Everyday Science

Ecosystem:

Definition:

A natural of habitat or system where living organisms and physical components of their

environment interact with one another and exchange materials so as to achieve a functional

stability is called an ecosystem.

Characteristics Of Ecosystem:

• An ecosystem is a basic unit of ecology of living organisms.

• An ecosystem may be natural like a pond, lake, stream, river, ocean or a forest.

• It may also be artificial like an Aquarian, an artificial pond or an agricultural field.

• A pond is an excellent example of a small ecosystem to demonstrate interrelationship between

abiotic and biotic component of the ecosystem.

Components Of Ecosystem:

i) Abiotic Components Of Ecosystem.

Following are the abiotic components of ecosystem.

a. Light

b. Temperature

c. Water

d. Atmosphere and wind

e. Fire

f. Soil

g. Topography

h. Gravity

i. Inorganic nutrients

ii) Biotic Factors.

Following are the biotic components of ecosystem.

a. Producers: Green Plants

b. Consumers: Animals and Man

c. Decomposers and reducers: Bacteria, fungi

Types Of Ecosystem:

There are two main types of ecosystem:

i) Terrestrial Ecosystem: it includes Forest and Desert Ecosystem

ii) Aquatic Ecosystem: it includes small pool, a pond, stream, river, lake and an oceanic

ecosystem.

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Environmental Pollution:

―Destabilization of the balance of the atmospheric composition.

OR

―It is an unstable change in the composition of the environment due to its physical, chemical and

biological changes, which is harmful for human life and other animals living on the earth.‖

Types Of Pollution:

i) Air pollution

ii) Water pollution

iii) Land pollution

iv) Noise pollution

v) Industrial pollution

vi) Commercial or domestic sector pollution

vii) Chemical pollution

viii) Radioactive pollution (contamination)

Causes of Pollution

The ultimate cause of pollution is human activity itself. Pollution is a human contribution to

nature. Science has evolved technologies and technologies have helped the human welfare. In the

process, the pollution has been a part of technology and therefore a part of human miseries.

Human activities mainly include:

• Industries for various human needs - directly and indirectly

• Agriculture for food production and industrial needs

• Health care for health of human beings and animals

• Transport for mobility of human beings

• Dwelling for settlement in city or villages

• Energy for various direct human needs and industrial needs.

Pollutants:

Pollutants are those substances which alter the natural composition of the atmosphere or destroy

it to harmful level.

Types Of Pollutants:

1. Primary Pollutants

Primary pollutants are those substances which are directly produced by a process. These are:

ix) Sulphur oxides

x) Nitrogen oxides

xi) Carbon monoxide (CO)

xii) Carbon dioxide

xiii) Volatile organic compounds (VOC), such as hydrocarbon fuel vapours and solvents

xiv) Particulate matter (PM), such as smoke and dust.

xv) Metal oxides, especially those of lead.

xvi) Chlorofluorocarbons (CFCs)

xvii) Ammonia (NH3)

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xviii) Garbage, sewage and industrial wastes.

2. Secondary Pollutants

Secondary pollutants are those pollutants which are not emitted. Rather, they form in the air when

primary pollutants react or interact.

These are:

i) Ground level ozone (O3)

ii) Nitrogen dioxide

iii) Peroxyacetyl nitrate (PAN)

Effects Of Pollution:

1) Air Pollution: Irritation of eyes, nose, mouth and throat, Increased respiratory disease, Cancer,

Reduced lung functioning, Premature death. Acid rain, Ozone,

2) Water Pollution: Waterborne diseases such as; Typhoid, Hepatitis, diarrhoea, vomiting, and

stomach aches, death of aquatic animals, May disrupt photosynthesis in aquatic plants

3) Soil Pollution: Causes cancers including leukaemia, developmental damage to the brain,

kidney damage; depression of the central nervous system, Also causes headaches, nausea, fatigue,

eye irritation and skin rash, Contamination of crops, reduce crop yields.

Water Pollution:

Definition:

―The presence of undesirable substances into fresh and natural water which cause harmful

diseases in human beings as well as aquatic life is called water pollution.‖

Types Of Water Pollution:

Following are the major types of water pollution.

i) Sea-water Pollution

ii) River water Pollution

iii) Land Water Pollution

Causes Of Water Pollution:

1) Pollution Through Domestic Activities:

Domestic activities pollute the water when following kinds of wastes are added.

i) Soap and detergents

ii) Chemicals used in the houses

iii) Waste from slaughter house

iv) Waste from hospitals

v) Waste from bakeries

vi) Human and animal faeces

vii) Waste food

2) Pollution Through Industrial Activities:

Industrial sector is a great source of pollution of water and air. Many industrial units produce

waste materials in the shape of solids, liquids and gases. The industrial wastes are.

i) Poisonous gases

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ii) Acids, bases and harmful salts

iii) Pesticides and plastics

iv) Radioactive wastes

v) Toxic wastes from fertilizer factories

vi) Wastes from chemical factories

Water Pollution In Pakistan:

In Pakistan people do not take pain to dispose the waste materials in a proper way. Instead of

dumping wastes in the drums and places meant for them they freely throw these into the water

drains.

Water pollution is very prominent and widespread as a result of urban and industrial activity.

Sewage waste from cities and industrial waste are the main factors of water pollution. Many other

kinds of wastes which pollute water are from agricultural lands which contain pesticides, waste

foods, fertilizers and animal excreta. Wastes from power plants contain radioactive materials, hot

water and minerals which also pollute the water. Soaps, detergents, human excreta, animal faeces,

wastes from slaughter houses, disease causing micro-organisms from patients and chemicals etc.

are drained into water which causes massive water pollution.

Two Important Industries Of Pakistan Causing Water Pollution:

1) One of the biggest sources of water pollution is the tanning and leather industry. The industry

uses toxic chromium metal and many other toxic substances/chemicals. These toxins are released

in natural waters. Effluent of this industry has polluted ground water and water of nearby rivers.

This industry is frequent in Kasur and Sialkot area.

2) Pesticide industry in Kala Shah Kaku near Lahore releases huge quantity of acids, pesticides

and other dangerous wastes. These wastes are getting entry into a stream flowing nearby. The

water of the stream is dangerously polluted. This water ultimately goes to the rivers.

Effects:

i) Bacteria, viruses, protozoa and worms are carried in polluted water. The diseases caused by

them are as under:

a) Bacteria: Typhoid, cholera, Dysentery, enteritis.

b) Viruses: Hepatitis, Polio, Viral enteritis.

c) Protozoa: Amoebic dysentery, diarrhoea.

d) Parasitic worms: Schistostomiasis

ii) It causes death of aquatic animals.

iii) It decreases the fertility of the soil and results in low production.

Methods To Control Water Pollution:

Different methods can be used to control water pollution.

i) The whole sewage waste should be dumped after any treatment.

ii) Sewage treatment plants should be installed in cities.

iii) The sewage waste must not be drained in river to save water from pollution.

iv) Industrial waste should be treated before reaching natural water.

v) Industries should be established away from cities and rivers.

vi) Nuclear dumping in oceans should be banned.

vii) Modern scientific methods should be used in agriculture.

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Deforestation:

It is the process of destruction of the forests.

Causes Of Deforestation:

A number of agents are responsible for removal of forests. These are fires. Droughts or animals.

The principle agent of deforestation is man himself. Humans are cutting forests to colonize the

forest areas or to prepare more agricultural lands or for getting food.

Effects Of Deforestation:

i) Deforestation has many bad effects on human life. With destruction of the forest the process of

cleaning of air and production of oxygen is badly affected.

ii) Forests are major agents of evaporation and rainfall. With deforestation rainfall is decreased. 

iii) With cutting of forests, pollution is increasing as the hazardous gases are not completely

absorbed by plants.

iv) With deforestation carbon dioxide is increasing which is causing global warming.

v) With reduction in area of forest, soil erosion is taking place resulting in floods which destroy

crops and human life.

vi) Deforestation has badly damaged wild life and reduced recreation sites.

Earth:

Features Of Earth:

i) The earth is the fifth largest planet of the solar system, where life exists.

ii) Its equatorial diameter is 7,927 miles.

iii) Its polar diameter is 7900 miles.

iv) The earth has average density of 5 ½ g/cc.

v) the rotation period of the earth is 23 hours, 56 minutes and 4 seconds.

vi) the revolution period of the earth is 365 days.

vii) The total mass of the earth is 6*1021 tons.

viii) The earth is composed of shells or layers, which are, the crust, mantle and core.

ix) It is surrounded by a blanket of gases, which is known as the atmosphere, mainly composed of

Nitrogen and Oxygen.

x) The surface of the earth is rich in oxygen, silicon, iron, magnesium, sodium etc.

Structure Of The Earth:

The earth comprises of the following layers:

a) The crust

b) Moho discontinuity

c) The mantle

d) The Core

a) The Crust:

i) It is the outermost layer of the earth.

ii) It extends to about 25 miles (40kms) and comprises of rocks.

iii) The crust is divided into the oceanic and the continental crust.

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iv) Out of these the oceanic crust is 808 meter thick and consists of sedimentary mud.

v) The continental crust is divided into upper continental and lower continental crust.

b) Moho discontinuity:

i) The sharp boundary between the crust and mantle is called Moho Discontinuity.

c) The Mantle:

i) The layer of the earth lying below the crust and above the core is known as the mantle. 

ii) It is almost 2900 kms (1800 miles) thick and comprises about 80% of the volume of the earth.

iii) The chemical composition of the entire mantle is fairly homogenous.

iv) However, temperature and pressure increases with depth.

v) The behaviour of the earthquake waves as they travel through the mantle further tells us that it

consists of several layers and they are:

a) Lithosphere

b) Asthenosphere

c) Mesosphere

d) The Core:

i) The innermost part of the earth is known as the core.

ii) It extends from the base of the mantle to the centre of the earth.

vi) This portion consists of melted iron and nickel that is why it is known as Nife.

vii) The density of this molten mass of the core is 345 pounds per cubic feet.

Types Of Movements Of Earth:

• There are two types of motions of the earth.

• One is around its own axis which is called Rotation. One rotation completes in 23 hours, 56

minutes and 4 seconds.

• The other motion of earth is round the sun, and is called revolution of the earth.

• One revolution completes in 365 days.

• Northern end of the earth‘s axis is called the North Pole and the Southern end is called South

Pole.

• An imaginary line drawn round the earth midway between the poles is called equator.

• The path which the earth takes round the sun is called earth‘s orbit.

Effects Of These Movements:

• Rotation of earth round its axis cause days and nights.

• That portion of earth, which is within the circle of illumination caused by the rays of sun, has its

day.

• The other side earth, which is away from sun, remains dark and therefore has its night.

Longer And Shorter Days:

• The circular areas near the North and South Pole of the Earth are called Arctic and Antarctic

circles, respectively.

• These are situated at 66 ½0 North and 66 ½0 South of the equator, respectively and form limits

of polar region.

• On June, the earth is in position A. north pole is inclined towards the sun and south pole is away

from it.

• Obviously any place in Northern Hemisphere will have longer days because it remains in light

for more than half the time of earth‘s rotation.

• Places on equator remains in light for half the time making days and nights equal in this region.

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• The southern hemisphere remains in light for less time than half the rotation of earth so the days

are shorter here.

• Positions of days and nights in the northern and southern hemisphere are reversed on 22nd

December, when the earth completes its half revolution around the sun, so days are longer in

southern hemisphere than those in the north.

Change Of Season:

• The second type of motion of earth is round the sun and is called revolution of the earth.

• This is the cause of change of seasons.

• On June 21, the earth is in position A, when the north pole is inclined towards sun while the

south pole is away from it.

• As the sun rays fall vertically and for a longer period in the northern hemisphere, it is summer

here but in the southern hemisphere it is winter.

• On December 22, when the earth completes half revolution, the conditions become reversed; it

is summer in the southern hemisphere and winter in the northern hemisphere.

Atmosphere:

The layer of the gases which surrounds the earth is known as the atmosphere.

OR

The atmosphere is a thin layer of the gases held to the earth by the gravitational attraction.

OR

Atmosphere is the huge blanket of gas that circles the entire earth.

Composition Of The Atmosphere:

The atmosphere consists of:

i) Nitrogen: 78.03%

ii) Oxygen: 20.99%

iii) Argon: 0.94%

iv) CO2: 0.03%

v) Hydrogen: 0.01%

vi) Neon: 0.0018%

vii) Helium: 0.0005%

viii) Krypton: 0.0001%

ix) Ozone: 0.000001%

Layers Of The Atmosphere:

The atmosphere of the earth is divided into following layers.

i) Troposphere

ii) Stratosphere

iii) Ionosphere

iv) Exosphere

Ionosphere is sub-divided into:

i) Mesosphere

ii) Thermosphere

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1) Troposphere:

i) Troposphere is the lowest layer of the atmosphere.

ii) It extends roughly to a height of 8 kms near the poles and 16-18 kms at the equator.

iii) It is troposphere where the people, plants, animals and insects live.

iv) It is the layer where all weather occurs that‘s why it is also referred as ―The weather Zone‖.

v) In the Troposphere temperature gradually falls with increasing altitude.

vi) There is a thin buffer zone between the troposphere and stratosphere is called tropopause.

2) Stratosphere And Ozone Layer:

i) The second layer of the atmosphere is known as the stratosphere.

ii) The stratosphere extends from the tropopause to about 30-31 mile above ground level.

iii) The important ozone layer is found in this region where heat is generated by absorption of

UV.

iv) Here the temperature either remains constant or increases with altitude.

Stratopause:

It is the upper boundary of the stratosphere which occurs beyond 52 kms. Here the temperature

remains constant with increase in height.

3) Ionosphere:

i) The third major layer of the atmosphere is the ionosphere.

ii) It lies above the stratosphere.

iii) It lies between about 30 and 90 miles above the surface of the earth.

iv) It is divided into mesosphere and thermosphere.

v) The ionosphere is bombarded by cosmic radiation and solar x-rays, which causes the gases in

the ionosphere to ionize.

vi) Brilliant displays of colored lights in the sky called Aurora Borealis in the northern

hemisphere and the Aurora Auralis in the southern hemisphere occur when streams of electrically

charged particles from the sun (solar wind) ionize the atmosphere gases.

4) Exosphere:

i) The uppermost layer of the atmosphere extending beyond Ionosphere is called exosphere.

ii) Beyond 300 miles is the very rare field exosphere which consists only of scattered atmosphere

of O, H and He.

Latitude:

Definition:

It is the distance on the surface of the earth measured in degrees north and south of the

equator. 

The equator is at zero degree where the poles are at 90 degree. The latitude of the north pole

is 900 North and that of south pole is 900 South.

Characteristics OF Lines Of Latitudes:

i) All lines of latitudes are parallel to the equator as well as parallel to one another.

ii) Parallels in the north of the equator are north latitudes while those in the south of equator

are known as south latitudes.

iii) They are drawn on the globe as circles running in east to west direction.

iv) The length of the equator is the maxim um and it goes on reducing till the pole is only a

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point.

Longitude

Definition:

The distance on the earth‘s surface measures in degrees east and west of a line joining the

geographical north and south poles and passing through Greenwich in England. Greenwich is

at zero degrees longitude.

The sun rays have highest altitude simultaneously on all the places at a particular line of

longitude as a result of which these are also called as Meridians (Meridian is a Latin word

which means Mid-way). Among the latitude, equator is the longest and is taken as reference

line. But all the lines of longitude are of the same length and selecting a longitude as lines of

reference is a serious problem.

Earthquake:

Earthquakes are those movements of the earth crust which make the ground vibrated and

shake backwards and forwards or in simple words an earthquake is trembling in the earth.

The shocks waves are generated at a point within the crust called the focus, and the point on

the earth‘s surface vertically above the focus is called the epicentre of the earthquake. The

shock waves travel in all directions from the focus. On the earth‘s surface, the shaking is thestrongest near the epicentre. These waves are detected by seismograph. 

Occurrence Of Earthquake:

i) Earthquakes occur when rocks subjected to great stress suddenly break, releasing the

accumulated energy, which shakes the ground. Vibrations spread out from the epicentre like

ripples in water.

ii) It may also be caused by movements of the plates, resulting from convection currents in

the hot mantle of the earth. 

iii) Earthquakes are also associated with volcanic activity-eruption of magma. Collapse of

mines can also produce small earthquakes.

Volcanoes:

An opening in the earth's crust through which molten lava, ash, and gases are ejected.

Occurrence Of Volcanoes:

i) Rocks below the Earth have a very high temperature.

ii) The great pressure upon these keeps them in a semi-solid state.

iii) If the pressure weakens, then some of rocks become liquid.

iv) This liquid is called magma.

v) The magma forces its way into cracks of the crust and may either reach the surface of the earth

where it forms lava and flow out.

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Types Of Volcanoes On The Basis Of Activity:

There are three types of volcanoes on the basis of volcanic activity, which are as under.

i) Active Volcanoes:

Volcanoes are said to be active when they frequently erupt or at least when they have erupted

within recent time.

ii) Dormant Volcanoes:

The volcanoes that have been known to erupt and show signs of possible eruption in the future

are describes as dormant volcanoes.

iii) Extinct Volcanoes:

The volcanoes that have not erupted at all in historic times but retain the features of volcanoes are

termed as extinct volcanoes.

Causes of The volcanoes Eruptions:

i) Seafloor spreading

ii) Convergence of lithospheric plates

iii) Percolation of cold water

iv) Orogenic Movements

v) High temperature in the interior of the Earth.

Rocks:

Igneous Rocks:

• The word igneous means the fires and the rocks formed by solidification of molten rock

material known as magma are known as igneous rocks.

• The first minerals to crystalize out of the melt are high-temperature minerals-the olivines and

pyroxenes, which are silicates of magnesium and iron.

• They tend to be denser than magma and so they sink, leaving the remaining fluid deficient in

magnesium and iron.

• The next group of minerals to solidify are the feldspars (silicates minerals of potassium, sodium,

calcium and aluminium); the magma thus loses its metallic constituents first.

• Finally, any remaining silica crystalizes out as quartz.

• The entire solidification process therefore results in dense iron-and magnesium-rich rocks and

less dense silica rich rocks from the same original fluid.

• In this way, different types of rocks can be seen in the same rock mass.

• The most important igneous rocks are: a) Granite rocks b) Gabboro rocks c) Basalt rocks

Sedimentary Rocks:

• Sedimentary rocks are formed from the deposition and compaction or lithification of rocks and

mineral grains derived from other rocks.

• These grains broke away from existing rocks by the action of water, wind and ice.

• Many sedimentary rocks begin their existence as loose deposits of sand or gravel at the bottom

of a sea or lake, on beach, or in a desert.

• 

• Later the sediment is lithified i.e. compressed into a rock.

• Following are the major classes of sedimentary rocks:

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i) Calcareous sedimentary rocks

ii) Carbonaceous sedimentary rocks

iii) Siliceous sedimentary rocks

iv) Ferruginous sedimentary rocks

v) Arenaceous sedimentary rocks

vi) Argillaceous sedimentary rocks

vii) Rudaceous sedimentary rocks

Metamorphic Rocks:

• The word metamorphic has been derived from two Greek words Meta means change and

Morpha means shape. 

• Thus metamorphic rocks include those rocks that have been changed either in form or

composition without disintegration.

• Metamorphic rocks are formed from igneous as well as sedimentary rocks but are different from

them.

• Example:

i) Sandstone, made of quartz grains and silica cement, becomes quartzite, a very hard metaphoric

rock that resist weathering.

ii) Limestone is converted into much denser and harder marble.

iii) Mica, an igneous rock, is converted into schist after metamorphosis.

iv) Sedimentary rock slate is converted into a slightly higher grade metamorphic rock phyllite.

Branches Of Biology:

i) Zoology: Zoology is that branch of biology which deals with the study of animals.

ii) Botany: Botany is that branch of biology which deals with the study of plants.

iii) Microbiology: It is the branch of biology which deals with the study of microorganisms such

as viruses, bacteria etc.

iv) Morphology: It deals with the shape and structure of living organisms.

v) Histology: It is the microscopic study of tissues of plants and animals.

vi) Cytology: It deals with the structure of cell and organelles present inside the cell.

vii) Physiology: It deals with the study of functions of different parts of plants and animals.

viii) Ecology: It is the science of ecosystem and explains the relationship between organisms and

their environment.

ix) Taxonomy: It deals with the naming and classification of organisms.

x) Genetics: It deals with the study of heredity and variations.

xi) Biotechnology: It deals with the application of biological processes.

xii) Haematology: Study of blood and its constituent cells.

xiii) Geology: Study of features and properties of earth and its constituents rocks

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Characteristics Of Living Organisms:

Following are the main characteristics of living beings which are not present in non-living

organisms.

i) Metabolism

ii) Growth

iii) Irritability

iv) Reproduction

v) Movement

vi) Nutrition

vii) Respiration

viii) Excretion

Virus:

• Viruses are the micro-organisms which are strict or obligate parasites of animals or plant

cells.

• Many of the viruses are also parasites on bacteria.

• A large number of viruses cause diseases in plants and animals.

Characteristics Of Virus:

• A virus consists of two components, a protein coat and a core of nucleic acid which is either

DNA or RNA.

• DNA viruses are called adenoviruses and RNA viruses are called retroviruses.

• The shape of a virus is due to its protein coat.

• Viruses are of many shapes i.e. rods, spherical, hexagonal or icosahedral.

• Sometimes their shape is complicated.

• Virus replicate inside a living cell and many viruses are synthesized along with their protein

coats and nucleic acid.

• The nucleic acid contains instructions for the shape of the virus.

Diseases Caused By viruses:

i) Polio

ii) AIDS

iii) Smallpox

iv) Measles

v) Hepatitis

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Bacteria:

Characteristics Of Bacteria:

• Bacteria are unicellular prokaryotic organisms which generally divide by transverse binary

fission.

• They possess rigid cell walls and act as pathogens

• Nucleus is not well organised

• No definite chloroplast, chlorophyll is dissolved in chromoplasm.

• There are three forms of bacteria which are:

i) Round called Cocci

ii) Rod like called Bacilli

iii) Spiral called Spirrila

Classification Of Bactria According To Mode Of Nutrition:

According to mode of nutrition, there are three types of Bactria:

a) Parasitic:

• Devoid of chlorophyll

• Are heterotrophic and get food from living animals and plants

b) Saprophytic

• Lack chlorophyll hence cannot prepare their own food.

• Get food from dead organic remains

c) Autotrophic

• Contain chlorophyll

• Can synthesis food by photosynthesis

• Few get their food by chemosynthesis

Reproduction In Bacteria

i) Vegetative: By Binary Fission

ii) Asexual: By Formation of Endospores

iii) Sexual: By Conjugation

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Cell Division:

The process in which the cells divide and replicate. This process is the basis for growth and

replication. There are two main types of cell division, which are as under:

1) Mitosis

2) Meiosis

Mitosis:

A type of cell division in which a cell divides into two identical daughter cells each having

same number of chromosomes as that of parent cell.

Stages Of Mitosis:

There are four stages of mitosis, which are as under:

i) Prophase

ii) Metaphase

iii) Anaphase

iv) Telophase

i) Prophase:

- Prophase is the first phase of mitosis.

- Chromatin material condenses and becomes visible

- The nucleolus of the cell disappears

- The nuclear membrane also disappears

- Centrioles begin to move opposite ends of the cell

ii) Metaphase:

- Metaphase is the second stage of mitosis.

- Chromosomes line up in the centre of the cell, separate and become a pair of identical

chromosomes.

- The chromatids become uncoiled and apart from each other.

iii) Anaphase:

- It is the third phase of mitosis.

- During this phase each set of chromosomes move towards the opposite end of the cell.

iv) Telophase:

- The fourth phase of mitosis is known as Telophase.

- During this phase spindle fibres disappear.

- Nuclear membrane appears

- Cell divides into two daughter cells

- Nucleolus re-appear

- The chromosomes disperse and are no longer visible.

Significance Of Mitosis:

1. Growth: The number of cells within an organism increases by mitosis and this is the basis

of growth in multicellular organisms.

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2. Cell Replacement: Cells are constantly sloughed off, dying and being replaced by new

ones in the skin and digestive tract. When damaged tissues are repaired, the new cells must be

exact copies of the cells being replaced so as to retain normal function of cells.

3. Regeneration: Some animals can regenerate parts of the body, and productions of new cells

are achieved by mitosis.

4. Vegetative Reproduction: Some plants produce offspring which are genetically similar to

themselves. These offspring are called clones.

Meiosis:

A type of cell division in a cell divides into four daughter cells with having half number of

chromosomes as compared to parent cell.

Characteristics Of Meiosis:

• Takes place in sexual reproduction at the time of formation of male and female gametes

• In animals it takes place during the formation of sperms and ova while in plants during spore

formation

• Diploid cells reduce to haploid cells

• Consists of two consecutive divisions

• First division is reductional or meiotic and the second is simple mitotic division.

Stages Of Meiotic Division:

i) Prophase I

ii) Metaphase I

iii) Anaphase I

iv) Telophase I

v) Prophase II

vi) Metaphase II

vii) Anaphase II

viii) Telophase II

Prophase I:

Prophase I consists of 5 sub stages, these are:

a. Leptotene

- Nucleus increases in size

- Chromosomes become long and uncoiled threads

- They become more visible

b. Zygotene

- Homologue (similar) chromosomes attract each other and form pairs.

- This process is called synapses

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c. Pachytene

- Chromosomes become condensed due to widening of coils

- They form chiasmata i.e. cross each other in double nature or bivalents.

d. Diplotene

- Homologous chromosomes go apart from each other except at chiasmata

- Chromosomes become more short and thicker

e. Diakinesis

- The bivalents become more apart.

- Chromosomes become deeply stained

- Nucleolus and nuclear membrane disappear and spindles become distinct

Metaphase I:

- Chromosomes now rearrange themselves in an equatorial line

- Spindles attach to the centrosome of the chromosomes

Anaphase I:

- Spindles start to contract

- Split the tetrahedral chromosomes into two chromatids and drag them to opposite poles

- Here the reduction takes place.

Telophase I:

- Spitted chromosomes reach to opposite poles

- Nucleolus and nuclear membrane reappear

- At the end of Telophase I, prophase II starts.

Prophase II:

- Chromatin network breaks into bivalent chromosomes

- Nuclear membrane and nucleolus disappear and spindles start to reappear

Metaphase II:

- Bivalent chromosomes rearrange themselves at equator

- Spindles attach to the centrosomes of each chromosome

Anaphase II:

- Spindles contract and split the chromosomes longitudinally into two chromatids

- Each chromatid travel to opposite pole

Telophase II:

- Each chromatid reach to the opposite pole

- Spindles disappear and nuclear membrane and nucleoli reappear

- As a result 4 nuclei are formed

Significance Of Meiosis:

- To allow trait inheritance in offspring

- To maintain diploid number in each generation

- To ensure the production of haploid gametes in sexual reproduction

- To produce genetic variations among offspring

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Classification Of Plants:

Plants are those organisms which contain chlorophyll and synthesize their own food through

photosynthesis. Plants are divided into:

1) Flowering Plants OR Phanerogams

2) Non-Flowering Plants OR Cryptogams

Flowering Plants: 

Flowering plants are those plants which contain seed. These are known as Phanerogams.

They are further subdivided into:

i) Gymnosperms

ii) Angiosperms

Gymnosperms:

Gymnosperms are those flowering plants which contain naked and unprotected seeds.

Examples: Pine, Fir, Cedar, Spruce and Cypress etc.

Angiosperms:

Angiosperms are those flowering plants whose seeds are protected by a fruit or seed pod.

Examples: Grass, Crops, Vegetables, Fruits and weeds.

Non-Flowering Plants:

Non-Flowering plants are also known as cryptogams. These are the plants which do not have

seed or in other words they are seedless. Following are the main characteristics of these

plants:

- They reproduce by spores

- They have long life

- They have no long fibres

- They cannot grow to greater size

- They generally have simple structure, except ferns.

Examples: Moses, Ferns, Algae.

Flower & Its Parts:

The flower is the reproductive part of the plant. It is mainly concerned with formation of

seeds. It is regarded as the modified shoot for the purpose of reproduction.

Parts Of Flower:

A typical flower consists of a short axis known as the thalamus, on which floral leaves are

inserted in four distinct whorls, which are as under:

i) Calyx

ii) Corolla

iii) Androecium

iv) Gynaecium

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Calyx:

Calyx is the outermost whorl of floral leaves called sepals. The sepals can be defined as the

green and leaf like structures which are mainly concerned with the protective function.

Corolla:

Corolla is the second whorl of floral leaves called petals. The petals are beautifully coloured

which are responsible for the attraction to the insects towards them.

Androecium:

The third whorl of the leaves consists of stamens. It is considered as the male part of the

flower.

Gynaecium:

Gynaecium is the inner most whorl of the floral leaves called carpels. It is considered as the

female part of the flower.

Parts Of Plants:

i) Ginger: Modified Stem (rhizome) and it is also a root.

ii) Cinnamon: Bark of stem

iii) Radish: Root

iv) Potato: Stem (tuber)

v) Peanut: Seed

vi) Saffron: Stigma/flower

vii) Almond: Fruit

viii) Chillies: Fruit

ix) Spinach: Leaves

x) Tomato: Fruit

xi) Turnip: Root

xii) Carrot: Root

xiii) Cucumber: Fruit

Photosynthesis:

Definition:

Photosynthesis is a process in which plants manufacture their food (simple carbohydrates) in

the presence of chlorophyll and sunlight by the combination of carbon dioxide and water.

Raw Material For Photosynthesis:

i) Carbon dioxide: Taken from air

ii) Water: Absorbed by roots from soil

iii) Sunlight: From Sun

iv) Chlorophyll: green pigment present in leaves

By-Products Of Photosynthesis:

i) Carbohydrates (simple sugar): used by plants as a food material and excess of it is

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converted into starch

ii) Oxygen: Released into air

Importance Of Photosynthesis:

i) Major process of food production in plants

ii) Utilization of CO2 of the atmosphere and liberation of oxygen

iii) Important in reducing CO2 of the atmosphere which is dangerous for the human beings as

well as animal health.

Pollination:

• It is the process by which seeds are produced.

Definition:

Pollination is the phenomenon of transfer of pollen from male reproductive organ (anther) to

female reproductive organ (stigma) in flowering plants through biological or physical agency. 

Types Of pollination:

There are two types of Pollination

i) Self-Pollination:

In this type of pollination pollens are transferred to the stigma in the same flower. Some

plants are by nature self-pollinated as wheat and grasses.

ii) Cross Pollination:

In this type the pollen grains are transferred from the anther of one flower to the stigma of

another flower. The cross pollination is considered and advantageous to the plant as the seeds

produced by cross-pollination are usually greater in number and the plant germinated from

them are superior in vigour, height and weight.

Vehicles For Pollination:

Vehicles for pollination are animals, water, wind and insects. Therefore cross pollination may

be:

a) Entomophily-by insects

b) Anemophily-by wind

c) Hydrophily-by water

d) Zoophily-by animals

Importance Of Pollination:

• Vital process for reproduction in plants

• Reproduction is carried out by reproductory organs of plants due to pollination

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Fertilization:

The fusion of male and female gametes is called fertilization.

Types Of Fertilization:

Following are the major types of fertilization:

i) External Fertilization

ii) Internal Fertilization

iii) Self-Fertilization

iv) Cross-Fertilization

External Fertilization:

• This type of fertilization is generally observed I simple aquatic animals.

• In such animals both ova and sperms are released into the water where fertilization occurs.

• In terms of evolution external fertilization is of primitive type and is not better biologically as

compared to internal fertilization.

Internal Fertilization:

• In the internal fertilization the females keep ova inside their bodies and males deposit sperms

within the tube of reproductive tacts of females.

• For all land animals internal fertilization is almost must because sperms are quickly killed by

dehydration.

• In terms of evolution internal fertilization is highly evolved and much better biologically as

compared to external fertilization.

Self-Fertilization:

• Self-fertilization occurs within the same animal.

• It is that fertilization in which sperms are used by the ovaries of same animal e.g. Tapeworm

Cross-fertilization:

• Cross-fertilization is the process in which sperms of one animal are transferred into the body of

another animal e.g. Earthworm.

Genetic Engineering:

The deliberate modification of the characteristics of an organism by manipulating its genetic

material.

OR

Scientific alteration of the structure of genetic material in a living organism. It involves the

production and use of recombinant DNA and has been employed to create bacteria that

synthesize insulin and other human proteins.

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Significance Of Genetic Engineering:

i) To Cure the genetic disorders

Heredity diseases can possibly be treated by this technique by transplanting normal genes in

the place of abnormal or diseased genes.

ii) To Prepare Better Crops

Crops with desired characteristics could possibly be produced by introducing desired genes.

iii) To Get Better Breeds Of Animals

Like plants better breeds of animals can also be produced by the introduction of recombinant

DNA.

iv) Interferon

Interferons are effectively used in the treatment of Hepatitis of A & B.

v) Insulin

Human insulin is being produced by genetic engineering to treat diabetes

vi) Vaccines

Genetic engineering has also helped in the production of vaccines which are used for

controlling and treating viral diseases.

Biotechnology:

The exploitation of biological processes for industrial and other purposes, esp. the genetic

manipulation of microorganisms for the production of antibiotics, hormones, etc.

OR

Biotechnology is the use of living organisms (especially microorganisms) in industrial,

agricultural, medical and other technological applications.

Importance Of Biotechnology:

i) To increases production

ii) To introduce improved quality of seeds and plants

iii) To introduce plants resistant to disease and insect pests

iv) To introduce verities suited to particular climates and soils.

v) To introduce verities resistant to lodging

vi) To improve nutritional value of crops

vii) To save rare varieties of plants by rapid clonal propagation for breeders to use in future.

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Teeth:

The humans have two sets of teeth one replaced by the second. The primary set or milk or

deciduous teeth are 20 in number while there are 32 permanent teeth in adults.

1. In children there are 20 deciduous or milk teeth. These are

Incisor: 2 pair × 2= 8

Canine: 1 pair × 2= 4

Premolars: 2 pair× 2=8

2. In adults there are 32 permanent teeth. In each jaw on each side there are:

Incisors: 2 pair × 2=8

Canines: 1 pair × 2=4

Premolars: 2 pair × 2=8

Molars: 3 pair × 2= 12

Incisors:

The central front teeth are called incisors. There are four in upper jaw and four in lower jaw.

Canines:

The pointed, dark colored teeth on either side of the incisors are canines. 2 in upper jaw and 2 in

lower jaw.

Premolars:

These are bi-cusped teeth after the canines. There are 8 premolars. 4 in the upper jaw and 4 in the

lower.

Molars:

There are 12 molars, 6 in the upper jaw and 6 in the lower jaw.

Structure Of Teeth:

Each tooth consists of a crown which is the visible part and the root, which anchors it in sockets

in the jaw. A tooth consists mainly of dentine. The crown is coated with even harder enamel,

while the root is covered with cementurn to help another it in the jaw. Inside each tooth, there is a

cavity full of pulp, carrying nerves and the tooth‘s blood and eats through the dentine to the pulp

when the decay reaches the pulp, pain and inflammation follows and tooth may die.

A nerve, an artery, a vein and lymph duct enters the pulp cavity through the root canal. The

nerves give sensation of hot and cold.

Antibody:

Antibody is a protein produced by white blood cells that help to destroy bacteria. Antibodies

react with the antigens and inactivate or destroy them. A large number of antibodies are

produced in blood which are targeted against various types of antigens. Antigens are foreign

molecules, cells, bacteria, viruses or fungi which enter the body usually a disease causing

microorganisms. Antibodies are the integral part of the defence mechanism of human body.

They are also involved in immunity against disease.

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Hemophilia:

• It is a disease in which the peron have prolonged blood clotting time resulting in excessive

bleeding fron injury.

• It is due to the deficiency of vitamin K.

• It is a semilethal disease controlled by recessive gene.

• It is less common in women than in men.

Important Facts About Human Physiology:

The largest gland of the body: Liver

The largest organ of the body: Skin

The longest bone of the body: Femur

The total number of bones in the body: 206

The hardest bone of the body: Tooth

The smallest bone of the body: Stapes

Total number of muscles in the body: 600

The filter of the body: Kidney

The pump of the Body: Heart

Total number of bones in vertebral column: 33

The normal body temperature: 98.4 F (37 C)

The normal respiratory rate of the Body: 16-18 per min

The total volume of blood in body: 4-5 litres

Total number of bones in face: 14

Vascular connection between foetus and uterus: Placenta

Brain:

Human brain is contained in skull. It has three major parts.

i) The Cereberum ot bigger brain

ii) The Cerebellum or Smaller brain

iii) Medulla Oblongata or hind brain

The cereberum constitutes the major volume of brain. It consists of two large masses of

nervous material known as cereberal hemispheres. Human consciousness, thought, emotions,

sight, will, hearing, sensation of pain, memory and speech are centere in the creberum. Some

parts of it also control motor nerves, operating the arms and legs.

The cerebellum or the smaller brain is related with the coordination of action of nerves and

muscles. In this way movements of body are manged. Medulla or hind brain contains the

centres for reflex actions in addition to automatic movements such as breathing and walking.

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Reflex Action:

- Reflex actions are the responsed to environmental changes both internal and external and are

immediate or automatic and are without intervention of will.

- These reflexes amy be simple or conditioned e.g. watering of mouth on seeing or smelling of

food.

- Simple reflexes are inborn, inherited or unlearnt responses to stimuli.

- The structural and functional basis of simple reflex is called reflex arc.

- Impulses are carried from receprtors to sensory neurons to CNS from where they are passed on

via motor neurons to the effectors for necessary response.

Thermoplastics:

Substances (esp. synthetic resins) that become plastic on heating and harden on cooling and

are able to repeat these processes

OR

A type of plastic that can be softened by heat, hardened by cooling, and then softened by heat

over and over again.

Properties of Thermoplastics:

Thermoplastics have wide ranging properties. 

- They can be very much like rubber, or as strong as aluminium. 

- are light in weight, 

- Can withstand temperature extremes of up to 600 F, while others retain their properties at -100 F. Some 

- Thermoplastic materials have no known solvents at room temperature. 

- Most thermoplastic materials are excellent insulators, both electrical and thermal. 

- Are recyclable materials that are used frequently today to create objects such as foam cups,

polyethylene squeeze bottles, acrylic lenses and safety helmets.

- In general the combination of light weight, high strength, and low processing costs make

thermoplastics well suited to many applications.

Uses:

- They are useful for a variety of applications, including consumer goods, machine parts,

medical equipment and packaging and storage materials.

Examples:

• PVC/Vinyl

• Polystyrene

• Polyethylene

• Cellulose Acetate

• PTFE/Teflon

• Nylon/Polyamide

• Polyester

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Synthetic Polymers:

Polymers are composed of very large molecules (macromolecules) formed by linking together

many smaller, more simple units called monomers. There can be as few as five or as many as

several thousand monomers units in a polymer. There are a large number of synthetic polymers

prepared and in use. Some of these are polyamides(nylon), polyethylene, propylene,

polyvinylchloride, synthetic rubber, cellulose acetate, cellulose nitrate and silicones.

Heredity:

Terminology Of Genetics:

Gene:

The basic unit of hereditary material which is responsible for development of a trait.

Alleles:

Alternatives forms of genes are called alleles, e.g. tall versus dwarf.

Dominant:

The dominant alleles are those traits which show complete expression even in heterozygous state.

Dominant alleles dominate the recessive alleles in heterozygous state.

Recessive:

Recessive alleles or traits are those which fail to express themselves in heterozygous state. For

example r and y are recessive alleles for wrinkle and green seeds.

Homozygous:

Homozygous is a condition in which an individual possess similar alleles for a particular trait. For

example TT for tallness and tt for dwarfness.

Heterozygous:

Heterozygous is a condition in which an individual possess dissimilar alleles for a particular trait.

For example Tt for tallness.

Genotype:

Genetic make of an organism is called genotype. 

Phenotype:

External appearance or expression of genotype is called phenotype. For example, roundness,

wrinkleness of seeds and tall or dwarf plants represent different phenotype.

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Gene:

Definition:

The fundamental unit of heredity, formed as a sequence of bases in DNA.

Characteristics Of Genes:

• Each gene has a definite position at the chromosome and may occur as alleles.

• The name gene was introduced by Johannsen in 1909 and the structure of DNA was elaborated

by Watson and Crick in 1953.

• Genes determine all the structural and functional characters of an individual, like eye colour,

skin colour, height, weight, blood group, hair, intelligence, temperament and all others.

• The characters from one generation to other are taken by genes. 

• They sometimes change through the process of mutation. This gives variety in characters.

• The accurate structure of the proteins and enzymes in the body is determined by genes.

Chromosomes:

A chromosome is a rod-like portion of the chromatin of a cell nucleus, performing an important

part in meiotic cell division, and in the transmission of heredity characteristics. Normally they are

constant in number for any species; there are 22 pairs of chromosomes and two sex chromosomes

in the human.

Types Of Chromosomes: in higher animals and plants, there are two fundamental types of

chromosomes, which are classified on the basis of sex determination these are:

i) Autosomes

ii) Sex Chromosomes:

Autosomes:

These are paired somatic chromosomes that play no part in sex determination of organisms.

These chromosomes are similar in males and females.

Sex Chromosomes:

The chromosomes that determine sex in organisms are called sex chromosomes. There are two

types of sex chromosomes.

a) X- chromosome

b) Y- Chromosome

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Animals:

Types Of Animals:

i) Invertebrates: Animals having no backbone or vertebral column.

ii) Vertebrates: Animals with backbone or vertebral column.

Classification Of Invertebrates:

The invertebrates are classified into following categories:

i) Phylum Protozoa

ii) Phylum Porifera 

iii) Phylum Coelentrata

iv) Phylum Platyhelminthes

v) Phylum Nematode

vi) Phylum Annelida

vii) Phylum Mollusca

viii) Phylum Arthropoda

ix) Phylum Echinodermata

Following are the most common examples of invertebrate animals with their relative phyla:

- Euglena: Phylum Protozoa

- Paramecium: Phylum Protozoa

- Amoeba: Phylum Protozoa

- Sponges: Phylum Porifera

- Hydra: Phylum Coelentrata

- Jelly fish: Phylum Coelentrata

- Tapeworm: Phylum Platyhelminthes

- Ascaris: Phylum Nematode

- Hookworm: Phylum Nematode

- Filaria: Phylum Nematode

- Snails: Phylum Mollusca

- Squids: Phylum Mollusca

- Cockroach: Phylum Arthropoda

- Honey bee: Phylum Arthropoda

- Mosquito: Phylum Arthropoda

- Butter fly: Phylum Arthropoda

Classification Of Vertebrates:

Vertebrates have been divided into following five major classes:

i) Fishes

ii) Amphibians

iii) Reptilian

iv) Birds

v) Mammals

Some Animals & Their Location

i) Blue whale: Found in all oceans

ii) Panda: China

iii) Dolphin: In seas

iv) Porpoises: 

v) Kangaroo: Australia

vi) Snow Leopard: Central Asia

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vii) Yak: Central Asia

viii) Llama: South America

ix) Ibex: Wild mountain goat

x) Cobra: South Asia

xi) Alligator: N.America

xii) Tortoise: Water

xiii) Rattle Snake: America

xiv) Lizards: 

xv) Crocodiles:

xvi) Ostrich: Deserts Of Africa

xvii) Penguin: Antarctic Region

xviii) Kiwi: New Zealand

xix) Rhea: South America

xx) Emu: Australia

xxi) Shark: Found in all oceans

xxii) Trout: Fresh water fish

xxiii) Cod: 

Scavenger:

Scavengers are the animals that ‗Clean up‘ after the other animals by consuming their leavings and

sometimes prey on sick or dying animals or consume dead bodies. Scavengers are also called detritus

feeders. Vultures, coyotes, jackals, hyenas and wild dogs are scavengers which eat the left over prey or

dead bodies of hunted animals.