Download K.L.S Science Preparatory 2 First Term 2013

K.L.S
Preparatory 2
Science
First Term
2013-2014
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K.L.S
Preparatory 2
Science
First Term
Unit 2
The atmospheric layers
Lesson 1
Atmospheric envelope of the earth:
It is a gaseous envelope rotating with the Earth around its
axis and it extends about 1000 km
above the sea level.
Earth
Atmospheric envelope
To understand what’s meant by
? atmospheric pressure
When you stand on the floor, you exert a force against the
floor. The pressure you exert is your body weight divided by
the surface area under your feet or shoes, so pressure
equals
Pressure = force (weight) ÷ area
But what about atmospheric pressure:
Atmospheric pressure:
It is the weight of air column of an
atmosphere height on a unit area.
 The atmospheric pressure is
measured by a unit called a bar
(1
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bar = 1000 millibar)
K.L.S
Preparatory 2
Science
First Term
The atmospheric pressure at sea level is called normal atmospheric
pressure and it equals 1013.25 mb.
Atmospheric pressure differs from one place to another
according to some effects; one of these effects is the change
of height from sea level.
 Study the following figure to understand how
atmospheric pressure will differ from place to another:
A
B
Sea Level
 As the elevation above the sea level decreases, the
atmospheric pressure increases due to increasing the length of
air column.
 As the elevation above the sea level increases, the
atmospheric pressure decreases due to decreasing the length of
air column.
The measuring instrument of atmospheric pressure:
The atmospheric pressure is measured by
instruments called barometers.
1.
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Aneroid.
K.L.S
Preparatory 2
Science
First Term
2.
Altimeter.
 In airplanes, pilots can determine the elevation from sea
level by altimeter.
3. Isobar.
It is the curved lines that join the points of equal pressure in
atmospheric pressure maps.
Layers of atmospheric envelope:
Atmospheric envelope is divided into several
layers according to the changes in the atmospheric pressure and
temperature.
First layer: Troposphere
It means the disturbed layer where most of the weather
changes occur in this layer.
Characteristics of the troposphere:
1)-It extends 13 Km above sea level to the tropopause (the
region between troposphere and stratosphere where the temp.
remains constant).
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Preparatory 2
Science
First Term
2)-As we go up, the temp decreases by a rate of 6.5⁰C per 1 Km
height – until it reaches the lowest value of about -60⁰C at
tropopause.
3)-Atmospheric pressure decreases as we go up, where it
reaches about 0.1 of the normal pressure at sea level.
4)-It contains about 75% of the atmospheric mass.
This explains why all atmospheric phenomena like rain, wind,
clouds occur in this layer.
5)-It contains about 99% of the atmospheric water vapor.
6)-The air movement in this layer is vertical (the warm air
currents go up and the cold currents go down).
Example:
If the temp at the base of Mount Everest is 20.6⁰C, how much
is the temp at its top if the mountain height is
8862 m?
Solution:
The decrease in the temp = height x 6.5⁰C
The decrease in the temp =
x 6.5 = 57.6⁰C
Temp at the top = temp at the base – the decrease in the temp.
Temp at the top of the mountain = 20.6 – 57.6 = -37⁰C
Second layer: Stratosphere
Characteristics of the stratosphere:
1)-It extends from 13Km to the stratopause 50 Km.
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Preparatory 2
Science
First Term
2)-At the lower part, the temp. is constant at -60⁰C then
increases gradually until it reaches 0⁰C at the end of this layer.
This is due to the presence of ozone layer which absorbs the
ultraviolet radiation.
3)-Ozone layer is concentrated between 20 - 40 Km above sea
level.
4)-The atmospheric pressure decreases on going higher until it
reaches (0.001 of the normal pressure at sea level) at the end
of this layer.
5)-Pilots prefer to fly their planes in this layer.
Because the lower part does not contain clouds or weather
disturbances and the air movement is horizontally making it
suitable for flying.
Third layer: Mesosphere:
1)-It means the middle layer – it is the coldest layer.
2)-It extends from 50km to 85 Km with thickness 35 Km.
3)-Temp decreases with height and reaches -90⁰C at its end.
4)-This layer is much vacuumed.
Because it contains only a limited amount of Helium and
Hydrogen gases.
5)-Meteors burn in this layer due to friction with air molecules.
Fourth layer: Thermosphere:
Characteristics of the Mesosphere:
1)-It means the heated layer as it is the hottest layer.
2)-It extends from 85 km to 675 km with thickness 590 km
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Preparatory 2
Science
First Term
3)-Temp increases rapidly with going higher until it reaches
1200⁰C at its end.
4)-Its upper part contains charged ions, so it called ionosphere.
5)-Ionosphere layer plays an important role in wireless
communication and broadcasting.
Because: it reflects radio waves transmitted by radio stations
and communication centers.
6)-Ionosphere is surrounded by two magnetic belts known as
(Van-Allen) belts – these belts play an important role in
dispersing the harmful charged cosmic
radiation away from the Earth.
Aurora phenomenon:
This phenomenon appears as brightly colored light curtains at
both North and South poles of the Earth.
Exosphere:
It is a region in which the atmosphere envelope is inserted with
outer space
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K.L.S
Preparatory 2
Unit 2
Science
First Term
Erosion of ozone layer and global warming
Lesson 2
Since the twentieth century, the Earth faces two dangerous
phenomena:
First: Erosion of ozone layer phenomena:
Question
What is meant by ozone layer?
Formation of ozone layer
1 – Oxygen gas molecule O2 absorbs ultraviolet radiation (UV) ,
which causes the breakdown of the double covalent bond
between the two oxygen atoms
O2
UV
O +
O
2 – Each oxygen atom combines with O2molecule forming Ozone
molecule O3
O +
O2
O3
(ozone molecule)
3- Ozone layer is formed in the stratosphere, and is located at a
height between 20:40 km above sea level.
The importance of ozone layer:
Why
1.
Ozone layer is act as a protective shield for living
organisms.
Because ozone layer does not allow penetration of all far and
medium ultraviolet radiation, which have very harmful effects.
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K.L.S
Preparatory 2
?
Science
First Term
Look at the opposite figures and explain them:
From the figure, we observed that:
100% of far UVC rays don’t penetrate ozone layer – 95% of
medium UVB rays don’t penetrate ozone layer - 100% of near
UVA rays penetrate ozone layer.
But according to the formation of ozone layer hole, it is dangerous
to enter far and medium ultraviolet rays because they are harmful
rays.
Harmful effects of far and medium ultraviolet radiation:
Organisms
Effects
Living organisms Harmful effects
Human
Skin cancer – cataract – weakness of immunity
Amphibians
Spoil eggs – decreasing rate of reproduction
Marine organisms Death of plankton (food of small animals) – destroying the
marine food chains.
Terrestrial
Upset the photosynthesis process – shortage of crops
plants
production
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K.L.S
Preparatory 2
?
Science
First Term
What is meant by erosion of ozone layer?
It means that the thickness of ozone layer will decrease
from its normal thickness (losing a part of ozone layer).
Example Original thickness
percentage
300
Today thickness
150
Erosion
50%
Erosion of ozone layer:
The English Scientist Dobson assumed that the thickness of O3
layer is 3mm only if it were under the normal pressure and 0⁰C
temp. (STP) standard temp and pressure.
He assumed that the natural amount of ozone equals 300
Dobson units.
Example:
What is the ratio of erosion of the O3 layer in an area if you
know that the degree of its O3 is 150 Dobson?
Solution
The ratio of erosion =
= 50%
Pollutants of ozone layers:
1– Chlorofluorocarbon compounds CFC (Freon):
Used as a cooling materials in air conditions sets - as propellant
of aerosols – as inflating material in making foam – as solvent
for cleaning electric circuit slides.
2– Methyl bromide:
Used as insecticide to preserve stored agricultural crops.
3– Halons: Used in fire extinguishers
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Preparatory 2
Science
First Term
4– Nitrogen oxides: Resulted from burning of fuel in airplanes.
Effect of CFC compounds on the ozone layer:
Erosion of ozone layer by CFC compounds takes place through 3
steps:
1 – UV radiation break down the CFC compound and Cl atoms are
produced.
CFCl3
UV
CFCl2 + Cl
2 – Chlorine atom reacts with ozone molecule forming chlorine
monoxide.
Cl + O3
O2 + ClO
3 – Chlorine monoxide reacts with other ozone molecule and
produce other active chlorine atoms.
ClO
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+
O3
202 + Cl
K.L.S
Preparatory 2
?
Science
First Term
How can you protect ozone layer?
Protecting of ozone layer:
1)-Using of CFC compounds must be reduced and find safer
alternatives.
2)-Stop producing the ultrasound concord planes because their
exhausts affect the ozone layer.(according to the
recommendation of Montreal protocol)
Second: Global Warming Phenomena:
It is the continuous increase in the average temp. of the Earth’s
near-surface air
Proof of global
warming:
From the graph that the average
temperature of air close to the
Earth increases.
To understand the global warming, study the green house
phenomena
Green house phenomena:
1)-Greenhouse gases play the role of glass in the greenhouse.
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Preparatory 2
Science
First Term
2)-They permit the visible light and the short-waved radiation
from the sun to pass to the Earth.
3)-The Earth absorbs these rays and reemits the radiation back
in the form of infrared radiation which has a thermal effect.
4)-The infrared radiation cannot penetrate the atmospheric air
because it has a long wavelength – So it is kept trapped in the
troposphere causing the rise of planet Earth temp.
The most important green house gases:
1)-CO2: its ratio increased to 0.038%
2)-CFC compounds.
3)-Methane gas CH4.
4)-Nitrous oxide N2O.
5)-Water vapour H2O
The negative effects of global warming:
1 – Melting of polar ice which
threats coastal areas – extinction
of some polar animals like polar
bear and seals.
2 – Severe climate changes
Tropical hurricanes - Destructive floods Drought waves – Forests fire
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K.L.S
Preparatory 2
Science
First Term
Fossils
Unit 3
Lesson 1
Fossils:
They are traces and remains of old living organisms that are
preserved in sedimentary rocks.
(Trace)
(Remain)
Fossils may be traces or remains of living organisms.
Traces: Indicate the activity (moving – food – life cycle) of
old living organisms.
Examples:
1.
Worm’s tunnels
2. Dinosaur’s foot print
Remains: They are remains of old living organisms
Examples:
1.
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Remains of a shark‘s teeth.
2. Remains of a dinosaur’s
skull
K.L.S
Preparatory 2
Science
First Term
1)-Fossil of complete body:
2) Cast
3) Mold
4) Petrified fossils.
1)-Fossil of complete body:
It was formed when the organism died and was buried (whole
body) fast in a medium that preserved it from
decomposition.
Examples:
Story:
A)-Mammoth fossil:
A snow becomes more from 25000 years ago, caused the death
and burying of mammoth, when the first mammoth discovered,
they found that it was complete as the whole shape, hair, tissues
and even the food in its bowels.
B)-Amber fossil:
Story
:
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Old, there are pine trees and these trees secreted
resinous (sticky) matter, this matter covered insects and
after sticky matter had been solidified it was changed into
amber and preserved the bodies of these insects from
decaying.
K.L.S
Preparatory 2
Science
First Term
2)-Cast:
It is a type of fossil that indicate the internal details of a
skeleton of once an old living organisms.
Examples:
1)-Ammonites cast.
2)-Nummulites fossil.
3)-Trilobite fossil.
How is cast fossil formed?
(Formation of ammonites cast)
Steps: 1)-When a small shell (calm) dies, it falls on the sea
and is buried in sediments.
2)-The sediments fill up the shell cavities and are solidified
as the time passes.
3)- The shell could decompose completely, leaving a rock cast
carrying the internal details of the snail.
3)-Mold:
It is a type of fossil that indicate the external details of a
skeleton of old living organisms.
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Preparatory 2
Science
First Term
Examples:
1)-Mold of ferns.
2)-Fish mold.
To make a model of a mold:
Steps
1)-Bring clay and
press by your hand
to soft it.
2)-Put the shell on
the surface of the
clay and press it.
Observation
The external
shape of the shell
print on the clay.
Conclusion
The details formed
on the clay are the
external surface of
shell.
4)-Petrified fossils:
It is a type of fossil that the
minerals replace the organic matter for organism part by
part leaving the shape without any change.
Examples:
1)-Dinosaur’s tooth.
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2)-Dinosaur’s egg.
K.L.S
Preparatory 2
Science
First Term
3)-Petrified wood.
They are fossils which are formed as a result of replacing
the organic matter of wood by the silica part by part and
they give us details about the life of old
plant.
Importance of fossils:
Fossils are important because they help in:
1)-Age of determination of sedimentary rocks.
Fossils indicate the age of sedimentary rocks because the
age of rocks is the same age of fossils existed in them.
2)-Figuring out the paleoenvironment.
Fossils give an idea about the environment and also they
indicate the climate of these ages.
Examples:
A)-Nummulites fossils: They are found in Gebel ElMokattam and indicate a sea floor in these areas.
B)-Ferns fossils: They indicate the environment that it was a
hot and rainy tropical environment.
C)-Coral fossils: They indicate the environment that it was
clear warm shallow seas.
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K.L.S
Preparatory 2
Science
First Term
3)-Studding life evolution.
Fossils indicate the extinction and evolution of organisms.
Examples:
Fossils indicate that Life started in the sea then on the land
Also algae appeared before mosses and ferns.
Also, Angiosperms appeared before gymnosperms.
Also, Invertebrates appeared before vertebrates.
The first vertebrate to appear was the fish followed by
amphibians and reptiles.
4)-Petroleum exploration.
When searching for petroleum, geologists take samples from
the rocks of the wells. If the samples contain foraminifera
and radiolaria, then this is a good indication for petroleum
formation.
1)-Presence of hard skeleton of organism.
2)-The organism body must be buried immediately after
death.
3)-The existence of a suitable medium.
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K.L.S
Preparatory 2
Science
First Term
Extinction
Unit 3
Lesson 2
Extinction
It is the continuous decrease without compensation in the number
of certain species of living organisms until all members of species
die out
The moment of extinction
It is the date of death of the last
individual of that species.
Studying fossil record shows
Q
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1.
The terrestrial life appeared 570 million years ago.
2. Some species flourished and then they suffered from
rapid decrease in number until they become extinct.
3. 98% of organisms appeared and become extinct before
man. (dinosaurs)
4. The ratio of living organisms now only about 2% of the
total species that have appeared since established of the
earth.
5. Fossils of some living organisms aren’t similar to their
living counterparts now.
What are the reasons which lead species of living organisms
to extinct?
K.L.S
Preparatory 2
Science
First Term
Factors causing extinction of species
Most of the species became extinct followed by appearance of
another more evolved types
Some scientists believe that we live the 6th extinction age
where the rate of extinction is 40 times larger than the normal
rate of extinction
So, we are going to classify the factors into old factors and
recent factors:
1. Causes of old extinction
1.
2.
3.
Meteors impact with earth.
Onset of glacial age.
Emission of poisonous gases from active volcanoes.
2. Causes of recent extinction
a)- Destroying natural habitat.
b) - Overhunting.
c) - Environmental pollution.
d) - Climate changes and natural disasters.
a)-Destroying natural habitat

Tropical forests include about 1/3 of the terrestrial living
organisms

Each tree forms a shelter for more than 300 species

Overcutting the trees destroy the habitat of these species

Scientist estimate that we lose about 68 species of trees
every day
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K.L.S
Preparatory 2
Science
First Term
b)-Overhunting
It is one of the important causes of extinction of hundreds of
mammals and reptiles due to:

The absence of laws that control wild animal hunting at the
beginning of 20th century

The development of the hunting weapons

The increase rate of interest of animal skin and fur.
C)-Environmental pollution

Acidic rains destroy forests.

Chemical insecticide breaks down the food chain.

Oil leaks in oceans and seas cause the death of marine
birds.
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Preparatory 2
Science
First Term
D)-Climate changes and natural disasters
Drought – Tornadoes - Floods - Lightning& Torrents storm –
Earthquakes-Volcanoes- Tsunami waves.
First: The extinct species
Hundreds of millions organisms of old times became extinct.
The most recent types are:
1. Dodo bird
It is non flying bird ,Small sized wings,
Short legs
Extinct in 1681 in the Indian islands
It is an easy target for hunters due to the reduced wings
(non flying bird) as it cannot run fast.
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K.L.S
Preparatory 2
Science
First Term
2. Quagga
It is mammal; it is the midway between horse
and zebra.
The last one was killed in South Africa by
hunters in 1883.
3. Passenger pigeon
The last member of its species died in
one of the zoos in 1914 due to:

The cutting the oak and beech trees
where they used to build their nests.

Mass hunting of the bird and the
female lays only one egg each spring.
4. Australian wild cat

This animal has a wolf’s head, dog’s
tail, and a pouch like a kangaroo and a
striped skin like a tiger.

It was hunted by peasants because
it preys on sheep and chickens.

The last member was died in Sidney zoo Australia in
1936.
5. Golden frog
It has disappeared since May 1989.
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K.L.S
Preparatory 2
Science
First Term
Second: The endangered species
There are about 5000 endangered species and they are being
followed up and their state is under investigation.
1. Panda bear
It lives in the Bamboo forests in china.
It is one of the most endangered
species due to:

Its weak rate of reproduction.

And the scarcity of bamboo plant
which doesn’t blossom except once every 100 year.
2. Rhinoceros
It is endangered because

Its habitat is being transformed
into cultivated land

It is being over hunted for using
its horn for medical purposes.
3. Bald eagle

Its head is covered with white
feather which makes it looks bald.

It is endangered because it feeds
on fish contain poisonous matter that
being dumped in lakes and rivers.
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K.L.S
Preparatory 2
Science
First Term
4. Ibis bird
It disappeared from Aswan after the
building of the High Dam due to loss of its
nests.
It must be imported back to reproduce its species in the
protectorates established in the Nile islands in Aswan.
5. Papyrus plant

Grow in swamps of the upper Nile.

The pharaohs used it to manufacture
writing papers.

It disappears due to the drying of these swamps.

It is now reproduced in Pharaonic Village in Giza.
E
a
c
h living organism plays a role in transferring the energy
through the food chain
When an organism disappears its role stops affecting the
rest of members of the food chain or food web
Extinction of species or group of species in a balanced
ecosystem causes a cavity (gap) in the ecosystem that would
disturb the ecosystem equilibrium or destroy it.
Ecosystems can be classified according to the degree of
effect of extinction on it into:
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K.L.S
Preparatory 2
Science
First Term
1. Simple ecosystem
It is severely affected by the absence of one of its species
because of the rarity of alternative that compensates this
absence.
Example
Desert ecosystem
2. Complicated ecosystem
It is not affected much by the absence of one of its species
because it has many alternatives.
Example
Tropical forest ecosystem
The best ways to protect rare and endangered living organisms
are shown as the following:
1.
Issuing legislation and rules to organize and control
hunting especially for rare types.
2. Increase the awareness about the importance of natural
life to sustain the existence of mankind.
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K.L.S
Preparatory 2
Science
First Term
3. Tearing and reproducing the endangered species and
sending them back to their native habitats
4. Establishing gene banks for those much endangered
species
5.
Establishing natural protectorate areas.
Examples of natural protectorates
1.
Bluestone protectorate: in USA for grey bear.
2.
Panda protectorate :in china for Panda bear
3. Ras Mohamed protectorate : in South Sinai Egypt for
rare species of coral reefs and coloured fish and numerous
of rare plants and animals.
4. Wadi hetan: it is a part of wadi elrayan protectorate in
Fayoum it contains complete whales skeletons fossils that
are dated to be as old as 40 million years.
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