UPSC 1997 Science and Technology Questions with Answers

Explanation

Option (a) is correct: Hydrogen has the highest calorific value of around 120-150 MJ/kg, making it an efficient and eco-friendly fuel. Combustion of hydrogen produces only water, contributing to clean energy initiatives. Options (b), (c) and (d) are incorrect:

Charcoal: Has a calorific value of 30 MJ/kg(approx.), significantly lower than hydrogen. Natural gas: Primarily composed of Methane, With a fuel value of around 55 MJ/kg(approx.), it is lower than hydrogen but widely used due to availability. Gasoline: Though energy-dense around 47 MJ/kg (approx.), but lower than hydrogen.

Explanation

Option (d) is correct: Ethylene glycol is a widely used anti-freeze for automobile engines. It effectively lowers the freezing point of the coolant, preventing it from freezing in cold climates. Additionally, it raises the boiling point of the coolant, ensuring efficient heat transfer during engine operation. Options (a), (b) and (c) are incorrect:

Propyl alcohol is rarely used as an anti-freeze due to its lower efficiency and higher cost compared to ethylene glycol. While ethanol has some anti-freeze properties, it is volatile and less efficient than ethylene glycol. Although methanol can be used as an anti-freeze, it is highly toxic and less efficient compared to ethylene glycol.

Explanation

The pituitary gland, often termed the "master gland,” regulates various endocrine glands through its tropic hormones. The parathyroid gland regulates calcium and phosphate balance in the body via parathyroid hormone (PTH) and its activity is independent of pituitary gland control. It is self-regulating, depending directly on calcium levels in the blood. Options (a), (b), and (c) are incorrect: The thyroid, gonads, and adrenal glands are regulated by pituitary tropic hormones such as TSH (thyroid-stimulating hormone), LH/FSH (for gonads), and ACTH (adrenocorticotropic hormone) for the adrenal glands. These glands depend on the pituitary to regulate the production of key hormones that control metabolism, growth, and stress responses.

Explanation

Oxygen transportation in the human body is essential for cellular respiration, which generates energy in the form of ATPs. This process ensures oxygen is delivered to tissues and carbon dioxide is removed efficiently. Oxygen enters the body through the lungs (2), binds to hemoglobin in the blood (1), and is transported to the tissues (3) where it is utilized for energy production. This sequence reflects the physiological process of oxygen transport.

Explanation

Option (b) is correct: The corpus luteum is a temporary endocrine structure found in the ovary formed after ovulation. It produces progesterone, which is critical for maintaining the uterine lining and supporting pregnancy in the early stages. Options (a), (c), and (d) are incorrect: The corpus luteum is specific to the ovary and is unrelated to the brain, pancreas, or spleen.

Explanation

Alpha-keratin is a fibrous structural protein that forms the primary component of the skin, hair, nails, horns, and hooves in mammals. It belongs to the keratin family of proteins and is rich in disulfide bonds, which provide strength, durability, and elasticity to epithelial cells. In the skin, alpha-keratin creates a protective barrier against physical damage, dehydration, and pathogens. In hair and nails, it contributes to their hardness and resistance to wear. Options (a), (c), and (d) are incorrect: Alpha-keratin is not found in blood, lymph, or eggs. These tissues have other proteins like hemoglobin (in blood) or albumin (in eggs).

Explanation

Option (a) is correct: The average fat content of buffalo milk is approximately 7.2%, significantly higher than that of cow>s milk. Buffalo milk is richer in fat compared to cow>s milk, which typically contains around 3-4% fat. The higher fat content in buffalo milk contributes to its creamy texture and makes it ideal for producing dairy products like butter, ghee, and cheese. Options (b), (c), and (d) are incorrect: 4.5% is typical of cow’s milk, while 9.0% and 10.0% are not average values for buffalo milk.

Explanation

Option (d) is correct: Fructose is the major component of honey making up about 38-40% of its composition. It is a monosaccharide and is sweeter than glucose. The high fructose content is responsible for honey>s sweetness and its resistance to crystallization compared to glucose. Options (a), (b), and (c) are incorrect:

Glucose is one of the primary sugars found in honey, but it is not the major component. Honey typically contains about 30-35% glucose. Glucose is a monosaccharide and contributes to the sweetness and crystallization of honey. Sucrose is a disaccharide composed of glucose and fructose. While it is present in honey, it is found in very small amounts (usually less than 5%). Most of the sucrose in nectar is broken down into glucose and fructose by enzymes during the honey-making process. Maltose is not a significant sugar in honey. It is also known as maltobiose or malt sugar which is a disaccharide formed from two units of glucose joined with an -bond between the glucose units.

Explanation

Option (c) is correct: Coronary arteries are responsible for supplying oxygen-rich blood to the heart muscle. They ensure the heart gets the necessary oxygen and nutrients for its functioning. Options (a), (b), and (d) are incorrect:

The carotid arteries are major blood vessels in the neck that supply oxygenated blood to the brain, face, and neck. The hepatic arteries supply oxygenated blood to the liver along with the hepatic portal vein. The pulmonary arteries carry deoxygenated blood from the heart to the lungs for oxygenation.

Explanation

Option (d) is correct: The recommended dietary allowance (RDA) of protein for a moderately active woman is 46 grams per day. This value is based on the average need for maintaining health, muscle repair, and proper physiological functioning. The Recommended Dietary Allowance (RDA) for protein is a modest 0.8 grams of protein per kilogram of body weight. Options (a), (b), and (c) are incorrect: 30 g, 37 g, and 40 g are below the daily requirement for a moderately active woman.