Answer. The picture that formed in our mind is described below:

Most of the later work in astronomy in Iron Age is merely a detailed version of the astronomical knowledge already found in Rig-Veda. Actually, astronomy degenerated into astrology in the later years of this period.

Arithmetic was equally well developed. Numbers in multiples of 10 going up to as high powers of 10, as 10¹², were known and used. All the arithmetic operations on numbers were also known. Quadratic equations, indeterminate equations, permutations and combinations also appear in the sulvastras.

The level of chemical knowledge and practices in the new ordered society is reflected in the pottery. Iron tools and glass objects were found at various Iron Age sites. Ceramic bowls, dishes, lids, etc. also found in these sites. Fermentation methods, dyeing technique, the preparation and use of a number of chemicals and colour pigments were well known.

The domestication of the animals like horses and elephants and their use in warfare necessitated the study of their anatomy and physiology. A survey of Vedic literature has revealed that more than 260 animals were known at that time. Human physiology had also been studied. Post-Vedic literature also contains the names of animals and a vast storehouse of observations on their natural history. These observations may have stimulated the later thoughts and concepts about classification, heredity, embryology, etc.

The Carakas and Susrutas in India were roaming physicians who went about healing ordinary rural folk and fostered democratic thinking and worldviews. Greek medicine, on the other hand, could continue its older traditions because of the support it received from the aristocracy. In era when Greek society was declining from the highest point of its achievement, wealthy citizens could not do without doctors as they led an increasingly unhealthy life of pleasure and abundance.

The technical developments in the Mauryan period form the treatise, arthasastra. In arthasastra, there are detailed descriptions of military machines which use the principle of centrifugal forces. However, the ideas to power these machines with inanimate sources such as wind, water, steam or electricity did not exist then. The greatest contribution to the advancement of technology was, made in the area of metallurgy and metal working.

Pepper and spices were grown for exports as well as domestic consumption. A wide variety of crops like rice, wheat, barley and betel were grown. New fruits like pears and peaches were introduced for the first time. There were proper manuals which gave information on the type and quality of soil required for each plant, various plant diseases, the distances between plants as well as sowing techniques.

The Jainas attached great importance to mathematical proficiency in their religious teachings. Works such as sthananga-sutra, suryaprajnapti and others deal at great length with mensuration, surds, fractions, permutations and combinations, geometry, law of indices, etc. These subjects and the various technical terms used by the Jainas later passed on into the mathematical works of scholars, irrespective of their religious beliefs.

The greatest contributions of ancient Indian civilization was the invention of numerals. The necessity for numerals and numerical notation by words and letters had arisen when human beings started dealing with very large and very small numbers, such as in astronomy and in precision measurements of precision metals. Some of the numeral notations used in this period were the kharosthi and brahmi.

Q. 1 (b) You may have come across statements such as 'India is a land marked by continuity with change'. Do you agree or disagree with this statement? Justify your in answer in about 250 words using your understand of ancient society.

Answer. Yes, we agree that India is a land marked by continuity with change. The following text justifies our answer:

Use of metals: Human beings were attracted by shiny gold and copper which are found free in nature and used them originally as ornaments. Bits of metal have been found in necklaces and other ornaments of Stone Age. Later on alloy of copper and tin was discovered. It was harder and stronger than copper and could be cast into tools weapons. The new metal was widely used for making weapons and tools and it became a commodity of distant trade.

Astronomy and Mathematics: Most of the later work in astronomy in Iron Age is merely a detailed version of the astronomical knowledge already found in Rig-Veda. Actually, astronomy degenerated into astrology in the later years of this period. Arithmetic was equally well developed. Numbers in multiples of 10 going up to as high powers of 10, as 10¹², were known and used. All the arithmetic operations on numbers were also known. Quadratic equations, indeterminate equations, permutations and combinations also appear in the sulvastras.

Mechanics: Another branch of science is mechanics developed out of the necessities of irrigation, moving of heavy bodies, ship-building and making military equipment with known tools and methods. As the invading armies of Alexander came in contact with the craftsmen of the middle-eastern countries, a number of inventions such as the pulley, windlass and screw came into use and were improved upon. Archimidies aided this process of building machines by his ideas of forces having to balance each other to keep a body static. And his contribution to the study of floating bodies and hydrostatics is useful even today.

Chemistry: The level of chemical knowledge and practices in the new ordered society is reflected in the pottery. Iron tools and glass objects were found at various Iron Age sites. Ceramic bowls, dishes, lids, etc. also found in these sites. Fermentation methods, dyeing technique, the preparation and use of a number of chemicals and colour pigments were well known.

Crafts: Rapid strides were made during this era in metallurgical and weaving crafts. Rust-proof iron and copper alloys were found and worked into intricate articles for civilian as well as military purposes.

In weaving, techniques were perfected for the making of cotton and silk materials. Manufacture of dyes and their widespread use in coloring textiles came into practice.

Trade: The importance of direct producers became greater as internal and external trade reached unprecedented volume and proportions. The existence of a huge market, spread over a vast empire, gave rise to extensive circulation of money through a flourishing trade.

Algebra: As a distinct branch of mathematics, algebra appeared from about the time of Brahmagupta. Indian algebraists, possibly for the first time in history, used abbreviations of names of colours or gems, as symbols of unknown quantities and operations, like power, roots, etc. They distinguished negative quantities by a dot.

Q.2 a) "The Arabic civilization served to provide a crucial link between ancient and modern scientific knowledge". Justify this statement with suitable examples from the history of science. Limit your answer to 250 words.

Answer. The contributions of Arabs in some areas of science such as astronomy, mathematics, medicine and chemistry are described below:

Astronomy and Mathematics: Arabs carried on the Greek tradition in astronomy. They translated Ptolemy's Almagest and continued astronomical observations in spite of occasional religious interference. The practice of astronomy provided the necessary incentive to develop mathematics. In this, the Arabs adopted the Indian system of numbers and introduced them on a large scale, to the extent that warehouse clerks and traders started using these numerals to conduct their business. Arabs translated Indian works on algebra and trigonometry and applied them solve many physical and practical problems.

Geography: The Arabs were great travelers. They wrote well-ordered and rational accounts of their journeys and made maps and charts. They laid the foundation of modern geography of Asia and northern Africa.

Scientific Chemistry: The Arab doctors, perfumers and metallurgists made their greatest contribution in chemistry. The Arab chemists greatly improved the earlier distillation apparatus and used it for large-scale production of perfume. While they perfected new techniques, they were not satisfied till they were able to get at the bottom of the reactions that made these techniques possible. Arab chemists stipulated the positive and negative nature of two reacting constituents. This was the first time that chemical transformation was approached rationally, to lay the basis for modem chemistry.

Medicine: The Arabs continued the Greek tradition in medicine also, but added to it the knowledge of new diseases and drugs, which was made possible by the wide geographical spread of Islam. They concerned themselves with questions of the effect of climate, hygiene and diet on health. Arab scholars rescued Greek science from the decadent state it had fallen into under the later Roman Empire. They also extended the techniques of algebra and trigonometry and laid the foundations of optics and scientific chemistry.

Q.2 b) What do you understand by 'scientific temper'? In your opinion, is our society 'scientifically tempered'? Justify your answer in about 250 words, giving appropriate facts, figures and examples.

Answer. Yes according to me, our society is scientifically tempered. Jawaharlal Nehru, one of the great promoters of science, preferred the word Scientific Temper as it could be applied to many areas of social and personal life. If the great scientific enterprise has succeeded because certain broad methods of enquiry have been used, or problems have been tackled by certain attitudes of mind, it is worthwhile to examine these so as to benefit from them in all other spheres of life.

Objectivity is one such characteristics of the scientific temper that implies approaching a problem with an open mind, without trying to fit our personal whims, fancies or prejudices into the result. It also implies, on the other hand, that social pressure or the existence of some great authority already having an opinion on the question, should not affect out scientific approach to a problem. For example, let's suppose that 1000 acres of land is to be cleared for making a plant for producing cars. The scientists should neither be carried away by emotion, nor unconsciously justify the clearing of land, or yield to any pressure be politicians, local inhabitants, or money. Great integrity is part of objectivity in making a scientific study. Of course, it does not mean that human problems or even suffering likely to be created by the change of land use would not be carefully assessed in the study and given due weight in arriving at the conclusions. In the course of scientific work, one has to be flexible and ready to change from one kind of approach to another if the first approach does not succeed.

In the scientific temper, reason and logic have a major part to play because they are the basic tools of all analysis. But imagination and even speculation are simultaneously used to tackle every problem.

Q.3 a) Name two Indian scientists from the pre-independence British era. Describe the scientific contributions of any of them.

Answer. The two Indian Scientists from the pre-independence British era are Jagdish Chandra Bose and Chandrasekhara Venkata Raman.

He was born in November 30, 1858 at Mymansingh in Bangladesh. He had a fascination for innovative experiments in Physics even during his school days. He completed his B.Sc. from St. Xavier's college and D.Sc. from London University. Bose announced his discovery at the International Conference of Physicists in Paris in 1900 and later in England. Bose proved that plants respond to pain and suffering ver much like humans even when the plants are cut or transplanted. To prove his theory, Bose invented an instrument called the "Resonate Recorder". This instrument was very senstive and could record the subset of changes inside a plant. On the basis of his proposed theory and experiments he concluded that in plants as in animals the underlying protoplasmic matter has the same fundamental properties of irritability, contractility, conductivity and rhythmicity. These characteristics were explained in greater detail in his famous publication entitled "Plant Physiological Investigation". He made outstanding research on electrophysiology of excitation in plant and animal tissues. He contributed about 150 articles and 11 monographs. He established Bose Institute ate Calcutta, of which he was the Life Director till his death in 1937. Bose has made significant contributions in advancement of scientific knowledge and his findings on plants earned him wide respect and admiration from scientists all over the world.

Q.3 b) How has human understanding of the universe evolved from the day of river valley civilizations to modern times? State the significant evidences that led to the changes in this understanding. Limit your answer to 250 words.

Answer. The primitive human beings depended on food gathering and hunting for their survival. The availability of food depended on the seasons and the seasons depended on the movement of the sun and stars. Thus, the sun and the stars controlled the seasons, food and warmth. Similarly, the moon's motion controlled the tides and the life cycles of many animals. Hence, it was natural that the primitive people noted the rising and setting of the sun, the reappearance of the crescent moon after the new moon and the waxing and waning of the moon. The more accurately they knew the position and movements of the sun, moon and stars the more reliably they could predict when to hunt, when to gather the tribe and when to move to warmer places. In other words, their survival depended, to a great extent, on their ability to read the 'calendars' in the sky. The earliest such records are in the form of bone engravings depicting the phases of the moon. These are estimated to be about 30,000 years old.

However, the primitive people's universe was restricted to only the small patch of land bounded, perhaps, by rivers, distant hills or by the blue line of the sea. Overhead was the sky across which rode the sun, a god giving light and warmth, and the moon, a lesser god shining with paler light. With the moon at night rode innumerable brilliant stars.

With the passage of time, human thought began when philosophers in many societies all over the world tried to understand the universe without invoking the intervention of gods. They observed the world around them and looked for rational answers to questions like why the sun rises at different places? Why did the moon change its shape? Why did a few stars, later called planets, move among the others? However, with their limited tools of observation and experimentation, their theories about the universe did not, for a long time, progress beyond on earth-centered system. The earliest ideas of the Egyptian and Sumerians about the universe may seem strange to us. The earth appeared flat and solid to them.

Q. 3 c) Compare the Big Bang Theory and the Steady state Theory of the origin and evolution of the universe. Give reasons why the Big Bang theory is more acceptable currently. Answer in about 250 words.

Answer. Big Bang Theory: Big Bang Theory, currently accepted explanation of the beginning of the universe. The big bang theory proposes that the universe was once extremely compact, dense, and hot. Some original event, a cosmic explosion called the big bang, occurred about 10 billion to 20 billion years ago, and the universe has since been expanding and cooling.

The theory is based on the mathematical equations, known as the field equations, of the general theory of relativity set forth in 1915 by Albert Einstein. In 1922 Russian physicist Alexander Friedmann provided a set of solutions to the field equations. These solutions have served as the framework for much of the current theoretical work on the big bang theory. American astronomer Edwin Hubble provided some of the greatest supporting evidence for the theory with his 1929 discovery that the light of distant galaxies was universally shifted toward the red end of the spectrum (see Redshift). This proved that the galaxies were moving away from each other. He found that galaxies farther away were moving away faster, showing that the universe is expanding uniformly. However, the universe’s initial state was still unknown.

One widely accepted version of big bang theory includes the idea of inflation. In this model, the universe expanded much more rapidly at first, to about 10⁵⁰ times its original size in the first 10^-32 second, then slowed its expansion.

Steady-State Theory, theory of cosmology, or the study of the universe and its origins, that was once a rival to the big bang theory, which proposes that the universe was created in a giant explosion. The steady-state theory holds that the universe looks, on the whole, the same at all times and places. The Austrian-British astronomer Hermann Bondi and the Austrian-American astronomer Thomas Gold formulated the theory in 1948. The British astronomer Fred Hoyle soon published a different version of the theory based on his mathematical understanding of the problem. Most astronomers believe that astronomical observations contradict the predictions of the steady-state theory and uphold the big bang theory.

The expanding universe suggests that the matter was packed much more densely in the early stages of the universe. The proof for this also comes from the distant objects quasars. When we look at quasars situated 6 to 8 billion light years away, we are looking at them as they existed then. We do see such high density among them.

Astronomers believed that if there was a cosmic explosion long ago, radiation from that event should still exist within the universe. This radiation may be weak, it may have lost its energy due to the expansion and cooling of the universe, but it should exist. Calculations done by astrophysicists show that this radiation, called the cosmic microwave background radiation, is a relic of the ancient past when the universe was in its first throes of creation in the Big Bang.

This means that the elements, hydrogen and helium, first created in the aftermath of creation are found to be most abundant in the universe. By examining the light coming from the various parts of the universe, astronomers have found out that, out of every 100 atoms, almost 93 are hydrogen atoms and seven are helium atoms. Elements heavier than helium are present in traces only. This suggests that the universe started out with a Big Bang from very hot and dense state and quickly cooled as it expanded.

Q.4 a) Describe various theories related to origin of life and explain Pasteur's contribution in this context.

Answer. Various theories of "origin of life" are:

1) Theory of special creation: Theory of 'special creation' is unsound, because fossils of plants and animals, which must have lived a hundred thousand or more years ago, have been discovered. In fact, researches show that life existed on the earth even 3.5 billion years ago. It seems that simple forms of life came into being from non-living matter, and that these forms grew more complex over period of time.

2) Theory of spontaneous generation Spontaneous Generation, or abiogenesis, ancient theory holding that certain lower forms of life, especially the insects, reproduce by physicochemical agencies from inorganic substances.

3) Theory of chemical evolution: Soviet biochemist Oparin and the British biologists, Haldane, tried to do answer the question of how life came into being in the first place. In other words, to understand the problem of origin of life one must have knowledge of the origin of 'organic molecules' on the earth. In the early stages of its form what are rocks, today, the earth acted as the huge factory, producing many kinds of compounds.

4) Miller's Experiment Miler, an American biologists subjected a gaseous mixture of methane, ammonia, water vapour and hydrogen in a closed flask at 80°C to electric sparking, for a week. This mixture, with its temperature, and electric discharge through it, represented a situation that might have prevailed on the earth before life came into existence. When the contents of the flask were examined a week later, they were found to have amino acids which are essential for the formation of proteins.

Pasteur, Louis (1822-1895), world-renowned French chemist and biologist founded the science of microbiology, proved the germ theory of disease, invented the process of pasteurization, and developed vaccines for several diseases, including rabies.

Q. 4 b) Explain Darwin's theory of natural selection. Why was it unacceptable to most people of that time?

Answer. Darwin applied Malthus’s argument to animals and plants, and by 1838 he had arrived at a sketch of a theory of evolution through natural selection. For the next two decades he worked on his theory and other natural history projects.

Darwin’s Theory of Evolution: Darwin’s theory of evolution by natural selection is essentially that, because of the food-supply problem described by Malthus, the young born to any species intensely compete for survival. Those young that survive to produce the next generation tend to embody favorable natural variations (however slight the advantage may be)—the process of natural selection—and these variations are passed on by heredity. Therefore, each generation will improve adaptively over the preceding generations, and this gradual and continuous process is the source of the evolution of species. Natural selection is only part of Darwin’s vast conceptual scheme; he also introduced the concept that all related organisms are descended from common ancestors. Moreover, he provided additional support for the older concept that the earth itself is not static but evolving.

REACTIONS TO THE THEORY
The reaction to the Origin was immediate. Some biologists argued that Darwin could not prove his hypothesis. Others criticized Darwin’s concept of variation, arguing that he could explain neither the origin of variations nor how they were passed to succeeding generations. This particular scientific objection was not answered until the birth of modern genetics in the early 20th century. In fact, many scientists continued to express doubts for the following 50 to 80 years. The most publicized attacks on Darwin’s ideas, however, came not from scientists but from religious opponents. The thought that living things had evolved by natural processes denied the special creation of humankind and seemed to place humanity on a plane with the animals; both of these ideas were serious contradictions to orthodox theological opinion.

Q.5 a) Why the steps in most food chains are limited to four or five? Explain with the help of an example.

Answer. One of the ways in which the organisms are related is through food, that is, one organism becomes food for the other. A sequence of organisms that feed on one another constitutes a food chain.

The number of links or steps in a food chain is usually limited to four or five. Each of the link is also referred to as a trophic level. The trophic level to which an organism belongs, indicates how far it is away from plants in the food chain. Green plants make up the first trophic level. The second level contains the plants eating animals, the herbivores, and higher levels are made of carnivores.

Energy is first captured by the producers. From the producers the energy passes to various consumers, via food. At the end of the chain we find that very less energy is left for the last trophic level, because some energy is lost in going from one level to another. This loss of energy limits the number of trophic levels in the ecosystem, and so they are seldom more than five.

Grass à Worm à sparrow à rat à owl

Q.5 b) What are the reasons for declining forest area in our country? Discuss the foreseeable repercussions of a decreased forest cover.

Answer. Reasons for destruction of forests

Removal of forests causes soil erosion, silting of lakes and rivers, resulting in devastating floods and loss of thousands of species of plants and animal forever.

When the trees are cut down to clear them for cultivation and the soil is ploughed, there is less protection from the wind and rain. Heavy rainfall washes the soil off the hillsides into the rivers. The hillsides, thus are left bare and useless and on the other hand, the rivers become choked up with mud and silt resulting in floods.

Q. 5 c) Explain how pesticides in long run cause more harm than benefit to the ecosystem.

Answer. Pesticides provides more harm then benefit to ecosystem. Once they enter the food chain, they become more concentrated at each level.

How DDT, a pesticide, becomes more concentrated as it passes along from producer to consumers. DDT was once a widely used pesticide. It is a substance that does not easily break down. It can persist in the environment for as long as fifteen years. It enters birds through the organisms they feed on which in turn get it from the organisms lower in the food chain. When a high concentration builds up in birds, their reproductive systems are affected. As a result they lay fragile eggs that easily break in the nests.

These pesticides not only kill the targeted pests, but also kill many harmless and even beneficial insects. They cause more harm then benefit. Therefore, DDT and many such agrochemicals have been banned in many parts of the world.

Q.6 a) What is remote sensing and how does it help in exploration of various natural resources?

Answer. Remote Sensing is a process of obtaining information about land, water, or an object, without any physical contact between the sensor and the subject of analysis. The term remote sensing most often refers to the collection of data by instruments carried aboard aircraft or satellites. Remote sensing systems are commonly used to survey, map, and monitor the resources and environment of Earth. They also have been used to explore other planets.

Remote sensing of water resources: Radio waves of the shortest known wavelengths are called 'gamma rays'. These are given off by atoms of several elements. As a result, the ground soil sends out gamma rays which can be picked up by detectors in the aeroplanes or satellites. This emission is affected by the presence of moisture or water in the soil and hence, it can be easily detected whether or not the soil holds water.

Survey of the vegetation cover: Forests of deciduous trees which shed leaves in a certain season can be easily identified with the help of pictures taken from the spacecraft specially during autumn when the deciduous trees shed leaves and there is no snowfall as yet to conceal the vegetation. Vegetation cover can be surveyed by measuring and analyzing infra-red-reflection, or with the help of photographs. Plants absorb solar energy to make carbohydrates. So by measuring ground temperature from a distance, the presence or absence of vegetation can be detected

Satellite pictures show very clearly if there is a break in the continuity of layers or rock, or other unusual features on the surface of the earth. The distinctive linear features are found to be very common centers where mineral deposits and ground water are accumulated. Radio waves and magnetic measurements also provide information about minerals and oil under the surface.

Q.6 b) Why is management of soil necessary? Describe the ways of its management.

Answer. Soil forms the uppermost layer of land. It is the most precious of all resources, because it supports the whole life system, provides food and fodder in the form of vegetation and stores water essential for life. It contains sand, silt and clays, mixed with air and moisture. Soil management involves six essential practices: proper tillage; maintenance of a proper supply of organic matter in the soil; maintenance of a proper nutrient supply; control of soil pollution; maintenance of the correct soil acidity; and control of erosion

• Tillage: The purpose of tillage is to prepare the soil for growing crops.
• Maintenance of organic matter: Organic matter is important in maintaining good physical conditions in the soil. It contains the entire soil reserve of nitrogen and significant amounts of other nutrients, such as phosphorus and sulfur. Soil productivity thus is affected markedly by the organic-matter balance maintained in the soil.
• Nutrient supply: The nutrients most necessary for proper plant growth are nitrogen, potassium, phosphorus, iron, calcium, sulfur, and magnesium, all of which usually exist in most soils in varying quantities.
• Soil pollution: Soil pollution is the buildup in soils of persistent toxic compounds, chemicals, salts, radioactive materials, or disease-causing agents, which have adverse effects on plant growth and animal health.
• Soil acidity adjustment: Maintenance of specific soil acidities is important in soil management because it controls the adaptation of various crops and native vegetation to different soils. For example, cranberries can be successfully grown only in moderately to strongly acid soils, whereas alfalfa and other legumes are successful only in weakly acid or slightly alkaline soils.
• Mechanical control of erosion: The mechanical loss of fertile topsoil is one of the gravest problems of agriculture. Such loss is almost always caused by erosion resulting from the action of water or wind.