UPSC 2011 Science & Technology Previous Year Questions

Question 1

Regular intake of fresh fruits and vegetables is recommended in the diet since they are a good source of antioxidants. How do antioxidants help a person maintain health and promote longevity?

Accepted Answer

Correct Option: C. They activate the enzymes necessary for vitamin synthesis in the body and help prevent vitamin deficiency | They prevent excessive oxidation of carbohydrates, fats and proteins in the body and help avoid unnecessary wastage of energy | They neutralize the free radicals produced in the body during metabolism | They activate certain genes in the cells of the body and help delay the ageing process. Antioxidants neutralize free radicals produced during metabolism, reducing oxidati

Question 2

Salinization occurs when the irrigation water accumulated in the soil evaporates, leaving behind salts and minerals. What are the effects of salinization on the irrigated land?

Accepted Answer

Correct Option: B. It greatly increases the crop production | It makes some soils impermeable | It raises the water table | It fills the air spaces in the soil with water. Salt accumulation can damage soil structure and reduce permeability, making some soils hard and less productive. It does not increase crop production or simply fill air spaces with water.

Question 3

A married couple adopted a male child. A few years later, twin boys were born to them. The blood group of the couple is AB positive and O negative. The blood group of the three sons is A positive, B positive, and O positive. The blood group of the adopted son is:

Accepted Answer

Correct Option: A. O positive | A positive | B positive | Cannot be determined on the basis of the given data. A biological child of AB and O parents can have A or B blood group, not O, because the AB parent cannot contribute an O allele. Therefore the O positive son must be the adopted child.

Question 4

Recently, "oilzapper" was in the news. What is it?

Accepted Answer

Correct Option: A. It is an eco-friendly technology for the remediation of oily sludge and oil spills | It is the latest technology developed for under sea oil exploration | It is a genetically engineered high biofuel yielding maize variety | It is the latest technology to control the accidentally caused flames from oil wells. Oilzapper is a bioremediation technology using oil-degrading microbes to treat oily sludge and oil spills. It is not an exploration, biofuel crop or flame-control technolo

Question 5

Aspartame is an artificial sweetener sold in the market. It consists of amino acids and provides calories like other amino acids. Yet, it is used as a low-calorie sweetening agent in food items. What is the basis of this use?

Accepted Answer

Correct Option: D. Aspartame is as sweet as table sugar, but unlike table sugar, it is not readily oxidized in human body due to lack of requisite enzymes | When aspartame is used in food processing, the sweet taste remains, but it becomes resistant to oxidation | Aspartame is as sweet as sugar, but after ingestion into the body, it is converted into metabolites that yield no calories | Aspartame is several times sweeter than table sugar, hence food items made with small quantities of aspartame

Question 6

The surface of a lake is frozen in severe winter, but the water at its bottom is still liquid. What is the reason?

Accepted Answer

Correct Option: C. Ice is a bad conductor of heat | Since the surface of the lake is at the same temperature as the air, no heat is lost | The density of water is maximum at 4 degrees C. | None of the statements (a), (b) and (c) given above is correct. Water is densest at 4 degrees Celsius, so that water sinks while colder water stays above and freezes. The ice layer also insulates, but the distinctive reason for liquid water at the bottom is maximum density at 4 degrees Celsius.

Question 7

The function of heavy water in nuclear reactor is to

Accepted Answer

Correct Option: A. Slow down the speed of neutrons | Increase the speed of neutrons | Cool down the reactor | Stop the nuclear reaction. Heavy water acts as a moderator in certain nuclear reactors. It slows down fast neutrons so that they are more likely to sustain a controlled fission chain reaction.

Question 8

A genetically engineered form of brinjal, known as the Bt-brinjal, has been developed. The objective of this is:

Accepted Answer

Correct Option: A. To make it pest-resistant | To improve its taste and nutritive qualities | To make it drought-resistant | To make its shelf-life longer. Bt brinjal carries a Bacillus thuringiensis gene that produces a toxin against specific insect pests, especially fruit and shoot borer. Its purpose is pest resistance.

Question 9

Karl Marx explained the process of class struggle with the help of which one of the following theories?

Accepted Answer

Correct Option: D. Empirical liberalism | Existentialism | Darwin's theory of evolution | Dialectical materialism. Marx explained social change and class struggle through dialectical materialism, where material economic relations and contradictions between classes drive historical development.

Question 10

Human activities in the recent past have caused the increased concentration of carbon dioxide in the atmosphere, but a lot of it does not remain in the lower atmosphere because of 1. its escape into the outer stratosphere. 2. the photosynthesis by phytoplankton in the oceans. 3. the trapping of air in the polar ice caps. Which of the statements given above is/are correct?

Accepted Answer

Correct Option: B. 1 and 2 | 2 only | 2 and 3 | 3 only. A major natural sink of atmospheric carbon dioxide is oceanic photosynthesis by phytoplankton. CO2 does not significantly escape into outer stratosphere, and polar ice trapping is not a major explanation for present atmospheric CO2 reduction.

UPSC 2011 Science & Technology PYQs with Answers