Everyday Science

7. Differences

1. Artery & Vein

Artery

i) Arteries are blood vessels which transport blood away from the heart.

ii) Arteries have thick vascular walls.

iii) The inside bore or lumen of arteries is narrow.

iv) Arteries carry oxygenated blood with the exception of pulmonary artery.

v) The walls of arteries are more elastic.

vi) The blood is under great pressure in the arteries.

vii) Arteries are generally deeply placed.

viii) Arteries end in the capillaries.

Vein:

i) Veins are the blood vessels which always carry blood towards heart.

ii) Veins have thin muscular walls.

iii) The inside bore or lumen of veins is wide.

iv) Veins carry deoxygenated blood with the exception of pulmonary veins.

v) The walls of veins are less elastic.

vi) The blood is under less pressure in the veins.

vii) Veins are generally superficially placed.

viii) Veins start from the capillaries.

2. PNP and NPN Transistor

1. NPN has higher electron mobility than PNP. Therefore, NPN bipolar transistors are often more

favoured than PNP transistors.

2. NPN is easier to create from silicon than PNP.

3. The main difference of NPN and PNP is the base. One is just the opposite of the other.

4. With the NPN, a P-dope semiconductor is the base, while with the PNP, the ‗base‘ is a N-dope

semiconductor.

3. Electronic & Static Electricity

Electronic Electricity

i) This is electricity in motion.

ii) It involves flow of electrons.

iii) It has high voltage.

Static Electricity:

i) This is electricity at rest.

ii) It does not involve flow of electrons.

iii) It has low voltage.

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4. Concave & Convex Lens

Concave Lens

i) It is the lens which is narrower in the centre and broader towards the corners.

ii) When a beam of light strikes a concave lens all the rays after passing through it diverge. 

iii) It gives mostly virtual image.

iv) They are also called diverging lenses.

Convex Lens:

i) It is the lens which is narrower towards the corners and broader towards the centre.

ii) When a beam of light strikes a convex lens all the rays after passing through it converge at a single

point.

iii) Mostly real images are formed except when the ray of light passes through it when object is

palced between optical centre and focus.

iv) They are also called converging lenses.

5. Absorption & Adsorption

Absorption

i) Absorption is a process in which a substance takes up another substance, such as blotting paper

(solid) absorbing water (a liquid). OR Adsorption and absorption are two different things. Absorption

is the chemical integration of one chemical into another. When you drink a glass of water, you are

absorbing it, as the water becomes part of you.

Adsorption:

i) Adsorption is a process in which a substance adheres to the surface of another substance.

Adsorption is important in some types of catalysis, notably where gases adsorb on metal surfaces.

The reaction is then made easier by a consequent lowering of activation energy. OR Adsorption

occurs when one substance holds another via physical bonds. If you spill a glass of water on your

shirt, it is adsorbed as the fibres will hold the water until heat dries out the shirt.

6. Fats & Oils

Fats

i) are solid at room temperature

ii) made by animals, mostly

iii) are more saturated

Oils:

i) are liquid at room temperature

ii) are made by plants, mostly

iii) are less saturated

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Hypoglycaemia:

i) The fall in sugar level in the blood below the normal physiologic level known as Hypoglycaemia.

Normal physiologic range of sugar in blood is 60-90mg% at fasting and 120-140 mg% at random.

ii) It is treated by giving intravenous glucose.

iii) It causes mental confusion, visual problem and often coma etc.

iv) It causes weakness and increases in food desire.

Hyperglycaemia:

i) Hyperglycaemia is a condition in which blood sugar level rise above its normal range.

ii) It is treated by exercise, medicine or by intravenous insulin therapy.

iii) It causes weakness, calf pain, unhealed wounds and kidney problem.

iv) It causes excessive urination, dryness of lips and increased thirst etc.

2. Epidemic & Endemic

Epidemic:

i) If at one place and times a great number of people suffer from a disease is known as epidemic.

ii) It can travel from one place to another.

iii) Examples: Influenza, Smallpox, Cholera etc.

Endemic: 

i) If a disease persists in a particular locality, certain area or one region, it is known as endemic

disease.

ii) It cannot travel from one place to another place.

iii) Example: Goitre in iodine deficient areas.

3. Herbivores & Carnivores

Herbivores

i) The animals eating green plants, grass and fodder are known as Herbivores.

ii) Animals have specific digestive system to digest leaves, plants and fodder.

iii) The teeth are specifically designed to cut and chew leaves, plants and fodder.

iv) Jaw movement is specific for side motion.

v) Examples: goats, cattle, sheep, buffalo, cow etc.

Carnivores:

i) The animals eating flesh and meat are known as carnivores.

ii) Digestive enzymes are specific.

iii) Their teeth are short and to cut and chew leaves, plants pointed especially for flesh eating.

iv) Jaw movement is specific for up and down movement.

v) Examples: Tiger, dog, cat, lion etc.

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4. Respiration & Photosynthesis

Respiration

i) Respiration is a catabolic process in which compounds are broken down.

ii) In this process carbohydrates are broken down into simpler compounds.

iii) The end-products for this process are CO2 and H2O.

iv) In respiration Oxygen enters the plant body and CO2 is released.

v) It occurs during both day and night. Light is not necessary for this process.

vi) In respiration energy is released from food material.

Photosynthesis

i) It is an anabolic process in which compounds are formed.

ii) In this process carbohydrates are manufactured.

iii) The end-product of this process is simple carbohydrates.

iv) In photosynthesis CO2 enters the plant and O2 is released.

v) It occurs during day time only. Light is essential for this process.

vi) It is energy consuming process.

5. Pollination & Fertilization

Pollination

i) It is a process involving transfer of pollens form male reproductive organ to female reproductive

organ of plants.

ii) It occurs in flowering plants.

iii) The products of pollination are seed.

iv) It takes place through animals, birds, insects, wind and water.

Fertilization:

i) In fertilization fusion of egg and sperm occurs.

ii) It occurs markedly in animals.

iii) The product of fertilization is zygote.

iv) It takes place by physical contact and mating of male and female.

Thermoplastics

i) Plastics that can be melted again and again are known as thermoplastics.

ii) They behave just like wax.

iii) These plastics can be shaped again and again.

iv) Examples: Nylon, PVC, Teflon etc.

Thermosetting Plastics:

i) Plastics that can be melted only once are known as thermosetting plastics.

ii) They become hard after melting.

iii) These plastics cannot be shaped again and again.

iv) Examples: Polyesters and Bakelite.

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Lunar & Solar Eclipse

Lunar Eclipse

i) It occurs when the earth comes between moon and sun.

ii) Moon goes through series of partial eclipses when moon comes out of umbral region of earth‘s

shadow.

iii) Earth lies in umbral region at total eclipse when earth lies exactly between moon and sun and its

shadow covers the whole moon.

Solar Eclipse

i) It occurs when moon comes between earth and sun.

ii) Partial eclipse of sun occurs as in Penumbra can see a part of the sun.

iii) At the total eclipse of the sun, the shadow of moon which it throws on earth consists of an umbra

and penumbra people on earth who are in umbral region cannot see the sun.

Asteroid & Meteorite

Asteroid:

i) The small rocky objects which are orbiting the sun between orbits of Mars and Jupiter are known

as asteroids.

ii) Its origin is concentrated to the remains of planets that fell apart.

iii) Asteroid means star like but these are known as minor planets.

Meteorite:

i) Tiny chunk of material floating in space, which can also enter the earth‘s atmosphere and become

meteor are known as meteorites.

ii) It may originate by the disintegration of comet.

iii) A falling star (Meteor) is seen as a streak of light in sky.

Renewable & Non-renewable resources

Renewable Resources

i) Renewable resources are used continuously and can be used again and again.

ii) Major examples are: air, water, soil, wildlife, forests, fish etc.

iii) These resources support millions of people all over the world.

iv) Renewable resources are constantly renewed by bio-geochemical cycles of nature.

Non-renewable Resources

i) Non-renewable resources cannot be used again and again after their consumption.

ii) Major examples include: Coal, oil, natural gas etc.

iii) These resources cannot support millions of people all over the world.

iv) Non-renewable resources are being exhausted day by day because their demand rises. Due to

worldwide demand of fossil fuels, its supplies are declining.

OR

Renewable resources- 

1) the resources that can be renewed by reproduction are called renewable resources.

2) Renewable resources are inexhaustible.

3) Renewable resources are not affected by the human activities.

4) All biotic resources are renewable.

5) For example: air and water.

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Non-renewable resources-

1) the resources that are present in fixed quantities are called non-renewable resources.

2) Non-renewable resources are inexhaustible.

3) Non-renewable resources are affected by human activities.

4) Some abiotic resources are non-renewable.

5) For example- fossil fuels and minerals.

Endothermic & Exothermic Reaction

Exothermic Reaction

i) Energy is drawn in from the external environment, causing its surroundings to loose heat, or "cool

down."

ii) The endothermic chemical reaction creates a product that has a higher energy level than the

original materials, causing the reactant's stored energy to decrease. (In scientific terms, the reactants

have "less total enthalpy" than the product.)

iii) The resulting product of the reaction is less stable because, the higher the energy bond, the less

strength its molecules possess.

iv) Most endothermic reactions are not spontaneous.

v) Example: Melting ice. In order for ice to melt, it needs to draw in the heat (energy) from its

surroundings. The ice becomes less stable as it responds to the increased heat. The ice stored energy

decreases. The end product is water, which has a higher energy level than the ice.

Exothermic Reactions

i) Exothermic chemical reactions cause their surroundings to warm up by giving off heat.

ii) The reactants contain more stored energy than the product because energy from external sources is

not required, but given off. This gives the product more stability due to the lower amount of energy

needed. (In this case, the reactants have a "greater total enthalpy" than the product.)

iii) Exothermic reactions are usually spontaneous.

iv) Example lighting a match. When the head of the match is struck, it results in the spontaneous

release of stored energy (heat) from the reactants into the surroundings. The flame that is produced

has a lower level of energy than the match and the striking surface because the reaction is giving off

stored energy and not required to draw energy in from its surroundings

 Star & Planet

Star

i) Stars are self-luminous heavenly bodies.

ii) They do not revolve around the sun.

iii) They are usually stationary.

iv) Examples: fixed stars, binary stars.

Planet:

i) Planets are rocky non-luminous bodies.

ii) They revolve round the sun.

iii) They usually move.

iv) Examples: Mercury, Venus, Jupiter etc.

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Nuclear Fission & Fusion

Fission:

i) Lighter atoms are fused together at a very high temperature to form heavier elements.

ii) It is difficult to carry out on the earth.

iii) It has no nuclear waste problem.

iv) It requires cheaper and abundant elements.

v) Not possible at concerning scale as high temperature is needed to start it.

Fusion:

i) Heavier unstable atoms are broken down to produce energy.

ii) It is easy to carry out on the earth.

iii) It has nuclear waste radioactivity disposal problem.

iv) It requires expensive and rare elements.

v) Possible to commercialize under controlled measure.

RAM

i) It stands for random access memory.

ii) It is an optical disc, where data and information is stored permanently.

iii) RAM is the primary storage media.

iv) RAM is the primary storage device from which the system boots.

v) RAM is stored on RAM chip.

vi) The data or information stored on it can be written on or it can be erased.

ROM

i) It stands for read only memory.

ii) It is that part of CPU, where temporary information is stored.

iii) RIOM is the secondary storage media.

iv) System does not boot from ROM.

v) ROM is stored on a compact disc.

vi) The data or information stored on it neither be written on, nor it can be erased.

BIT & BYTE

A bit is defined as: a single basic unit of information, used in connection with computers and

electronic communication. All modern computers store and use data in digital form. The smallest unit

of storage and measurement is one binary digit, therefore its name.

A byte, pronounced ‗bite‘, is the next size up basic unit of measurement for information storage,

usually consisting of eight bits. These 8 bits are grouped together to form a byte that is, a total or 8

grouped bits representing one character of data.

Therefore, so far we have two basic units of measuring digital information storage that have different

capacities, they are:

• 1 Bit

• 8 Bits equal 1 Byte

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CU & ALU

CU

i) It stands for Control Unit.

ii) Control unit controls overall activates of computer.

iii) CU does not perform the functions of calculations.

ALU

i) It stands for arithmetic logic unit.

ii) It performs arithmetic and logical operations.

iii) ALU performs functions of addition, subtraction, multiplication and division.

Hardware & Software

Hardware:

i) All the physical components of computer which can be touched, measured have weight and occupy

space are collectively called computer hardware etc.

ii) Examples of hardware are: keyboard, mouse, joy stick, scanner, printer, CPU etc.

Software:

i) Software can be defined as a set of instructions and codes written in a defined manner. In other

words software are pre-written programs, which control the operation of computer.

ii) Examples of software are; DOS, windows, UNIX, XENIX, Linus, JAVA, Oracle, Antivirus etc.

PC/Minicomputers & Mainframe computers

PC:

i) It is a small computer based on microprocessor.

ii) One user can use it at a time.

iii) These are very low priced computers. An individual can afford it.

iv) User friendly software are used to operate this computer.

v) Minicomputers were launched in 1959 by Digital Equipment Corporation (DEC)

vi) Minicomputers are also made by Data General, Hewlett-Packard & IBM

Mainframe Computers:

i) The largest computers called mainframe computers are the oldest category of computer system.

ii) They are capable of great processing speed and data storage.

iii) These are always kept in air-cooled rooms.

iv) They are mainly used in banks, airlines and industrial companies.

Email & Snail Mail

Snail mail:

i) "Snail mail" is a term used to refer to mail that is sent in the traditional way — through the postal

service — rather than by email, fax, or other electronic means of communication.

ii) It is called "snail mail" because it can be very slow, as is a snail. Snail mail generally takes 2 or 3

days to go from origin to destination, if not many more, 

iii) Snail mail has gone out of fashion for simple letters, though it is still necessary for sending

packages, or legal documents that require signatures.

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Email:

i) Email is electronic mail which is very quick means of communication through computers and

telephone line.

ii) Email can be sent instantly.

iii) With email, a message is sent directly from a user's mail program to another person's email

address. Though many email messages simply contain words, they may also include photos or other

digital files, such as songs, or links to websites.

Apes & Monkeys

Apes:

i) Apes do not have tail. 

ii) Apes have rounded nasal openings. 

iii) Apes generally have bigger brains and larger bodies than monkeys. 

iv) Apes do not have web foot. 

v) Apes are bigger in size. 

vi) Apes are: Humans, Chimps, Gorillas, Orangutans and Gibbons. 

Monkeys

i) Monkeys have tails.

ii) Monkeys have slanted nasal openings. 

iii) Monkeys have web foot.

iv) Monkeys are smaller in terms of size 

v) Monkeys are all primates non-apes and non-prosimians (lemurs)

Hydrostatics & Hydrodynamics

Hydrostatics:

i) Hydrostatics is a branch of science which deals with physical behaviour of liquids at rest.

ii) The consideration of liquids at rest, involves problems of buoyancy and flotation, pressure on

dams and submerged devices, and hydraulic presses.

Hydrodynamics:

i) Hydrodynamics is the branch of science which deals with behaviour of liquids in motion.

ii) The study of liquids in motion is concerned with such matters as friction and turbulence generated

in pipes by flowing liquids, the flow of water over weirs and through nozzles, and the use of

hydraulic pressure in machinery.

Comet & Meteor

Comet:

i) Comet is a collection of gas, dust, and volatile ice that travel around the sun, generally in very

eccentric orbit.

Meteor:

i) Meteor is a streak of light seen in the night sky signify the burning up in earth‘s atmosphere of

inter-planetary material.

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Barrage & Dam

Barrage:

i) Barrages are constructed not at a much height but at a low height.

ii) Barrages are single purpose constructions i.e. for irrigation.

iii) Electricity cannot be produced in barrages.

iv) It is constructed on plains.

v) Sukkur barrage is an example.

Dam:

i) Dams are constructed at higher elevation or at a height.

ii) Dam is multipurpose. It acts as reservoir, control flood, and for irrigation.

iii) Dam is constructed to generate electricity.

iv) It is impossible at ground level.

v) Tarbella dam is an example.

Isotopes:

These are the elements having same atomic number but different mass number. They have

the same atomic number because the number of protons inside their nuclei remains the same.

The difference in their mass number is due to the difference in their number of neutrons.

Isobars 

Where Isotopes are chemically the same and physically different, the converse is true in

Isobars. That is isobars are elements, which are chemically different but physically the same.

So, isobars are atoms of different elements having the same atomic mass but different atomic

number. Since their number of electrons is different, their chemical properties are different.

The light nuclei have unstable isobars. Heavy nuclei have stable isobars and these occur in

pairs. Suppose the number of protons of one isobar matches with that of another they are

called as mirror-nuclides of each other. 

Autopsy & Biopsy

Autopsy:

i) An autopsy is the dissection and analysis of a dead subject.

ii) , autopsies are limited to the deceased and there are two kinds of autopsy; External

examination and internal examination.

iii) Autopsy is performed for medico-legal purpose.

Biopsy:

i) A biopsy is a medical test in which cells, tissue, or fluid is removed for examination.

ii) Biopsy is not limited to only living people because they are routinely taken from organs

that are going to be used for transplantation.

iii) Autopsy is performed for diagnosis purpose.

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Mitosis & Meiosis

Mitosis:

i) Mitosis takes place within somatic cells (cells that make up the body).

ii) One single division of the mother cell results in two daughter cells.

iii) A mitotic mother cell can either be haploid or diploid.

iv) The number of chromosomes per nucleus remains the same after division.

v) It is preceded by a S-phase in which the amount of DNA is duplicated.

vi) In mitosis, there is no pairing of homologous chromosomes.

vii) There is no exchange of DNA (crossing-over) between chromosomes.

viii) The centromeres split during anaphase.

ix) The genotype of the daughter cells is identical to that of the mother cells.

x) After mitosis, each daughter cell has exactly same DNA strands.

Meiosis:

i) Meiosis takes place within gamete cells (sex cells).

ii) Two divisions of the mother cell result in four meiotic products or haploid gametes.

iii) A meiotic mother cell is always diploid.

iv) The meiotic products contain a haploid (n) number of chromosomes in contrast to the (2n)

number of chromosomes in mother cell.

v) In meiosis, only meiosis I is preceded by a S-phase.

vi) During prophase I, complete pairing of all homologous chromosomes takes place.

vii) There is at least one crossing-over or DNA exchange per homologous pair of

chromosomes.

viii) The centromeres do separate during anaphase II, but not during anaphase I.

ix) Meiotic products differ in their genotype from the mother cell.

x) After meiosis, each daughter cell has only half of the DNA strands.

Hard water & Heavy Water

Hard Water:

i) Hard water is that type of water which does not form lather easily.

ii) Its formula is H2O.

iii) Hard water is not used in nuclear power plants.

Heavy Water:

i) Heavy water is deuterium oxide in which hydrogen of water is replaced by its heavier

isotope, Deuterium.

ii) The formula of heavy water is D2O.

iii) Heavy water is used in nuclear power plants.

Climate & Weather

Climate:

i) Climate is the normal weather conditions for an area during a season or a year.

ii) Climate of an area is described by means of an average means of an average of the

statistics of the various weather factors over a period of time, normally 30-years.

Weather:

i) Weather is the condition of the atmosphere at any one place and time.

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ii) Weather is described by air, temperature and humidity, wind speed and direction, cloud

amount and precipitation, sunshine and visibility.

Cardiac & Skeletal Muscles:

Cardiac Muscles:

i) Cardiac muscles are present in the heart only.

ii) They have centrally placed nuclei.

iii) They never fatigue.

iv) They are composed of long fibres.

v) They are under involuntary control.

Skeletal Muscles:

i) Skeletal muscles are present in the skeleton of the body.

ii) Nuclei are not centrally placed in skeletal muscle.

iii) They can fatigue.

iv) They are not composed of long fibres.

v) They are under voluntary control.

Haze & Smog

Haze:

i) The dust particle smoke etc. that may be visible in atmosphere close to the earth‘s surface

is known as Haze.

ii) It does not affect natural visibility.

iii) It does not occur particularly near coastal areas.

Smog:

i) It is a mixture of solid and liquid fog as well as particles of smoke. It is formed when

humidity is high.

ii) Smog reduces visibility.

iii) It occurs near coastal areas.

Enzyme & Hormone

Enzyme:

i) These are organic catalysts produced in the protoplasm of all living cells.

ii) These are mostly protein in nature.

iii) They control all biochemical reactions of the cell.

iv) These are present in all cells and show their activity there.

Hormone:

i) These are organic substances produced in places away from their functional sites.

ii) These are mostly acids.

iii) They promote and inhibit growth, flowering, sex expression, etc.

v) These are mobile. They are produced at one site and show their activities at other sites.

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Igneous & Sedimentary Rocks

Igneous Rocks:

i) Igneous rocks are formed when magma (or molten rocks) has cooled down and solidified.

ii) Igneous rocks are commonly found inside the Earth‘s crust or mantle, 

iii) Igneous rocks can be an important source of minerals,

iv) Examples of Igneous rocks include granite and basalt.

Sedimentary Rocks:

i) Sedimentary rocks are formed by the accumulation of other eroded substances, 

ii) Sedimentary rocks are usually found in water bodies (sea, oceans etc.).

iii) Sedimentary rocks, or their bedding structure, are mostly used in civil engineering; for the

construction of housing, roads, tunnels, canals etc.

iv) Examples of Sedimentary rocks include shale, limestone and sandstone. 

OR

What is the difference between Igneous Rocks and Sedimentary Rocks?

- Igneous rocks are formed from molten liquid minerals called magma, while sedimentary

rocks are formed from lithification (cementing, compacting and hardening) of existing rocks.

- Igneous rocks are non-porous for water, while sedimentary rocks are porous to the water.

That is water cannot penetrate through igneous rocks but can through sedimentary rocks.

- Igneous rocks are having fossils very rarely, while sedimentary rocks are rich in fossils.

- Igneous rocks are harder than sedimentary rocks.

- Tendency to react with acids is higher to sedimentary rocks when compared to igneous

rocks.

- Igneous rocks may be light or dark coloured, while sedimentary rocks have great colour

variety.

Producers & Consumers

Producers:

Producers are organisms that make their own food through photosynthesis or other reactions

and are a food source for other organisms (ex. plants, extremophile benthos communities). 

Consumers: 

Consumers are organisms that ingest other organisms, like plants, in order to gain energy (ex.

herbivores, carnivores, omnivores, and detrivores).

Microcomputer & Minicomputer

Microcomputer:

i) A microcomputer is a standard desktop computer used at a home and in business.

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ii) A microcomputer is a computer with a microprocessor as its CPU.

iii) They are cheap, compact and can be easily accommodated on a study table.

iv) Microcomputer is a single-user computer.

v) The two most common types of storage devices used with microcomputers are tapes and

disks.

vi) Microcomputer is not powerful or as fast as minicomputer.

-vii) Examples are- Modern computers like desktop, laptop etc.

 Minicomputer:

i) Minicomputers are mid-sized computer used in universities, research labs and small

corporations.

ii) Minicomputers are faster than microcomputers.

iii) They are expensive and larger than microcomputer.

iv) Minicomputer is a multi-user computer.

v) For secondary storage, most minicomputers use magnetic disks or tapes.

vi) Minicomputer is powerful than microcomputer but not as super computer and mainframe

computer.

vii) Examples are- IBM 9375, Motorola 68040 etc.

Mainframe & Super Computers

Mainframe Computers:

i) The largest computers called mainframe computers are the oldest category of computer

system.

ii) They are capable of great processing speed and data storage.

iii) These are always kept in air-cooled rooms.

iv) They are mainly used in banks, airlines and industrial companies.

Super Computers:

i) The super computers are fastest of all computers.

ii) It was invented by two brothers Gregory and David in New York.

iii) These computers have high capacity to work.

iv) These also require air-conditioned rooms.

v) The super computers are mainly used in a) Automotive engineering b) Modelling nuclear

explosion c) Aeroplane designing d) Oil exploration e) Weather forecasting etc.

RAM & Cache Memory

RAM

i) It stands for random access memory.

ii) It is an optical disc, where data and information is stored permanently.

iii) RAM is the primary storage media.

iv) RAM is the primary storage device from which the system boots.

v) RAM is stored on RAM chip.

vi) The data or information stored on it can be written on or it can be erased.

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Cache Memory:

i) Cache memory is a special high speed memory that the CPU can access quickly.

ii) It is used in computers with very fast CPUs, so that these CPUs don‘t have to wait for Data

to be delivered from RAM.

iii) The most frequently used instructions are kept in the cache memory.

iv) This allows the CPU to run faster because it does not have to take time to swap

instructions in and out of RAM.

Rotation & Revolution Of Earth:

Rotation Of Earth:

i) it is the movement of the earth in which the earth makes rotation around its axis.

ii) Rotation of the earth occurs from West to East.

iii) The main effect of the rotation of the earth is the formation of days and nights.

Revolution Of Earth

i) it is the movement of the earth, in which the earth makes revolution around the sun.

ii) Revolution of the earth occurs in counter clockwise direction or from right to left.

iii) The main effect of the revolution of the earth is the change of seasons.

Dicot & Monocot Stem

Dicot Stem:

i) In dicot stem pericycle is broken.

ii) There are few vascular bundles. 

iii) The vascular bundles are open.

Monocot Stem:

i) In monocot stem pericycle is not broken.

ii) there are many vascular bundles.

iii) The vascular bundles are closed.

Penumbra & Umbra

Penumbra:

The term relates to the solar and lunar eclipse. When during its revolution, the moon comes

between the sun and the earth then solar eclipse takes place. A shadow is created. The outer

shadow region in the eclipse is called penumbra.

Umbra:

Similarly, when the solar eclipse takes place, two regions of shadow are created. Out of these

the dark inner shadow region is called Umbra.

Nucleus & Nucleolus

Nucleus:

i) The nucleus is the main organelle.

ii) It is mostly present in the centre of the cell.

iii) It is membrane bound.

iv) The nucleus contains DNA.

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v) It contains hereditary material in the form of chromosome and genes and controls all the

activities of the cell.

Nucleolus:

i) The nucleolus is a sub-organelle.

ii) It is present in nucleus.

iii) It is non-membrane bound.

iv) It contains RNA.

v) It takes part in protein formation.

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.

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.

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

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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.

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

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as we're not used to seeing images of light that's passed through things - think of silhouettes

or slide projectors.

Periscope & Pyrometer:

Periscope:

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

Pyrometer:

Instrument used for measuring high temperatures.

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.

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.

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.

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.