UPSC 2003 Science and Technology Questions with Answers

Explanation

Assertion (A) is false: Electron affinity generally decreases as you move down a group due to increasing atomic radii and weaker nuclear attraction for the incoming electron. Additional electron shells increase the shielding effect, further reducing effective nuclear pull. Reason (R) is true: As you go down a group, additional electron shells are added, making the atomic radius increase. This is because the outermost electrons are farther from the nucleus, and the shielding effect from inner electrons increases. Directions: The following Items consist of two statements. One labeled as the ‘Assertion (A)’ and the other as ’Reason (R)’. You have to answer these items using the code given below:(2003)

Explanation

Detergents are cleaning agents used to remove dirt, grease, and stains from surfaces and fabrics. Key additives like sodium sulphate prevent clumping by keeping the powder dry, while sodium silicate maintains alkalinity, enhancing the cleaning efficiency.

Statement 1 is correct: Sodium sulphate is added to keep the washing powder dry by preventing it from absorbing moisture.

Statement 2 is correct: Sodium silicate is used to maintain the alkalinity of the detergent, which enhances the cleaning action by breaking down grease and dirt.

Explanation

Photochemical smog is a type of air pollution that occurs when sunlight reacts with pollutants like nitrogen oxides and volatile organic compounds (VOCs), including hydrocarbons. The reaction leads to the formation of ozone, which is a key component of photochemical smog. Key Components of Photochemical Smog are:

Nitrogen Oxides - Released from vehicles, industrial emissions, and power plants. They react with sunlight to form ozone. Hydrocarbons: Organic compounds that also contribute to ozone formation when exposed to sunlight. Ozone: The primary harmful product of photochemical smog, which can cause respiratory problems and damage to vegetation. Methane is a potent greenhouse gas, but it does not directly form photochemical smog. While it can contribute indirectly to smog formation by reacting with other pollutants, it is not a primary component like ozone, hydrocarbons, or nitrogen oxides.

Explanation

Statement 1 is correct: Spirogyra and Ulothrix are types of blue green algae that can be found in both freshwater and marine environments. They are typically found in ponds, rivers, and even oceans in some cases. Spirogyra is known for its spiral-shaped chloroplasts and forms slimy green filaments/ mats on the water surface, especially when nutrients like nitrogen and phosphorus are abundant while Ulothrix is characterized by its simple, unbranched filaments and typically grows in both freshwater ponds and coastal regions. These algae play an important role in the aquatic food chain.

Statement 2 is correct: Chameleons have a unique ability to move their eyes independently of each other. They can focus one eye on an object in front while the other eye looks in a different direction, even behind them. This independent eye movement enables them to have a 360-degree view of their surroundings, aiding in predator detection and prey surveillance.

Explanation

Saturated fats are typically solid at room temperature and are found in animal products like butter, lard, and fatty cuts of meat, as well as some plant oils like coconut and palm oil. They are composed of fatty acids with no double bonds between carbon atoms, making them less reactive. Unsaturated fats are liquid at room temperature and are mainly found in plant-based oils (such as olive, sunflower, and canola oil) and fish. They contain one or more double bonds between carbon atoms which introduce "kinks" in the structure making them more reactive and beneficial for heart health when consumed in moderation. Assertion (A) is true: Unsaturated fats have at least one double bond between carbon atoms, making them more reactive. These double bonds are sites where chemical reactions can occur more easily compared to the single bonds in saturated fats. Reason (R) is false: Unsaturated fats contain at least one double bond in their carbon chain, not only single bonds. Saturated fats have only single bonds.

Explanation

Statement 1 is correct: Molasses is a thick, dark syrup that remains after the extraction of sugar from sugarcane or sugar beets. It is a common by-product in the sugar industry. It serves as a feedstock for producing synthetic chemical fertilizers and ethanol.

Statement 2 is correct: Bagasse, the fibrous residue left after extracting juice from sugarcane, is commonly used as a biofuel in the sugar industry to generate steam and electricity, making the process more energy-efficient.

Statement 3 is incorrect: Sugar is produced from various raw materials including sugarcane and sugar beets. Other sources for sugar production include sorghum and palm sap.

Explanation

The octopus is a mollusc in the class Cephalopoda (including squids and cuttlefish), part of the phylum Mollusca. Cephalopods are soft-bodied, bilaterally symmetrical, lack external skeletons, and have prominent heads with arms or tentacles. Octopuses lack an external shell, allowing for flexibility and the ability to squeeze through tight spaces. Their eight arms, equipped with suction cups, help with locomotion, prey capture, and interaction. Octopuses are highly intelligent, demonstrating problem-solving and tool use. Mollusca is a phylum of invertebrates, including snails, clams, and cephalopods.

Explanation

The word AIDS stands for Acquired Immuno Deficiency Syndrome. This means deficiency of the immune system, acquired during the lifetime of an individual. ‘Syndrome’ means a group of symptoms. AIDS is caused by the Human Immunodeficiency Virus (HIV), a member of a group of viruses called retrovirus. It leads to various symptoms such as Swollen lymph nodes occur due to immune system deterioration, commonly affecting the neck, armpits, and groin. Night sweats and recurring fevers are signs of opportunistic infections as the body struggles to regulate temperature. Memory loss and cognitive impairment arise when the virus affects the nervous system, leading to neurological complications. Significant weight loss results from chronic infections, metabolic changes, and increased energy demands.

Explanation

Statement 1 is incorrect: The renal artery is responsible for delivering oxygenated blood from the heart to the kidneys for filtration. After the kidneys filter the blood by removing waste products and excess substances, the cleansed blood is returned to the systemic circulation via the renal vein, not the renal artery.

Statement 2 is correct: From Bowman’s capsule, the glomerular filtrate(filtered liquid) passes into the proximal convoluted tubule (PCT), where essential substances, including glucose, are actively reabsorbed. This reabsorbed glucose along with other nutrients is then transported into the peritubular capillaries and eventually returned to the bloodstream via the renal vein. This ensures that the body retains necessary nutrients while excreting waste.

Explanation

Milk does contain several B-vitamins such as Vitamin B2 (riboflavin) and Vitamin B12 (cobalamin) along with Vitamin D, calcium, and proteins. For instance, a 200ml glass of semi-skimmed milk provides approximately 0.47 mg of riboflavin, which is about 33% of the recommended daily intake. Options (b), (c) and (d) are correct:

Vitamin A is found in foods like carrots, liver, and dairy products and is crucial for maintaining healthy skin. A deficiency in vitamin A can cause xerosis (dry, scaly skin) due to its role in maintaining healthy skin and mucous membranes. Scurvy is caused by a deficiency in vitamin C. One of its symptoms is joint pain, along with others like fatigue, swollen gums, and bruising. Vitamin C is found in citrus fruits, amla, and guava. A severe deficiency in Vitamin B1(thiamine) can result in beriberi, which affects the cardiovascular system, potentially leading to heart failure. Symptoms include shortness of breath, swelling of the lower legs, and increased heart rate. It is present in whole grains, nuts, and legumes.