History of Computer
The history of computer starts with the birth of abacus. Basically it is a wooden rack holding horizontal wires with beads strung on them. It was implemented around 2000 years ago. Charles Babbage is called the father of computer. In 1822 Babbage began to design an automatic mechanical machine called difference engine. Basically it is a type of counting machine. He also invented another machine called Analytical Engine. The Analytical Engine could store information on punched cards.
Generation of computer
Commonly we can divide the journey of computers in five generations. Each of the generations is explained in the following points.
First Generation (1940-1956)
First generation computers, such as UNIVAC (Universal Automatic Computer) and ENIAC (Electronic Numerical Integrator Analyzer and Computer) were very large and took huge space because they used vacuum tubes for circuits and magnetic drums for memory storage. They consumed large amount of electricity and generated a lot of heat. They used machine language. (See Figure. 6.1.1)
Second Generation (1956-1963)
Second generation computers basically used two types of devices. These two types of devices were transistors and magnetic core. They were used for memory storage. First generation computers were outwitted by Second generation computers due to transistors which made the computers smaller in size, faster, cheaper, energy efficient and more reliable. In second generation computers, transistors took over the vacuum tubes but still generated huge amount of heat that caused damage to the computers. Generally the language used by second generation computers was assembly language. The assembly language is also called 2GL. This language is not directly processed by microprocessor. A translator converts assembly language into machine language is called assembler. Assembly language is very fast. Second generation computers are smaller and faster in comparison of first generation computers.
Third Generation (1964-1971)
The third generation computers were the enhanced version of second generation computers, here the computers used integrated circuit and these were smaller as well as cheaper from the previous generation computers. The computers of third generation used parallel processing to improve the processing efficiency.
Fourth Generation (1971-Present)
Fourth generation computers were introduced after third generation computers which generally used microprocessor. Microprocessor generally consists of thousands of integrated circuit which is built on a single chip known as silicon chip. (See Figure 6.1.2)
Fifth Generation (Present)
After the invention of fourth generation computers, the fifth generation computers were introduced. The fifth generation computers or modern day computers are based on an artificial intelligence more... 
Introduction
A computer an electronic machine which performs task according to the given instruction and commands. Central processing unit of the computer performs operations and its supporting computers provide input and receive output after processing. A RAM is the memory unit which stores information tempering feather by the CPU. This computer includes the basics of the computer. 
Food Chain
Food chain is a sequence of organisms in an ecosystem, in which, each species is the food of the next member of the chain.
Look at the following figure of the food chain
Here it has been shown how nutrients, after synthesizing in plants body, are transferred from one organism to another.
Food chain are composed of many components like producer and consumer.
Let us study them in detail.
Producer
Producers are those, which can synthesize food using carbon dioxide and water.
All the green plants are producers.
Consumer
Animals and insects are consumer because they all, directly or indirectly, depend on plants for their food , On the basis of food that the animals take in, they have been classified into three groups, that is, herbivorous, carnivorous and omnivorous.
Herbivorous
Animals of this group feed on only green plants. In other word plant eating animals are called herbivorous. For example, buffalo, cow, camel etc.
Carnivorous
Animals of this group feed on only flesh of other animals. In other words, flesh eating animals are called carnivorous. For example lion, tiger, fox, etc.
Omnivorous
Animals of this group feed on both plants and flesh. For example, human, bear etc.
Balanced Food
Balanced food is essential for us. All living organism obtain their energy from the food they take. Therefore, our food should contain all necessary nutrients, that is, carbohydrates, vitamins, fats, proteins, roughage, water and minerals. Carbohydrates and fats are energy giving food, proteins are body building food and vitamins and minerals are protective food. Requirement of energy in kilocalories depends on age and working habit.
Read the Following about the Energy Requirements
| Age | Daily energy requirement in kilo joule |
| Up to 8 years | 2000 KJ to 9000 KJ |
| 8 to 15 years | 9600 KJ to 12600 KJ |
| Adult | 9600 KJ to 20000 KJ |
| Pregnant and nursing mothers | 10000 KJ to 11300 KJ |
Carbohydrates
This is the organic compound of carbon, hydrogen and oxygen. The source of energy in our body are carbohydrates and fats. One gram of carbohydrate produces one kilocalories of heat energy. The rich sources of carbohydrates are rice, potato, bread, wheat etc.
Look at the following table:
| Sources of carbohydrates | |||||
| Wheat flour | |||||
| Rice | |||||
| Date | Temperature | Max. humidity | Min. humidity (%) | Rainfall (mm) | |
Max. temp  |
Min. temp |
||||
| 10.4.11 | 32.5 | 22.2 | 78 | 42 | more...
 Introduction
Various types of living and non-living things exist in our environment. The living and non-living things are differentiated according to their characteristic features. However, some features of both living and non-living things are same. For example, every living and non-living things have mass; they both are made up of unit particles etc. But some characteristic features of living and non-living things are different. For example, living things grow. They possess self-intelligence and reproduce their offspring. They adopt themselves according to their surroundings to survive. These features are absent in non-living things. Living organism is also called biotic component and non-living is called abiotic component and both of them are the components of environment. In this chapter, we will study about the different components of our environment.
Abiotic Component
The non-living components of environment are called abiotic component. These are water, soil, light, air etc. Biotic components are greatly affected by abiotic components.
 Water
This is an important component for all living organism on earth to survive. Life is not possible without water. All living organism require water for different purposes.
Availability of water on the earth's surface varies from place to place. Some part of the earth has huge amount of water, whereas some areas are desert. An important property of water is, it dissolves gases. This property of water helps aquatic animal to live under water. Water takes more time to heat as compare to air and its cooling time is also longer as compare to air. Water is natural resource and its primary source is rain. The most part of the earth (71 %) is covered with water. The forms of water changes on increased and decreased temperature. Water evaporates on heat and changes into water vapor which form cloud for precipitation. Water on the earth follows a cycle is known as the water cycle.
Light
Light is another important natural resource for the living organisms. Without light, plant cannot make their food. We see the things around us in the presence of light. Living organisms require light for two main purpose. For example, for photosynthesis in plants and vision for animals. The organ, which is responsible for the detection of light is called photoreceptor. Photosensitive pigments sense the incoming beam of light. The photoreceptor in a green plant is called chloroplast. Algae has plastids to sense the light. Rods and cones in the vertebrates work as the photoreceptor. Invertebrates have eyes to sense the light. A beam of light has different colours. Some colours are visible and some are not.
Air
Air is a mixture of different gases. These gases are Nitrogen, Oxygen, Carbon dioxide, Argon etc. Percent of these gases in air are as follows: more...  Biotic components
Living organisms in our environment is called its biotic component. Biotic components are dependent on each other for their nutritional needs. The biotic components that produce foods for others are called producer and those are obtaining food from producer directly or indirectly are called consumer. Some organism in our environment obtain food from producer directly, therefore, they are called primary consumer. Some are obtaining food from primary consumer, and hence they are called secondary consumer. Microorganism in our biotic environment is called decomposers.
 Producer
Green plants are the only biotic component in our environment which produce food for other living organism (non green). Hence, they are called producers. Green plants absorb water and mineral from soil and carbon dioxide from atmosphere and make their food in the presence of sun light. The process in which plant make their own food is called photosynthesis and the mode of nutrition for obtaining the food is called autotrophic mode of nutrition. Plants make glucose and oxygen during the photosynthesis.
Some part of the photosynthesis product i.e. glucose is absorbed by the plant itself for their nutritional need and growth. Some part are stored in the fruits of the plant, which are consumed by the consumer. Consumer and plant breathe in oxygen.
Consumer
Living organisms which feed directly or indirectly on the plants are called consumer. A deer feed on plant hence called primary consumer and a lion which feed on deer or deer like animal is called secondary consumer. Living organisms (non-green) which cannot make food for themselves depend on plants for their nutrition. This mode of nutrition in non-green living organism is called heterotrophic mode of nutrition. There are three types of consumers on the basis of their food habit.
Look at the following picture to understand the types of consumer on the basis of their food habits:
Decomposers
Some microorganism and non-green plants like mushroom feed dead and decaying elements. They break down dead and decaying elements into small substances. Some part of these broken substance dissolve in soil and some part is released in the atmosphere. Microorganism which break down these dead and decaying elements into small substances is called decomposers. Decomposers play an important role in our environment and improve the fertility of soil.
Ecosystem
An ecosystem is constituted of living organism, non-living organism and decomposers. Necessary life supporting elements are used by the living organism. The ecosystem may be in lake, sea and on the earth. The space which is occupied by the living organism is called its habitat. All biotic and abiotic components live together without affecting the existence of more... Current Affairs CategoriesArchive
Trending Current Affairs
You need to login to perform this action. |
Garbage
Garbage may refer to the waste, an unwanted or undesired material or substance.
Types of Waste
There are two types of garbage biodegradable and non-biodegradable. Biodegradable: The waste that can be decomposed by the microorganisms is called biodegradable waste. Biodegradable waste typically originating from plant or animal sources. For example fruit and vegetable peels, leaves, papers, cow dung, wood etc.
Non-biodegradable: The waste that cannot be decomposed by the microorganisms is called non-biodegradable waste. For example plastics, glass, metals etc.
Vermicomposting: In this method biodegradable waste is converted into manure by redworms. The compost made by redworms is of high quality and known as vermicompost.
Recycling: In this method papers, some plastics, glasses and metal objects are separated from garbage and sent them to the respective industries for processing. Thus fresh papers, plastics, glasses and metals are obtained for reuse.
Reuse: This is the way of reusing papers, plastics, glasses and metal objects in the possible ways. For example a damaged plastic bucket can be used as a pot for growing a flower plant. So if we use these non-biodegradable waste for other useful purposes, we can reduce a great amount of garbage produced by us and this will help us in keeping the environment clean. Landfills: Landfill is a low-lying open area of ground where city's garbage is normally dumped.
A landfill also may refer to ground that has been filled in with soil and rocks instead of waste materials, so that it can be used for a specific purpose, such as for building houses. Unless they are stabilized, these areas may experience severe shaking or liquefaction of the ground at a large.
Which one of the following is a biodegradable substance?
(a) Clothes
(b) Copper
(c) Tin
(d) Polythene
(e) None of these
Answer: (a)
The microorganisms present in the soil decomposes biodegradable waste
Introduction
Air, water and weather are the important components for the survival of all kinds of living organisms on the Earth. Now a days, air is getting polluted by the activities of living organism and also by the natural phenomena like, eruption of volcanic ash, fire in the forest, etc.
Water is another important component for the living organism to survive. Living organisms are present both on land and water. Earth has only a small portion of potable water which is found below the ground, in glaciers and in rivers. The water in the sea is not potable due to the presence of huge amount of salt in sea water. Weather of a place depends to a large extant on the condition of air and water of that place. In this chapter, we will study about air, water and weather.
Air as the Mixture of Gases
In the picture below, one third of the tub is filled with water (mixed with acoustic soda and ink) and a burning candle is placed in it. The tub is covered with a jar which does not allow the air to pass in the tub.
After some time, the candle will stop burning and coloured water will rise to fill the vacuum formed by burning of air components (oxygen). This happens because; acoustic soda absorbs the carbon dioxide formed by the burning of air components. A vacuum is created on empty portion of water containing jar due to the absorption of carbon dioxide by the acoustic soda and therefore, water rises to fill the vacuum. From this experiment we can arrive at the following conclusion:
(i) Air has oxygen which helps the burning of candle.
(ii) Air has carbon dioxide which does not help the burning of candle.
So we can say air is the mixture of different gases.
Water
Water is formed by the chemical composition of hydrogen and oxygen. One molecule of water \[({{H}_{2}}O)\] has two atoms of hydrogen and one atom of oxygen. Both elements, hydrogen and oxygen are combined with covalent bond. The balanced chemical equation for the formation of water molecules is as follows:
\[2{{H}_{2}}\] \[{{O}_{2}}\] \[2{{H}_{2}}O\]
(two molecules of hydrogen) (one molecule of oxygen) (two molecules of water)
The earth is covered with 71 % of water and oceans contain the most part of water (97 %) present on the earth. The glaciers and polar ice caps cover 2.4 % of water and rest of the water is found in rivers, ponds and below the ground of the earth.
Water is odorless, colourless and transparent liquid. It can dissolve most of the available substances, therefore, it is called universal solvent. Changing of water into water vapour and then again into water on the earth goes through a cycle which is called water cycle.
Look at the following picture of water cycle:
Water cycle is also called the hydrologic cycle. It is defined as the continuous formation of water by changing the forms of water. Forms of water changes in a water cycle. The water which is stored in the ocean, rivers, glaciers and any other medium evaporates by the solar energy and convert into clouds or water droplets for precipitation. Therefore, the balance of water on the earth remains unchanged due to each molecule of water comes on the earth and go in the atmosphere and again comes back. In this process, water goes through all three states of matter, like, solid in the form of ice, liquid in the form of water and gas in the form of water vapor.
Different Processes in the Water Cycle
Let's study about the processes, which keeps water cycle goes on continue.
Evaporation
The forms of water on the earth are in liquid and solid. Both the forms of water do not have the ability to move upwards on their own. Water converts into gas by the energy radiated from the sun. The solid form of water like, ice and snow directly converts into water vapor, called sublimation. The process by which water converts into
Weather
Weather is the condition of the atmosphere at a place. It is associated with the temperature, humidity, speed of wind and rainfall etc. of a place. The maximum and minimum temperature at a place are also the important factor on which the weather of a place depends. Humidity is the amount of water vapor present in the air. Weather at a place changes on day to day basis. All weather phenomena, as such as, tornadoes, hurricanes, ice storms, etc. occur in the layer of troposphere. Weather of the earth at a particular area also depends on the weather phenomena which occurs in stratosphere. Different seasons on the earth happen due to the revolution and tilted axis of the earth. Uneven heating of the earth causes the cloudiness and precipitation. The parameters which are recorded on day to day basis at a place for weather records are, temperature (minimum and maximum), rain fall, humidity (minimum and maximum).
Look at the following table to understand the recorded parametres of weather at a place:
