Table of Contents

The cell...........................................................................................................................4

The internal structure(ultra-Structure) of an animal cell............................................5

Function of parts of an animal cell.............................................................................5

Comparative study of the animal and plant cell.........................................................7

Cellular exchanges.........................................................................................................8

Definition:..................................................................................................................8

Types of solutions......................................................................................................8

Diffusion.....................................................................................................................9

Experiment to demonstrate diffusion.....................................................................9

Factors affecting the rate of diffusion..................................................................10

Importance of diffusion........................................................................................10

Osmosis....................................................................................................................11

Experiment to demonstrate osmosis in a living tissue.........................................11

Importance of Osmosis.........................................................................................13

Active transport........................................................................................................13

Importance of active transport to living things....................................................14

Differences between diffusion and active transport.................................................14

Facilitated Diffusion.................................................................................................14

Importance of Facilitated Diffusion.....................................................................14

Food..............................................................................................................................15

Definition.................................................................................................................15

Food Hygiene...........................................................................................................15

Food preservation.....................................................................................................15

Clothing........................................................................................................................15

Definition.................................................................................................................15

Types of Fabrics.......................................................................................................15

Importance of clothes...............................................................................................18
 How to take care of your clothes..............................................................................19

Housing........................................................................................................................20

Definition.................................................................................................................20

Importance of house to man.....................................................................................21

Points to consider when choosing a building site.....................................................21

How to prevent overheating in a house....................................................................22

Precautions to be taken when constructing a house in a waterlogged area or

swampy region.........................................................................................................22

How to make a house rat proof or rat free................................................................23

Characteristics or features of a modern kitchen.......................................................23

Ventilating a house...................................................................................................24

Lighting a house.......................................................................................................25

Heating a house........................................................................................................25

Human reproductive system.........................................................................................26

Male reproductive system........................................................................................26

Major Male secondary sexual characteristics.......................................................27

Functions of the male reproductive system..........................................................27

Female reproductive system.....................................................................................27

Female genitalia...................................................................................................27

Production of gametes..............................................................................................28

Diseases of the human reproductive system.............................................................31

First aid.........................................................................................................................40

Responsibilities of a first aider.................................................................................40

First aid treatment.....................................................................................................41

First aid treatment for snake bites........................................................................41

First aid treatment for epilepsy.............................................................................41

First aid treatment for broken bones.....................................................................41

 First aid treatment for electric shock....................................................................42

First aid treatment for accidental poisoning.........................................................42

Importance of first aid..............................................................................................42

Ecology.........................................................................................................................42

Intoduction...............................................................................................................42

Terms used in ecology..............................................................................................42

Feeding relationships in an ecosystem.................................................................43

Habitat..................................................................................................................43

The Biosphere.......................................................................................................43

Niches...................................................................................................................43

Types of Habitats......................................................................................................44

The difference between an ecosystem and a habitat................................................44

Levels of Organization.............................................................................................44

Population.............................................................................................................44

Community...........................................................................................................45

Symbiosis.................................................................................................................46

Food chains..........................................................................................................47

Food web..............................................................................................................48

How energy flows through an ecosystem.................................................................48

Cycles in Nature.......................................................................................................49

Water cycle...........................................................................................................49

Carbon cycle.........................................................................................................50

Nitrogen cycle......................................................................................................51

Phosphorous cycle................................................................................................52

Succession: Changes over Time...............................................................................54

Primary succession...............................................................................................54

Secondary succession...........................................................................................54
 Biomes......................................................................................................................54

Types of biomes...................................................................................................54

How climate affects biomes.................................................................................56

Human impact on the ecosystem..................................................................................57

Pollution...................................................................................................................57

Types of pollution................................................................................................57

Sewage and refuse disposal......................................................................................60

Reasons why sewage is considered as a pollutant................................................60

Methods of sewage disposal.................................................................................60

Water............................................................................................................................63

Introduction..............................................................................................................63

Sources of water.......................................................................................................63

1) Wells....................................................................................................................63

Types of impurities likely to be found in water...................................................64

Hardness of water.................................................................................................64

Purification of water.............................................................................................65

The cell

Definition: A cell is the basic (smallest) structural and functional unit of living things.
The internal structure(ultra-Structure) of an animal cell

Function of parts of an animal cell

 Centrioles: Centrioles are self-replicating organelles made up of nine bundles of

microtubules and are found only in animal cells. They appear to help in
organizing cell division, but aren't essential to the process.

 Cilia and Flagella: For single-celled eukaryotes, cilia and flagella are essential
for the locomotion of individual organisms. In multicellular organisms, cilia
function to move fluid or materials past an immobile cell as well as moving a cell
or group of cells.

 Endoplasmic Reticulum: The endoplasmic reticulum is a network of sacs that

manufactures, processes, and transports chemical compounds for use inside and
outside of the cell. It is connected to the double-layered nuclear envelope,
providing a pipeline between the nucleus and the cytoplasm.

 Endosomes and Endocytosis: Endosomes are membrane-bound vesicles, formed

via a complex family of processes collectively known as endocytosis, and found
 in the cytoplasm of virtually every animal cell. The basic mechanism of
endocytosis is the reverse of what occurs during exocytosis or cellular secretion.
It involves the invagination (folding inward) of a cell's plasma membrane to
surround macromolecules or other matter diffusing through the extracellular
fluid.

 Golgi Apparatus: The Golgi apparatus is the distribution and shipping

department for the cell's chemical products. It modifies proteins and fats built in
the endoplasmic reticulum and prepares them for export to the outside of the cell.

 Intermediate Filaments: Intermediate filaments are a very broad class of fibrous

proteins that play an important role as both structural and functional elements of
the cytoskeleton. Ranging in size from 8 to 12 nanometers, intermediate filaments
function as tension-bearing elements to help maintain cell shape and rigidity.

 Lysosomes: The main function of these microbodies is digestion. Lysosomes

break down cellular waste products and debris from outside the cell into simple
compounds, which are transferred to the cytoplasm as new cell-building
materials.

 Microfilaments: Microfilaments are solid rods made of globular proteins called

actin. These filaments are primarily structural in function and are an important
component of the cytoskeleton.

 Microtubules: These straight, hollow cylinders are found throughout the

cytoplasm of all eukaryotic cells (prokaryotes don't have them) and carry out a
variety of functions, ranging from transport to structural support.

 Mitochondria: Mitochondria are oblong shaped organelles that are found in the
cytoplasm of every eukaryotic cell. In the animal cell, they are the main power
generators, converting oxygen and nutrients into energy.

 Nucleus: The nucleus is a highly specialized organelle that serves as the

information processing and administrative center of the cell. This organelle has
two major functions: it stores the cell's hereditary material, or DNA, and it
coordinates the cell's activities, which include growth, intermediary metabolism,
protein synthesis, and reproduction (cell division).
 Peroxisomes: Microbodies are a diverse group of organelles that are found in the
cytoplasm, roughly spherical and bound by a single membrane. There are several
types of microbodies but peroxisomes are the most common.

 Plasma Membrane: All living cells have a plasma membrane that encloses their
contents. In prokaryotes, the membrane is the inner layer of protection
surrounded by a rigid cell wall. Eukaryotic animal cells have only the membrane
to contain and protect their contents. These membranes also regulate the passage
of molecules in and out of the cells.

 Ribosomes: All living cells contain ribosomes, tiny organelles composed of

approximately 60 percent RNA and 40 percent protein. In eukaryotes, ribosomes
are made of four strands of RNA. In prokaryotes, they consist of three strands of
RNA.

Comparative study of the animal and plant cell

Differences between plant and animal cells

Plant cell Animal cell

Has cell wall Has no cell wall

Large centrally located vacuole Many small vacuoles

Chlorophyll in chloroplast No chlorophyll at all

Have a fixed shape Has no fixed shape

Store food as starch Store food as glycogen

Small cytoplasm Large cytoplasm

Usually large Usually small

Cellular exchanges

Definition:

Cellular exchange is the movement of substances in and out of the cell. This occurs
through the following processes: Diffusion, osmosis, active transport and facilitated
diffusion.

Definition of some terms:

1) A solute: This is a substance that dissolves in a solid. E.g. sugar, salt etc.

2) A solvent: This is any liquid in which the solute dissolves. E.g. water, kerosine,
alcohol etc

3) A solution: It is a uniform mixture formed from a solute and a solvent.

4) Concentration gradient: This is the difference between the concentrations of

two solutions.

Types of solutions

There are 3 types of solutions: hypertocic, hypotonic and isotonic solutions.

1) Hypotonic solution: This is a solution with a lower concentration when

compared with another solution or contains a lower number of solute molecules.

2) Hypertonic solution: This is a solution with a higher concentration when

compared with another solution or contains a higher number of solute molecules.

3) Isotonic solution: This is a solution of equal concentration when compared with

another solution or contains equal number of solute and solvent molecules.
Diffusion

Definition: This is the movement of molecules from a region of higher concentration

to a region of lower concentration until equilibrium is reached. E.g. when perfume is
sprayed a a certain corner in a room, the smell would be gotten at the other end in
seconds. The movement of the perfume molecules in air is seen in the diagram below.

Experiment to demonstrate diffusion

Aim: To demonstrate the process of diffusion.

Requirements: Water, beaker, drops of blue ink.

Procedure:

 A beaker is filled with water.

 3 drops of ink are added to it.

 The setup is observed for 5 minutes.

Observation

The colour of water in the beaker changed from colourless to blue as seen on the
diagram below
Explanation

Molecules of ink move from a region of higher concentration to a region of lower

concentration spreading throughout the water. The uniform colour of the water shows
the uniform distribution of molecules of ink throughout the water.

Precautions:

 Do not distort the beaker after adding the ink drops.

Factors affecting the rate of diffusion

1) Size of diffusing particles.

2) Temperature of the surrounding medium.

3) Differences in concentration gradient between the two solutions.

4) Surface area across which diffusion occurs.

Importance of diffusion

1) It is used in the absorption of useful substances from the small intestine after
digestion.

2) It helps cells to send out waste gases like CO2.

3) It helps in the regulation of fluid content in cells.

4) It is used by industries in the manufacture of perfumes.

5) It is the essential process in the exchange of gases (O 2 and CO2) during

photosynthesis.

6) It helps in the uptake of water and mineral salts by plants through their roots.

7) It helps in the removal of excess water by transpiration.

8) It causes air pollution.

9) It is needed for the production of energy.

Osmosis

Definition: This is the movement of water molecules only from a region of higher
concentration to a region of lower concentration across a selectively permeable
membrane. Osmosis in a sugar solution is demonstrated in the diagram below.

Experiment to demonstrate osmosis in a living tissue

Aim: To demonstrate osmosis in a living tissue.

Requirements: Beaker, water, sugar, boiled and unboiled potato tubers, knife, 4
paper pins.

Procedure:

 The potato tubers are peeled with the knife.

 One side of the potato tubers is cut to obtain a flat surface.

 A hole is born into the flat surface of the potato tubers.

 A sugar solution is put into the born cavities of the potato tubers up to a quarter of
the space.

 The initial levels of water are marked with the paper pins.

 The boiled potato is placed in a beaker of water (A) and the unboiled potato
placed in another beaker of water (B) with the born part of the tubers facing up.

 The setup is allowed for an hour and observed.

Setup (diagram):
Observation:

The level of solution in ‘B’ rises above the initial level, while the volume of solution
in ‘A’ remains the same.

Explanation:

Water level inside the living potato increased because water moved by osmosis from
the region of higher water potential (beaker) to the region of lower water potential
(the cavity of the potato tuber) across a selectively permeable membrane (living
potato tissue). There was no change in ‘B’ because boiling destroyed the cell of the
potato and hence no osmosis.

Conclusion: Osmosis occurs in living tissue.

Some processes related to osmosis

1) Plasmolysis: This is a situation which comes about when a plant cell is placed in
a hypertonic solution. Water leaves the cell into the solution. The cytoplasm
shrinks from the cell wall and the cell becomes flaccid.

2) Turgidity: This is a situation which comes about when a plant cell is put in a
hypotonic solution. The cell pulls in water into the cell vacuole which swells and
develops a force against the cell wall.

3) Crenation: This is a situation which comes about when an animal cell is placed
in a hypertonic solution Water moves from the cell cytoplasm across the cell
membrane into the solution. The cell membrane crinkles and shrinks, hence, it
becomes shrivelled.
4) Hymolysis: This is situation which comes about when an animal cell is placed in
a hypotonic solution. Water moves from the solution through the cell membrane
into the cytoplasm of the cell. The cell swells and eventually burst to release its
contents.

Importance of Osmosis

1) Enable plants to take in water and minerals from the soil through their roots.

2) Osmosis plays a role in the formation of tissue fluid.

3) It controls the opening and closing of the stomata in leaves.

4) In animals, it helps to maintain blood osmotic pressure in cells.

5) It enables movement of water from one living cell to another within the plant.

6) Osmosis helps plant cells retain water, hence maintaining their shape.

7) Osmosis helps maintain the amount of water present in cells.

Active transport

Definition: This is the movement of substances from a region of lower concentration

to a region of higher concentration across a selectively permeable membrane with the
use of energy in the form of ATP (Adenosint Triphosphate). Examples of active
transport include:

 Uptake of glucose from the small intestine of humans into blood.

 Uptake of Iodine by seaweeds.

 Uptake of mineral ions into root hairs of plants.

Importance of active transport to living things

1. Active transport helps in the absorption of nitrate ions (NO3-) from the soil.

2. Active transport helps in the absorption of some food molecules such as glucose
from the intestines.

3. Active transport helps in the selective re-absorption of molecules such as glucose

by the kidney tubules.

Differences between diffusion and active transport

Diffusion Active transport

Not selective Selective

Substances move down the concentration gradient Substances move up the concentration gradient

Living cells membrane not necessary Living cells membrane necessary

Energy is not used up Energy from respiration is used

Facilitated Diffusion

Definition: This is the process whereby; substances are carried across a cell
membrane by carrier proteins which are specific for the substance they carry. It is a
faster mode of diffusion.

Importance of Facilitated Diffusion

1. Allows the transport of substances across the cell membrane that cannot be
transported by any other way.

2. It is a faster way by which substances

 Food

Definition

Food is any nutritious substance that living things take into their bodies in order to
maintain life and growth.

Food Hygiene

1) Prevent contaminating food with mixing chemicals, spreading from people, and
animals.

2) Separate raw and cooked foods to prevent contaminating the cooked foods.

3) Cook foods for the appropriate length of time and at the appropriate temperature
to kill pathogens.

4) Store food at the proper temperature.

5) Use safe water and raw materials.

Food preservation

Clothing

Definition

These are fabrics, animal hair, or a combination of these used to cover the human
body.

Types of Fabrics

Different Types of Fabric Used for Clothing:

There are various types of fabric used for garment manufacturing, those are explained
below:

1. Brocade Fabric:
Brocade is a jacquard fabric that is figured heavily. The figure is developed by
floating weft yarn, warp yarns, or both. Brocade fabric is sued for formal wear and
furnishing.

2. Cambric Fabric:

Cambric is a lightweight, closely woven fabric which is normally used in

handkerchiefs. Cambric can be given additional stiffening. It is also used in children’s
dresses, ladies’ garments, nightwear etc.

3. Chambray Fabric:

Chambray is a lightweight plain weave cotton woven fabric. It has a white weft and
colored warp. Chambray produces a blotchy appearance. It is used in women’s and
children’s garments, shirts and sportswear.

4. Chintz Fabric:

Chintz fabric is a highly lustrous plain weave cotton fabric. Chintz fabric is normally
finished with calendaring to give luster. Chintz fabric is used in manufacturing
sportswear and furnishing.

5. Chiffon Fabric:

Chiffon is a very lightweight, delicate and sheer fabric. Chiffon was originally
produced by using of silk yarns, but now even man-made fibers such as polyester are
being used to produce chiffon fabric. It is used in blouses, dresses and gowns.

6. Denim Fabric:

Denim is a durable woven cotton twill fabric. Normally, it was indigo dyed and warp
was yarn dyed with un-dyed weft yarn. It is used in leisure wear and work-wear.

7. Double Cloth:

Double cloth is also called double face as it is reversible in nature. Two component
fabrics are held together by the means of the following methods – self-stitching,
center-stitching or interchanging. Double cloth is used in coats, dresses, jackets and
furnishings.

8. Flannel Fabric:
Flannel fabric is a plain or twill weaves fabrics that are lightweight or medium
weight. Normally flannel fabric is made in wool. It might be slightly raised. Flannel
fabric is used in shirts and nightwear manufacturing.

9. Fleece Fabric:

Fleece is a woven fabric which is made from woolen yarn that has a raised pile on its
surface. Fleece fabric is used in jackets and coats manufacturing.

10. Interlock Fabric:

Interlock fabric is a fine, weft knitted fabric which has good stretch characteristics and
is also reversible in nature. Interlock fabric is used in blouses, dresses, T-shirts and
underwear.

11. Lawn Fabric:

It is a lightweight plain weave woven fabric. Lawn fabric is generally produced by

using cotton with very fine yarns. It is generally printed. Lawn fabric is used in
making dresses and blouses.

12. Organdy Fabric:

Organdy fabric is very fine fabric. It is also semi-transparent, delicate, light-weight

fabric which is characterized by a permanent stiff finish. This type of fabric is used in
manufacturing blouses and dresses.

13. Oxford Fabric:

Oxford fabric is a plain weave cotton fabric. The fabric has two warp ends woven as
one. Oxford fabric is used in manufacturing of blouses and shirts.

14. Organza Fabric:

Organza fabric is a thin transparent, plain weave fabric, with a stiff finish. It is
generally produced by using silk yarn. Organza fabric is used in formal wear,
interlinings and blouses.

15. Poplin Fabric:

Poplin fabric is a plain weave cotton fabric. The fabric is produced by using dense
warp over a coarse weft, which give a design of fine weft way ribs. Poplin fabric is
used in manufacturing of jackets, shirts, blouses, trousers and coats.

16. Rib Jersey Fabric:

Rib jersey fabric is a weft-knitted double-sided fabric. Rib jersey fabric is used in the
collars of t-shirts and cuffs.

17. Single Jersey Fabric:

Single jersey fabric is a weft-knitted fabric characterized by plain stitches throughout

the fabric. The fabric is sued for manufacturing blouses, T-shirts and nightwear.

18. Voile Fabric:

Voile is a lightweight and plain weave fabric. The fabric is produced from highly fine
yarns. Voile fabric is used in blouses and dresses.

Importance of clothes

1. It provides protection from heat, cold, wind, and rain. We all know extreme
weathers can affect our skin and body.

2. It protects us from any possible injury.

3. Some clothes serve as uniforms (a specific cloth worn by all the people of an
organization), thereby making it easy to identify which organization one belongs
to.

4. Many people wear special styles and colors of clothing for special occasions in
their lives.

5. Clothes are one of the important factors that represent the status symbol of an
individual.

6. Clothes made of a particular quality is used by people working in some special

jobs.

7. Clothes add beauty to our body.

8. Clothes are used as formal vestments in occasions to denote the emotional

climate.
9. Some clothes are used as nsignias (badges or emblems that show membership in
a group).

10. Certain types of clothing, colors, and accessories have become representative of
certain groups, activities, and occupations.

How to take care of your clothes

1. Purchase quality clothing.

2. Follow the instructions written on the tag found on the neck or down the side
seam of your shirt.

3. Wash dark clothing inside-out.

4. Use a clothesline or drying rack.

5. Wash dresses with metal parts separately when using a washing machine.

6. Don’t wash coloured dresses with bleach.

7. Wash your clothes less often.

8. Before washing clothes, the following should be done:

 Set aside any dry-clean only articles of clothing

 Group together any delicate or cold-wash only clothing

 Group towels and heavy linens

 Separate the rest of your clothes into whites and dark or colored groups.

 Turn T-shirts inside out to prevent the outside from wearing out and fading.

9. Know well the settings of your washing machine.

10. Pre-treat any stained items with a stain removing spray or pen and follow the
rules below:

 Don't clean stains with hot water, as this will set the stain. Try to get to the stain
before it dries, while it is still wet.

 Don't put stained clothes into the dryer as this will make the stain permanent.
Redo the stain treatment, then wash the garment again.
 Be aware that it may not be possible to remove all stains entirely. In this case,
fade the stain as much as possible.

11. Wear aprons or old "junk" clothes while cleaning and cooking.

12. Add detergent and fabric softener (if desired) to the washing machine.

13. If you used an automatic dryer it is important to remove clothes from the dryer
immediately.

14. Practice good hygiene such as showering daily, wearing deodorant, and using
proper undergarments.

15. Learn to complete basic repairs on your clothing such as replacing a loose thread
or a missing button.

16. Always use the right heat level for the type of fabric you’re ironing or invest in a
steamer.

17. Rotate your clothes

18. Practice good storage habits; fold heavy sweaters on a shelf, button buttons and
zip zippers, invest in better hangers, space your clothes, and your closet should be
“cool and dry.” Never store clothes in a humid bathroom or moist basement
closet.

19. Dye faded clothes

20. Dress after your hair and makeup, not before.

21. Adjust your dryer

Housing

Definition

This is the activity of providing a place for someone to stay.

Importance of house to man

1) It provides shelter against enemies

2) It protects man from hot and cold weather conditions.

 3) Some people get a lot of money from renting their houses.

4) Houses are used for storage of food.

5) A house is used to improve privacy.

6) A house is used for cooking.

Points to consider when choosing a building site

1) The soil should be well drained e.g. loam soil.

2) The site should not be subjected to landslide.

3) The area should be elevated, well drained and airy.

4) There should be an ample space around the house.

5) The house should have access to water supply, roads, schools and hospitals.

Sitting houses in temperate and tropical regions

How to prevent overheating in a house

1) The house should have extended leaves or wide veranda to provide shade. The
veranda has the following functions.

a) Provide a sitting place.

 b) Serve as a playground for children.

c) Prevent soiling on walls.

2) The walls of the house should be painted white. This is because white reflects
light and does not absorb heat.

3) There should be canopy projecting over the windows to prevent direct sunlight
rays.

4) The walls must be double, with an air space between the outer and inner walls to
act as an insulator.

5) Aluminum roof should be used which reflects light and heat.

6) There should be a ceiling between the roof and the floor.

7) The floor should be covered with tiles.

8) The house should be surrounded by green trees which act as shade.

9) The ceiling must have air holes.

10) The roof must have air vents.

Precautions to be taken when constructing a house in a waterlogged area or

swampy region

Houses in this type of area are not good for human habitation because moisture
promotes the breeding of bacterial and fungal spores. The moist nature of the house
can cause chills and hypothermia in elderly persons when abandoned in such homes.

So, for the above reasons, houses in marshy or swampy areas should be constructed as
follows:

1) The houses should be erected on stilts or pillars.

2) The houses should be tiled since tiles are made up of impervious material and
would prevent water from entering the houses.

3) The foundation should be high up and contain a damp-proof course.

4) The house should have a good drainage system or enough gutters to channel
runoffs away from the house.

5) Trees should be planted away from the house to prevent the leaves of the trees
from directing water to the walls of the house.

6) The doors and windows should be facing the East-West direction to allow sun’s
rays to enter the house and provide warm conditions.

7) The lower section of the doors must be at least 50cm in height to prevent water
from entering through the doors.

How to make a house rat proof or rat free

1) The house must have tight fitting doors and windows.

2) A metal flange should be fixed around each pillar to prevent rats from climbing
into the house.

3) The floor must be concreted and continuous with the walls.

4) The foundation must be sufficiently deep into the ground to prevent rats from
digging below it.

5) The house should be properly lighted since rats are partially nocturnal organisms.

Characteristics or features of a modern kitchen

1) The kitchen must be far from the toilet.

2) It must be well lighted and ventilated.

3) The kitchen equipment must be kept on clean surfaces.

4) Preparation of ingredients must be done on clean surfaces. Plastic surfaces are

better than wooden surfaces which harbour bacteria between cracks.

5) The doors and windows should have mesh to prevent the entry of flies which are
potential contaminants.

6) Doors and windows must be tight-fitting to prevent rats and insects from entering.

7) Cooking is done with a gas cooker.

8) It should have a refrigerator for the storage of perishable food items.

Ventilating a house

This is the act of creating air current in a house to comfort the occupants i.e. those
staying inside. Air that does not move (stagnant air) is more often hot because of
water vapour from the lungs and heat from the skin. People living in this type of
environment feel tired and inattentive. The three main aims of ventilation are: to keep
the air moving, cool and dry.

There are two main types of ventilation, namely:

a) Natural ventilation achieved through the provision of adequate doors and

windows and

b) Artificial ventilation achieved by using fans and air conditioners.

In natural ventilation systems, adequate windows are situated on opposite walls of

the house to let in fresh air and the hot, stagnant and lighter air is forced out through
the opposite window by cross ventilation and convection currents. These
convection are very effective when the ceiling of the house contains air holes. Here,
ventilation bricks are also used which allows fresh air to enter, but prevents the entry
of sun’s rays.

In artificial ventilation systems, a fan or air conditioner is used to increase the speed
of the air circulation to cause further cooling. Artificial ventilation in large buildings
is achieved effectively through three main systems which are:

i. Propulsive system: In this system, fresh air is blown into the building by fans
and hot air escapes through the large windows and doors.

ii. Extractive system: With this method, the hot, stagnant and lighter air is
extracted by the fan and fresh air enters through the windows.

iii. Balanced system: In this system, the propulsive fan is there to blow in fresh
air and the extractive fan is also available to remove the hot, less dense air out
of the hall.
Lighting a house

Enough lighting indoors is very important for safety in places such as stairs and to
avoid eye strain when reading or writing. Lighting can be achieved by using either
natural or artificial light.

Natural light comes from the sun and enters the house through the doors and
windows created on the walls. The windows and doors in tropical regions should not
face the sun directly, while in temperate regions, the windows should face the
direction of sunrise.

In artificial lighting, fluorescent bulbs are used in the presence of electricity.

Minimum measures should be taken to ensure that the intensity of light is not too high
to cause eye straining and head ache. Artificial lighting is also achieved with bush
lamps and candles which are not the best when reading because it produces a lot of
smoke and causes eye straining.

Heating a house

 Natural heating:

1) The house should have short leaves to allow sun’s rays enter the house.

2) There should be large windows and doors facing the direction of sunrise i.e. East-
West direction.

3) The wall plastering and rooting material should be good insulating and absorbing
materials of heat.

 Artificial heating:

1) Burning of firewood and coal to produce heat to keep the house warm. The
advantages of this method is that fire wood is cheap and the disadvantage is that it
produces smoke which disturbs our eyes and also stains our dress and makes them
stink of smoke.

2) In modern houses, an electric heater is used at a temperature which causes it to

become red and radiates heat which keeps the house warm.
3) In temperate regions, water is heated by electric current and this hot water is
circulated through pipes buried in the walls of the house. This method is very
effective, but also very expensive.

Human reproductive system

Introduction

Human reproduction usually involves internal fertilization by sexual intercourse.

An important sexual hormone of males is androgen (particularly testosterone).

Male reproductive system

The male reproductive system is a series of organs located outside the body and
around the pelvis region of a male that contribute towards the reproduction process.

The major reproductive organs of the male can be grouped into three categories. The
first category produces and stores sperm (spermatozoa). These are produced in the
testes, which are housed in the temperature-regulating scrotum; immature sperm then
travel to the epididymis for development and storage. The second category are the
ejaculatory fluid producing glands which include the Cowper's gland (also called
bulbo-urethral gland), seminal vesicles, prostate, and vas deferens. The final category
are those used for copulation and deposition of the sperm within the female; these
include the penis, urethra, and vas deferens.
Major Male secondary sexual characteristics

These include: larger, more muscular stature, deepened voice, facial and body hair,
broad shoulders, and development of an ‘Adam's apple’.

Functions of the male reproductive system

The male reproductive system has one function: to produce and deposit sperm.

Female reproductive system

The human female reproductive system is a series of organs primarily located inside
the body and around the pelvic region of a female that contribute towards the
reproductive process. The human female reproductive system contains three main
parts: the vulva, which leads to the vagina, the vaginal opening, to the uterus; the
uterus, which holds the developing foetus; and the ovaries, which produce the
female's ova. Each ovary contains hundreds of egg cells or ova (singular ovum).

Female genitalia

The vagina meets the outside at the vulva, which also includes the labia, clitoris and
urethra. The vagina is attached to the uterus through the cervix, while the uterus is
attached to the ovaries via the Fallopian tubes.
Approximately every 28 days, the pituitary gland releases a hormone that stimulates
some of the ova to develop and grow. One ovum is released and it passes through the
Fallopian tube into the uterus. Hormones produced by the ovaries prepare the uterus
to receive the ovum. The lining of the uterus, called the endometrium, and un-
fertilised ova are shed each cycle through the process of menstruation. If the ovum is
fertilised by sperm, it attaches to the endometrium and the foetus develops.

Production of gametes

Gametes are produced within the gonads through a process known as gametogenesis.
This occurs when certain types of germ cells undergo meiosis to split the normal
diploid number of chromosomes (n=46) into haploid cells containing only 23
chromosomes.

In males, this process is known as spermatogenesis, and takes place only after puberty
in the seminiferous tubules of the testes. The immature spermatozoa or sperm are then
sent to the epididymis, where they gain a tail, enabling motility. Each of the original
diploid germ cells or primary spermatocytes forms four functional gametes which is
each forever young[clarification needed]. The production and survival of sperms
require a temperature below the normal core body temperature. Since the scrotum,
where the testes is present, is situated outside the body cavity, it provides a
temperature about 3 °C below normal body temperature.

Human sperm cell

In females, gametogenesis is known as oogenesis; this occurs in the ovarian follicles
of the ovaries. This process does not produce mature ovum until puberty. In contrast
with males, each of the original diploid germ cells or primary oocytes will form only
one mature ovum, and three polar bodies which are not capable of fertilization. It has
long been understood that in females, unlike males, all of the primary oocytes ever
found in a female will be created prior to birth, and that the final stages of ova
production will then not resume until puberty.However, recent scientific research has
challenged that hypothesis. This new research indicates that in at least some species of
mammal, oocytes continue to be replenished in females well after birth.

Human ovary

Copulation (sexual intercourse)

In this process, the male inserts his penis into the female's vagina and
ejaculatessemen, which contains sperm. During intercourse the female genitalia is
lubricated by mucus secreted by the Bartholin's glands.

Fertilisation

Proceeding copulation, after ejaculation, a small proportion of the sperm pass through
the cervix into the uterus, and then into the Fallopian tubes for fertilization of the
ovum.
Only one sperm is required to fertilise the ovum. Upon successful fertilization, the
fertilised ovum, or zygote, travels out of the Fallopian tube and into the uterus, where
it implants in the uterine wall. This marks the beginning of gestation.

Gestation (pregnancy)

This is the nine months period during which the foetus develops. At the end of
gestation is the process ofchildbirth, which involveslabour.

Labour

During labour, the muscles of the uterus contract and the cervix dilates over the
course of hours, and the baby passes out of the vagina. Human infants are nearly
helpless and require high levels of parental care. Infants rely on their caregivers for
comfort, cleanliness, and food. Food may be provided by breastfeeding or formula
feeding.

Functions of the female reproductive system

1. Production of egg cells (ova)

2. Protection and nourishment of the foetus until birth.

Diseases of the human reproductive system

1. Genetic or congenital abnormalities.

2. Cancers.

3. Infections, which are often sexually transmitted diseases.

4. Sexual dysfunction and infertility, whichoften arisefrom sexually transmitted
diseases.

5. Peyronie's disease in males.

6. Endometriosis in females.

7. Turner syndrome.

8. Klinefelter's syndrome.

9. Cystic fibrosis.

10. Bloom syndrome.

Family planning

Definitions

Family planning is the term given to activities which enable individuals to determine
freely the number and spacing of their children and to select the means by which this
may be achieved".

Contraception is birth control by the use of devices (diaphragm or intrauterine device

or condom), drugs or surgery. It is the main way in which family planning is achieved
these days

Benefits of family planning

1. Some family planning methods, such as condoms, help prevent the transmission
of HIV and other sexually transmitted infections.

2. It reduces the need for abortion, especially unsafe abortion.

3. It reinforces people’s rights to determine the number and spacing of their

children.

4. It prevents deaths of mothers and children by preventing unintended pregnancy.

5. Family planning allows people to attain their desired number of children and
determine the spacing of pregnancies.
6. It prevents pregnancy-related health risks in women

7. Family planning can prevent closely spaced and ill-timed pregnancies and births,
which contribute to some of the world’s highest infant mortality rates.

8. Family planning reduces the risk of unintended pregnancies among women living
with HIV, resulting in fewer infected babies and orphans.

9. Family planning enables people to make informed choices about their sexual and
reproductive health.

10. Family planning is key to slowing unsustainable population growth and the
resulting negative impacts on the economy, environment, and national and
regional development efforts.

Contraceptive methods

Modern methods

Method Description How it Effectiveness to Comments

works prevent
pregnancy
Combined oral Contains two Prevents the >99% with Reduces risk of
contraceptives hormones release of correct and endometrial and
(COCs) or “the (estrogen and eggs from consistent use ovarian cancer
pill” progestogen) the ovaries 92% as
(ovulation) commonly used
Progestogen-only Contains only Thickens 99% with correct Can be used while
pills (POPs) or "the progestogen cervical and consistent breastfeeding; must
minipill" hormone, not mucous to use be taken at the same
estrogen block sperm 90–97% as time each day
and egg commonly used
from
meeting and
prevents
ovulation
Implants Small, flexible Thickens >99% Health-care
rods or capsules cervical provider must insert
placed under the mucous to and remove; can be
skin of the upper block sperm used for 3–5 years
 arm; contains and egg depending on
progestogen from implant; irregular
hormone only meeting and vaginal bleeding
prevents common but not
ovulation harmful
Progestogen only Injected into the Thickens >99% with Delayed return to
injectables muscle or under cervical correct and fertility (about 1–4
the skin every 2 mucous to consistent use months on the
or 3 months, block sperm 97% as average) after use;
depending on and egg commonly used irregular vaginal
product from bleeding common,
meeting and but not harmful
prevents
ovulation
Monthly Injected monthly Prevents the >99% with Irregular vaginal
injectables or into the muscle, release of correct and bleeding common,
combined contains eggs from consistent use but not harmful
injectable estrogen and the ovaries 97% as
contraceptives progestogen (ovulation) commonly used
(CIC)
Combined Continuously Prevents the The patch and the The Patch and the
contraceptive patch releases 2 release of CVR are new and CVR provide a
and combined hormones – a eggs from research on comparable safety
contraceptive progestin and an the ovaries effectiveness is and
vaginal ring (CVR) estrogen- (ovulation) limited. pharmacokinetic
directly through Effectiveness profile to COCs
the skin (patch) studies report that with similar
or from the ring. it may be more hormone
effective than the formulations.
COCs, both as
commonly and
consistent or
correct use.
Intrauterine device Small flexible Copper >99% Longer and heavier
(IUD): copper plastic device component periods during first
containing containing damages months of use are
copper sleeves sperm and common but not
or wire that is prevents it harmful; can also
inserted into the from be used as
uterus meeting the emergency
 egg contraception
Intrauterine device A T-shaped Thickens >99% Decreases amount
(IUD) plastic device cervical of blood lost with
levonorgestrel inserted into the mucous to menstruation over
uterus that block sperm time; Reduces
steadily releases and egg menstrual cramps
small amounts of from and symptoms of
levonorgestrel meeting endometriosis;
each day amenorrhea (no
menstrual bleeding)
in a group of users
Male condoms Sheaths or Forms a 98% with correct Also protects
coverings that fit barrier to and consistent against sexually
over a man's prevent use transmitted
erect penis sperm and 85% as infections,
egg from commonly used including HIV
meeting
Female condoms Sheaths, or Forms a 90% with correct Also protects
linings, that fit barrier to and consistent against sexually
loosely inside a prevent use transmitted
woman's vagina, sperm and 79% as infections,
made of thin, egg from commonly used including HIV
transparent, soft meeting
plastic film
Male sterilization Permanent Keeps sperm >99% after 3 3 months delay in
(vasectomy) contraception to out of months semen taking effect while
block or cut the ejaculated evaluation stored sperm is still
vas deferens semen 97–98% with no present; does not
tubes that carry semen evaluation affect male sexual
sperm from the performance;
testicles voluntary and
informed choice is
essential
Female sterilization Permanent Eggs are >99% Voluntary and
(tubal ligation) contraception to blocked informed choice is
block or cut the from essential
fallopian tubes meeting
sperm
Lactational Temporary Prevents the 99% with correct A temporary family
amenorrhea contraception for release of and consistent planning method
method (LAM) new mothers eggs from use based on the natural
whose monthly the ovaries 98% as effect of
bleeding has not (ovulation) commonly used breastfeeding on
returned; fertility
requires
exclusive or full
breastfeeding
day and night of
an infant less
than 6 months
old
Emergency Pills taken to Delays If all 100 women Does not disrupt an
contraception pills prevent ovulation used progestin- already existing
(ulipristal acetate pregnancy up to only emergency pregnancy
30 mg or 5 days after contraception,
levonorgestrel 1.5 unprotected sex one would likely
mg) become pregnant.
Standard Days Women track Prevents 95% with Can be used to
Method or SDM their fertile pregnancy consistent and identify fertile days
periods (usually by avoiding correct use. by both women
days 8 to 19 of unprotected 88% with who want to
each 26 to 32 vaginal sex common use become pregnant
day cycle) using during most (Arevalo et al and women who
cycle beads or fertile days. 2002) want to avoid
other aids pregnancy. Correct,
consistent use
requires partner
cooperation.
Basal Body Woman takes Prevents 99% effective If the BBT has risen
Temperature her body pregnancy with correct and and has stayed
(BBT) Method temperature at by avoiding consistent use. higher for 3 full
 the same time unprotected 75% with typical days, ovulation has
each morning vaginal sex use of FABM occurred and the
before getting during (Trussell, 2009) fertile period has
out of bed fertile days passed. Sex can
observing for an resume on the 4th
increase of 0.2 to day until her next
0.5 degrees C. monthly bleeding.

TwoDay Method Women track Prevents 96% with correct Difficult to use if a
their fertile pregnancy and consistent woman has a
periods by by avoiding use. vaginal infection or
observing unprotected 86% with typical another condition
presence of vaginal sex or common use. that changes
cervical mucus during most (Arevalo, 2004) cervical mucus.
(if any type color fertile days, Unprotected coitus
or consistency) may be resumed
after 2 consecutive
dry days (or
without secretions)
Sympto-thermal Women track Prevents 98% with correct May have to be
Method their fertile pregnancy and consistent used with caution
periods by by avoiding use. after an abortion,
observing unprotected Reported 98% around menarche or
changes in the vaginal sex with typical use menopause, and in
cervical mucus during most (Manhart et al, conditions which
(clear texture) , fertile 2013) may increase body
body temperature.
temperature
(slight increase)
and consistency
of the cervix
(softening).

Traditional methods

Method Description How it works Effectivene Comments

ss to
prevent
pregnancy
Calendar Women monitor The couple 91% with May need to delay or use
method or their pattern of prevents pregnancy correct and with caution when using
rhythm menstrual cycle by avoiding consistent drugs (such as
method over 6 months, unprotected use. anxiolytics,
subtracts 18 from vaginal sex during 75% with antidepressants,
shortest cycle length the 1st and last common NSAIDS, or certain
(estimated 1st fertile estimated fertile use antibiotics) which may
day) and subtracts days, by abstaining affect timing of
11 from longest or using a condom. ovulation.
cycle length
(estimated last
fertile day)
Withdrawal Man withdraws his Tries to keep 96% with One of the least effective
(coitus penis from his sperm out of the correct and methods, because proper
interruptus) partner's vagina, and woman's body, consistent timing of withdrawal is
ejaculates outside preventing use often difficult to
the vagina, keeping fertilization 73% as determine, leading to the
semen away from commonly risk of ejaculating while
her external used inside the vagina.
genitalia (Trussell,
2009)

First aid

First aid is the help given to someone who is injured or ill, to keep them safe until
they can get more advanced medical treatment by seeing a doctor, health professional
or go to hospital.

A person who is involved in an accident is called a casualty and the person who offers
first aid is called a first aider.

Responsibilities of a first aider

1. Assess the situation quickly and calmly.

2. Protect the victim(s) and his/herself from any danger.

3. Prevent infection between you and them.

4. Comfort and reassure the victim(s).

5. Assess the casualty.

6. Give first aid treatment.

7. Arrange for the right kind of help.

First aid treatment

These are the tasks to be performed for every case that needs first aid treatment.

First aid treatment for snake bites

 Suck out the venom with the mouth and spit it out immediately.
 Enlarge the wound by cutting it deep to allow the blood carry out the venom
freely.
 Tie the bitten portion above and below to slow down blood circulation.
 Calm the victim by re-assuring him/her that he/she will not die.
 Do not give the patient alcohol.
 Rush with the patient to the hospital with either the killed snake or name of the
species to facilitate treatment of the casualty.

First aid treatment for epilepsy

 Take the casualty far away from fire and water.

 Remove all sharp and hard objects around the person.
 Place a piece of wood between the upper and lower teeth to prevent biting of his
tongue.
 Let the victim sleep and have enough rest after the fits.

First aid treatment for broken bones.

 Avoid moving injured parts so as to prevent further damage to neighboring

tissues.
 Cover any protruding bone with a sterile cloth to prevent contamination.
 Support the fractured part with a splint.
 Give the casualty some pain relief drugs while seeking medical attention.
 Bandage the affected part to a fixed part of the body.
 Apply cool compress to reduce pains and swelling.
 The patient should be taken to the hospital preferably on a stretcher to reduce
pains.
 If it is a sprain, massage it with warm water.
 Don’t wash the affected part in the case of a compound fracture to avoid loss of
some pieces of bones.
First aid treatment for electric shock

 Do not touch or even go near a casualty who is unconscious and still connected to
the source of current electricity.
 Switch off the current at the source before touching the unconscious person.
 If breathing is stopped, then resuscitation should be done i.e. “giving the kiss of
life”.

First aid treatment for accidental poisoning

 If you suspect that a person, especially a child has swallowed a harmful substance,
ask at once what it was or try to get a sample so that a suitable antidote can be
prepared at the hospital. If the patient is conscious, he should be given water or
milk to drink so as to dilute the poison. The casualty should be persuaded to
vomit.

Importance of first aid

 It prevents the casualty’s condition from getting worse.

 It makes recovery easier.
 It reduces loss of lives.

Ecology

Intoduction

Ecology is the study of the relationships of living things to their surroundings and to
one another i.e. how living things and non-living things in the environment affect
each other.

Terms used in ecology

Abiotic factors

The non-living parts or physical factors in the environment including temperature,

light, water, weather conditions, altitude and essential elements like oxygen, carbon
and nitrogen are referred to as the abiotic factors.

Biotic factors
The relationships amongst organisms are the biotic factors. Everything that happens
among organisms in relation to their surroundings is taken into account when studying
an ecosystem i.e. a section of the biosphere in which living and non-living things
interact and inter-relate.

Feeding relationships in an ecosystem

Producers grow, Consumers eat producers and/or some producers and Decomposers
cause decay. The consumers that feed on plants only are called herbivores, and those
that feed on animals only are called carnivores. The consumers that feed on both
plants and animals are called omnivores. Some organisms bring about the
decomposition or decay of living organisms that have died. They are called
decomposers.

Habitat

The place where an organism lives i.e. where it is most frequently found, is called its
habitat. All organisms depend on their surroundings for support for the activities of
life, so nature ensures that organisms develop features which help them to adapt to
and survive in the prevailing conditions of their habitats. One such feature is a change
of colour to that which blends in with the colour scheme of the habitat. This feature is
called camouflage, for example, a stick insect among twigs or a green iguana in a
tree.

The Biosphere

The biosphere is the portion of Earth that supports living things. It includes the air,
land, and water where organisms can be found. The biosphere supports a wide variety
of organisms in a wide range of conditions. Climates, soils, plants, and animals can be
very different in different parts of the world. All over the world, though, living things
are affected by both the physical, nonliving environment and by other living things.

Niches

A niche is all strategies and adaptations a species uses in its environment. It is how
the species meets its specific needs for food and shelter. It is how and where the
species survives and reproduces. A species’ niche includes all its interactions with the
biotic and abiotic parts of its habitat

Types of Habitats

There are aquatic habitats like fresh-water lakes, ponds and streams; salt-water seas or
oceans; and terrestrial habitats which are on land.

The difference between an ecosystem and a habitat

An ecosystem is a section of the environment. It consists of the organisms and non-

living things. Scientists who study ecosystems are called ecologists. A habitat is a
particular place in an ecosystem, therefore, each ecosystem would have a number of
habitats.

Levels of Organization

Ecologists study individual organisms. They study relationships among organisms of

the same species and connections among organisms of different species. They also
study the effects of abiotic factors on species that live together. To make it easier to
examine all of these biotic and abiotic interactions, ecologists have organized the
living world into levels. The levels are the organism by itself, populations,
communities, and ecosystem

Population

Definition

A population is a group of organisms of the same kind or species in a particular place.

One of the factors influencing an ecosystem is the number of each species of
organism present. Food chains and food webs tend to keep the numbers of organisms
constant and distribution often depends on such relationships as predator prey and
parasite-host relationships. Such relationships always affect the size of populations.

Example of a population

Let us consider a predator-prey situation. A large spider population eats a lot of

insects. The number of insects may decrease as they are eaten by spiders. Then the
spiders would have less food and competition amongst the spiders for food could
result in a smaller spider population. With fewer spiders, the insect population might
increase again. Likewise, in the parasite-host relationship, the parasite population is
limited by the size of the host population, e.g. there could only be as many full-grown
tapeworms as there are hosts.

Note that competition occurs when there are limited materials and every organism has
to work 'against' other organisms to meet its needs.

Community

A biological community is made up of different populations in a certain area at a

certain time.

Life in a Community

In a community, there is inter-specific (between species) and intra-specific (within

same species) interaction.

In a biological community, changes in one population may cause changes in other

populations. For instance, if the number of mouse-eating hawks in a community
increases slightly, the number of mice in that community will decrease slightly. Other
changes can be more extreme. For example, one population may grow so large that it
threatens the food supply of another population.The physical factors in any
environment play a vital role in the interactions that take place in an ecosystem. The
physical factors such as light, temperature, rain (water) and wind form part of the
climatic conditions in a region. The climatic factors in these regions affect organisms
in many ways.

Light :

Plants must have light to make food. Some, such as the sunflower need more light
than others. Some organisms avoid light and seek dark habitats. Some animals are
active during the day and rest at night. These are diurnal animals. Those that are
active only in the night are called nocturnal animals.

Temperature :

Heat and cold affect the growth and behaviour of plants and animals. Humans and
some other animals, for example, birds are homoiothermic, that is, they can keep their
body temperature fairly constant, despite temperature changes in the environment.
Some animals, such as lizards are poikilothermic, that is, they cannot control their
body temperature, which varies with the temperature of the environment. In extremes
of heat or cold such animals are very inactive.

Water :

Water is essential for life. Adequate supplies of fresh water in the environment are
maintained by the water cycle.

Water occurs in the atmosphere as watervapour, the presence of which is called

humidity. Too much water or too little can be harmful because the concentration of
cell fluid should be constant. In tropical rain forests, the vegetation is lush while in the
desert there is scant growth of plants because there is more water in the rain forest
than in the desert.

Wind :

The movement of air caused by differences in atmospheric temperature is known as

wind. The wind plays its part in causing rain. It has a cooling and drying effect on
plants and on animals. It also helps in the dispersal of seeds, fruits, pollen and spores.
Strong winds, however, can damage plants and blow away topsoil from the land. This
removal of top soil is erosion.

Symbiosis

People once thought that animals in the same environment fought each other for
survival. In reality, most species survive because of the relationships they have with
other species. A relationship in which there is a close and permanent association
between organisms of different species is called symbiosis. Symbiosis means living
together. There are three major kinds of symbiosis: mutualism, commensalism, and
parasitism.

Mutualism

Mutualism is a relationship between two species that live together in which both
species benefit.

Examples of mutualism
The relationship between ants and an acacia tree. The ants protect the tree by
attacking any animal that tries to feed on the tree. The tree provides nectar as a food
for the ants. The tree also provides a home for the ants.

A mycorrhiza is in which a fungus lives symbiotically with a plant. Most of the fungi
that form mycorrhizae are basidiomycotes. Fine, thread-like hyphae grow around the
plant’s roots without harming the plant. More nutrients can enter the plant’s roots
because the hyphae increase the absorptive surface of the plant’s roots. Minerals in
the soil are absorbed by the hyphae and then released into the roots. The hyphae help
to maintain water around the roots. The fungus benefits from the relationship too. The
fungus receives organic nutrients such as amino acids andsugars from the plant.

A lichen is a symbiotic association between a fungus and green algae or

cyanobacteria. The fungus is usually an ascomycote. The algae or cyanobacteria are
photosynthetic. The photosynthetic partner provides food for both organisms. The
fungus provides its partner with water and minerals that it absorbs from rain and the
air. The fungus protects the partner from changes in environmental conditions.

Commensalism

Commensalism is a relationship in which only one species benefits and the other
species is not harmed or helped. For example, mosses sometimes grow on the
branches of trees. This does not help or hurt the trees, but the mosses get a good
habitat.

Parasitism

Parasitism is a relationship in which a member of one species benefits at the expense

of another species. For instance, when a tick lives on a dog, it is good for the tick but
bad for the dog. The tick gets food and a home, but the dog could get sick. The tick is
a parasite. A parasite is the organism that benefits from the relationship. The dog is a
host. The host is the organism that is harmed by the relationship.

Food chains

Ecologists study feeding relationships and symbiotic relationships to learn how matter
and energy flow in ecosystems. These scientists sometimes use a simple model called
a food chain. Food chains show how matter and energy move through an ecosystem.
In a food chain, nutrients and energy move from autotrophs to heterotrophs to, in the
end, decomposers. A food chain is drawn using arrows. The arrows show the direction
in which energy is transferred. An example of a simple food chain in a forest
ecosystem is shown below.

Most food chains are made up of two, three, or four transfers, or steps. Each organism
in a food chain represents a feeding step,or trophic level, in the transfer of energy and
matter. The amount of energy in the last transfer is only a small part of what was
available at the first transfer. At each transfer, some of the energy is given off as heat.

Food web

Food webs are models that show all possible feeding relationships at each trophic
level in a community. A food web is a more realistic model than a food chain

A food chain shows only one possible path for the transfer of matter and energy
through an ecosystem. Many other paths may exist because many different species
can be on each trophic level.For instance, in the food chain example on the previous
page, there are many animals in the forest other than mice that ea berries. Also, many
different kinds of organisms eat more than one type of food. This means that a single
species may feed at several different trophic levels. because most organisms depend
on more than one type of organism for food.

How energy flows through an ecosystem

Food chains and food webs deal with both matter and energy. An ecological pyrami
shows how energy flows through an ecosystem. There are different types of
ecological pyramids. Each pyramid has the autotrophs or first trophic layer, at the
bottom. Higher trophic layers are then layered on top of one another.

The sun is the source of all the energy in the biosphere.

The pyramid of energy shows that the amount of available energy becomes less from
one trophic level to the next. The total energy transfer from one trophic level to the
next is only about ten percent because organisms do not use all the food energy in the
trophic level below them. An organism uses energy to do all the things necessary for
life. Organisms use energy to move, to interact with their environment, and to digest
their food. The also use energy to build body tissue. Some of this energy is given off
as heat. The law of conservation of energy states that energy in either lost nor gained.
Even though some of the energy transferred at each trophic level enters the
environment as heat, it is still energy. It is just in a different form.

A pyramid of numbers shows the number of organisms eaten by the level above it. In
most cases, the number of organisms decreases at each higher trophic level.

Biomass is the total weight of living matter at each trophic level. A pyramid of
biomass shows the total dry weight of living material at each trophic level.

Cycles in Nature

Matter, in the form of food, moves through every organism. In this way, matter is
found at every trophic level. Matter is never made or destroyed. It just changes form
as it cycles through the different trophic levels. There is the same amount of matter
today as there was when life on Earth began.

Water cycle
Water also cycles through different stages. It is always moving between the
atmosphere and Earth. For instance, when you leave a glass of water out for a few
days, some of it seems to disappear. It has evaporated or changed into water vapor in
the air. Similarly, water from lakes and oceans evaporates. At some point, this water
vapor condenses, or comes together, and makes clouds. After even more
condensation, drops of water form. This water then falls back to Earth as rain, ice, or
snow.

Carbon cycle
All life on Earth is based on carbon, and all living organisms need carbon. The carbon
cycle starts with autotrophs. In photosynthesis, autotrophs use the sun’s energy to
change carbon dioxide gas into energy-rich forms of carbon.

Autotrophs use this carbon for growth and energy. Heterotrophs then feed on
autotrophs or feed on other animals that have already fed on autotrophs. The
heterotrophs then use the carbon for growth and energy. As autotrophs and
heterotrophs use this carbon, they release carbon dioxide into the air. The carbon
cycle continues very slowly. How rapidly it cycles depends upon whether the carbon
is found in soil, leaves, roots, in oil or coal, in animal fossils, or in calcium carbonate
reserves.

Nitrogen cycle
Nitrogen is another element important to living things. Although 78 percent of air is
nitrogen, plants cannot use this form well. There are bacteria, though, that change the
nitrogen from air to a form plants can better use. This form is found in the soil. Plants
use this nitrogen to make proteins. Animals eat the plants and change the plant
proteins into animal proteins. These proteins are used in building muscle and blood
cells. Urine is an animal waste that lets animals get rid of nitrogen they do not need.
This urine returns nitrogen to the soil. When organisms die and decay, nitrogen
returns to the soil. Plants then reuse this nitrogen. Soil bacteria also act on these dead
organisms and put nitrogen back into the air. In this way, nitrogen is always cycling
through the system.

Phosphorous cycle
Phosphorus also cycles through ecosystems. It is another element that all organisms
need. It cycles in two ways. In the short-term cycle, plants get phosphorus from the
soil. Animals get phosphorus from eating plants. When these animals die, their
decaying bodies release phosphorus back into the soil to be used again.

In the long-term cycle, materials containing phosphorus are washed into rivers and
oceans. As millions of years pass, the phosphorus becomes locked in rocks. Millions
of years later, as the environment changes, some of the rock is no longer covered. As
this rock wears away, the phosphorus is released back into the environment.

Limiting factor

Anything that limits an organism’s ability to live in a particular environment is known

as a limiting factor. For example, in most mountain trees cannot grow above the
timberline. It is too high, too cold, too windy, and the soil istoo thin.

Tolerance

The ability of living thingto survive the changes in theenvironment is called tolerance.
An organism reaches its limits of tolerance when igets too much or too little oan
environmental factor. Foexample, corn plants need warm, sunny weather and a
regular supply of water.

Succession: Changes over Time

Succession is the process of gradual, natural change and species replacement that
takes place in the communities of an ecosystem over time. There are two types of
succession: primary and secondary.

Primary succession

Primary succession takes place on land where there are no living organisms. For
example, when lava flows from a volcano, it destroys everything around it. When it
cools, land forms, but there are no living organisms in the new land. The first species
to live in such an area is called a pioneer species. Decaying lichens, along with bits of
sediment in cracks and crevices of rock, make up the first stage of soil development.
Gradually, other life forms take hold. After some time, primary succession slows
down and the community becomes stable. Pioneer species eventually die. Once little
or no change occurs, the community is called a climax community. A climax
community can last for hundreds of years.

Secondary succession

Secondary succession is the pattern of changes that takes place after an existing
community is destroyed. The destruction can be caused by a forest fire or when a field
is plowed over and not replanted. During secondary succession, as in primary
succession, organisms come into the area and change gradually. But, because soil
already exists, the species involved in secondary succession are different from those
in primary succession. Secondary succession may take less time than primary
succession to reach the stage of a climax community.

Biomes

A biome is a large group of ecosystems that shares the same type of climax
community. All the ecosystems within the biome have similar climates and
organisms.

Types of biomes
Aquatic Biomes

Approximately 75 percent of Earth’s surface is covered with water. Most of that water
is salty. Salt water is found in oceans, seas, and some inland lakes. Freshwater is
found in rivers, streams, ponds, and most lakes.

Types of aquatic biomes

Marine biomes

Most of the organisms that live in the marine (saltwater) biome are plankton. Plankton
are tiny organisms that float in the waters of the photic zone. The photic zone is the
area of the ocean that is shallow enough for sunlight to penetrate. Plankton include
autotrophs (organisms that make their own nutrients), diatoms, eggs, and very young
marine animals. Plankton are important because they form the base of the entire
aquatic food chain. This means that every aquatic animal either eats plankton or eats
an animal thateats plankton.

Freshwater biomes

Bodies of freshwater are another kind of biome. Lakes and ponds serve as home to
many organisms. Plants grow around the shorelines and into the water. The shallow
waters where these plants grow are home to tadpoles, aquatic insects, worms, certain
fishes, and many other living things. All the life forms are part of the local food chain.
In deeper waters, it is colder and there are fewer species. Dead organisms drift to the
bottom. There, bacteria break down the organisms and recycle the nutrients.
Organisms decay more slowly at the bottom of a deep lake than in shallow water.

Estuaries

An estuary is a coastal body of water partly surrounded by land that forms where
rivers meet the ocean. Freshwater and salt water come together in an estuary. The
amount of salt in an estuary depends on how much freshwater the river brings into the
estuary. Grasses that can grow in salt water can become very thick in an estuary.
Their stems and roots trap food material for small organisms like snails, crabs, and
shrimp. These organisms feed on thetrapped, decaying materials. The nutrients in the
food pass through the food chain when these smaller organisms are eaten by larger
predators, including birds.
Terrestrial Biomes

Terrestrial biomes vary greatly. At the north pole, the weather is very cold and there
are no plants. As you move south, the weather gets warmer and there is a change in
the size, number, and kinds of plants that cover the ground. As you continue south,
the temperatures rise and you encounter forests. Still farther south are grasslands and
deserts, with high summer temperatures and little rainfall. Near the equator, you find
lush growth and much rainfall.

Types of terrestrial biomes

1. Tundra biome

2. Taiga biome

3. Desert biome

4. Grassland biome

5. Rain forest biome:

Tropical rain forests have warm temperatures, wet weather, and lush plant growth.
They are located near the equator.

6. Temperate forest biome:

Temperate or deciduous forests have precipitation that ranges from 70 to 150 cm

annually. The soil has a rich humus top layer and a deeper layer of clay.

How climate affects biomes

Climate is a group of abiotic factors that influences the kind of climax communities
that develop in an area. Climate includes wind, cloud cover, temperature, humidity,
and the amount of rain and snow an area receives. The most common terrestrial
biomes that result from differences in climate are tundras, taigas, deserts, grasslands,
temperate forests, and tropical rain forests.
 Human impact on the ecosystem

Pollution

This is the accumulation of toxic waste substances or energy in quantities that are
harmful to the environment making it unfit for organisms. There are four types; noise,
air, land, and water pollution.

Types of pollution

1) Noise pollution

Causes:

 Industrialization.
 Poor urban planning.
 Social events.
 Transportation.
 Construction activities.

Effects:

 Hearing problems.
 Psychological health issues.
 Sleeping disorders.
 Cardiovascular issues.
 Trouble communicating.
 Effect on wildlife.
 Pale skin.

Control:

Source control:

 Prescribing noise limits for vehicular traffic.

 Ban on honking (usage of horns) in certain areas.
 Reduction of traffic density in residential areas.
 Giving preference to mass public transport systems.

Transmission path intervention:

 Redesigning buildings to make them noise proof.

 Receptor control: Creation of silence zones near schools and hospitals.

2) Air pollution
Causes:

 Combustion of fossil fuels (petrol, natural gas).

 Discharge of gaseous chemicals from industries and transport vehicles.
 Cigarette smoke.

Effects:

 The effect resulting the increase of CO2 in the atmosphere is known as Green
House Effect which increases the amount of heat retained within the earth’s
atmosphere resulting in increased temperatures and water levels.
 CO2 from vehicle exhaust combine with hemoglobin hindering the transport of O2.
 Radioactive contaminants like carbon-14 from nuclear energy reactors poison
reproductive cells causing genetic diseases.
 SO2 from chemical industries gives rise to acidic rain which destroys houses and
crops.
 Ozone discharged from industries irritates the eyes and also destroy plant foliage
thus, reducing crop yield.
 Chloroflourocarbons from planes and refrigerators destroy the ozone layer.
 CO2 brings about global warming.
 Black lung disease is common due to breathing of coal dust from gold mines.

Control:

 Laws should be passed by government on pollution reduction strategies.

 Education through the mass media to make the population aware of pollution
dangers.
 Radioactive contaminants should be rendered inactive or kept in sealed containers.
 Imposing high penalties on defaulting companies.

3) Water pollution

Causes

 Indiscriminate dumping of refuse and sewage in water bodies.

 Runoff of fertilizers from agricultural farms.
 Oil spills from tankers.
 Untreated sewage, promoting eutrophication.
 Detergents from industries.
 Dumping of radioactive materials or testing of bombs in water bodies.

Effects:

 Causes death of aquatic animals e.g. fish.

 Reduces food supply from the sea.
 Destroy aquatic habitat.
 Destroy breeding grounds of marine birds.
 Disrupt food chains.
 Prevent the penetration of sunlight leading to the death of plankton.
 Prevent the penetration of oxygen leading to suffocation.

Control:

 Water catchments should be located uphill away from human settlement and away
from grazing animals to minimize their contamination.
 Sewage should be treated before released into water.
 Crude oil carries should avoid spillage as much as possible.
 Enforcing strict regulations on crude oil companies.
 Regular check of vessels and equipments transporting crude oil.
 Imposing high penalties on defaulting companies.
 Proper training of workers in such companies.
 General mass education of the people on the dangers of water pollution.
 Reduce fertilizer runoffs in the water bodies by not using fertilizers on sloppy
land.
 Laws to protect water from pollution.

4) Land pollution

Causes:

 Indiscriminate dumping of refuse and sewage onto the surroundings.

 Use of pesticides.
 Discharge of toxic waste on land.
 Fall outs from atomic bomb explosions, nuclear accidents and discarded motor
vehicles.

Effects:

 Bareness of land as a result of the deposition of huge amounts of oil.

 Poor crop yield.

Control:

 Composting of kitchen waste.

 Use of biological control to eliminate pests rather than insecticides.
 Reuse of some materials like bottles.
 Recycling of solid waste like papers.
 Incineration of solid waste.
 Efficient and regular disposal of rubbish.
 Mass education of the population on better waste disposal methods.
 Prevent oil spills from getting on to land.
 Sewage and refuse disposal

What is sewage? This is a combination of faeces, urine, and wastewater from

domestic and industrial use which contains detergents e.g. omo.

Sewage treatment is the use of micro-organisms in the breakdown of raw sewage

into simple chemical compounds which are useful and harmless.

Refuse is the term given to accumulated solid waste as a result of domestic and
industrial activities. Examples of house hold refuse include: papers, tins, plastic bags,
containers, broken pots, broken plates, broken glasses etc.

The above examples of refuse are called non-biodegradable pollutants or materials

because they cannot be broken down by micro-organisms.

Kitchen waste such as plantain, yams, and banana peelings, vegetables fruits etc are
called biodegradable pollutants or materials because they are easily broken down by
micro-organisms.

Reasons why sewage is considered as a pollutant

1) It contains micro-organisms that cause diseases like cholera and typhoid.

2) It contains heavy chemicals like mercury which can cause the mina meta disease.
3) Hot water discharged from the industry will kill aquatic organisms and also reduce
oxygen solubility in water.
4) Detergents in sewage cause foaming thereby reduce the amount of oxygen in
water.
5) Sewage rich in inorganic fertilizers will cause eutrophication (nutrient
enrichment).

Methods of sewage disposal

There are two main methods of sewage disposal namely: the dry conservancy method
and the water carriage method.

I. The conservancy method:

This is a method in which sewage is disposed without the use of water. Some of
these methods include: a bucket latrine, bore latrine, drop latrine, pit latrine etc.
 Points to be considered when constructing a pit latrine

1) It should be at least 4m deep to prevent flies from living inside.

2) It should be far away from streams and wells to prevent water contamination.
3) It should be situated far from the house especially the kitchen to avoid food
contamination by flies.
4) A latrine shelter (hut) should be built over the pit latrine to prevent animals and
children from falling into it. The hut also keeps away flies and rats (vermins) and
maintains privacy.
5) The squatting surface should be washed periodically.
6) The latrine shelter over the latrine should have a window for ventilation i.e. air
moving in and out.
II. Water carriage method: This is the best method of sewage disposal and is
applied only where piped water supply is available. In this method, urine,
faecesetc run from a lavatory pan or water closet into a cessepool, septic tank or
through underground pipes called sewers to a sewage treatment plant.
The walls of the lavatory pan are well polished to prevent accumulation of bacteria
and dirt on them.

N.B: A disinfectant cannot be introduced into the water system because it will kill all
the bacteria helping in the breakdown process.

Biological filter method (B.F.M) of sewage treatment in towns and cities

1) Raw sewage from houses and factories is passed through metal grits to remove
papers and sticks, bottles, plastics etc.
2) The screened sewage enters the grit or detritus chamber where the large suspended
particles e.g. stones settle out as sewage moves slowly.
3) The sewage then runs into the sedimentation tank, where the smaller particles and
most organic matter settle out to the bottom as sludge.
4) The process of sedimentation is speeded up by the slow movement of the sewage
and the addition of alum.
5) The remaining liquid, now called effluent contains dissolved organic matter which
has to be oxidized.
6) When the effluent moves into the oxidation bed or chamber, it is spread over the
biological filter consisting of aerobic bacteria, algae and protozoans etc.
7) Spreading is carried out by a sprinkler and this enriches the effluent with the
oxygen needed by the aerobic bacteria to decompose the sewage into harmless
substances.
8) Algae also provide more oxygen.
9) The ciliates feed on the bacteria, while midges’ larvae feed on the ciliates.
10) The midge larvae later develop into adult flies and fly off.
11) The remaining liquid which is harmless can then be disposed of into water bodies
or reused.

Activated sludge method (A.S.M) of sewage disposal

With this method, from the sedimentation tank, the effluent is pumped into an
aeration tank where air rich in oxygen is added to the effluent to help aerobic bacteria
act effectively and faster.
Importance of sewage treatment

1) It prevents water pollution.

2) Digested and dried dudge is used as manure.
3) Methane gas obtained from the digestion of sludge is used as fuel in vehicles and
gas cookers.

Differences between B.F.M. and A.S.M.

B.F.M. A.S.M.
Is cheaper (advantageous) Is expensive (disadvantageous)
Takes a longer time (disadvantageous) Takes a shorter time (advantageous)

Water

Introduction

Water is a chemical compound of hydrogen and oxygen in which the hydrogen to

oxygen ratio is 2:1. It is a universal solvent and can exist in any of the three states of
matter (solid, liquid, and gas) depending on its temperature.

Sources of water

i. Rainwater if the environment is not polluted.

ii. Water from deep wells if they are well protected and cared for.
iii. Water from artesian wells or springs.
iv. Water from rivers, lakes, and streams after boiling locally at home.

1) Wells

This is a hole sunk into the ground or it may simply be a shallow depression. There
are three main types of wells:

a) Deep wells: The water here is safe for drinking because it has been filtered
through many layers of the soil.
b) Surface wells: Here, the water is not sufficiently filtered and it is advised to boil
the water before drinking.
c) Artesian well: The water in this case flows right up to the surface under pressure.
It is a good source of drinking water.

Qualities or characteristics of a good well

1) It should be constructed far away from pit toilets to prevent contamination.

2) It should be deep to ensure proper filtering.
3) It should have a lid or cover to prevent dirt from falling into it.
4) A fence should be constructed round the well to block animals from entering.
5) A gutter should be dug round the well to channel waste water away.
6) The pulley system should be applied to save energy during water fetching.

Types of impurities likely to be found in water

1) Pathogenic micro organisms e.g. bacteria, protozoa.

2) Suspended soil particles.
3) Suspended decaying organic matter.
4) Poisonous industrial waste.
5) Inorganic fertilizers.

Hardness of water

Hard water is water that does not easily lather or foam with soap because it contains
insoluble compounds of calcium and magnesium. There are two types of hardness of
water namely:

a) Temporal hardness: This is caused by the presence of bicarbonates of calcium

(Ca (HCO3)2) and magnesium (Mg (HCO3)2).

Temporal hardness can be removed by boiling. Heat breaks the bicarbonates and
releases CO2 i.e.

Ca (HCO3)2 CaCO3 + CO2 + H2O

CaCO3 CaO + CO2

b) Permanent hardness: This is caused by the presence of sulphates (SO4) of

calcium (Ca SO4) and magnesium (Mg SO4). It can be removed by treatment with
chemicals e.g. washing with soda (Na2CO3). When Na2CO3 is added, there is
exchange of radicals.

Na2CO3 Na2SO4 + CaCO3

Advantages of hard water

1) The calcium salt present in hard water is useful in the formation of bones and
teeth.
2) Poisonous effect of lead pipes is neutralized by calcium coating.

Disadvantages of hard water

1) It wastes soap.
2) It causes skin irritation and intestinal disorder.
Purification of water

Purification is the process by which impure water is rendered pure and safe for
drinking. Water is purified at two levels, namely:

a) At domestic level in the home

Some of the methods used in treating water for household use include boiling,
sedimentation, and filtration, adding of alum, chlorine, and exposure to sunlight.

Clean and pure water

Water that is clean is not necessarily pure. Clean water is water that does not contain
visible impurities, but may still contain microbes (germs) which are not visible to the
human eye. Pure water on the other hand does not contain any impurities or germs.

b) Purification of water at town or city level

At town or city level, where there is increased demand for water, the source of the
water may be a polluted river or lake. So, the water must be treated before
consumption. Below is a summary of the processes and principles involved in the
purification of water for a village or community in Cameroon.

1) Water from the catchment area is passed through screens or iron grids to remove
sticks, rags, weeds, and dead animals.
2) The screened water then enters the sedimentation tank, where particles found in
water settle to the bottom as sludge.
3) The sedimentation process is speeded up by the addition of alum in the
coagulation tank.
4) The sedimentation tank is left open to allow U.V. light from the sun to strike the
water surface in order to kill germs.
5) From the coagulation tank, water passes into a filtration bed (chamber) where
suspended particles in water pass through layers of sand and stones.
6) The layer of algae on sand act as a biological filter by trapping bacteria.
7) The water now moves into a chlorination tank, where a calculated quantity of
chlorine is added to a calculated volume of water to kill bacteria i.e.

H2O + Cl2 HCl + HOCl

8) It is the hypochlorous acid (HOCl) that oxidizes bacteria when the active oxygen
in it is liberated.
9) From the chlorination chamber, water is pumped to a storage tank, which is
usually located up hill, to ease the distribution of water by gravity and to prevent
recontamination of water by domestic animals.
10) From the storage tank, water is distributed to various quarters and homes by pipes
underground.