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Old Tuesday, November 15, 2011
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DIFFERENCES FROM PAST PAPERS (2003)


1. Lava & Magma

• Magma is the molten rock material deep inside earth’s crust, while the same magma, when it finds its way to a volcano through fissures and cracks, and comes out of the mouth of the volcano, is referred to as lava.

• So magma is deep underground, while lava is the hot mixture of gases and molten rocks that comes out of the volcano.

• The most notable difference between magma and lava pertains to their location.


2. Fold & Fault

Fold:
A fold is a bend in a rock layer caused by forces within the crust of the earth. Folds usually occur in a series and look like waves in the rock.

Fault:
Rock layers can also break, in which case a fault occurs. A fault zone is where the sides of broken rock have moved relative to each other.

3. Caustic Soda and Caustic Potash

Sodium hydroxide (NaOH) and potassium hydroxide (KOH) are both strongly alkaline, corrosive solids. As chemical re-agents, they are mostly interchangeable, although some differences exist in specific applications.

1. Chemistry in Air

o Sodium hydroxide, also known as lye or caustic soda, and potassium hydroxide, also known as caustic potash, are both white solids. They are hygroscopic, meaning they will absorb water from the air.
Sodium hydroxide will form sodium carbonate (Na₂CO₃, washing soda) by absorption of carbon dioxide (CO₂):
2 NaOH + CO₂ ' Na₂CO₃ + H₂O
Potassium hydroxide, however, will form potassium bicarbonate (KHCO₃):
KOH + CO₂ ' KHCO₃

2. Solubility
o Sodium and potassium hydroxide are strong bases. At room temperature, they exhibit almost identical solubilities in water - 111 grams of sodium hydroxide will dissolve in 100 millilitres of water vs. 110 grams of potassium hydroxide.

Applications
o Both hydroxides can be used in the saponification of fats to form soap. Soaps prepared from potassium hydroxide tend to exhibit greater solubility and are commonly referred to as "soft" soaps.

Manufacture
o Sodium and potassium hydroxides are prepared commercially by electrolysis of sodium chloride (NaCl, table salt) or potassium chloride (KCl):
2 NaCl + H₂O ' H₂ + Cl₂ + NaOH
2 KCl + H₂O ' H₂ + Cl₂ + KOH

Differences

o In many applications, potassium and sodium hydroxide can be freely interchanged. The primary difference between them is cost. In ton quantities, potassium hydroxide is about three times more expensive than sodium hydroxide.

4. SEM & TEM

SEM:
SEM involves shooting an electron beam at a specimen and observing the reactions on the specimen surface. When the electron hits a molecule on the surface, its energy is absorbed by the molecule, which in turn emits a lower amount of energy. This energy can be in the form of a secondary, less energetic electron, a photon of light, or x-rays. Differentiation between these emissions is used to produce image contrast. However, in order to produce a coherent image, the sample must often be prepared with a conductive coating or by embedding a resin for many biological samples.

TEM:
TEM acts much like a typical bright field microscope in the sense that it sends electrons through a specimen. As it propagates through the specimen, some of the electrons are scattered and some are transmitted. The transmitted electrons is passed through an objective lens and then projected onto a scintillating material which can then be recorded photographically. This requires samples to be prepared in very thin slices in order to allow transmission of the electrons through transparent sections.

OR


A SEM (scanning electron microscope) images using the electrons reflected from a specimen. A TEM (transmission electron microscope) images using the electrons that pass through it.

The image from an SEM thus looks somewhat like a normal photo (we're used to imaging using the light reflected from objects). However, a TEM image takes a bit more interpretation as we're not used to seeing images of light that's passed through things - think of silhouettes or slide projectors.
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  #42  
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DIFFERENCES FROM PAST PAPERS (2004)


1. Periscope & Pyrometer:

Periscope:
Instrument used by submarines to see above the surface of the sea.

Pyrometer:
Instrument used for measuring high temperatures.

2. Cell & Battery

Cell:
A cell is a DC voltage source in which chemical energy is converted into electricity.

Battery:
It is a device which produces electricity through the use of acid and other chemicals. It is assembly of many cells.

3. Perimeter & Altimeter

Perimeter:
A perimeter is a path that surrounds an area. The word comes from the Greek peri (around) and meter (measure). The term may be used either for the path or its length - it can be thought of as the length of the outline of a shape. The perimeter of a circular area is called circumference.

Altimeter:
An altimeter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth underwater.

4. Pelage & Plumage

Pelage:
It is a growth of hair/fur/wool covering the skin of animals.

Plumage:
Plumages are feathers covering the body of birds.

5. Smog & Smoke

Smog
Smog is formed by the interaction of pollutants present in the air in presence of sun light (photochemical smog), it usually restricts visibility and is hazardous to health.

Smoke:
Smoke is the thin fine particles usually result from the combustion.
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DIFFERENCES FROM PAST PAPERS (2005)


1. Radiotherapy & Chemotherapy

1.Β Radiation targets only the cancer cells. However, chemotherapy is administered through the blood and therefore, affects both cancerous and non-cancerous cells

2. Though they can be used for any sort of cancer, radiation mainly targets solid tumours like those of the cervix, spine and skin.

3. Chemotherapy treats cancers through medicines, while radiation deals with cancer cells through rays

4. Radiation results in additional side effects like internal inflammation, especially in the stomach and the intestine.

2. Springtides & Neap tides

Springtide:
i) Spring Tides When the moon is full or new, the gravitational pull of the moon and sun are combined.

ii) At these times, the high tides are very high and the low tides are very low. This is known as a spring high tide.

iii) Spring tides are especially strong tides (they do not have anything to do with the season spring).

iv) They occur when the Earth, the Sun, and the Moon are in a line. The gravitational forces of the Moon and the Sun both contribute to the tides.

v) Spring tides occur during the full moon and the new moon.

Neap tides:
i) Neap Tides During the moon's quarter phases the sun and moon work at right angles, causing the bulges to cancel each other.

ii) The result is a smaller difference between high and low tides and is known as a neap tide.

iii) Neap tides are especially weak tides.

iv) They occur when the gravitational forces of the Moon and the Sun are perpendicular to one another (with respect to the Earth).

v) Neap tides occur during quarter moon.

3. Penumbra & Umbra (already described in paper 2002)

4. Vertebrates & Invertebrates

• Vertebrates have a backbone with a spinal cord, whereas invertebrates do not.

• The diversity is exceptionally high among the invertebrates compared to vertebrates.

• Vertebrates are always bilaterally symmetrical, while invertebrates could show either bilateral or radial symmetry.

• Vertebrates are usually large-bodied and move fast compared to invertebrates.

• Vertebrates have a closed blood system, a well-developed brain, either gills or lungs for respiration, and a complex and sophisticated nervous system, whereas those are primitive in invertebrates. Therefore, it concerns that vertebrates have many specializations to extract the best out of the environment compared to invertebrates.


5. Fluorescent & Neon Light

A neon light is the sort of light you see used in advertising signs. These signs are made of long, narrow glass tubes, and these tubes are often bent into all sorts of shapes. The tube of a neon light can spell out a word, for example. These tubes emit light in different colours.

A fluorescent light, on the other hand, is most often a long, straight tube that produces white light. You see fluorescent lights in offices, stores and some home fixtures.

The idea behind a neon light is simple. Inside the glass tube there is a gas like neon, argon or krypton at low pressure. At both ends of the tube there are metal electrodes. When you apply a high voltage to the electrodes, the neon gas ionizes, and electrons flow through the gas. These electrons excite the neon atoms and cause them to emit light that we can see. Neon emits red light when energized in this way. Other gases emit other colours.
A fluorescent light works on a similar idea but it has an extra step. Inside a fluorescent light is low-pressure mercury vapour. When ionized, mercury vapour emits ultraviolet light. Human eyes are not sensitive to ultraviolet light (although human skin is -- see How Sunburns and Sun Tans Work!). Therefore, the inside of a fluorescent light is coated with a phosphor. A phosphor is a substance that can accept energy in one form (for example, energy from a high-speed electron as in a TV tube -- see How Television Works) and emit the energy in the form of visible light. In a fluorescent lamp, the phosphor accepts the energy of ultraviolet photons and emits visible photons.

The light we see from a fluorescent tube is the light given off by the phosphor that coats the inside of the tube (the phosphor fluoresces when energized, hence the name). The light of a neon tube is the colored light that the neon atoms give off directly.
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  #44  
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DIFFERENCES FROM PAST PAPERS (2006)


1. Telemeter and Multimeter

Telemeter:
A telemeter is a device used to remotely measure a quantity. Telemeters are generally the physical devices used in telemetry. Electronic devices are widely used in telemetry and can be wireless or hard-wired, analogue or digital. Other technologies are possible, however, such as mechanical, hydraulic and optical.

Multimeter:
A multimeter or a multi-tester, also known as a VOM (Volt-Ohm meter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter may include features such as the ability to measure voltage, current and resistance. Multimeters may use analogue or digital circuits—analogue multimeters (AMM) and digital multimeters (often abbreviated DMM or DVOM.) Analog instruments are usually based on a micro-ammeter whose pointer moves over a scale calibrated for all the different measurements that can be made; digital instruments usually display digits, but may display a bar of a length proportional to the quantity being measured.
A multimeter can be a hand-held device useful for basic fault finding and field service work or a bench instrument which can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems.

2. Perimeter & Altimeter (already described in 2004)

3. Periscope and Microscope

Periscope:
A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirrors at each end set parallel to each other at a 45-degree angle. This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I. Military personnel also use periscopes in some gun turrets and in armoured vehicles.

More complex periscopes, using prisms instead of mirrors, and providing magnification, operate on submarines. The overall design of the classical submarine periscope is very simple: two telescopes pointed into each other. If the two telescopes have different individual magnification, the difference between them causes an overall magnification or reduction.

Microscope:
A microscope (from the Greek: μικρός, mikrσs, "small" and σκοπεῖν, skopeξn, "to look" or "see") is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy. Microscopic means invisible to the eye unless aided by a microscope.

There are many types of microscopes, the most common and first to be invented is the optical microscope which uses light to image the sample. Other major types of microscopes are the electron microscope (both the transmission electron microscope and the scanning electron microscope) and the various types of scanning probe microscope.

4. Nucleon and Photon

Nucleon:
A nucleon is a collective name for two particles: the neutron and the proton. These are the two constituents of the atomic nucleus. Until the 1960s, the nucleons were thought to be elementary particles. Now they are known to be composite particles, each made of three quarks bound together by the so-called strong interaction.

The interaction between two or more nucleons is called inter-nucleon interactions or nuclear force, which is also ultimately caused by the strong interaction. (Before the discovery of quarks, the term "strong interaction" referred to just inter-nucleon interactions.)

Photon:
A photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic. It is also the force carrier for the electromagnetic force. The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has no rest mass; this allows for interactions at long distances. Like all elementary particles, photons are currently best explained by quantum mechanics and will exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a single photon may be refracted by a lens or exhibit wave interference with itself, but also act as a particle giving a definite result when quantitative momentum (quantized angular momentum) is measured.

5. Cusec and Comet

Cusec;
Cusec is a measure of flow rate and is informal shorthand for cubic feet per second (28.317 litres per second).

Comet:
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. Comets have been observed since ancient times and have traditionally been considered bad omens.
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DIFFERENCES FROM PAST PAPERS (2007)


(a) BIT and BYTE ( see 1997)

(b) RAM and ROM (see 1997)

(c) Epidemic and endemic (see 1995)

(d) Photosynthesis and respiration (see 1995)

(e) Herbivores and carnivores (see 1995)
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DIFFERENCES FROM PAST PAPERS (2008)


1. Fission and fusion (see 1996)

2. Star and Planet (see 1996)

3. Pollination and Fertilization (see 1995)


4. Telescope and Microscope

Telescope and Microscope are two scientific instruments that serve their purposes differently. One of the main differences between a telescope and a microscope is that a telescope is used to view things that are far whereas a microscope is used to view things that are very near.

It is indeed true both the instruments are used to watch the minute details of the objects or things more clearly. Another important difference between telescope and microscope is that the focal length or the distance from the focal point to the lens is different in these two scientific instruments.
As a result of this the focal point in the case of a telescope may be at a far off place. On the other hand the focal point in the case of a microscope is just a fraction of an inch off.

The difference in the diameter of the lens used in the two instruments also matter a lot when it comes to the difference between them. The lens diameter or the aperture is much larger in a telescope. This is to ensure that the aperture allows tiny amount of natural light at the focal point.

On the other hand only artificial illumination is used in a microscope. The artificial illumination is made to fall at the focal point in a microscope. It is interesting to note that a telescope and a microscope differ from each other in terms of the curvature of the lens.

A microscope is used to look into smaller details like the structure of the cells and the unicellular organism. On the other hand larger objects that are very far off are the targets of a telescope. In short it can be said that a telescope is used to look into space. Magnification is the keyword in both the scientific instruments.

5. Antibiotics and Vaccines

1) Vaccine kills virus while antibiotics kill bacteria.

2) Vaccine is taken once and has permanent effect whereas antibiotics work during the time of disease.

3) Antibiotics are available in different forms like tablets, capsules, drops or ointments. Vaccines can be given orally or through injection.

4) Vaccines are preventive method that is taken before getting infected. Antibiotics are taken after getting infected.

OR


- Vaccines act against most microorganism, whereas antibiotics act against bacteria.

- Vaccines are provided before the manifestation of the infection, but antibiotics are given mostly after.

- Vaccines usually have a specific single type of microbe, whereas antibiotics would act against a multitude of species.

- Vaccines enhance the natural immunity, and antibiotics cause destruction of the biochemistry of the organism.

- Vaccines are highly effective against organism, but there may be resistance to antibiotics needing the development of newer antibiotics.

- Both have equally lethal complications, but vaccines carry a lesser range of complications related to antibiotics.
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DIFFERENCES FROM PAST PAPERS (2009)


1. Umbra and Penumbra (see 2002)

2. Heavy water and hard water (see 99)

3. Smog and Smoke (see 2004)


4. Myopia & Hyperopia

Myopia:
Myopia (short sightedness) is an eye disease in which the patient cannot see the distant objects clearly. This disease can be corrected by using convex lenses in glasses.

Hyperopia:
Hyperopia (long sightedness) is defect of vision in which a person cannot see the clearly objects lying close to him. The disease can be corrected by using convex lenses in glasses.

5. Lava and Magma (see 2003)

6. Periscope & Perimeter

Periscope:
Instrument used by submarines to see above the surface of the sea.

Perimeter:
A perimeter is a path that surrounds an area. The word comes from the Greek peri (around) and meter (measure). The term may be used either for the path or its length - it can be thought of as the length of the outline of a shape. The perimeter of a circular area is called circumference.

7. X-rays & Gamma Rays

1. Gamma rays cause more harm to human body than the X- rays.

2. Gamma rays have shorter wavelengths than the X-rays.

3. X rays are emitted by the electrons outside the nucleus, and gamma rays are emitted by the excited nucleus itself.

4. X rays are used in hospitals for taking X-rays but gamma rays are not.
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DIFFERENCES FROM PAST PAPERS (2010)


1. Hydrometer & Hygrometer

Hydrometer
Hydrometer is an instrument used to measure the specific gravity of liquids. It should be noted that specific gravity is the ration of the density of the liquids to density of water.

Hygrometer:
A hygrometer is an instrument used to measure relative humidity. A simple form of hygrometer consists of two thermometers, one of which has a dry bulb and the other, a wet bulb.

2. Perimeter & Telemeter

Perimeter:
A perimeter is a path that surrounds an area. The word comes from the Greek peri (around) and meter (measure). The term may be used either for the path or its length - it can be thought of as the length of the outline of a shape. The perimeter of a circular area is called circumference.

Telemeter:
A telemeter is a device used to remotely measure a quantity. Telemeters are generally the physical devices used in telemetry. Electronic devices are widely used in telemetry and can be wireless or hard-wired, analogue or digital. Other technologies are possible, however, such as mechanical, hydraulic and optical.

3. Isotope & Isomer

Isotope:
Isotopes are different types of atoms of same element whose atoms of same element whose atomic number is same but atomic mass is different. Isotopes have similar chemical properties but different physical properties.

Isomers:
Isomers are compounds with the same molecular formula but different structural formula. Isomers do not necessarily share similar properties unless they have same functional groups.

OR


Isotopes and Isomers
An isotope refers strictly to pure elements. Atoms of the same element that have different numbers of neutrons in their nuclei are called isotopes. For instance, hydrogen-1 (1H) and hydrogen-2 (2H or deuterium) are isotopes of each other.

An isomer refers strictly to molecules. Two molecules that have the same composition (i.e., the same molecular formula) but are different in the connectivity, shape or orientation, are called isomers. For instance, n-propanol (1-propanol) and isopropanol (2-propanol or rubbing alcohol) are isomers of each other. Ethanol is not an isomer of propanol, however, because they have different formulas.

4. Flying Mammal & Bird

Flying Mammals:

i. Mammals are the class of animals which give birth to live offspring and feed their young ones on milk from their breast.

ii.Flying mamma is the type of animal which belongs to mammalian group with additional quality of flying.

iii.Bats are representative animals of this group.

iii.Bats have many unusual characteristics.

v.They cannot walk very well because of skin that reaches over its front and back legs.

vi. It flies at night and stays in caves and other dark places during the day.

vii.Hanging upside down by the claws of its back legs, it looks like flying mice.

Birds:
i. Birds are winged, bipedal, endothermic warm-blooded, egg laying vertebrate animals.

ii.There are around 10,000 living species across the world.

iii.All birds have fore-limbs modified as wings and most can fly with few exceptions like ratites, penguins and number of various island species.

OR

Difference between Bats and Birds

The variation between bats and birds is their structure and class. Bats came from the Chiroptera and Aves family. Bats are webbed structured flying animals while birds are feathered winged animals. Bats are mammals, so they don’t lay eggs, compared to birds that are known as egg-laying animals. When flying, bats don’t flap their forelimbs completely compared to birds. Generally, bats have teeth which help them when eating while birds have beaks in picking up food and eating them. Bats are nocturnal animals; they hunt and go around their business at night and sleep during the day while birds work and hunt for food during daytime and sleep at night.

5. Vertebrates & Invertebrates (see 2005)
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DIFFERENCES FROM PAST PAPERS (2011)


1. Typhoons & Tornado

• Hurricane (also called typhoons) is a result of tropical disturbance on a water body, while a tornado is always formed on land.

• A tropical storm is labelled a hurricane if it takes place between Atlantic and Pacific Ocean, but the same storm is called a cyclone if it takes place in Indian Ocean.

• Though both have eyes or centre, the centre of a tornado can be huge, extending up to 20 miles in diameter, whereas the eye of a tornado is very small being only a few feet in diameter

• Hurricanes occur in the months of June to November, whereas Tornados occur in the months of April to June

• Tornados last for a few minutes or hours, whereas hurricanes can have a very long duration lasting for 2-3 weeks.

• Thunderstorms are effects of hurricanes, whereas they are the cause of a tornado

• Hurricanes can cause floods and tsunamis, whereas tornados spread epidemics and also contaminate water sources.

OR

A tornado is a violently rotating column of air extending from the base of a thunderstorm to the ground. In weather terms tornadoes are small, 50 yards wide on average and rarely exceeding a mile wide, though on rare occasions tornadoes up to 2.5 miles wide have occurred. Tornadoes are also short lived, lasting 10 minutes on average, though a few have lasted for over 3 hours. Tornadoes form from interactions of air currents in a thunderstorm.

Hurricanes and typhoons are essentially the same thing, only a hurricane is in the Atlantic ocean or north-eastern Pacific ocean while a typhoon is in the north western Pacific ocean. Both are tropical cyclones with winds of at least 74 mph. In addition to having strong winds these storms bring heavy rain and flooding. The average hurricane/ typhoon is about 300 miles wide and forms over the course of several days. Unlike tornadoes, which are generally as land-based event These systems develop from disorganized clusters of thunderstorms that feed of the moisture from warm ocean water, organize, and intensify.

2. Microscope & Telescope

Telescope and Microscope are two scientific instruments that serve their purposes differently. One of the main differences between a telescope and a microscope is that a telescope is used to view things that are far whereas a microscope is used to view things that are very near.

It is indeed true both the instruments are used to watch the minute details of the objects or things more clearly. Another important difference between telescope and microscope is that the focal length or the distance from the focal point to the lens is different in these two scientific instruments.
As a result of this the focal point in the case of a telescope may be at a far off place. On the other hand the focal point in the case of a microscope is just a fraction of an inch off.

The difference in the diameter of the lens used in the two instruments also matter a lot when it comes to the difference between them. The lens diameter or the aperture is much larger in a telescope. This is to ensure that the aperture allows tiny amount of natural light at the focal point.
On the other hand only artificial illumination is used in a microscope. The artificial illumination is made to fall at the focal point in a microscope. It is interesting to note that a telescope and a microscope differ from each other in terms of the curvature of the lens.

A microscope is used to look into smaller details like the structure of the cells and the unicellular organism. On the other hand larger objects that are very far off are the targets of a telescope. In short it can be said that a telescope is used to look into space. Magnification is the keyword in both the scientific instruments.

3. Ultrasonics & Infrasonic:

Ultrasonics:
The study of sound aves with high frequencies beyond the upper limit of human hearing or 20 thousand Hz. This technique is employed to locate a tumour, to scan a pregnant woman’s abdomen in order to produce a picture of foetus or to treat certain neurotically disorders.

Infrasonic:

These are the sound waves which have the frequencies lowest than the lowest limits of human hearing or 20 Hz.

OR

The sounds having frequency more than 20,000 hertz (Hz) are called ultrasonic or ultrasound and the sounds having frequency less than 20 Hz are called infrasonic or infrasound. Both of these sounds cannot be heard by human beings. The audible range for of hearing by human beings is 20 Hz to 20000 Hz.

4. Heavy & Hard Water (see 1999)

5. Isotope & Isomer (see 2010)

6. Antibodies & Antibiotics:

Antibodies:


Protein synthesized in the blood in response to the entry of foreign substances or organisms into the body. When the body get infected through virus or bacteria, specific antibody is produced which fights the disease.

Antibiotics:
These are substances which can stop the growth or destroy the bacteria or other microorganisms. The antibiotics are used to eliminate fatal diseases such as typhoid, plague and cholera etc.

OR

Antibodies
l They are what your body produces in response to the presence of antigens (bacterial or viral surface structures)
l They merely assist your white blood cells in identifying
l They also destroy and invade the unidentified microorganisms.

Antibiotics
l They are chemicals that work to destroy invading bacteria (usually by disrupting the outer cell wall and making it "leak" or by messing up the bacteria's metabolic processes. They are not produced by the body)
l Antibiotics can be antibacterial or antiviral. Antibacterial will only destroy bacteria and antiviral will only destroy viruses. There are not many antibiotics for viruses. Also a virus is not a eukaryote.

7. Antigen & Vaccine

Antigen:
A substance or organism that induces the production of an antibody. The antigen reacts with antibody. The antigen tissue proteins can cause problems in the transplant of organs by rejecting the introduction of new organ in the body.

An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as pollen or cells such as bacteria. The term originally came from antibody generator[1][2] and was a molecule that binds specifically to an antibody, but the term now also refers to any molecule or molecular fragment that can be bound by a major histocompatibility complex (MHC) and presented to a T-cell receptor. "Self" antigens are usually tolerated by the immune system; whereas "Non-self" antigens are identified as invaders and attacked by the immune system. self-antigens.

Vaccine:
The agent which is used to give immunity against various diseases. A vaccine consists of modified disease organisms such as live weakened viruses or dead that can induce the production of antibodies within the blood.
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and "remember" it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.

Vaccines can be prophylactic (example: to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer are also being investigated; see cancer vaccine).
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Solar System


• The solar system is the family of the sun, planets revolving around it, the satellites of the planets and the asteroids or meteoroids and comets etc.

• There are eight planets in the solar system.

• Starting from the sun there are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

• All the planets revolve around the sun in their orbits.

• Meteorite analysis shows that the age of solar system is about 4530 million years.

• The sun is not the largest star of the Milky Way; rather it is an average sized star.

• It is not at the centre of the galaxy but shifted towards a side.

• The diameter of the sun is 1, 392, 140 km and its mass is 2 * 1027 tonnes.

• The outermost layer of the sun is called photosphere, has an average temperature of 5570 0C.

• The photosphere rotates at a rate of 25.38 days per turn.

• At the centre of the sun hydrogen is undergoing nuclear fusion reaction which provides energy for the heat and light so sun.

• The planets of the solar system as well as the moons get light and sometimes heat from the sun.

• The four inner planets of the solar system are called terrestrial plants because of their rocky nature.

• The outer planets are called gaseous planets because they don’t have solid surface and are composed of gases.

Planets And Their Characteristics:

1. Mercury

• Its distance from Sun is 58 million kms.
• Its revolution period is 88 days.
• Its rotation period is 58 days, 15 hours and 30 minutes.
• It has no moon.
• It is the nearest planet to the sun.
• It is also the smallest planet of the solar system.
• It is the fastest planet.
• Its radius is 2,433 kms and diameter is 4,878 kms.
• It is covered with holes called Craters.
• It has no atmosphere.
• The temperature on mercury vary between 420 0C (7900F) in the day and -180 0C (-2900F) at nights.

2. Venus

Apart from the moon, Venus is the brightest object in the sky. Venus can be seen with naked eye in the morning or in the evening. Following are the main characteristics of the Venus.

• Its distance from the Sun is 108 million kms.
• Its revolution period is 224.7/225 days.
• Its rotation period is 243 days and 14 hours (longest day)
• It has no moon.
• It is the nearest neighbour of the earth in the solar system.
• It is the brightest planet.
• It is also the hottest planet.
• Its diameter is 12,102 kms.
• It is wrapped in thick clouds of CO2 gas.
• It rotates from east to west as opposite to most other planets.

3. Earth

The earth is the largest and the densest of the four terrestrial planets. It is the most wonderful planet of the solar system. Following are the features of the Earth.

• Its distance from the Sun is 150 million kms.
• Its revolution period is 365 Ό days.
• Its rotation period is 23 hours, 56 minutes, 40 seconds.
• It has one moon.
• It is the densest planet.
• It is also the watery and bios planet.
• Its diameter is 12756 km (7927 miles equatorial and 7900 miles polar diameter)
• It has atmosphere which contains 78% Nitrogen, and 21% Oxygen.
• Its two-thirds surface is covered with oceans.
• The earth’s surface is rich in Oxygen, Silicon, Aluminium, Iron, Calcium, Sodium etc.

4. Mars

• Distance form sun 228 million kms.
• Revolution period 687 days.
• Rotation period 24 h, 37 min and 22 sec.
• It has two moons Phobos and Deimos.
• Its diameter is 6794 kms.
• Mars is covered with red dust.
• It has an atmosphere composed almost entirely of CO2.
• Its average temperature is -53 0C.

5. Jupiter

• Its distance from sun is 778 million kms.
• Revolution period 12 years.
• Rotation period 9h, 50min, and 30 sec. (smallest day)
• It has 63 moons.
• It is the largest planet of the solar system.
• It has the largest number of satellites.
• Its diameter is 1, 24,800 kms.
• Its diameter is eleven times greater than the earth’s diameter.
• It has a dense, cloudy atmosphere of hydrogen and helium.
• It has a rock-iron-ice core about 15, 000 km (9,000 miles) thick.
• Jupiter radiates 67% more heat than it receives from the sun. this is mainly due to dissipation of the primordial heat of the planet.

6. Saturn

In 1610, Galileo became the first person to look at Saturn through telescope.

• Distance from Sun 1427 million kms.
• Revolution period 30 years.
• Rotation period 10h, 14 mins.
• It has 62 moons.
• The largest moon of Saturn is the Titan and it is the second-largest moon in the solar system. Titan is larger than the planet Mercury.
• It is the second largest planet.
• It has a magnificent system of rings.
• Its diameter is 1, 20, 000 km.

7. Uranus

When sky is very dark and very clear Uranus can be seen with the naked eyes. The planet was discovered by William Herschel in March 1787.

• Its distance from Sun is 2869.9 million kms.
• Revolution period is 84 years.
• Rotation period is 16h, and 10 mins.
• It has 27 moons.
• Titania is the largest moon of Uranus.
• It has an atmosphere which is dominated by hydrogen and helium.
• Its diameter is 52, 400 km.

8. Neptune

Neptune was discovered by the German astronomer Johann Galle.

• Distance from Sun 4496, 6 million kms.
• Revolution period 165 years (largest year)
• Rotation period 18 hours.
• Neptune has 13 moons that we know of. The largest moon is Triton.
• It is the coldest planet.
• It is the slowest to move around the sun.
• Its diameter is 49,100 kms.
• It is known as the twin of Uranus due to their similarity of size, mass and composition.
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