By Mwanza Matthews
GRADES 8 AND 9 INTEGRATED SCIENCE
HUMAN BODY
1. (1) Identify organs of the human reproductive system.
 Male: testes, sperm duct, scrotum, urethra and penis.
Front view

Side view
Female: ovaries, oviduct, uterus, cervix, virginal.
Front view
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Side view
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(2) Explain the functions of the parts of the reproductive system.
Males


Penis Testes -

Scrotum


Epididymis
Sperm duct

Urethra
depositing sperms into the vagina
producing the sperm cells and the male sex hormone,
Testosterone.
skin sac that holds the testes outside the body to
Keep them cooler than the body temperature.
Long, coiled tube that stores sperm cells.
tube that transports sperm cells from the testes to
The urethra
tube that transports the semen through the penis and
Urine from the bladder to the outside of the body.
Females:


Ovary
Cervix
-


Oviduct
Vagina
-

Uterus
-
producing the ovules (eggs)
lower narrow end of the uterus where it joins the
Vagina.
where fertilization occurs
it accepts the penis during copulation and is the
Birth canal for the feotus during normal child birth.
where the embryo develops during pregnancy.
(3) Identify changes associated with puberty for both male and female.
Males:
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pubic hair grows at the base of the penis
the penis enlarges
the testicles grow
wet dreams
chest enlarges
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Females:
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The breasts grow
Pubic hair appears on the vulva
Hair grows in the arm pit
The body grows in height
The hips become wider.
The first menstruation occurs
(4)Explain the importance of observing personal hygiene of the reproductive organs.
 Avoids inflections
 Avoids diseases
(5)Describe the process of fertilization in human beings.
 Fertilization is the fusion of the sperm and an egg (ovum) in the oviduct to
form a zygote. Contact between sperm and ovum makes the sperm to
release enzymes which break through the wall of the ovum. A small path
is created that allows the head of the sperm to enter the ovum. The nucleus
of the sperm and the nucleus of the ovum then fuse (i.e. fertilization).
 Once fertilization has occurred, the wall of the ovum becomes thickened
to prevent further entry of another sperm. The zygote formed during this
process contains information from both the mother and the father.
(6)Explain the functions of the parts important for development of the embryo.
PLACENTA
 Allows the nutrients to pass from the maternal blood into the foetal blood
 Allows the waste products to pass from foetal blood to the maternal blood
 Allows carbon dioxide to pass from foetal blood to the maternal blood
 Allows oxygen to pass from the maternal blood to the foetal blood
AMNION

This membrane ensures that the liquid that surrounds the developing
embryo/ foetus does not drain away.
UMBILICAL CORD

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This cord transports blood from the embryo /foetus to and from the
placenta.
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AMMINIOTIC FLUID

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This fluid allows the foetus to move freely inside the uterus while it is
still developing
It ensures that the development of the foetus will be normal and that
the foetus will have symmetrical growth
protects the foetus from mechanical shocks (being bumped)
Protects the foetus from dehydration.
(7) Describe Gestation period and Birth.
Gestation period

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

Gestation period is the period of foetal development in the uterus
until birth. In humans the average length of the gestation period is
266 – 270 days (38 – 38.5 weeks) or 9 – 9.5 months.
Stages of embryo development, that is, zygote – embryo - foetus and
baby.
Birth
Birth happens at the end of a pregnancy when one or more newborn
infants are pushed out from a human’s uterus.
The stages of birth are:
- The dilation and shortening of the cervix.
- The descent and birth of the infant.
- The expulsion of the placenta.
HEALTH – NUTRITION
1.
Describe the different types of food nutrients.
 Carbohydrates: a food type that can be broken down to release
energy; also known as starch.
 Protein:a food type that contains nitrogen; they make up the
structural parts of body cells and tissues.
 Lipids: a food type that includes fats and oils.
 Minerals salts: inorganic substances which are essential in small
amounts in a person’s diet for good health.
 Vitamins: an organic substance that is essential in small amounts in a
person’s diet for normal growth and good health.
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2. Describe the dietary needs for different persons
 Baby
more proteins and mineral salts
 Pregnant Mother more proteins, calcium, lron and vitamins D.
3. Identify common nutritional deficiency diseases of symptoms and their diseases
Kwashiorkor
Symptoms
 Hair Loss
 Swollen stomach
 Swollen ankles, feet and hands
 An enlarged fatty liver
 Diarrhea
 Anemia
 Loss of teeth
 Loss of skin colour
 Loss of appetite
Marasmas
Symptoms
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Swollen stomach
Dry skin
Loose skin folds
Extreme hunger
General tissue and muscle wasting

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Aching bones
Dental problems
Muscle weakness
Rickets
Symptoms
Scurvy
Symptoms
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Tiredness
Spongy gums
Bleeding from the mucus membrane
Pale skin
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
Depression
Anaemia
Symptoms
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Pale yellow skin
Weakness
Hair loss
Fainting
Missed menstrual cycle
Depression
Mouth ulcers
4. Describe the importance of children’s clinics.
 For nutrition, growth and monitoring.
 Providing immunization
 Providing nutritional advice
ENVIRONMENT
WATER, AIR AND LAND POLLUTION
1. Explain what pollution is.
 Pollution is addition of harmful substances to the environment.
2. Identify different types of pollution to the environment.
 Water pollution
 Air pollution
 Land pollution
3. Identify causes of pollution to the environment
Water pollutionCauses



Untreated sewage
Washing clothes in rivers and streams,
chemicals from factories and farm land
Air pollution
Causes


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Smoke, dust, fumes
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Land pollution
Causes
 Garbage, effluents from factories
4. Describe the effects of pollution in the environment
Water pollution
 Outbreak of diseases
 Poisonous
 Effects aquatic life
Air pollution

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Breathing difficulties
Global warming
Acidic rain
Land pollution
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Outbreak of disease
Unpleasant smile
Unproductive land
5. Describe ways of preventing pollution of the environment.
 Conservation of resources’ -3Rs reduce, Re- use and Recycle of
pollutants.
PLANTS AND ANIMALS (PLANTS CELLS)
(1) Identify the main parts of the microscope.
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Mirror
Stem
Lens
Stage
Eye piece
Adjustment knob
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(2) Examine the plant cell structure using a microscope.
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Cell wall
Cell membrane
Cytoplasm
Nucleus
Chloroplast
Vacuole
PLANT GROWTH AND NUTRIENTS
1. Identify regions of growth of a plant
 Shoot
 Roots
 Stem
2. Demonstrate responses to stimuli in shoots and roots
Roots and shoots of plants determine the growth rate of a plant. These are dependent on
the response of the root or shoot to external stimuli. Shoots respond to light. The response
of shoots to light is called phototropism. The figure below illustrates the response of
shoots to light.
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Note:The response of the root to light is negative and this is called negative
phototropism Roots however, respond positively to gravity, hence they are positively
geotropic. We call this response as positive geotropism. The response of roots to gravity
is beneficial in that the plant is able to get fixated in the soil; it is able to absorb water and
mineral salts.
Plant roots also respond to water the same way they respond to gravity. The response of
plants to water is hydrotropism.
Experiment;To find out about geotropism in roots and stems using a newly germinated
bean.
Materials: germinating bean seeds, beaker or glass jar, cotton wool.
Method- soak the cotton wool in water
-
-
Place the cotton wool into the beaker.
Place the germinating bean seeds between the walls of the beaker and
soaked cotton wool so that they can be seen through the glass wall of the
beaker.
when positioning the seeds, arrange at a 45⁰ angle so that their radicals
(roots) point upwards and their plumules (shoots) point downwards
Place in a warm, sunny place.
Allow standing for three to five days. Ensure that the cotton wool is kept
moist at all times
draw your seed in the correct biological way
Explain your results and observations
Observations/results


The roots of the germinating seeds curve away from the top of the beaker and
grow downwards.
The shoots of the germinating seeds curve away from the bottom of the beaker
and grow downwards.
The figure below illustrates predicted results for the experiment described above.
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Conclusion
This shows that:
 The stems are negatively geotropic as the shoots are growing upwards (away from
the earth)
 The roots are positively geotropic as they are growing downwards (towards the
earth).
3. Describe nutrients important to plant growth
- Three major elements are:
 Potassium
 Nitrogen
 Phosphorous
These elements are present in the form of salts such as potassium nitrate,
potassium phosphate and calcium nitrate.
Other nutrients required by plants are;
 Calcium
 Magnesium
 Sodium
 Iron
 Sulphur.
The following table describes the function and effects of deficiency of these
nutrients in plants.
Effects of deficiency
Nutrient
Function
Nitrogen
phosphorous
Potassium
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Constituents of
amino acids and
proteins, coenzymes and
chlorophyll
Useful in the
formation of ATP
and regulation of
several enzyme
systems
Very important in
the formation of
cell membrane
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-Chlorosis (yellowing) in older
leaves.
-poor growth of all plant organs
Stunted growth and leaf fall
Reduced plant growth
-reduced root, fruit and seed
development
-chlorosis ((yellowing) of
leaves.
-brown scorching of leaves
-curling of leaf tips
Calcium
Magnesium
Sulphur
Sodium
Useful in the
formation of the
middle lamella
Is a component of
chlorophyll
molecule
-poor growth of plant
General yellowing of leaves.
-drying back of the meristem of
roots and shoots
Formation of plant General yellowing of leaves
proteins
Reduced plant growth
Iron
Chlorosis of leaf veins
inhibition of photosynthesis and
cellular respiration
4. Investigate how plants obtain dissolved mineral salts from the soil
Plants absorb all mineral salts that they need through their roots in the form of
mineral salts. Roots have tiny hair like structures, called root hairs, near their tips.
These root hairs allow water and dissolved mineral salts (ions) from the soil to
enter them.
Water moves into the root hairs by a process known as osmosis. The process by
which the mineral salts move into the root hairs is known as diffusion. The water
with the dissolved mineral salts is carried from the roots up through the stem into
the branches, leaves and flowers of the plant. This upward movement of water in
the plant is due to a number of factors. The most important factor is the suction
force that is created by a process known as transpiration. Transpiration is the
loss of water vapour from the parts of the plant that occur above the ground,
mainly the leaves.
Experiment:-To show how plants absorb water and dissolved mineral salts
Materials; two beakers, red/blue ink (to represent dissolved minerals), coloured
chalk dust (to represent insoluble particles, scarpel/razor, two young
plants such as black jack ( Bidenspilosa).
Method: -Pour an equal amount of water into both beakers.
-To one beaker, add an equal volume of red/blue ink where as to the other beaker add chalk dust.
- Carefully remove two young plants from the soil and place one plant into each beaker.
- Place the beakers on the window sill in the classroom or in a sheltered
well-lit position.
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-Allow them to stand for one hour and observe the colour of the stems of
both plants
-Remove the plants from the beakers
-Use the blade to cut the cross section through the stem and main (tap)root.
-Carefully observe each cross section and record your observations in a
table like the one below.
-If possible, observe the cross sections using a magnifying glass or
microscope
water and chalk dust suspension
observation
plant
water and ink solution
water and chalk dust
part suspension
Root
Stem
The cross section of the root and stem from the plant that was placed into the ink
solution shows the colour of the ink in the areas of the root and stem that
correspond to the position of the vascular bundles (i.e. xylem cells). This shows
that the ink together with the water has been absorbed by the roots and past into
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the vascular bundles (xylem cells for transport up the plant to the leaves. This
means that minerals dissolved in water will be transported within plants
The cross section of the root and stem from the plant that was placed in the
chalk suspension does not show the colour of the chalk anywhere. This shows that
unless a substance, such as a mineral, is dissolved in the water, a plant will not
absorb that substance.
5)Identify sources of plant nutrients
Sources of plant nutrients are:
(i)
Organic fertilizers ( manure, compost),- these are dead, decaying
substances such as leaves, cow dung, poultry manure and stalks of
cereals, for example, maize, sun flowers and bean stems.
(ii)
Inorganic (artificial) fertilizers- these are made in factories by
industrial companies such as nitrogen chemicals. Examples of these
fertilizers include; urea, D compound and ammonium nitrate.
6). Explain the advantages and disadvantages of inorganic and organic fertilizers.
Advantages of using organic fertilizers
Organic fertilizers make the soil rich. Adding humus for example,
-Improves soil texture by creating air spaces in between the soil particles.
-Improves water retention (ability to hold water) in the soil).
-Makes the soil soft for cultivation
-enables bacterial action in soil
Disadvantages of using organic fertilizers
-May not be easily available to farmers
-They take a long time to decompose and so the nutrients take a long time to be
available to plants.
-They may promote the growth of weeds in the field.
-They may encourage worms, termites and ants which feed on crops, causing them
harm.
Advantages of using inorganic fertilizers
-
Inorganic fertilizers are easy to use on large areas of land
They are easy to transport over long distances
They are quick acting
They are effective if correctly bused and greatly increase crop yield.
Disadvantages of using of using chemical fertilizers
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-
They are costly because farmers must buy them
Chemical fertilizers change the amount of acidic substances in the soils, for
example, soils may become acidic.
7). Explain the effects of excessive use of inorganic fertilizer to the soil;
-
The soils become too acidic, which causes the plants to stop growing properly
or to die
Excessive use inorganic fertilizers promote overgrowing of plants.
PLANTS AND ANIMALS
1. Describe the basic structure of an animal cell
It is made up of the following parts:



Cell membrane
Cytoplasm
Nucleus
2. Describe the functions of the parts of the cell
 Cell membrane selectively permeable to materials.
 Nucleus
controls all the activities of the cell.
 Cytoplasm
jelly - like material that fills a cell and
contains organelles which perform functions
that is vital for the survival.
3. Identify different features in the basic structure of an animal cell and a plant cell.
Plant cells
Animal cells
They have a definite shape
They have an irregular shape.
They have cell walls.
They have no cell walls.
Some have chloroplasts.
None of them have chloroplasts.
They usually have a large cell vacuole; if
there is more than one vacuole, they are
usually all big.
They usually have no vacuoles; if present, they
are small and numerous.
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MATERIALS AND ENERGY
Composition of matter
1. Describe the composition of matter.
All matter is made up of particles called atoms (basic building block of
matter). Most atoms can combine with other atoms to form molecules.
An element is a form of matter made up of only one kind of atom.
2. Describe the basic structure of atoms.
 Nucleus (centre) surrounded by electrons in shells
3. Identify common atoms using symbols
 Carbon
(C)
 Oxygen
(O)
 Copper
(Cu)
 Aluminum
(Al)
 Hydrogen
(H)
 Nitrogen
(N)
 Iron
(Fe)
4. Demonstrate the formation of simple molecules using models of atoms:
Molecules
 Oxygen (O2)
 Hydrogen (H2)
 Water (H2O)
 Carbon dioxide (CO2)
A:Anoxygen molecule represented by two identical spheres joined together. B: An
oxygen molecule represented by the nucleus and energy level with electrons for both
atoms. The four blue balls at (a) represent the four shared electrons that join the two
oxygen atoms.
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A
B
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C: A hydrogen molecule represented by two identical spheres joined
together. D:A hydrogen molecule represented by the nucleus and energy level
with electrons for both atoms. The two blue balls at (a) represent the two shared
electrons that join the two hydrogen atoms.
C
D
E: A nitrogen molecule represented by two identical spheres joined
together. F:A nitrogen molecule represented by the nucleus and energy level with
electrons for both atoms. The six blue balls at (a) represent the six shared electrons that
join the two nitrogen atoms.
E
F
G: A carbon dioxide molecule represented by two identical red spheres
representing oxygen atoms that are joined by a black sphere representing a
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carbon atom. H:Acarbon dioxide molecule represented by the nucleus and
energy level with electrons for both atoms. The four blue balls at (a ) and
(b) represent the two groups of four shared electrons that join the two
oxygen atoms to the carbon atom.
G
H
I: A water molecule represented by two identical white spheres
representing hydrogen that are joined by a red sphere representing oxygen.
J:Awater molecule represented by the nucleus and energy level with
electrons for both atoms. The blue ball at (a) and (b) represent the two
shared electrons that join the two hydrogen atoms to the oxygen atom.
PHYSICAL CHANGE OF STATE
1. State what physical change is?
 It is change from one state to the another
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2. Describe the arrangement of atoms in the three states of matter.
 Solids Atoms very close together
 Liquids Close together
 Gas
Spread far apart
3. Identify the temperature at which water changes state.
- Melting point is the temperature at which a solid changes into a
liquid. The melting point of ice is 0℃.
- When a liquid is heated it changes into a gas. This process is called
evaporation. Once the liquid reaches a certain temperature it starts
- to boil. The temperature at which this happens is called boiling
point. The boiling point of water under normal conditions at sea
level is100℃.
-
Interpreting the graph.
A. The temperature of ice rises steadily as heat is observed by ice.
B. Ice is been converted to water at the melting point. Although heat is
absorbed, the temperature remains constant through the change.
C. Added heat now increases the temperature of the liquid until the
boiling point is reached.
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D. At the boiling point, the vapour pressure of the water equals the
external atmospheric pressure. Added heat is used to overcome the
intermolecular forces. The temperature remains constant until the
liquid has completely vapourised.
E. The temperature of the steam increases steadily as the heat increases.
MIXTURES
1.
Explain what a mixture is.
 Substance made up of two or more substances that are not
chemically combined.
2. Identify different types of mixtures:
(a) Homogeneous mixture, examples:
 sugar water (sugar solution)
 Sea water
 Air
 Blood
(b) Heterogeneous mixture, examples
 Soil
 Salt
 Fruit salad
 sand in water
 Marbles
 Corks
 Oil and water
 Soups and stews
3. Identify methods of separating mixtures
 Filtration
 Simple distillation
 Fractional distillation
 Evaporation
 Magnetization
 Crystallization
4. Explain some of the industrial applications of separation techniques:
 Making sugar
 Formation of salt from sea water
 Separation of scrap metals.
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MASS AND WEIGHT
1. State what mass is?
- Mass is the amount of matter in a substance.
2. How can you measure the mass of different objects?
- Mass is usually measured in kilograms (kg) and grams (g).
- We can measure mass using a beam balance. A simple beam balance
employs already known masses to determine the unknown masses. Other
balances used to measure the mass of different objects are the triple beam
balance and the digital or electronic balance.
Example: measure the mass of salt.
Place an empty beaker on the triple beam balance and record its mass as M1. Pour the salt
in the beaker and record the new mass as M2 (mass of beaker and salt). Calculate the
difference between M1 and M2. This gives the mass of the salt. Repeat the experiment
using other substances such as flour or rice.
3. State what weight is?
- Weight is the pull of gravity on the mass of an object.
Weight = mass × acceleration due to gravity
Note: Acceleration due to gravity is 10N/kg on earth
4. How can we measure the weight of a given object?
We measure weight with a spring balance and its unit is Newton (N). When measuring
weight, hold a spring balance or attach it to a fixed surface by its ring at the top. Attach
the object you want to weigh to the hook at the bottom of the balance. This causes the
spring in the balance to stretch. Measure the weight of the object then. The marker on
the outside of the spring balance moves down the scale of the spring balance.
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a spring balance
5. Calculate the weight of a substance with a given mass.
Example: (i) Calculate the weight of a 20kg stone on earth (acceleration due to gravity is
10m/s2)
Solutions
Weight = mass × acceleration due to gravity.
Weight = 20kg × 10m/s2
Weight = 200N
Note:When an object is taken to another planet, the weight differs from the weight on
earth, while the mass remains unchanged.
6. Distinguish between mass and weight.
- Mass is the quantity of matter in a body while weight is the pull of gravity on
a body.
- Mass is measured with a beam balance while weight is measured with a
spring balance.
- Mass is measured in grams (g) or kilograms (kg) while weight is measured in
Newton (N).
- Mass is constant while weight varies from place to place
DENSITY
1. Explain the meaning of density
Density is mass per unit volume of a substance.
Density =
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𝑚𝑎𝑠𝑠
𝑣𝑜𝑙𝑢𝑚𝑒
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-
The unit for density is grams per cubic centimeter (g/cm3)
2. Demonstrate how to determine the densities of different substances
(i)
Determining the density of a stone
.
- Weigh the stone by placing it on a beam balance. Read and record its mass
(m)
- Pour water into a measuring cylinder and record its volume as V1.
- Tie a thin string to the stone and gently lower it into the water until it is fully
submerged (under water).
- Record the total volume of the water and the stone as V2.
- Now calculate the density of the stone as follows:
Density =m
v2 – v1
The figure below illustrates how the density of a stone can be determined.
(ii)
To determine the density of a block of wood.
Draw a table for the results like the one shown below.
Mass
Length (L)
Width (W)
Height (H)
Volume
(g)
(cm)
(cm)
(cm)
L × W × H (cm3)
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Using a beam balance, measure the mass of the block of wood and record
your results in the table above.
- Measure and record the length, width and height of the block of wood.
- Calculate the volume of the block of wood using the formula,
V=L×W×H
or
V=l×b×h
- Calculate the density of the wooden block using the formula
-
Density =
(iii)
-
𝑚𝑎𝑠𝑠
𝑣𝑜𝑙𝑢𝑚𝑒
To determine the density of a liquid e.g. water.
Draw a table for your results like the one shown below
Liquid
(A) Mass of
cylinder (g)
(B) Mass of
cylinder +
water (g)
(C) Mass of water
C=B–A
(g)
(D) volume of
water
(cm3)
Water
-
Carefully determine the mass of the empty measuring cylinder using the
beam balance.
Record this in column A in the table above.
Pour water into the measuring cylinder and record the volume of this water in
column D.
Now place the measuring cylinder with the water on the beam balance.
Record the mass in column B.
Calculate the mass of water in column C.
Use the data recorded in your table to calculate the density of the water.
3. Demonstrate that an object will sink or float on a liquid.
- Denser objects sink and less dense objects float in relation to the density of a
liquid.
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Oil
Wood
WaterWater
Stone
4. Describe how vessels float:
- Vessels float because they have a larger volume and are less dense.Their
average density is less than that of water.
5. Explain the effects of overloading vessels.
- It causes sinking of vessels
- It causes accidents
HEAT TRANSFER
1. Demonstrate the types of heat transfer.
The types of heat transfer are conduction, convection and radiation.
- Conduction is the transfer of heat through solids. In conduction, heat is
transferred from the hot region to the cold region by vibration of particles.
- Conduction can be demonstrated using the following experiment:
In this experiment, the pins fall off one by one starting with pin A. This is because
particles at the end of the wire in the flame become hot and start to vibrate more
strongly. As these particles vibrate, they hit other particles next to them and make
them vibrate as well. In this way the hot particles transfer some of their heat to the
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cooler particles next to them. This continues until heat reaches the other end of the
wire. In this way we say heat has been conducted along the wire.
Convection is the transfer of heat through liquids and gases. In convection, heat is
carried by the particles from the hot region to the cold region. Convection can be
demonstrated as illustrated in the experiment below:
In this experiment, used tea leaves are sprinkled into the water and the water is heated
gently.
Observation
When the water is heated in the experiment above, the hot particles of the water at the
bottom rises to the top. At the same time, the cold particles of water at the top moves
down to the bottom and also become heated.
This process of the hot articles rising and cold particles moving downwards results in
convection currents which are shown by the movement of tea leaves.
Radiation is the method of heat transfer from the source without requiring particles of
a solid, liquid or gas. The heat reaching your hands when you hold them near a fire
reaches them by radiation. Heat from the sun reaches us also by radiation.
2. Investigate the movement of heat in matter.
- The following experiments can be performed to investigate the movement of
heat in matter.
(a) In solids
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-
Place the concave end of a spoon over or in the source of heat for some time.
If you keep your hand on the handle of a spoon, you would soon feel warm.
This is because heat has been conducted from the source to the end of a
spoon and finally to your hand.
(b) In liquids
As in an experiment described in question (1) above under convection in
liquids. This experiment can also be performed using a few crystals of
potassium permanganate dropped into the bottom of the beaker through a
straw. The result is the same.
(c) In air
Fix a box with two chimneys with a candle at the bottom of one of them as
shown in figure below. Light the candle and observe through the transparent
plastic wrap. Put a smoldering paper near the top of the cold chimney and
make observations.
Observation
The smoke is carried down the cold chimney and up the hot chimney by
convection currents in the air.
Conclusion
Heat travels through the air by convection currents.
3. Describe how a vacuum flask works.
A vacuum flask is a device that keeps liquids hot or cold by preventing heat transfer.
Main parts of a vacuum flask
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The main insulator in the vacuum flask is the inner glass container which has double
silvered walls, namely, inner wall and outer wall. These silvered walls reduce heat
loss by radiation. This is done by the inner wall reflecting heat back into the liquid. In
this way a hot liquid put into the flask remains hot for a long time.
Heat gain is reduced by the outer wall reflecting heat towards the outer housing (outer
casing). In this way a cold liquid put into the flask remains cold for a long time.
Between the inner wall and the outer wall is a vacuum to reduce heat loss or gain by
convection or conduction. A cork or plastic stopper in the mouth of the flask reduces
heat loss or gain by convection and conduction.
The outer housing protects the glass vessel from damage. The sealed tip on the inner
glass container is where the air was sucked out from between the walls.
HEAT AND EXPANSION OF SUBSTANCES
1. Demonstrate expansion of substances.
- Expansion is the increase in amount of space used by another due to heating.
Expansion of solids
-
-
Different solids have different expansion rates from fastest to slowest; the
rates of expansion for some solids are aluminum, copper, brass and steel. For
example, aluminum expands more than copper does when they are heated to
the same temperature.
This difference in expansion can be shown by heating a bimetallic strip.
A bimetallic is a strip of two different metals joined together. When heated or
cooled, one metal expands or contracts faster than the other, causing the strip
to bend as shown below.
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Expansion of liquids
Liquids are kept in containers because they have no fixed shape. To see the increase in
volume of a liquid due to heating, we also heat the container in which the liquid is.The
container will also expand
Note: if the liquid level in the container rises as it is being heated, then the liquid has
expanded more than the container. The experiment below illustrates that liquids expand
when heated.
In this experiment, the water level falls at first, and then rises steadily. The initial drop in
the water level occurs because the flask expands first, before the heat reaches the water.
The next rise in the water level is due to the volume of the water increasing as it is
heated. We can therefore conclude that liquids expand when heated.
Expansion of gases
The expansion of gases is so large that we can ignore the expansion of the containers they
are stored in. To show that gases expand when heated, the experiment is set as shown
below.
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In this experiment, bubbles start coming out of the submerged delivery tube in the beaker
due to the expansion of the air inside the flask caused by the heating.
2. Describe the use of the expansion of different substances in everyday life.
- In thermometers. In most thermometers the liquid used is mercury because
it expands quickly when heated. Other thermometers use alcohol.
- In thermostats: thermostats are devices used to maintain temperature
between certain limits in electrical appliances and indoor areas. These
devices use bimetallic strips as switches.
- In internal combustion engines:Internal combustion engine, the mixture of
fuel and air is drawn into the cylinder where it is ignited by a spark from a
spark plug.
This hot air now expands rapidly and pushes on a piston, pushing it down. When
the piston moves, it pushes a crankshaft that turns the wheels. Most internal
combustion engines operate using four strokes, which repeat themselves over and
over.
3
Explain the effect of expansion and contraction of substances.
- Fracture of bridges.
- Breakage of glass e.g. window pane.
- Buckling of rail tracks.
REFLECTION AND REFRACTION OF LIGHT
1. Describe what reflection is.
- Reflection is the bouncing of light off a surface.
- Light that bounces off a smooth surface such as a mirror is reflected in a
regular way while light bouncing off a rough surface is reflected in an
irregular way. The figures below illustrate regular (smooth) reflection and
irregular (diffused) reflection.
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2. Investigate the characteristics of reflection of light in a mirror.
This can be done by carrying out an experiment as follows:
- Place the plain paper on the cardboard and fix it at the edges using paper
clips.
- Draw a horizontal line on a sheet of plain paper and then draw a
perpendicular line to the horizontal line. This is the normal.
- Measure a 300 angle to the perpendicular line and draw the line AB.
- Place a plain mirror upright on the horizontal line with the reflecting surface
facing the normal.
- Fix three drawing pins P.Q and R on the line AB representing the incident
ray. Look into the mirror and find the images P, Q and R.
- Fix pins S, T and U to the paper in line with the image P, Q and R, as shown
in figure below.
-
Measure the angles formed that represent the angle of incidence and the
angle of reflection.
Repeat the experiment using different angles.
Observation
The angle of incidence and the angle of reflection are always equal, no matter
what the size of the angle of incidence is.
Conclusion
When light is reflected, the angle of incidence is always equal to the angle of
reflection.
3. Describe what refraction is
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-
-
Refraction is the bending or changing of direction of light rays when they
pass from one material into another. Refraction takes place at the boundary
of the two media (singular – medium).
When light passes from a less dense medium to a denser medium, it is
refracted towards the normal.
Light travelling from a denser medium to a less dense medium is refracted
away from the normal.
However, whether light is from a less dense medium to a denser medium, or
vice versa, refraction will not occur if it strikes the surface at right angles as
shown in figure (c) below.
4. Identify the real and apparent depths of an object under water.
Note: light from point D is refracted away from the normal at the water surface. Light
reaching the observer appears to come from point B, which is directly above point D. the
object D appears to be in position B. thus RB is its apparent depth. The true or real
depth is RD since the coin has not been raised. The apparent depths are always less than
the real depths of the object.
5.Explain the application of reflection and refraction.
-
Reflection is applied in:
(i)
Searchlights
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(ii)
(iii)
Headlamps
Magnifying mirrors
Refraction is applied in lenses of instruments such as camera, binoculars, telescope,
spectacles and microscope.
COMPOSITION OF AIR
1. Identify the components of air.
The components of air are: nitrogen, carbon dioxide, oxygen and water vapour.
2. Investigate the proportion of each substance in air.
- This can be done by first investigating the proportion of oxygen in air as
explained below:
- Fix the candle firmly to the bottom of a dry trough and place enough water in
the trough to cover the lower half of the candle. Light the candle and while
the candle is burning, cover it with a dry gas jar. The experiment is set as
shown in (a) below.
It is observed that as the candle burns, the level of the water in the gas cylinder
rises until the candle goes out. The water rises to replace the air that has been used
during burning (combustion). The water rises to a level of about one fifth (21%)
of the height of the gas cylinder. This shows that oxygen is the gas that supports
combustion and that it makes about 21% of the air in the atmosphere. In the
experiment, the water did not fill the whole jar as seen in (b) because some air
was not used in burning. We call this the (inactive) part of the air which is a
mixture of several gases, the main one being nitrogen occupying approximately
four fifth 78% of the volume of air around us. Air also contains carbon dioxide
and water vapour which occur in very small amounts (1%)
3. Describe the nature of each substance in air
(i)
-
Nature of Nitrogen
It is colorless
It is odourless (has no smell)
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-
It is slightly soluble in water
It has almost the same density as that of air
(ii)
Nature of Oxygen
- It is colorless
- It is odourless
- It is slightly soluble in water (100cm3 of water contains about 4cm3 of
oxygen
- Its density is approximately the same as that of air
(iii)
-
Nature of carbon dioxide
It is colorless
It is soluble in water
It is denser than air
It is odourless
(iv)
Nature of hydrogen
Hydrogen is the lightest, simplest and most abundant element in the universe,
which does not normally exist as a free gas but present in compounds, such as
water, ammonia and ammonium compounds, for example, in artificial
fertilizers. Hydrogen however has the following properties:
- It is colorless
- It is odourless
- It is less dense than air
4. Describe the uses of each substance in air
(a) Uses of Nitrogen
- It provides a non-reactive (inert) environment, for example,
 Inside an incandescent (ordinary) light bulb to prevent the filament from
reacting with oxygen in air.
 To protect historical documents by preventing paper and ink from
reacting with oxygen in air. This stops the document decomposing
(rotting).
 It is used to freeze materials and keep things cold during transportation.
 It is used in the preparation of ammonia when it is made to react with
hydrogen
 It is an important element that is found in fertilizers such as ammonium
nitrate.
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 Plants with nodules containing bacteria such as legumes can convert
nitrogen into nitrates thereby enriching the soil for good plant growth.
(b) Uses of Oxygen.
The uses of oxygen will be classified into medical industrial and others.
(i)
Medical uses of oxygen
 It is used in incubators for premature babies
 It is used in ventilators for patients on life support system
 Oxygen therapy is used to treat some infections, diseases and
disorders
 Oxygen supplementation increases the oxygen levels in patient’s
blood
(ii)





(iii)
Industrial Uses Of Oxygen
It is used in oxy-acetylene flames for welding and cutting of
metals
It is used for manufacturing steel from iron by oxidizing
impurities such as carbon, sculpture and phosphorous which are
found in iron. The steel is then pure.
It is important in combustion process such as the motor car
engine and rocket fuel in which it is mixed with the fuel
It is used in the purification of water
It is used in the chemical industry for the manufacturer of some
chemical compounds.
Other Uses Of Oxygen
 It is used by both animals and plants to produce energy during
aerobic respiration
 It is used by deep sea divers and mountain climbers to assist
them in breathing
(c) Uses of Carbon dioxide
 It is used in fire extinguishers, this is because it does not
support combustion, and it is non- flammable and is denser
than air.
 It is used to make carbonated (fizzy) drinks.
 It is used as a refrigerant because it can be made into a white
solid (dry ice).
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 It is used in bakeries where it is produced through
fermentation thereby causing the dough to rise as the gas
begins to escape.
 It is used by green plants for the process of photosynthesis.
(d) Uses of Hydrogen
 It is used in the production of ammonia
 It is used for removing impurities in refining petrol
 It is used in extracting metals such as iron from oxide ores
 It is used in the production of fertilizers such as ammonia
compounds
 It is used for hardening vegetable oils, changing them into
solid saturated facts such as margarine.
GRADE 9
THE HUMAN BODY
SUB-TOPIC: CIRCULATORY SYSTEM
1. Describe the blood circulatory system?
ANS
The blood circulatory system involves the movement of blood in vessels around the body.
It involves the heart, blood, blood vessels and lungs
2. Identify the components of blood and their functions?
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ANS
- Red blood cells
- White blood cells
- Platelets
- Blood plasma
FUNCTIONS
- Red blood cells: transport oxygen and carbon dioxide
- White blood cells: fight diseases
- Platelets: for blood clotting
- Plasma: transports water, body wastes, food nutrients (glucose, amino acids, lipids)
3. Describe the internal structure of the heart.
ANS
to head
and body
to lungs
aorta
pulmonary
artery
from head
and body
semi-lunar
valve
pulmonary
vein
from lungs
vena cava
right
atrium
left
atrium
bicuspid valve
tricuspid valve
right
ventricle
valve tendons
left
ventricle
muscle
The
heart consists of 4
chambers,the left Atrium and the right atrium(plural:atria) at the top and the left ventricle and the
right ventricle below.Ventricles have thick muscular walls because they pump blood at high
pressure.
Left atrium-receives oxygenated blood from the lungs through the pulmonary vein.
Right atrium-receives deoxygenated blood from the rest of the body through the vena cava.
Left ventricle-Pumps blood to all parts of the body through the aorta.
Right ventricle-Pumps blood to the lungs through the pulmonary artery.
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Bicuspid valve-prevents back flow of blood from the left atrium.
Tricuspid valves-prevents back flow of blood to the right atrium.
Semilunar valves-prevents the back flow of blood.
4. Illustrate the movement of blood in the double circulatory system.
ANS
A. Pulmonary circulation.
The pulmonary circulation involves the pumping of blood from the heart to the lungs
and back from the lungs to the heart.
Heart—>Lungs—>Heart.
B. Systemic circulation
In this circulatory system, blood is pumped from the heart to the rest of the body and
back to the heart.
Body—>Heart—>Body.
5. Identify the role of the heart, lungs and blood vessel in blood circulation?
ANS
The heart pump blood to all parts of the body
The valves prevent back flow of blood.
The lungs add oxygen to the blood and remove carbon dioxide from the blood. (it is
where gaseous exchange take place).
Arteries carry blood from the heart to the body while veins take blood to the heart.
All veins transport deoxygenated blood back to the heart except the pulmonary vein.
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All arteries transport oxygenated blood to all parts of the body except the pulmonary
artery.
RESPIRATORY SYSTEM
1. Identify organs of the respiratory system of a human being?
nasal cavity
tongue
epiglottis
trachea
bronchus
ribs
ribs
intercostal
muscle
bronchiole
heart
alvioli
diaphragm
Mouth,nose,trachea,bronchi,bronchiole,lungs (air sacs),ribs,diaphragm,inter-costal muscles.
2. Explain the functions of the organs of the respiratory system?
ANS
Mouth:it is used for breathing when the nose is blocked due to flu.
Nose: has two nostrils through which the air from outside is allowed to pass into the
lungs. The nostrils contain small hairs which help trap the dust particles from air before it
enters the lungs.
Trachea:it acts as a passage for air and has cilia and mucus that trap dust.It is a cylindrical
tube lined with rings of cartilage to prevent collapsing.
Bronchi:directs air to the lungs.
Lungs: this is where gaseous exchange take place.
Ribs: give physical protection of the lungs.
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Diaphragm: is a tough sheet of muscles that separates the chest cavity from the
abdominal cavity.
Air sacs: it is the site for gaseous exchange (make up the lungs).
3. Demonstrate the mechanism of ventilation in a human being?
ANS
Mechanism of ventilation (breathing) involves two processes.
1. Inhalation / inspiration
- Diaphragm muscles contract and flattens
- External intercostal muscles contract
- Ribs move upwards and outwards
- Volume of chest cavity increases.
- Lungs inflate
- air is drawn inside.
2. Exhalation / expiration
- Diaphragm relax and moves upward (becomes dome shaped)
- External inter-costal muscles relax
- Ribs move downwards and inwards.
- Volume of chest cavity decreases.
- Lungs deflate
- Air is drawn outside
4. Describe the exchange of oxygen and carbon dioxide in the lungs?
ANS
Oxygen diffuses into the blood stream and carbon dioxide into the lungs from the blood.
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air in
bronchiole
oxygenated blood
deoxygenated bloo
alvioli
5. Explain tissue respiration?
ANS
Tissue respiration or cellular respiration is a chemical process in cells by which energy is
released from food (glucose).Glucose combines with oxygen to release carbon
dioxide,water and energy.
WORD EQUATION
Glucose +oxygen ->Carbon dioxide +water+Energy
6. Explain the effect of cigarette smoking on the respiratory system?
ANS
Causes,
- Lung cancer
- Bronchitis
- Stomach ulcers
- Bladder cancer
- Osteoporosis (brittleness of the bones)
HEALTH
SEXUALLY TRANSMITTED INFECTIONS
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1. Identify the common sexually transmitted infections?
ANS
HIV and AIDS, Syphilis, Gonorrhea,Genital Warts.
2. Explain transmission of Sexually Transmitted Infections.
Sexually transmitted infections are transmitted through
- Unprotected sex
- Blood transfusion with contaminated blood
- Having multiple sexual partners
3. Describe the prevention of STIs?
- Correct and consistence of condom use
- Stick to one faithful partner
- Avoid casual sex
- Abstinence from sex.
- Avoid sharing sharp instruments, i.e. needles,razor blades.
4. Explain the impact of HIV and AIDS on the population?
- Brings poverty
- Increase of orphans
- Pressure of health services
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THE ENVIRONMENT
CYCLES IN THE BIOSPHERE
1. Describe what Oxygen and Carbon cycle are?
- Oxygen cycle is the circulation of oxygen in the atmosphere
- Carbon dioxide is the circulation of carbon dioxide in the atmosphere
- Carbon dioxide and oxygen cycles are balanced by respiration and photosynthesis.
- Carbon dioxide is removed in the atmosphere by photosynthesis and it is added by
respiration
- Oxygen is added to the atmosphere by photosynthesis and is removed from the
atmosphere by respiration.
2. Identify factors affecting Oxygen and Carbon cycle?
- Plants take in carbon dioxide during photosynthesis and give off oxygen.
- Animals take in oxygen and give off carbon dioxide during respiration
3. Describe the nitrogen cycle?
- Lightening converts nitrogen in the atmosphere to nitrates
- Nitrogen fixing bacteria convert free nitrogen to nitrates in the soil. (fix nitrogen in
the soil)
- Legume plants e.g. beans increase the amount of nitrogen in the soil.
- Nitrogen rich fertilizers increase the amount of nitrogen in the soil.
4. Explain the natural balance of gases in the atmosphere.
- Oxygen 21%
- Nitrogen 78%
- Carbon dioxide 0.03%
- Other inert gases 0.97%
- WATER MANAGEMENT
1. Describe the importance of water management in our daily life.
- Generating electricity
- Irrigation
- washing and cleaning
- mixing chemicals
- cooking food
2. Describe effective water management system.
- Construction of dams
- Water reservoirs
- Purification of water, involves the following process
- Screening
- Sedimentation
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-
Filtration
Disinfection(chlorination)
PLANTS AND ANIMALS
CONSERVATION OF ANIMALS AND PLANTS
1. Explain the importance of domesticating animals and plants.
PLANTS
- Are a source of food
- Provide building materials like poles and timber
- Some plants are medical hence used to cure certain diseases.
- Provide beauty and shade at home
- Control soil erosion by covering the ground
- Provide manure and biogas
- Some plants with nice flowers may provide income when flowers are sold.
ANIMALS
- Major source of protein (food)
- Animal products such as hinds and skins are important in making leather products
- Animals are kept as pets to beautify the homes
- Some animals like dogs are kept for protection purposes
- Some for recreation e.g. animals in national parks and zoos
- Some animals used as dowry during marriage.
- Some animals are used for transport and cultivation.
2. Explain ways of improving domestic breeds of animals and plants.
- By crossing animals and plants that have desirable characteristics to produce offsprings with desirable characteristics
- In plants by cross pollination(transfer of pollen grains from the anthers of one plant to
the stigma of another plant)
3. Identify animals and plants threatened by extinction.
ANIMALS
Wild dogs, black rhino, antelopes, honey badger, elephants, crocodiles.
PLANTS
Mutondo, mukwa and mukula
4. Describe the importance of protecting endangered animals and plants.
- Source of food, medicines and industrial raw material
- For income
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- Foreign currency from tourists
- Plants reduce soil erosion
- For future generation
- For aesthetic / beauty
- Plants produce oxygen for photosynthesis.
5. Explain methods of protecting endangered animals and plants.
- Use of appropriate farming practices such as crop rotation
- Game cropping
- Setting up of conservation education programmes in the curriculum
- Controlling burning of charcoal
- Creation of game management area, forest reserves and game parks
PHOTOSYNTHESIS
1. Identify the conditions necessary for photosynthesis.
-sunlight, carbon dioxide, water and chlorophyll
2. Identify the products of photosynthesis in a leaf.
Glucose (sugar) and oxygen
3. Relate the process of photosynthesis to respiration
-Photosynthesis occurs only in green plants while respiration occurs in both plants and
animals.
-Photosynthesis produces sugar by use of energy while respiration burns sugar to release
energy.
-photosynthesis stores energy while respiration releases energy.
-photosynthesis uses water while respiration produces water.
-photosynthesis uses carbondioxide from air which is released by animals and human
beings during the process of respiration while respiration releases carbon dioxide which
is used by plants to make food during the day.
-photosynthesis produces oxygen which is used by animals and human beings for
breathing in while respiration uses oxygen from air which is released by plants during the
process of photosynthesis.
-photosynthesis takes place during the day while respiration takes place both during the
day and at night.
TRANSPIRATION
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1. Describe the process of transpiration?
Transpiration is the loss of water-vapour by plants through the leaves (stomata)
2. Investigate the factors that affect the rate of transpiration?
- Deforestation completely removal of vegetation
- Light intensity: light intensity influences stomata opening
- Humidity: the amount of water-vapour in the atmosphere
- Temperature: high temperature increases the rate of transpiration while low
temperature reduces the rate of transpiration because water will take long to turn into
vapour wind.
Structural factors
- Stomata
- Cuticle
- Leaf size and leaf shape
upper epidermis
chloroplasts
palisade
cells
vacuole
cytoplasm
air spaces
spongy
layer
leaf vein
3. Explain the importance of transpiration in plants?
It helps in transportation of water and materials from roots to the upper part of the plant.
MATERIALS AND ENERGY
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CHEMICAL REACTION
1. Describe what chemical reaction is?
A chemical reaction is one where a new chemical substance is formed from the original
substance.
2. Describe the nature of chemical reactions?
- During exothermic reaction heat is evolved (given out) to the surroundings
- During exothermic reaction heat is absorbed from the surroundings.
3. Classify different types of chemical reactions?Synthesis.Decomposition.Single
replacement.Double replacement.
4. Describe the chemical reactions.
-
Synthesis: is the combination of two or more elements to form a compound.
e.g. iron combines with sulphur to form iron sulphide iron + suphur iron (ll)
sulphide
-
Decomposition: is the breaking down ofa single compound into two or more
simpler substances e.g. heating copper (ll) carbonate beaks it to copper (ll) oxide
and carbon dioxide.
Copper (ll) carbonate copper (ll) oxide + carbon dioxide
-
Single replacement: is a type of a chemical reaction where an element reacts with
a compound and takes the place of another element in that compound.
e.g. AB +CA+BC. Chloride +Potassium iodidePotassium chloride +Iodine
Double replacement: during a double replacement reaction atoms or irons from
two different compound replace each other e.g. AB + CD  AB +CB
-
Barium nitrate + sodium sulphateBarium sulphate +Sodium nitrate.
4. Demonstrate the chemical reaction of water with electricity?
The electrolysis of acidified water (dilute sulphuric acid) is an example of a
decomposition reaction. When a direct current is passed through the acidified water
(H2O), it decomposes into its components which are oxygen (O2 ) and hydrogen (H2)
(twice as much hydrogen as oxygen) by means of an electric current.
5. Explain the law of conservation of matter?
The total mass of substances before a chemical reaction is equal to the total mass of the
substances that are produced.
LIGHT AND ITS NATURE
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1. Describe the different types of lenses?
- A Converging lens is also known as a convex lens. It is thicker in the middle and
thinner at the edges. It makes parallel light rays passing through it to bend
inwards and meet (converge) at a point.
Converging lens
Concave lens
-
2.
3.
4.
5.
6.
A concave lens is also known as a diverging lens, is thicker at the edges and
thinner in the middle. This lens makes a beam of parallel light rays passing
through it to diverge (or bend as it spreads outwards) from a point.
Demonstrate the location of the focal point and focal length of a lens?
- The distance between the focal point and the centre of the lens ( or focus of the
lens ) is called the focal length.
- The principal focus or focal point is the point at which rays parallel to the
principal axis either converge or appear to be diverging after refraction or
reflection through the lens.
Explain the mechanism of a converging lens to produce real and virtue images?
- A real image is the image formed where the light rays are focused. Real images occur
when objects are placed outside the focal length of a converging lens or outside the focal
length of a converging mirror.
- A virtual image is formed at a location from where light rays appear to have
converged. Converging lenses form virtue images if the object distance is shorter than the
focal length.
Explain the uses of converging and diverging lenses?
-Converging and diverging lenses are used in a microscope, a magnifying glass, camera,
film projector and spectacles.
7. Demonstrate the production of a spectrum from white light?
- A spectrum (plural: spectra) is a complete range of colours as seen in a rainbow
into which white light can be separated when it passes through a prism.
8. Demonstrate the combination of colours of the spectrum to produce white light?
- A second triangular prism can used to combine the different colours of the
spectrum to form white light again. The second prism, of the same size as the first
one, is placed in an inverted or reversed order.
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9. Describe the production of a rainbow?
- A rainbow is a group of almost circular arcs of colours, all having a common
centre. Rainbows are formed from refraction of sunlight rays as they enter failing
droplets of water suspended in the atmosphere and the refraction of light from the
back of the droplet.
10. Explain why sunsets and sunrise appear red.
- Sunsets and sunrise appear red because the red light which a longer wavelength
and much stronger penetrating power, easily passes through this larger distance
and dust particle, thus the sky appears red to our eyes at sunset and sunrise.
COLOUR FILTERS
1. Explain that colours of an object depend on the colour of light it reflects?
- The colour of an object depends on the source of the light and the light it reflects.
2. Describe the effects of colour filters on light rays.
- A filter absorbs or reflects other colour light and only transmits the colour of the
filter.
ELECTRIC CURRENT AND VOLTAGE IN CIRCUIT
1. Explain the difference between electric current and voltage.
ANS
Electric current is the rate of electrical charged particles. While voltage is an
electromotive force or potential difference expressed in volts / potential difference is
work done in moving the electric charge from one point to another.
2. Demonstrate the use of an ammeter to measure electric currents in a circuit.
ANS
An ammeter is an instrument used to measure the electric current flowing in a circuit. The
ammeter in a circuit in connected in series in order to measure the current flowing
through a component in a circuit.
3. Demonstrate how to measure potential difference in a circuit.
- Voltage is measured in volts using an instrument called voltmeter. The symbol for
volts is. A voltmeter is connected in parallel across the components to measure in
a circuit. The number of cells affects the voltage across them. The more the
number of cells the higher the voltage.
4. Describe the relationship between potential difference and current.
- The relationship is ohms law which states that the current (l) flowing through a
metal wire is directly proportional to voltage (v) (provided the temperature
remains constant).
5. Explain the use of electric current in the local environment.
- Lighting in lamps
- Heating in electric irons
- Heating kettles
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Cooking and electric cookers
PRESSURE
1. State what pressure is?
- Pressure is the amount of force acting per unit area of a surface.
Pressure = force measured in N/M
2. Identify factors affecting pressure in gases?
- Factors affecting pressure are temperature, amount of the gas and volume.
ENERGY AND ITS CONSERVATION
1. Explain what energy is?
- Energy is the ability to do work
2. Identify different forms of energy?
- Potential energy
- Kinetic energy
- Chemical energy
- Electric energy
- Heat energy
3. Describe how different forms of energy can be changed?
- Combustion of fuels in motor vehicles, with the help of electric energy from a
battery, results in the conversions of chemical energy into kinetic, heat and light
energy. In the electric storage battery, chemical energy is converted to electrical
energy and later converted to light and sound energy.
4. Explain the law of energy conservation?
- Energy is neither created nor destroyed, although it may be converted from one
form to another.
5. Explain the effects of energy production on the environment?
- Depletion of resources
- Damage to natural geothermal features.
- Global warming and climate change.
- Water pollution.
- Air pollution.
- Land degradation.
- Wildlife and habitats loss.
6. Explain ways of conserving energy?
- Replacing light bulbs with fluorescent bulbs or LED bulbs.
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Reducing the use of outdoor lights for security purposes.
Switching off all electrical appliances and lighting equipment
Using natural light from the sun to brighten homes.
Reducing excessive heating and cooling in summer and winter respectively in
homes with summer cooling and winter heating systems.
Conserving fuels.
Higher use of renewable energy sources.
Practice the 3Rs (reduce, reuse and recycle)
Working in with others.
COMMUNICATION
1. Identify ways of sending and receiving information over long distances.
- Communication can be sent or received by the use of telephones, radios,
television and emails
2. Describe the advantages and disadvantages of the different ways of sending
messages?
Advantages
TELEPHONE
This is the most popular method of sending information that has been existing in different
Forms for the past years in both homes and business contacts. However mobile phones
Are now the preferred methods of communication. Mobile phones are also known as
A cellular phone is a phone that can make and receive telephone calls while moving
Around a wide geographical area. It is a hand held device and is a fast way of sending
Regardless of where you are.
Advantages
-
It provides for two-way communication and one on one communication. You get
immediate feedback during the communication.
Telephones provide current and timely information.
The conversation is relatively private between the people communicating.
Disadvantages
-
Telephones are expensive to buy and to install.
The person must be within the premises or available to pick up a telephone call.
If they are not available, communication will not take place.
- The use of telephones and mobile phones requires a certain amount of literacy.
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RADIO
For a very long time, radio has been the fastest and most technologically
advanced means of transmitting information. Radio communication involves the
converting of sounds into electrical signals known as audio signal.
Advantages
-
It is the cheapest form of media in terms of energy use, weight and cost.
People can listen to radio in the background while doing other work, for example,
while driving to and from work.
It has the ability to reach specific audience through specialized programming.
That way, it is possible to have radio stations using local languages so the
listeners can easily understand the message.
Disadvantages
-
Radio allows only one way communication. The sender can only send information
but in most cases there is no feedback.
Radios can only send radio signals without visual signals.
Radio signals are susceptible to interference so it can sometimes be hard to
receive a clear signal.
TELEVISION
Television is one of the popular ways of sending information around the world
Nowadays. It is very effective because it combines both audio and video signals.
Advantages
-
Television is able to combine both sound and pictures thus making the
communication process more effective.
It has a wide geographical coverage and broad audience.
Television keeps the audience well informed of current affairs and breaking news
around the world.
Disadvantages
-
It is an expensive method of communication. Buying a television for example, can
be very expensive.
The programmes are not aired at a convenient time for the viewer.
Unlike the radio, one cannot watch television while doing something else, such as
driving since it requires the full attention of the viewer.
EMAIL
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E mail stands for electronic mail. It enables a person to send well arranged text files
and pictures to another person’s e- mail address.
Advantages
-
-
Emails are fast. They are delivered at once around the world. No other form of
written communication is as fast as the email.
Aside from the cost of internet connections, email is free. One can send as many
messages, files, videos, documents and presentations as he or she wants without
having to pay anything.
Thousands of email messages can be archived into folders on your computer or
handheld communication device such as a cell phone to be retrieved when you
need them.
Disadvantages
-
Emails can carry viruses which can affect the computer systems. They can read
your email address book and send themselves to a number of people around the
world.
- Many people send unwanted emails to others. It could take a lot of time to them
out and sometimes important messages get lost in the many unsolicited emails.
- Sending an email requires both the sender and the recipient to have email
addresses and access to the internet or computer.
3. Describe the transmission of radio and television signals?
- Radio and television signals broadcast is the primary means by which information
and entertainment reach the public in virtually every country or nation around the
world.
4. Explain the amplification of sound?
- Amplify sound is to increase the strength of an electric signal by means of an
amplifier.
5. Explain the difference between digital and analogue transmission information?
- Analogue transmission conveys voice, data image, signal, or video
information using an information signal that is continuously varying while
digital transmission is the transmission of signals in a form of a stream of
binary numbers (combinations of zeros and ones). A digital signal uses
discrete (discontinuous) values.
6. Explain the use of satellite in long distance communication?
- A communication satellite is an artificial body or spacecraft placed in
geostationary or synchronous orbits around the earth or moon or another
planet in order to collect and transmit information or for communication.
It also sends signals from radio, television, telephone. In satellite
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communication, communications satellite receives signals from different
stations on the ground called Earth Stations or Ground Stations.
7. Describe the transmission of a live broadcast of an event from Africa to Europe
using raw block diagrams?
ANSWER
Live football match
at heroes stadium in
Lusaka
Sound and video actions
recorded by microphone and
camera respectively
Small transmitter on
mobile television van
(TV)
Satellite above
Indian ocean pick up
the signals and
transmits them
Earth station at Mwembeshi in
Zambia picks up the signal and
transmit them
Powerful transmitters at
BBC main studio station
picks up signals and sends
them
Earth station in
Paris, Europe picks
up the signals and
transmits them
Main transmitter in Paris picks
up the signals and transmit them
Televisions transmitters at
televisions stations in Paris
picks up signals and
transmits them
Transmitter in
provincial
headquarters picks
up signals and
transmits them
Repeater stations picks up the
signals and transmit them
Main transmitter in Paris
picks up signals and
transmits them
Television (TV) set
in a home picks up
the signal
Viewer watches a live match
football match
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