Science and Technology: UPSC Previous Year Questions (Prelims)

Explanation

Statement 1 is correct: Vitamin A is essential for maintaining healthy tear production and eye lubrication. Its deficiency can cause xerophthalmia, leading to dryness in the conjunctiva and cornea due to impaired lacrimal gland function. If left untreated, it can result in severe eye damage and vision impairment.

Statement 2 is correct: Vitamin B1 (thiamine) plays a crucial role in energy metabolism and nerve function. Its deficiency leads to beriberi, which occurs in two forms:

Wet beriberi affects the cardiovascular system, potentially causing heart enlargement, rapid heartbeat, and heart failure. Dry beriberi impacts the nervous system, leading to muscle weakness, nerve damage, and digestive issues such as indigestion.

Statement 3 is correct: A lack of Vitamin C results in scurvy, characterized by muscle pain, joint discomfort, and fatigue. Since Vitamin C is essential for collagen synthesis and its deficiency weakens connective tissues, leading to pain, fragile blood vessels, and slow wound healing.

Statement 4 is correct: Vitamin D is vital for calcium absorption in the intestines. Due to its deficiency calcium absorption decreases which leads to low blood calcium levels. The body compensates by increasing parathyroid hormone (PTH) secretion which draws calcium from bones. Without sufficient Vitamin D the kidneys may excrete more calcium in urine, leading to weakened bones and risk of osteoporosis.

Explanation

Insulin is a protein-based hormone produced by beta cells in the pancreas, specifically in the Islets of Langerhans. It consists of two peptide chains (A and B) connected by disulfide bonds and plays a crucial role in regulating blood glucose levels. By promoting glucose uptake in cells, it helps maintain energy balance and prevents hyperglycemia. Insulin was first discovered by Frederick Banting and Charles Best in 1921. It is the first recombinant DNA-based drug approved for human use.

Explanation

Statement 1 is incorrect: Pangolins (scaly anteaters) are fascinating toothless mammals covered in protective keratin scales. They use their long, sticky tongues to capture ants and termites, making them nature’s pest controllers. India is home to two species of pangolins:

Indian Pangolin (Manis crassicaudata) is found across most parts of India, except for the northeastern states. Chinese Pangolin (Manis pentadactyla) inhabits the forests of northeast India, including Assam, Arunachal Pradesh, and Meghalaya. Pangolins are the most trafficked mammals in the world due to demand for their scales and meat.

Statement 2 is correct: Hoolock Gibbon is India’s only ape species and is a true acrobat of the rainforest. Unlike monkeys, gibbons lack tails and move gracefully through the trees using brachiation (swinging from branch to branch). These lesser apes are found in Northeast India, especially in Assam (Hoollongapar Gibbon Sanctuary) Arunachal Pradesh, Meghalaya, Mizoram, Manipur, Nagaland and Tripura. Hoolock gibbons are known for their melodious calls, which echo through the dense forests. Sadly, habitat destruction and deforestation have put them at risk.

Explanation

The term "long bone" refers to bones that are longer than they are wide such as the femur and humerus. The bone marrow within these long bones is a primary site for lymphocyte production. This process is known as lymphopoiesis and involves the differentiation of hematopoietic stem cells into various lymphocyte types such as B cells, T cells, and natural killer cells.

Explanation

Statement 1 is correct: The femur, or thigh bone is the longest and strongest bone in the human body. It stretches from the hip to the knee and provides crucial support and stability, allowing us to walk, run, and jump. The femur can withstand forces up to 816-1,134 kg before breaking, making it one of the strongest structures in our skeletal system.

Statement 2 is correct: Cholera is a severe bacterial infection caused by Vibrio cholerae. It spreads mainly through contaminated water or food, leading to acute diarrhea and dehydration. In extreme cases a person with can lose up to 20 liters of fluid per day making rapid treatment with rehydration therapy essential.

Statement 3 is incorrect: Athlete’s foot (Tinea Pedis) is not caused by a virus, but by fungal infection. Dermatophyte fungi thrive in warm, damp environments like locker rooms, swimming pools, and sweaty shoes. The infection causes itchy, peeling, and cracked skin between the toes, making it a common concern among athletes and hence the name.

Explanation

METSAT (renamed as Kalpana - 1) was the first in the series of exclusive meteorological satellites built by ISRO.

Statement 1 is correct: India successfully launched its first full-fledged meteorological satellite, METSAT using the PSLV-C4 rocket. It was India’s first dedicated meteorological satellite, designed to monitor weather conditions and cyclone development in the Indian Ocean region.

Statement 2 is correct: PSLV-C4 carried METSAT (1,060 kg) into a geosynchronous transfer orbit (GTO), marking the first time PSLV carried a payload exceeding 1000 kg into GTO. This demonstrated ISRO’s ability to deploy heavier payloads into higher orbits, advancing India’s space technology capabilities.

Explanation

Assertion (A) is true: Weight is the force of gravity acting on an object, and gravity weakens as the distance from the Earth>s center increases. Since altitude represents a greater distance from the Earth>s center, the force of gravity and thus the weight of the body diminish. Reason (R) is true: The Earth is not a perfect sphere, being slightly flattened at the poles and bulging at the equator, this fact does not primarily explain the decrease in weight with altitude. The primary reason lies in the inverse square law of gravity, which states that the force of gravity between two objects decreases proportionally to the square of the distance between them. Hence, Reason (R) does not correctly explain the Assertion (A).

Explanation

Statement 1 is correct: When a vehicle takes a sharp turn at high speed, the centrifugal force may push the vehicle outwards. This can cause the vehicle to tilt outwards and potentially overturn about its outer wheels.

Statement 2 is incorrect: This is less likely to happen. The centrifugal force pushes the vehicle outwards, not inwards.

Statement 3 is correct: If the friction between the tires and the road is insufficient to provide the necessary centripetal force, the vehicle may skid outwards, away from the center of the turn.

Statement 4 is incorrect: Skidding typically occurs outwards, not inwards, due to the centrifugal force.

Explanation

When the oil tanker accelerates forward, the oil inside experiences an inertial force (pseudo force) acting in the opposite direction to the acceleration. This causes the free surface of the oil to tilt. 1. The rear end of the tanker has larger depth because the inertial force pushes the oil backward.

2. The front end has smaller depth as the oil moves away from it. Thus, The free surface of the oil becomes inclined, with the rear end having a larger depth

Explanation

Statement 1 is incorrect: Steam at 100°C contains significantly more heat than boiling water at 100°C. This is because steam has absorbed additional energy in the form of latent heat of vaporization which is the energy required to convert water at 100°C into steam at the same temperature without changing its temperature.

Statement 2 is incorrect: The latent heat of fusion of ice (the energy required to convert ice at 0°C to water at 0°C) is approximately 334 kJ/kg while the latent heat of vaporization of water (the energy required to convert water at 100°C to steam at 100°C) is approximately 2260 kJ/kg.

Statement 3 is correct: In an air-conditioner the refrigerant absorbs heat from the room air at the evaporator coils and cools the air. This heat is then transported to the condenser coils, where it is released to the outside environment. This process is based on the principles of thermodynamics and the refrigeration cycle.