for virtual objects. The statement “produces virtual images” is true as it is capable of doing so.
C) A convex lens can produce images equal, greater and smaller than the size of the object. This is correct. For real objects, a convex lens produces diminished images (object beyond 2F), same-sized images (object at 2F), and magnified images (object between F and 2F). It also produces a magnified virtual image (object between F and O).
D) A concave lens always produces images smaller than the size of the object. This statement is incorrect. While a concave lens always produces smaller, virtual images for *real* objects, it can produce magnified *real* images for certain *virtual* object positions (specifically, when a virtual object is placed between the focal point F and the optical center O). Therefore, it does not *always* produce images smaller than the object size when considering all possible object types.

– Convex lenses can form both real and virtual, magnified, diminished, or same-sized images depending on the object position.
– Concave lenses always form virtual, erect, and diminished images for real objects.
– The word “always” in statement D makes it universally true or false. Considering virtual objects, a concave lens does not always produce smaller images.

For a concave lens, a virtual object placed between the optical center (O) and the focal point (F) forms a real, inverted, and magnified image beyond F. This contradicts statement D, making it incorrect in the most general sense. If the question were restricted to real objects, all other options would be correct, which suggests D is the intended incorrect statement due to the inclusion of “always”.