UPSC NDA-2 Archives

11. A point object is placed at the centre of curvature of a spherical con

A point object is placed at the centre of curvature of a spherical concave mirror. Which one among the following would be the correct location of image formed ?

At infinity

At the centre of curvature

At the focal point

Between the focal point and the centre of curvature

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For a spherical concave mirror, when an object is placed at the centre of curvature (C), the image formed is also located at the centre of curvature (C).

When the object is at the centre of curvature of a concave mirror, the image formed is real, inverted, and has the same size as the object. Ray diagrams show that rays from the object passing through the focal point become parallel after reflection, and rays hitting the mirror perpendicularly pass through the centre of curvature after reflection. These reflected rays intersect at the centre of curvature.

The relationship between object distance (u), image distance (v), and focal length (f) for a spherical mirror is given by the mirror formula: 1/f = 1/u + 1/v. For a concave mirror, f is positive. The centre of curvature (C) is located at a distance 2f from the pole of the mirror. If u = 2f (object at C), then 1/f = 1/(2f) + 1/v. Solving for 1/v gives 1/v = 1/f – 1/(2f) = 2/(2f) – 1/(2f) = 1/(2f). Thus, v = 2f, meaning the image is also formed at the centre of curvature.

12. Organisms of which of the following phylum are called sponges ?

Organisms of which of the following phylum are called sponges ?

Coelenterata

Platyhelminthes

Porifera

Echinodermata

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Organisms belonging to the phylum Porifera are commonly known as sponges. The name “Porifera” means “pore-bearers,” which describes the characteristic feature of sponges having a body permeated by pores.

Porifera are the simplest multicellular animals, typically sessile aquatic organisms. They lack true tissues and organs and filter feed water that passes through their porous bodies.

Coelenterata (now more commonly called Cnidaria) includes jellyfish, sea anemones, and corals, characterized by a radial symmetry and stinging cells (cnidocytes). Platyhelminthes are flatworms (e.g., tapeworms, flukes), known for their flattened body shape and bilateral symmetry. Echinodermata includes marine animals like starfish, sea urchins, and sea cucumbers, characterized by radial symmetry (often pentaradial) and a water vascular system.

13. Which part of nephron of the human kidney is responsible for filtratio

Which part of nephron of the human kidney is responsible for filtration of blood for excretion ?

Collecting duct

Renal vein

Ureter

Bowman's capsule

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Filtration of blood in the human kidney for the purpose of excretion occurs in the renal corpuscle, specifically within the structure known as Bowman’s capsule. Blood is filtered from the glomerulus (a network of capillaries) into the space within Bowman’s capsule.

The nephron is the functional unit of the kidney. It consists of the renal corpuscle (Glomerulus and Bowman’s capsule) and the renal tubule. The renal corpuscle is where the initial step of urine formation, glomerular filtration, takes place.

After filtration in Bowman’s capsule, the filtrate passes through the renal tubule (proximal convoluted tubule, loop of Henle, distal convoluted tubule), where essential substances are reabsorbed back into the blood, and waste products are further secreted into the tubule. The collecting duct collects urine from multiple nephrons before it travels to the renal pelvis and out via the ureter. The renal vein carries purified blood away from the kidney.

14. In which part or organ of human body cartilage is NOT found ?

In which part or organ of human body cartilage is NOT found ?

Nose

Trachea

Bronchiole

Knee joint

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Cartilage is a flexible connective tissue found in various parts of the body. While present in the nose, trachea, and knee joints, it is absent in the smaller airways called bronchioles.

The respiratory tract contains cartilage in the trachea and bronchi to maintain their structure and prevent collapse. As the airways branch into smaller bronchioles (less than 1 mm in diameter), the cartilage rings disappear, and the walls become primarily smooth muscle and elastic tissue, which allows for regulation of airflow through bronchoconstriction and bronchodilation.

Cartilage provides support and flexibility. Different types of cartilage exist, such as hyaline cartilage (found in the trachea and joints), elastic cartilage (found in the ear and epiglottis), and fibrocartilage (found in intervertebral discs and menisci of the knee). The absence of cartilage in bronchioles is a key anatomical feature distinguishing them from larger airways.

15. Which one among the following combinations most appropriately represen

Which one among the following combinations most appropriately represent the components of balanced diet ?

Carbohydrate, vitamins, proteins, fat, minerals, fibres and water

Carbohydrate, vitamins, proteins, fat and minerals

Carbohydrate, vitamins, proteins, minerals and water

Vitamins, proteins, fat, minerals, fibres and water

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A balanced diet must provide all the essential nutrients required by the body in appropriate quantities for good health. The options provided list various food components. Option A includes all the major categories of nutrients and essential components needed for a balanced diet.

A balanced diet consists of carbohydrates, proteins, fats, vitamins, minerals, dietary fibres, and water. Each of these components plays a vital role in the body’s functions.

Carbohydrates are the primary source of energy. Proteins are essential for growth and repair. Fats provide energy and help absorb certain vitamins. Vitamins and minerals are micronutrients necessary for various metabolic processes. Fibres are important for digestive health. Water is crucial for numerous bodily functions, including transport and temperature regulation.

16. Which one among the following diseases is caused due to deficiency of

Which one among the following diseases is caused due to deficiency of Vitamin D in humans ?

Beriberi

Scurvy

Rickets

Pneumonia

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Beriberi is a disease caused by a deficiency of Vitamin B1 (Thiamine). Scurvy is caused by a deficiency of Vitamin C (Ascorbic Acid). Rickets is a condition in children caused by a deficiency of Vitamin D, calcium, or phosphate, leading to soft and weak bones. Osteomalacia is the equivalent condition in adults, primarily caused by Vitamin D deficiency. Pneumonia is an infection of the lungs, usually caused by bacteria or viruses, not a vitamin deficiency. Therefore, Rickets is caused by Vitamin D deficiency.

Vitamin D is essential for calcium and phosphate absorption and bone health. Deficiency can lead to impaired bone mineralization, resulting in Rickets in children and Osteomalacia in adults.

Vitamin D can be obtained from certain foods (fatty fish, fortified foods) and is synthesized in the skin upon exposure to sunlight. Sunlight exposure is a significant source of Vitamin D for many people.

17. The lowest part of most bolsons is occupied by a landform called playa

The lowest part of most bolsons is occupied by a landform called playa. Which category of landform formation does it represent ?

Fluvial landforms

Arid landforms

Glacial landforms

Periglacial landforms

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Bolsons are internally drained basins characteristic of arid and semi-arid regions, particularly in the Basin and Range topography of the United States. The lowest part of a bolson is often a playa, which is a flat, dry lakebed that forms when ephemeral lakes evaporate. Both bolsons and playas are landforms shaped by processes dominant in arid environments, including intermittent fluvial action (during rainfall) and significant evaporation. They are classic examples of Arid landforms. Fluvial landforms are shaped by permanent rivers. Glacial landforms are shaped by glaciers. Periglacial landforms are associated with cold climates near glacial margins, involving processes like frost heave and solifluction.

Playas are flat-bottomed depressions found in internally drained basins (bolsons) in arid regions, formed by the accumulation and subsequent evaporation of water.

Playas can accumulate evaporite minerals like salt, gypsum, or borax, depending on the dissolved load carried by the water. Famous examples include the Bonneville Salt Flats in the USA and Etosha pan in Namibia.

18. Which one among the following statements with reference to Benguela cu

Which one among the following statements with reference to Benguela current is NOT correct ?

It influences the climate of the West coast of North Africa

It is a cold current

Its direction is from South to North

It flows in the Atlantic Ocean

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The Benguela Current is a cold ocean current that flows northwards along the west coast of Southern Africa, from the Cape of Good Hope up to the border with Angola. Statement B is correct; it is a well-known cold current. Statement C is correct; its direction is from South to North along the coast. Statement D is correct; it flows in the South Atlantic Ocean. Statement A is incorrect; the Benguela Current influences the climate of the *west coast of Southern Africa*, not North Africa. The west coast of North Africa is influenced by the cold Canary Current.

Ocean currents significantly influence the climate of adjacent landmasses. Cold currents, like the Benguela, often lead to arid or semi-arid conditions on the western coasts of continents in tropical and subtropical latitudes.

The upwelling associated with the Benguela Current supports a very productive marine ecosystem off the coast of Namibia and South Africa. The aridity of the Namib Desert is partly attributed to the cooling and stabilizing effect of the Benguela Current on the overlying air.

19. Which one among the following is a landlocked water body ?

Which one among the following is a landlocked water body ?

Mediterranean Sea

Black Sea

Red Sea

Caspian Sea

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A landlocked water body is one that is completely surrounded by land and has no natural connection to the ocean. The Mediterranean Sea is connected to the Atlantic Ocean via the Strait of Gibraltar. The Black Sea is connected to the Mediterranean Sea via the Bosporus, Sea of Marmara, and Dardanelles. The Red Sea is connected to the Indian Ocean via the Bab-el-Mandeb strait. The Caspian Sea is the world’s largest inland body of water by area, completely surrounded by land, and has no natural outlet to the ocean. Thus, the Caspian Sea is a landlocked water body.

Landlocked water bodies are inland seas or lakes without natural connections to the global ocean system.

The Caspian Sea is often considered the world’s largest lake, though due to its size and salinity, it is also referred to as a sea. Its salinity varies across different parts. Other large landlocked bodies include the Aral Sea (though it has shrunk dramatically) and the Great Lakes of North America (freshwater).

20. Which one among the following local winds is NOT related to Mediterran

Which one among the following local winds is NOT related to Mediterranean Sea ?

Harmattan

Khamsin

Sirocco

Mistral

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The Harmattan is a dry, dusty trade wind that blows from the Sahara Desert over West Africa and into the Atlantic Ocean during the dry season (typically November to March). It is not related to the Mediterranean Sea region. Khamsin is a hot, dry, sandy wind blowing in Egypt, often from the south. Sirocco is a Mediterranean wind originating in the Sahara and blowing north across North Africa and Southern Europe. Mistral is a cold, dry regional wind in southern France that blows down the Rhone River valley to the Mediterranean Sea. Therefore, Harmattan is the local wind that is NOT related to the Mediterranean Sea.

Local winds are influenced by regional topography and pressure systems. Understanding their origin and direction helps determine their associated regions.

Other local winds related to the Mediterranean region include Bora (Adriatic coast), Etesian (Aegean Sea), and Leveche (Spain). The Harmattan is known for reducing humidity and visibility in West Africa.