BIOLOGY GRADE 9

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UNIT 1 @bluenileacademy
BIOLOGY AND TECHNOLOGY @samuelfromethiopia
Biology is the scientific study of life or living things.
Technology:- the application of scientific knowledge to the practical aims of human life or, as it is sometimes phrased, to the
change and manipulation of the human environment.
Science is a systematic study of natural and physical world through observations and experiments. Science
shapes the way we understand the universe, our planet, ourselves, and other living things. The scope of biology is
also broad and therefore contains many branches and sub branches. The three main branches of Biology are
1. Botany - the study of plants
2. Zoology - the study of animals
3. Microbiology- the study of microorganisms
Some other sub branches of biology are: JOIN ON Telegram @QesemAcademy
Mycology – study about fungi
Protozoology - study about protozoa
Phycology - study about algae and etc.
The scientific method is an organized way of solving problem or answering questions
Before publication of an idea/Research, several other scientists in the same field read and check or evaluate it, the
process is known as peer review
Scientist publish their works on special magazine known as scientific journal
1.1. Renowned Ethiopian biologist
1. Dr. Aklilu Lema - is pioneer Ethiopian biologist
Discovered a remedy for a disease called bilharzia/schistosomiasis that is caused by flat worm, which
spend part of their life cycle in fresh water snail and part in humans
The parasitic worms infect the blood vessels, liver, kidneys, bladder and other organs
It affects 200-300 million people in Africa (including Ethiopia), South America, Asia and parts of the
Caribbean
He made soapberry from local plant known as endod (phytolacca dodecandra) to kill the snail, which
is the intermediate host for flat worm (if the snail can be controlled, the spread of bilharzias can be
reduced)
Soapberry of Dr. Aklilu Lema is cheap and locally available to buy and use for African countries to
eradicate the disease
2. Dr. Tewolde Birhan Gebre Egziabher - an ardent lover of nature
recognized for his work on environmental protection and biodiversity
Works to safeguards the biodiversity and traditional rights of farmers and communities to their genetic
resources
3. Prof. Tilahun Yilma - professor of veterinary virology at the University of California
He has developed vaccine for terrible cattle disease known as Rinder pest using genetic engineering
Render pest is deadly viral disease, which killed millions of cattle in Africa
He works to develop vaccine for HIV/AIDS
His contributions in science and medicine have been recognized by many international organizations.
4. Prof. Yalemtsehay Mekonnen - the first female professor from Addis Ababa University
She works on:
Assessment of impact of chemical pesticides hazards on humans.
research on the use of plant as a medicine against human and animal disease
She has awarded research grant and fellowship from different national and international organization for her
contribution in the area.
5. Dr. Melaku Worede -
He has worked for many years to save the genetic diversity of Ethiopia’s domestic plants.
set up the plant genetic resources center in Addis Ababa 1
developed way of farming to produce high yields without commercial fertilizer
served as the first chair of African committee for plant genetic resources and chair of UN food and
agriculture organization's commission on plant genetic resources
6. Dr. Gebisa Ejeta
has developed high yield and drought resistance strain of sorghum
has awarded national hero award and world food prize for his massive contribution in science and
technology
7. Prof. Beyene petros - a biomedical scientists serving at Addis Ababa University
produced more than 43 publication in journal and books
He won Gold medal award from Ethiopian health association and fellowship from fulbright and center for
disease control and prevention, Atlanta, USA.
8. Prof. Sebsebe Demissew
Plant taxonomist, director of national herbarium and leader of Ethiopian flora project
9. Dr. Zeresenay Alemseged
Paleontologist, who discovered a 3.3 million years old humanoid fossil in 2006
10. Dr. Tsehaynesh Meselle - Leads research in human health, including HIV/AIDS.
11. Dr. Birhane Asfaw - discovered two 160,000 years old human skulls.
- His discoveries were published in famous scientific journal nurture
12. Prof. Legese Negash - pioneer in propagation of Ethiopian indigenous tree
- Founder and leader of the indigenous tree propagation and biodiversity department in Ethiopia
13. Prof. Mogese Ashenafi - works at Addis Ababa University and leads international research into food
microbiology
14. Prof. Ensermu Kelbesa - leading systematic botanist
- He has discovered and named different new plants
1.2. Biological research in Ethiopia
Biologist conducts different research in different area of biological science. To carryout researches, they need
different tool, laboratories and other biologist to discuss idea with and develop theory. Ethiopia has various
institutes which are involved in biological research. Biologist come to these institutes and our biologist also
travel other countries to take part in different research program.
Addis Ababa University (department of biology)
One of the major centers for biological research in Ethiopia
contains much modern and high level equipment that help in their study.
 Palace for many renowned Ethiopian biologists.
It also manage 2 major units
A. The national herbarium which serves as national repository of Ethiopian plant and center for plant
identification in the country
B. The zoological natural history museum (ZNHM) which contains collection of Ethiopian fauna
including endemic species. It provides visual education for general public, students, and tourists. Other research
institution and their focus area of research are summarized in the table below

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Institutions Focus area of research
Armauer Hansen Research in first set it carried out research only into leprosy later widened
Institute (AHRI) to tuberculosis, leishmaniasis, malaria and HIV/AIDS
Aklilu Lemma Institute of Microbiology of infectious diseases
Pathobiology (ALIPB) Vectors of disease and how to control them
- previously known as Human parasitic disease
department of pathology at Animal health and disease
AAU Endod and use of other plants as medicines.

Ethiopian Health and  Health and nutrition issues

Nutrition Research institute Other specific area of research includes
(EHNRI) HIV/AIDs vaccine
tuberculosis (TB)
infectious disease
nutritional status of baby and mother
Ethiopian Institute of Crop technology to achieve food security and nutritional quality
Agricultural Research) breeding, feeding and health improvement of livestock
(EIAR) also known as improving soil fertility
institute of Agricultural Forestry (rehabilitation, conserving and restoring forest ecosystem)
research (IAB) Crops for mechanized farming

Institute of Biodiversity Issue of biodiversity conservation, especially endemic plant and

conservation (IBC) animal of Ethiopia
Conserving gene of Ethiopian plant
Ecosystem conservation
Biotechnology and safety
Aquatic plant, medicinal plant, forests etc.

UNIT - 2
CELL BIOLOGY
2.1. The microscope
Microscope is a basic tool for biologist, which is used to see/study very small things that can't be seen by our
naked eyes.
Types of microscope
1. Light microscope is a type of microscope which use beam of light to form image. It can be classified in to
A. Simple light microscope - contains only one lens system. E.g. Hand lens
B. Compound light microscope (CLM) - contains two lens system, eye pieces/ ocular lens and objective
lens. It magnifies the object/specimen twice and produces much better magnification.
The 4 types of objective lenses
Low power objective lens - provide lowest power of magnification 4x
Middle power objective lens, provide 10 x magnifications
High power objective lens, provide 40x magnification
Oil emersion objective lens, provide the highest magnification (100x)
Magnification and resolution
The two important function or abilities of microscope are magnification and resolution.
Magnification - is the ability of microscope to increase the size of an object.
- The total magnification CLM = magnification of eye piece lens x particular objective lens
- Light microscope can magnify an object up to 2000 times
Resolution - the ability of microscope to see detail or scatter parts of an object
Approximately light microscope can resolve things about 200 nanometer (nm) apart
Staining - is a process adding chemical stain or dyes to slide tissues to make the cell or their parts easier to3
see. Some commonly used stains are:
 Types of stain types of cell main organelles stained
Haematxylin animal & plant cell nuclei stained blue (purple or brown)
Methylen blue animal cell nuclei stained blue
Acetocarmine animal and plant sell staining the chromosome in dividing nuclei
Iodine plant cell any material containing starch
Mounting - is a process of preparing an object or specimens to be seen under a microscope. Mounting
process involve the following major steps
having specimen to be seen under a microscope
place the object /specimens/ at the center of clean glass slide
cover the specimens with cover slip
remove excess fluid from slide
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Parts of compound light microscope @QesemAcademy

Parts of compound Description and Function

light microscope
Eye piece/Ocular lens A lens closer to viewer and used to look through
Objective lenses Lenses closer to the object which is used to magnify objects
Stage A flat surface on which slide with specimen is placed to be examined
base/foot Support the weight of the microscope
Course adjustment knob used to move the tube up and down for proper focusing
Fine adjustment knob Used to bring the object in to perfect focus (to get real image)
Nose piece Revolving part of microscope that hold objective lens
Diaphragm (Iris) Used to control the amount of light passing through the specimen
Mirror(light source) Reflects light upward through diaphragm to illuminate the specimens
Arms Support the tube and connect it to the base
Body tube Holds nose piece at lower end and eye piece at upper end
Stage clip Used to fix the slide in place

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Advantage and disadvantage of light microscope

LIGHT MICROSCOPE

Advantage
Disadvantage
- can see living cell
- limited resolving power
- can also be used without electricity
- limited magnification powers
- used anywhere in the world
- portable( relatively small and not very heavy)
- realatively cheap

Advantage and disadvantage of election microscope

Advantage Disadvantage
• can see much more detail • All the specimens are examined in a vacuum
• higher magnification and resolution • impossible to look at living material
• very expensive
• take up a lot of space and are usually kept in a
separate room
• rely on a constant source of electricity

Comparisons between light and electron microscope

Light microscope Electron microscope
- Low magnification and resolution power - Highest magnification and resolution power
- Use beam of light to form an image - Use beam of electron to form an image
- Used to study living and nonliving material - doesn't help to study living materials directly
- It is possible to use it without electricity - Depend on electricity
- Is relatively cheap - Is very expensive
- Simple to use - Require large space
- Easy to move from place to place - Not simple (required professional skills) to use
- Doesn't require large space -is not easy to move from place to place
- Use glass lens - It uses magnetic lens (Electron beams are focused
by magnetic lenses

2. Electron microscope is more powerful types of microscope with highest magnification and
resolution
power. It uses a beam of electrons rather than light to form an image
It can magnify objects up to 2,000,000 times and has resolution power up to 0.3 nanometer (nm)
apart
In electron microscope, the electron behave like light wave
It has shorter wavelength than LM, so it has high resolution power
As the wave length decrease, resolution power of microscope increase
How does an electron microscope work?
Under electron microscope, all the specimens are examined in a vacuum because air would
scatter the electron beam
The electron beam is focused by magnetic lenses.
In EM, Complex electronics produce image on screen that can be recorded as a photograph
known as electron micrograph 5
There are two types of electron microscope
A. Transmission electron microscope (TEM) in which beam of electrons is transmitted through a
specimen/sample and provides detailed three-dimensional images. An image is focused on florescent screen or
photographic plate
B. A scanning electron microscope (SEM) which produces images of an object by scanning the surface with
a focused beam of electrons and shows only the surface of objects. Image is focused on television-like screen.
2.2. The Cell
Cell is the basic structural and functional unit of living organism
It is a smallest unit of life or building block of life
All forms of life made up of one or more cell
Some organism are made up of one cell known as unicellular (e.g. bacteria and protozoans) others made up
of more than one cell known as multicellular organism.

Type of cells
Prokaryotic cell - is simple, unicellular (single celled) cell that lack true nucleus
Eukaryotic cell - is cell that have membrane bounded nucleus (true nucleus)
 Organelles are subcellular structures that have specialized function.
Size and shape of cell
Most cells are very small or tiny and cannot be seen without the aid of microscope
Some cells are large enough to be seen by our naked eyes. The biggest known cell is ostrich egg cell
Different cells have different shape. They may be flat, spiral, tubular, branched, irregular etc.
The shape of cells is mostly depends on their function
Cell theory
Cell were first seen (discovered) and described by English scientists, Robert Hook in 1965.
He observed tiny compartment in the cork, which he called cellulae - from Latin word (meaning - small
room). This term come down to as cell. He observed only dead plant cell.
The first living cell was observed by Anton Van Leeuwenhoek. He observed little organism, which he
called animalcules (meaning - little animal).
- In 1838 Mathias schleidin (German Botanist) states that "all plants are made up of cell".
- In 1839 (German zoologist) Theodore Schwan stated that "all animals are made up of cell".
-In 1859 Rudolf Virchow stated that "cells come from preexisting cell". The work of these three scientists
contributed to the cell theory.
The cell theory in modern form includes
1. All organisms are made up of one or more cell
2. New cells arise only from other living cells (pre-existing cell) by the process of cell division.
3. Cells are the basic structural and functional unit of life.
All living organisms have certain characteristics, which they carry out. The seven life processes that are
common to most living organism are:
1. Nutrition – all living organisms need food to provide them with the energy used by their cells. Plants make their own
food by photosynthesis, whereas animals eat other organisms.
2. Respiration – the process by which living organisms get the energy from their food.
3. Excretion – getting rid of the waste products produced by the cells.
4. Growth – living organisms get bigger. They increase in both sizes and mass, using chemicals from their food to build
new material.
5. Irritability – all living organisms are sensitive to changes in their surroundings.
6. Movement – all living organisms need to move to get near to things they need or away from problems. Animals move
using muscles, plants move more slowly using growth.
7. Reproduction – producing offspring is vital to the long-term survival of any type of living organism.
Cell structure and function
Almost all cells (plant and animal cells) have a nucleus, mitochondria, ribosome, cytoplasm,
endoplasmic reticulum & cell membrane.
Other features that are found in plant cell are cell wall, large central vacuoles, and plastids 6
Animal cell also have some unique features such as lysosomes and centrosome
Structure and function in unspecialized cell
 All of the process of life takes place within a single cell.
Every cell contains sub cellular structure known as organelles
Each organelle has specific functions within the cell
1. The nucleus - it control all activities of cell the (controlling center of a cell)
- It contains genetic material (chromosome) which carries genetic information
2. The cell membrane/Plasma membrane - Is thin living layer of both plant and animal cell
- composed of protein and lipids bilayer (lipo - protein)
- In animal cell, it is the outer most layers whereas in plant cell, it is found next to cell wall
- It is responsible to regulate the movement of material in and out of cell (selectively permeable
membrane or semi - permeable membrane); allow some materials to pass through and not others
3. The cytoplasm - is a jelly-like substance composed of mainly water (about 70%)
- found between the cell membrane and nucleus
- Site of most cellular activities (chemical reactions) JOIN ON Telegram
4. The Mitochondria (singular: mitochondrion)
- are often referred to as the "powerhouse" of the cell" @QesemAcademy
- It is a site of cellular respiration (energy production
5. Ribosome - are small organelles found attached to outer surface of endoplasmic reticulum (ER)
- They can be also found free in cytoplasm
- They are responsible to synthesis protein (site of protein synthesis)
6. Cell wall - is a rigid, non-living organelle lying just outside the cell membrane of plant cell.
- It can also found in fungi and bacteria but not in animal cell.
- In plant cell, it is composed of complex carbohydrates called cellulose
- It provides structural support, protection, and shape of cell.
6. Lysosomes - are small sac-like structures surrounded by a single membrane
- They are needed and found only in animal cell.
- contains digestive enzymes which help to break down and remove old worm out cell parts
- It is also known as "suicide sac (bags)".
7. Plastids - are organelles found in cytoplasm of plant cell
There are three types of plastids
A. Chloroplast - is site of photosynthesis
- It contains the green pigment called chlorophyll, which absorb sunlight
B. Chromoplast - contains red, yellow or orange pigment
- It gives the color of fruit and flowers
C. Leukoplast - it lack pigment (colorless) and serve as storage of starch
8. Vacuoles - are fluid filled organelles enclosed by a single membrane
- It is used to store fluid called cell sap, which contains water, salt, sugar, minerals, and waste products. It
provides turgidity of plant cell when filled with water
9. Endoplasmic reticulum (ER)
- A network of membranous tubules, extending through cytoplasm.
- Connects cell membrane with nuclear membrane and plays a major role in the production, processing, and
transport of proteins and lipids.
There are two types of ER
Rough endoplasmic reticulum (Rough ER) - contains ribosome attached on its surface and
synthesizes proteins
Smooth endoplasmic reticulum (Smooth ER) doesn‘t have ribosome and synthesizes lipids
10. Golgi bodies/Golgi apparatus/Golgi complex - are stacks of flattened membranous.
- It plays a major role in modification, packaging protein for transport.
Cell specialization in human
- In multi-cellular organism, most cells become specialized to carryout particular function
- Cells which adapt to carryout particular function are called specialized cells
- A combination of sperm cell and egg cell form embryo (single cell), which divide many times to form
mass of unspecialized/undifferentiated cells 7
- As the embryo develops, the cell become differentiated /specialized, this can be shown as
Embryonic stem cell → mass of unspecialized →specialized cell
Embryonic stem cells are unspecialized cell from cell early embryo that has potential to form any
specialized cell.
- Specialized cell with similar structure and function are grouped together to form tissue (eg-Muscle tissue,
nerve tissue, etc.)
- Tissues are combined to form organ (e.g. heart, lung, kidney etc.)
- Organs are working together to form organ system (e.g. digestive system).
- A number of system are working together make up organism, this can be shown as
Specialized cell → tissue → organ → organ system → organism
Some example of specialized cell in human
1. Epithelial cells specialized cell that cover and protect the internal and external surface of the body (skin,
gut, throat etc.)
2. Reproductive cell (egg and sperm cell)
- are specialized cell which involve in reproduction process
- They contain only half the number of chromosome of normal body cells
- Their nucleus contains genetic material (chromosome)
A. Egg cell/ova/ - is a female reproductive cell (female sex cell), produced in ovaries.
- Larger in size than male sex cell and have protective outer coat.
B. sperm cell - is a male reproductive cell (male sex cell).
- Have long tail (flagellum) containing muscle like protein that helps to swim towards eggs
- The middle section contains large number of mitochondria which provide energy for tail
- They have structure known as acrosome in head, which store digestive enzyme
- The enzyme is used to breakdown the protective coat of egg cell during fertilization
3. Nerve cell (neurons)
- Specialized cells, responsible to transmit electrical nerve impulse (signal) between different parts of the body and
control your body system
- Part of communication and control center of your body
Parts of neuron (nerve cell)
A. Cell body - structure which contains cellular structure (like mitochondria and nucleus)
B. Dendrite - hair like extension from cell body that communicates with other neurons
C. Axon (nerve fiber) - is long tiny extension of cell body that carry nerve impulse long distance
D. Myelin sheath - is fatty insulating layer of axon which help the nerve impulse to travel fast
4. Muscle cell (myocytes) - are responsible for movements of our body.
- Rich in proteins like actin and myosin, these enable the muscle to relax and contract
- contains large number of mitochondria to provide more energy for muscular movement

2.3. Cell and its environment

Cell obtained Material necessary for life ( (like O 2 & nutrient) from the environment and waste product (like
CO2) must be removed from the cell. materials can move into and out of a cell through its semi-permeable
membrane (cell membrane), which allow some materials to pass through and not others. There are two major
ways by which materials can move in and out of a cell. These are passive transport and active transport.
1. Passive transport (diffusion and osmosis) - movement of materials without the use of energy
2. Active transport - is the movement of materials using energy
A. Diffusion
- Random movement of molecules from area of its higher concentration to area of lower concentration
until the molecules tends to be in equilibrium/distribute uniformly.
- It occurs along concentration gradient (difference in concentration between two areas)
- Rate of diffusion can be affected by temperature, concentration gradient, size of particle etc.
- Diffusion is an important mode of nutrient uptake and gaseous exchange in cells
B. Osmosis - is a special kinds of diffusion in which water (solvent) diffuse (move) from dilute (weak)
solution to concentrated (strong) solutions across semi permeable membrane
NB: Dilute solution is a solution with high solvent/water concentration and relatively low solute
concentration, whereas concentrated solution is a solution with low solvent concentration and high solute
concentration. There are 3 types of solutions (osmotic conditions). These are:
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1. Hypertonic Solution (hyper - means more)
- If concentration of solution outside the cell membrane is greater than inside
- Water molecule move from inside to outside (loss water) and causes a cell to shrink
2. Hypotonic Solution (hypo - means - less)
- If concentration of solutions inside the cell membrane is greater than outside.
- The cell gain water and causes a cell to swell up due to osmosis
2. Isotonic Solution:
- If the concentration of solutions inside and outside of cell membrane is equal
- There is no net movement of water molecules and no change in the cell
Osmosis in animal cell - osmosis is important for movement of water in and out of the animal cell,
when needed. However, osmosis can affects animal cell
- If animal cell is placed in hypertonic solution, the cell loss water and will shrivel up (shrink). The
condition is called crenation.
- If animal cell is placed in hypotonic solution, the cell gains more water & swell up eventually burst
Osmosis in plant cell - osmosis is important in plant cell to support the stem and leaves. The swelling up of
cell keep stem and leaf of plant rigid and firm.
- If plant cell is placed in hypertonic solution, the cell loss water. Then vacuole shrink and the cell become
less rigid (flaccid), eventually the cytoplasm pulls away from the cell wall. This results in loss of turgor
pressure and is known as plasmolysis
- If plant cell is placed in hypotonic solution, the cell gain water and swell up.
- The swelling up of the cell creates pressure that pushes the cell wall outward.
- This pressure is known as turgor pressure. On the other hand, the cell wall in plant created wall pressure in
opposite to turgor pressure (push inward). This can avoid bursting of cell in plant and make them turgid.
C. Active transport - is a movement of molecules against concentration gradient, molecules move from
area of low concentration to area of high concentration. It required energy.
The importance of active transport: E.g.
1. Absorption of mineral ions from soil by root hair cell. Concentration of mineral in root hair is
greater than in the soil. So it required energy to move against concentration gradient.
2. Translocation of organic materials in plant - organic molecules produced by photosynthesis is moved
from their leaf to other parts of plants (stem and root).
3. Glucose in your gut and kidney tubules moved into your blood against concentration gradient.

Fig. 2.3. Observations of mineral ions by root hairs of plant (active transport)

UNIT 3

HUMAN BIOLOGY AND HEALTH

3.1 Food and nutrition

All living organisms need a source of energy to survive.

Organisms set in different categories depending on their source of food as follows;

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 Organisms

AUTHOTROPHS = can HETEROTROPHS = can't

make their own food make their own food

Photosynthetic Chemosynthetic Omnivore =

Herbivors = Carnivore =
= use light = use d/t consume both
consume plants consume meat
energy chemicals plant and meat

The human diet

Food: is the source of nutrients and energy for the body
 It has three main use to human
A. To provide energy for our cells to carry out all the functions of life
B. To provide the raw materials for the new biological material needed in our bodies to grow and also to
repair and replace damaged and worn out cells.
C. To provide the resources needed to fight disease and maintain a healthy body.

Nutrient: usable chemical compound found in food

Roughage: indigestible substance that do not provide energy

MACRONUTREINT: needed in large amounts

i. Carbohydrates,
ii. Proteins

Nutrient iii. Lipids(fat & oil).

MICRONUTREINT: needed in small amounts

iv. Minerals
V. Vitamins

i. CARBOHYDRATE:-
 They are made up of carbon, hydrogen and oxygen
 provide us with energy
 broken down to form glucose which is used in cellular respiration to produce energy
 Stores in the from glycogen, which is found in your liver, muscles and brain.
 excess carbohydrate that you eat is converted to fat
 glucose is the sugar made by plants in photosynthesis and it is vital in cells for energy
 starch is more complex carbohydrate stored in plants
 Obtained from food like injera, honey, Potatoes, rice, bread, etc
 They divide into three main types, depending on the complexity of the molecules

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 Simple Sugars

Double Comple Sugars

Sugars

The Simple Sugars/Monosaccharide/

 There is 1-oxygen atom and 2-hydrogen atoms for each carbon atom present in the molecule.
 (CH2O)n is general formula
 Example: C6H12O6 is general formula for Glucose.

Simple sugar
Glucose

Fructose

Galactose

The Double Sugars/Disaccharide

 made up of two simple sugars join together
 When two simple sugars join together to form a double sugar, a molecule of water (H2O) is removed
(condensation reaction).
 monosaccharide + monosaccharide → disaccharide

Glucose
Maltose
(malt sugar)
Glucose

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 Glucose
Lactose
(Milk sugar)
Galactose

Glucose Sucrose
(sugarcane
Fructose sugar)

 Most simple and double sugars have properties to dissolve in water and they taste sweet.

The Complex Sugars/Polysaccharide

 Many single sugar units are joined to form a long chain.

 properties of complex sugar are;
 very compact molecules (for storing energy)
 physically and chemically very inactive
 sweet test is lost
 do not dissolve in water
 here are some examples of complex sugar
a. Starch: energy store in plants
 The sugars produced by photosynthesis are rapidly converted to starch
b. Glycogen: sometimes referred to as ‘animal starch’
 it is energy store found in animals
 found mainly in muscle and liver tissue
c. Cellulose: important structural material in plants
 the main constituent in plant cell walls
 consists of long chains of glucose
 Human beings cannot break down its linkages and so they cannot digest cellulose.

Test for Carbohydrate

 Starch test
 help to test presence of starch
 reagent → iodine
 result/color change → change to blue black
 Benedict’s test (reducing, glucose) JOIN ON Telegram
 help to test for simple sugars @QesemAcademy
 reagent → benedict reagent/solution
 result/color change → change to yellow

ii. PROTEINS:-
 Made up of the carbon, hydrogen, and oxygen, in addition they all contain nitrogen.
 Some proteins also contain sulphur 12
 Are polymers, made up of many small units joined together called amino acids.
 There are about 20 different naturally occurring amino acids
 The bond found between two amino acid is peptide bond.
  proteins are coil, twist, spiral and fold amino acid
 proteins differ in:
 type
 number of their amino acid
 sequence
 shape

PROTEIN

Water soluble Water insoluble

-antibodies - connective tissue
- enzymes - tendons
- hormones - matrix of bone(collagen)
-muscles
-silk of spider web
- silkworm cocoons
- keratine

 protein make 17-18% of human body

 importance of protein are:
provide less energy than carbohydrate and lipid
for repair and damaged tissue and body building
to make enzymes
 the difference in temperature and PH denature the protein
 lack of protein causes Marasmus and Kwashiorkor
 Meat, fish, dairy product, white pea bean, egg, etc. are protein rich food.

Test for Protein

 Biuret test
 reagent – Potassium hydroxide
 and copper II salphate
 result/color change – purple (mauve) colour

iii. LIPID (FATS AND OILS):-

Fat Oil
Solid at room temperature liquid at room temperature
Mainly Animal product Mainly Plant Product

 lipids are made up of carbon, hydrogen and oxygen, but, lower proportion of oxygen than carbohydrates.
 the simplest form of lipid is Glycerol and fatty acids.
 fatty acids have a long hydrocarbon chain
 One glycerol combines with three fatty acids
 high levels of fat and Cholesterol in our diet are not good for health

Saturated → each carbon atom is joined to another by single bond

Fatty acid

Unsaturated → carbon chains have one or more double bonds

13
 source of energy in your diet and they are the most effective energy store
 they contain more energy per gram than carbohydrates or proteins
  Combined with other molecules, it has vital roles as hormones, in your cell membranes and in the nervous
system.
 All lipids are insoluble in water, but dissolve in organic solvents.
 Meat, oily fish, eggs, butter, beef fat, sesame oil, niger seed oil (nug) and olive oil are sources of lipid.
 Cholesterol: most made in your liver and some come from food we eat
 carried around your body in your blood
 Without cholesterol, you wouldn‘t survive.
 It makes the cells membranes, sex hormones and the hormones which help your body deal with
stress.
 High levels of cholesterol in your blood seem to increase your risk of getting heart disease or
diseased blood vessels.

Test for Lipid

 Reagent: Ethanol
 Place a small sample of fat/oil in a test tube
 add ethanol
 Shake the test tube
 add water
 Result: White cloudy layer formed

Testing for vitamin C For more join us on Telegram

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 DCPIP (dichlorophenol indophenol) reagent
 Pour about 3 cm3 of DCPIP into a clean test tube @QesemAcademy
@samuelfromethiopia
 Using a dropper, add orange or lemon juice drop by drop to DCPIP in the test tube.
 Positive result: gradual fading of the blue color of DCPIP

iv. MINERALS:
 minerals are needed in small amount

Mineral Approximate Location or role in body Example of foods Effects of deficiency

mass in an rich in mineral
adult body
(g)
Calcium 1000 Making bones and teeth Dairy products, fish, Rickets
bread, vegetables
Phosphorus 650 Making teeth and bones; part Most foods Improve formation of
of many chemicals, teeth and bones;
e.g. DNA failure of metabolism
Sodium 100 In body fluids, Common salt, most Muscle cramps
e.g. blood foods
Chlorine 100 In body fluids, Common salt, most Muscle cramps
e.g. blood foods
Magnesium 30 Making bones; found inside Green vegetables Skeletal problem; cell
cells chemistry affected,
defects in metabolism
Iron 3 Part of haemoglobin in red Red meat, liver, eggs, Anaemia
blood cells; helps carry green leafy
oxygen vegetables,
e.g. spinach

V. VITAMINS:
Vitamins Food rich in Vitamins Deficiency disease
Retinole (VA) Green pepper, carrot, leafy vegetables, cod Poor sight, poor growth
liver oil
Thiamin (VB1) Cereals, milk, liver, sprouted beans Beriberi, loss of appetite, disease of
muscle
Riboflavin (VB2) Green vegetables, liver, milk, meat, peas Slow growth, eye disease, tongue
inflammation
Niacin (VB3) Milk, meat, vegetables Pellagra
Ascorbic Acid (VC) Green pepper, lemons, orange, vegetables Scurvy, bleeding gum, slow healing 14
Calciferol (VD) Fish liver oils; also made in skin in sunlight Ricket
Tocopherol (VE) Cereal oil, milk, egg, yolk, lettuce, seeds Sterility
Phylloquinine (VK) Green leaf vegetables Prolonged blood clothing time
 v. The role of Water
 your body is 60%-70% water
 it is vital solvent
 Transport substance in the body. example. urea, sweat
 For body temperature regulation. example. sweat
 for removal of waste material
 it is a reactant in many important reaction in the body
 needed for osmotic stability of the body

Balanced diet
 Is taking food from all food groups in order to maintain a healthy body.

Malnutrition: when diet lacking in important elements needed for a healthy body.

Over nutrition: when too much food is eaten

Under nutrition: when too little food is eaten

3.2 The Digestive System

Digestion: breakdown large, insoluble molecules in to smaller, simplest, & soluble molecule

 It provides energy & new biological molecules.

Digestion

Physical (Mechanical) Chemical

 Break down food in to smaller unit peaces -accomplished by enzyme

 bite & chew food in mouth
 squeezes food in stomach

More about enzyme:-

1. enzymes are protein
2. enzymes are catalyst – remain unchanged
3. enzymes are specific – one enzyme catalyze only one reaction
4. enzymes are sensitive to temperature – all human enzymes are best at 37c0
5. enzymes are sensitive to PH – each enzymes have their own range of PH

Intracellular – secreted and work inside the cell

Enzymes Extracellular – different secretion and work outside the cell

Digestion in mouth
 Both chemical and physical digestion occur here
 Ingestion: the act of taking in food
 Mouth: select taste, smell and texture of food
 Bite, chew and chop the food by teeth known as mastication
 mix food with enzyme

Starch + H2O Maltose

The Human Teeth
 there are 4 types of teeth
 Incisors – front teeth
 Canine - long and pointed teeth
 Premolars - flat teeth
 Molars - found at the back

Structure of human teeth 15

 Enamel→ the outer cover
- The strongest part (hardest)
- white color that resist decaying
 - non-living part
 Dentine → found next to enamel
- very hard, similar to bone
 Pulp Cavity → the center of the teeth
- contain nerve and blood vessels
- sensitive to heat, cold and pain
 Cement → keep teeth firm with jaw (set in to your jaw)

Moving the food:-

Bolus: ball shaped saliva coated chunk of chewed food

Peristalsis: wave like muscle contraction to move food along the throat

Epiglottis: the flap that covers the trachea during swallowing so that food does not enter the lungs.

Digestion in Stomach
- Digestion in stomach take 1-4 hours
- Sphincter: ring of muscle found at the first and last parts of the stomach
- open only during swallowing and being sick
- In stomach food mixed with gastric juice

Hydrochloric acid (HCl)

Gastric Juice Mucus Pepsin

Protease enzyme, digest protein
Enzyme Rennin

- HCl: Make the food suitable for action of pepsin

- kill some bacteria
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Protein + H2O Pepsin Peptones

- Rennin: Mostly found in mammals

- Curdle milk protein
- Chime: is grey soup like mixture pass to the intestine from the stomach

Digestion in Intestine
Small Intestine: is about 6-8m coiled tube

- Produce protease, carbohydrase and lipase enzyme

Duodenum → the upper part

small intestine Jejunum → middle part
Ileum → Lower part, digestion end here,
both digestion and absorption occur

a. In Duodenum
- it contain bile and enzyme
- pancreas secret pancreatic juice 16

Pancreatic Juice
 Trypsin Lipase Pancreatic amylase

 Peptone trypsin peptide

 fat and oil lipase fatty acid and glycerol
 starch amaylase maltose
- Bile: secreted from liver, has no enzyme
- it is alkaline (base)
- stored in gall bladder
- help to neutralize acid

Fat Bile Fat droplet (emulsify fat)

b. In Jejunum and Ileum

- Intestinal juice is secreted here

Erepsin

maltase Intestinal juice lactase

sucrase

 Peptides Erepsin Amino acid

 Maltose maltase Glucose and glucose
 Lactose lactase Glucose and galactose
 Sucrose sucrase Glucose and Fructose

Absorption: glucose, amino acid and fatty acid and glycerol leave the small intestine by diffusion and go in to the blood
supply.

- Small intestine have finger like projection called Villi that absorbs food
- glucose and amino acid directly go in to the blood
- fatty acid and glycerol, move in to the lacteals
- lacteals is part of lymph system with lymph fluid it goes to blood supply
- Digested food in small intestine move in to the liver through hepatic portal vein then to each individual cell.

Assimilation: taking in and uses of digested food by the cell

Engestion: removal of the faeces from your body

Issue of digestive health

Constipation: compacted, hard and difficult to evacuate faeces, because of loss of water (lack of fiber)

- treated by: eating more fiber

- drinking plenty of water
- taking laxatives

Diarrhoea: very loose and watery faeces

- treated by: drinking water with rehydration salt

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3.3 The human respiratory system

Structure of human respiratory system

The respiratory system is a vital in order to get oxygen to oxidize food and release energy for
proper functioning of the body.
The human respiratory system consisting of the following structures:
Mouth: is an organ through which the air enters into respiratory structures
Nose/nasal cavity: is additional structure through which the air enters into respiratory tract.
Nose contains the nasal passages, which have:-
a large surface area,
a good blood supply,
Lots of hairs and a lining that secretes mucus.
 The hairs and mucus filter out much of the dust and small particles that we breathe in,
Whilst moist surfaces increase the humidity of the air we breathe into our bodies and the rich blood
supply warms it
 This means that the air we take in is warm, clean, and moist before it gets into the delicate tissue of our
lungs.
Pharynx: is the structure that serves as a common passage for both food and air
Larynx or voice box: the upper part of trachea by directing air leaving the lungs over the vocal cords.
Trachea: is the wind pipe which is made from C-shaped cartilage that supports it and holds it open.
The lining of the trachea secretes mucus, which collects bacteria and dust particles.
The cells that line the trachea are also covered in hair-like cilia that beat to move the mucus with any
trapped micro-organisms and dirt away from the lungs and towards the mouth.
 The opening of trachea is called glottis.
The entrance of food and dust particles into the glottis is prevented by epiglottis.
Bronchi (singular bronchus): are the branches that arise from the trachea, one leading to each lung.
Bronchioles: are small tubes branching from each bronchus in the lung. They are much smaller than bronchi.
Alveoli (singular alveolus): are tiny air sacs which are used for exchange of gases between the lungs and the blood
capillaries, they are called functional unit of the lung.
The lung is the major breathing organ of human; it is surrounded by membranous structure called pleural
membrane.
18
The lung is spongy and elastic organ which is protected by ribs, vertebral column, diaphragm and
intercostal muscle.
Diaphragm: muscle separating heart and lung from abdomen.
Intercostal muscle: are muscles that are found between the ribs and used in breathing.
There are two sets of intercostal muscle in normal quite breathing only external intercostal muscle is
involved, however if we need to breath deliberately internal intercostal muscle is involved

How is air brought into the lungs?

The process of breathing involves the process of inhalation and exhalation.
The breathing movements are brought about by two different sets of muscles that change the
pressure in the chest cavity.
The mechanism of breathing
Structure Inhalation (breathing in) Exhalation (breathing out)
Diaphragm Contract & flatten Relax & become dome shaped
External intercostal Contract Relax
muscle
Internal intercostal Relax Contract
muscle
Ribcage Moves up & outwards Moves down & inwards
Chest cavity Looks bigger Looks smaller
Pressure Decreases Increases
Lung Inflated (filled with air) Constricts(defleats)
The volume of thorax Increases Decreases
The process of gaseous exchange
 breathing in supplies us with the oxygen we need for cellular respiration
 when we breathe out waste carbon dioxide is removed from the body
 When the air is breathed into the lungs, O2 passes into the blood by diffusion along a concentration gradient.
 At the same time CO2 passes out of the blood into the air of the lungs, also by diffusion along a
concentration gradient.
 This exchange of gases takes place in the alveoli, the tiny air sacs with a large surface area that make up much
of the structure of the lungs.
 The movement of O2 into the blood and CO2 out of the blood takes place at exactly the same time
 There is a swap or exchange between the two and so this process is known as gaseous exchange
The mechanism of gas exchange in the alveoli depends on:-
a large surface area
moist surfaces
short diffusion distances
a rich blood supply These maintain steep concentration gradient
Factor affect breathing rate
The breathing rate is determined by the rate of breathing and depth of breathing
The normal rate of breathing in adult human being is 12-14 times per minute
Depth of breathing: is the amount of air inhaled or exhaled per breath
Tidal volume: is the amount of air that one can be breathed in & out at normal
resting situation
Vital capacity: is the maximum amount of air that is breathed in and out:
The rate of breathing can be affected by the following major factors. These are:

A. Exercise
During exercise when muscular activity increases, the breathing rate and depth of breathing increases
to supply more oxygen to release energy for the body.

B. Anxiety
During anxiety the body reacts as it is in danger, extra oxygen needed to more energy in order to
survive danger, therefore the rate & depth of breathing increases.
C. Drugs
Stimulant drugs such as khat and cocaine can increases the rate and the depth of breathing. 19
D. Altitude
At places of higher altitude; the level of oxygen becomes lower &lower. This makes breathing
 difficult thus the rate and depth of breathing becomes higher.
E. Weight
Excess weight can also affect the breathing rate.
It can be difficult to breathe deeply because of the fat around the abdominal organs, which makes it
difficult for the diaphragm & other structures around the lungs to relax properly.
F. Smoking
Smoking is a habit that directly affects your respiratory system as well as other areas of your body
The effect of smoking on The health:
The cigarette smoke consists of around 4000 chemicals that are inhaled into the lungs. some of these
include:

Nicotine: is the addictive drug found in tobacco smoke.

Carbon monoxide: is a very poisonous gas found in cigarette smoke .It takes up some of the oxygen
carrying capacity of the blood.
Tar: is a sticky black chemical in tobacco smoke and causes irritation of nose , throat & lung.
Carcinogenic substances: are cancer causing substances; the most commonly carcinogenic are arsenic
& benzeprene.
Smoking-related diseases
Smoker health may get affected in various ways :
Tar is a sticky black chemical in tobacco smoke that is not absorbed into the bloodstream.
It simply accumulates in the lungs, turning them from pink to grey.
In a smoker, the cilia which move things away from the lungs are anaesthetized by each cigarette and
stop working for a time, allowing dirt and bacteria down into the lungs.

Tar makes smokers more likely to develop bronchitis -inflammation and infection of the bronchi.

The build-up of tar in the delicate lung tissue can also lead to a breakdown in the alveolar structure.

In these chronic obstructive pulmonary diseases (COPD) the structure of the alveoli break down
and much larger air spaces develop.
Cancers of lung, lips, and throat can be caused due to carcinogenic substances
Smoking also affects heart & blood vessels which increases the risk of the heart attack and stroke.
Smoking and the family:
Smoking may have individual, family & the society; some of its effects include:
Economic crisis Increased risk of respiratory diseases
Psychological problems Conflict in the family
Breathing hygiene:
There are mechanisms that can be used to keep the breathing system into a healthy state:
- Good oral hygiene
- Covering the mouth during cough &sneezing
- Consult a doctor for any problems related to respiratory organs
3.4 Cellular respiration
The digestive system, breathing, and circulation systems all exist to provide the cells of the human
body with what they need for respiration.
Respiration: is the process in which energy is released from the breakdown of organic substances in
the body.
The energy that is used by the cells is stored in the form of a molecule known as ATP,
Which stands for adenosine triphosphate. This is an adenosine molecule with three
phosphate groups attached to it.
When energy is needed for any chemical reaction in the cell, the third phosphate bond is broken 20
in a hydrolysis reaction.
ATP+H2O→ ADP +Pi +energy
 ATP is formed by the bond between adenosine diphosphate & a free inorganic phosphate group (Pi)
and the all-important energy needed in the cell.
ADP +Pi →ATP+H2O
The importance of ATP to the body:
to build up large molecules from smaller ones to make new cell material (anabolism). And
also break large molecules down into smaller molecules (Catabolism).
Anabolism + Catabolism = Metabolism
To enable muscle contract and relax
Provide energy for the active transport of some substances across cell boundaries
Types of Respiration
I. Aerobic respiration
during the process of cellular respiration, glucose reacts with oxygen to release energy that can be
used by the cell. Carbon dioxide and water are produced as waste products.
The reaction can be summed up as follows:
Glucose + oxygen → carbon dioxide + water + energy (ATP)
Aerobic respiration takes place in the mitochondria in cells.
These are tiny rod-shaped bodies (organelles) that are found in almost all cells.
Cells that use a lot of energy contain lots of mitochondria

II. Anaerobic respiration

breaking down of food to release energy without oxygen
it is a type of respiration that does not use oxygen.
Anaerobic respiration produces far less ATP than aerobic respiration.
It also produces a different waste product called lactic acid.
Glucose → lactic acid + energy (ATP)
3.5 The circulatory system
 The transport system is required to supply the needs of the body cell & remove the waste products
they produce.
The human transport system is the blood circulation system. It has three elements: the pipes
(blood vessels), the pump (the heart), and the medium (the blood)
A double circulation:
Human circulatory system is called a double circulation.it consists:
i. One carrying blood from the heart to the lungs and back again to exchange oxygen and carbon dioxide with
the air. This is called pulmonary circulation
ii. The other carrying blood all around the rest of the body from the heart and back again. This is called
systemic circulation
A. The blood vessels
 A very important element of any transport system is the pathways along which the transport takes
place.
 In the human body there are three main types of blood vessels:-
Arteries, Veins & Capillaries

Arteries: carry blood away from the heart

The largest artery is called aorta

The smallest artery is called arterioles

It have thick walls that contain muscle and elastic fibres
It have a pulse: the pulse is the surge of blood from the heart when it beats 21
they have no valves
Most arteries carry oxygenated blood ‗except:
  Pulmonary artery which carry the blood away from your heart to your lungs
 Umbilical artery which carries blood away from a foetus into the placenta
Veins: carry blood towards the heart.
The largest vein is called venacava
The smallest vein is called venules
▲ They have much thinner walls than arteries & less elastic wall\
▲ They do not have a pulse but they often have valves
▲ Most veins carry deoxygenated blood except:
 Pulmonary vein, which carry oxygenated blood back from lungs to the left-hand side of
heart
 Umbilical vein, which carries oxygenated blood from the placenta back to the developing
foetus.
Capillaries
▲ They are narrow, thin walled blood vessels
▲ It help to connect arteries with veins and take blood to the tissues & cells
▲ They have no valve
▲ They are site of the exchange of substances within the body.
▲ Blood from the arteries passes into the capillaries, which have thin walls & massive surface area.

B. The Human heart

The human heart is a bag of reddish-brown muscle that beats right from the early days of development
until the end the life, sending blood around the body.
It is made up of a unique type of muscle known as cardiac muscle

The walls of the heart are almost entirely muscle.

These muscular walls are supplied with blood by the coronary arteries (supply oxygenated blood to
cardiac muscle).
The deoxygenated blood is carried away in the coronary veins, which feed back into the right atrium
(atria).
 Human heart is divided into 4 chambers
The two upper chambers are the right & left atria
The two lower chambers are the right & left ventricles
 The walls of the atria are relatively thin, so they can stretch to contain a lot of blood.
 The walls of the ventricles are much thicker, as they have to pump the blood out through the major
blood vessels.
 The muscle walls of the left-hand side of the heart are thicker than on the right. This is because the
left hand side of the heart has to pump blood around the whole body whilst the right-hand side
pumps only to the lungs.
The working of the heart
 The two sides of the heart fill and empty at the same time to give a strong, coordinated beat
Mechanism of blood circulation
Deoxygenated blood, which has supplied oxygen to the cells of the body and is loaded with carbon dioxide,
comes into the right atrium of the heart from the veins of the body. The atrium contracts and forces blood
into the right ventricle. The right ventricle contracts and forces blood out of the heart and into the lungs
where it is oxygenated - it picks up oxygen. Oxygenated blood returns to the left-hand side of the heart from
the lungs and the left atrium fills up. The left atrium contracts forcing blood into the left ventricle. The left
ventricle contracts forcing oxygenated blood out of the heart and around the body
22
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Valves
Valves: mechanism in the veins that allows blood to flow in one direction only.
inside the heart there are many different valves.
their names describe their appearance;
bicuspid (two parts): are found between the left atrium & left ventricle
Tricuspid (three parts) are valves between the right atrium & right
ventricles.
Semilunar (half-moon): valve found at the base of aorta and pulmonary
artery
Septum: - wall separating the right and left sides of the heart
Diastole is when the heart muscles relax and it fills with blood.
Systole is when the heart muscles contract and force the blood out of the heart
The pressure at which the blood travels around our arteries varies as the heart beats.

 A normal blood pressure is about 120 mmHg/80 mmHg -the nominator is systolic & the
denominator is diastolic pressure.
 Sphygmomanometer: is an instrument that is used to measure blood pressure.
C. The blood
Blood is a complex mixture of cells and liquid that carries a huge range of substances around the
body
Blood consists of a liquid called the plasma.
Plasma: - is a pale yellow liquid that transports all the blood cells & also number of other things.
There are components of blood cells. These are:

Red blood cells (Erythrocytes)

They are more in number than other types of blood cells
They are disc shaped & non-nucleated cells.
They are made in bone marrow, when they mature they lose their nucleus.
The RBC only live 100-120days so they are constantly being replaced.
They are used to carrying O2 around our body. Because they are packed with a special red substance
called haemoglobin, which picks up oxygen.
Hemoglobin is a special red pigment, a large protein molecule folded around four iron atoms.
23
In a high concentration of oxygen, such as in the lungs, the hemoglobin reacts with oxygen to form
oxyhaemoglobin.This is bright, which is why most arterial blood is bright red.
In areas where the concentration of oxygen is lower, such as the cells and organs of the body, the
 reaction reverses
The oxyhaemoglobin splits to give purple-red haemoglobin (the colour of venous blood) and oxygen
The oxygen then passes into the cells where it is needed by diffusion.
White blood cells (leukocytes)
They are much bigger than the red cells but they are fewer of them.
They have a nucleus and form part of the body‘s defense system against microbes
They can be classified as:
Lymphocytes- form antibodies against microbes
Phagocytes-engulf invading microorganisms
Platelets (thrombocytes)
They are small fragments of cells and very important in helping blood to clot at the site of a wound.
Platelets have thread like protein fiber called fibrin for blood clotting to trap blood cells, platelets and
fluid through a complex series of enzymes controlled reactions.
The clotting of the blood prevents from bleeding to death from a simple cut
It also protects the body from the entry of bacteria and other pathogens
Human blood groups
There are special proteins called antigens are found on the surface of all cells.
They allow cells to recognize each other and also to recognize cells from different organisms
If the cells of an immune system recognize a foreign antigen on a cell in the body, they will produce
antibodies & it destroy the foreign cells.
A number of different antigens are found specifically on the surface of the RBC, which gives different
human blood groups.
The blood grouping system is called ABO system.
Based on presence and absence of these antigens , there are four types of blood groups
There are two possible antigens : Antigen A & antigen B
There are also two types of antibodies:- antibody A & antibody B
 The below table describe the compatibility of Different blood groups
Blood group Antigen on RBC Antibody in the plasma Donate to Receive from
A A B A & AB A& O
B B A B & AB B&O
AB AB None AB only All groups
O None A and B All groups O only
Blood group ‗O ‗is called universal Donor, because it has no antigens so, it can be given to anyone.
Blood group ‗AB‘ is called universal recipient , which has no antibodies can receive any type of blood
If the blood from different blood groups is mixed together, there may be a reaction b/n the antigen & the
complementary antibody which makes the red blood cells stick together, this is called agglutination.
Two common problems of the circulatory system:
A. Anemia: it is caused when there are:
 too few red blood cells in the body, or too low levels of hemoglobin in the blood.
 It is most commonly due to lack of iron in the diet so it is treated by iron rich diet.
B. Hypertension (High Blood Pressure):
Is considered high if the systolic pressure is >140mmHg or the diastolic pressure is >90mmHg
There are a number of factors that can increase the risk of hypertension.
Many of these factors mean that blood vessels are likely to be getting narrower, or becoming
more rigid
These factors include: - sedentary (inactive) lifestyle,
Increasing age, smoking, 24
being overweight, kidney diseases, diabetes and
Excessive salt intake, certain medicines such as steroids
 Excessive consumption of alcohol,
Treatment of hypertension
Losing weight Lower salt level in diet
Life style adjustment using medicines like:

Diuretics: which increase frequency of urination to decrease the blood volume and
Beta blockers: - these blocks the nerves w/c narrows the arteries
UNIT: 4
MICROORGANISMS AND DISEASES
4.1. Micro-organisms
Micro-organisms are tiny living organisms that are usually too small to be seen with the naked eye,
these includes bacteria, viruses, yeast and mould
Many of microorganisms are very useful while other cause diseases.
Bacteria
 Are single celled organisms
 They are much smaller than the smallest plant& animal cells.
 They contain cytoplasm surrounded by a membrane
 They have non cellulose cell wall
 Some bacteria have flagella to help to them move
 They also come in a variety of different shape and size
Viruses
 are even smaller than bacteria
 They usually have regular geometric shapes, and
 They are made up of a protein coat surrounding genetic material containing relatively few
genes.
 They do not carry out any of the functions of normal living organisms except reproduction
 They are obligate intracellular parasites
 They have either DNA or RNA as genetic material
Fungi (Yeast and mould)
 Yeast are single -celled organisms
 Each yeast cell has a nucleus, cytoplasm, and a membrane surrounded by a cell wall.
 They reproduce is by asexual budding - splitting to form new yeast cells.
Moulds
 They are made up of, threadlike structures called hyphae.
 The hyphae are not made up of individual cells - they are tubes consisting of a cell wall containing
cytoplasm and lots of nuclei.
 They reproduce asexually by spore formation.
The germ theory of disease
Germs are micro-organisms responsible for cause of some diseases
The development of microscope Anton van Leeuwenhoek in 17th century helped different biologists
to explain the relationship between infectious diseases & micro organisms
The development of knowledge about micro-organisms is actually related to the theory of spontaneous
generation.
The theory of spontaneous generation
States that living things could arise from non-living things spontaneously. This theory is opposed by
many biologists & a French biologist Louis Pasteur disproved it finally by using an S- shaped flask
that traps dust & microorganisms.
Pasteur was convinced that any growths that appeared -for example, mould on food as it decayed -
came from microscopic organisms already present in the air.
25
First he showed that the theory of spontaneous generation was wrong. Then he showed that if he boiled
broth and sealed the container, the broth would stay clear until he introduced material which had been
exposed to the air.
At this point micro-organisms grew and the broth turned cloudy
 Pasteur went on to identify the micro-organisms that caused a number of diseases including anthrax,
rabies, and diphtheria.
The immune system
Immune system:- the system in the body which protects the body against invading microorganisms
and foreign proteins.
Like all living cells, pathogens carry unique protein molecules called antigens on their cell surfaces.
When a pathogen gets into the body the antigens on the surface stimulate a response by the immune
system.
White blood cells (lymphocytes) produce antibodies to disable the pathogen. Other white blood cells
(the phagocytes) then engulf and digest the disabled pathogens.
Once someone have had a disease, the immune system ‗remembers‘ the antigen and the right
antibody to deal with it.
Control of microorganisms
Sterilization is the killing of all micro-organisms in a material or on the surface of an object,
making it safe to handle. These include the use of:
High temperatures or heat
It is highly efficient means of sterilization
 Autoclaving: it involves the killing of microorganisms by boiling in water at 121 °C. under
high pressure for 15-45 minutes of ‗cooking‘ at these temperatures
 Ultra high temperature (UHT) is a way of treating food to kill all the micro-organisms on
it. The temperatures used range from around 135 °C to 150 °C
 Dry heat sterilization: Dry heat, over a long time, kills all micro-organisms. Special ovens
used in microbiology use temperatures of 171 °C for an hour, or 160 °C for 2hours,.
 Incineration - burning substances at high temperatures in the air - also kills micro-organisms
 Pasteurization: it involves boiling or heating of milk, beer and other foodstuffs at 71.6 °C for at least
15 seconds or 62.9 °C for 30 minutes.
A chemical approach to controlling micro-organisms
 Possible pathogens can be attacked chemically in a number of ways .for e.g.
1. A disinfectant is a chemical or physical agent that is applied to an inanimate object to kill micro-
organisms. Disinfection means reducing the number of living micro-organisms present in a sample
This method discovered by Joseph Lister. some of example of disinfectant include: house hold
bleach, Dilute bleach and calcium hypochlorite
2. Antiseptics: are chemical agents that are applied to living tissue to kill micro-organisms -disinfectants for
the skin.
it help to protect entrance of germs if the skin is cut or wounded.
Growing of microorganisms
Micro-organisms can be grown in laboratories under controlled condition.
It is important for various purposes; these include:
To know how to killed them
To develop vaccines
To identify their useful & harmful aspects
For growing microorganism‘s biologist need to fulfill the following precondition:

Isolating type of microorganisms to be studied

developing suitable nutrient like agar and broth
Agar: is a solid nutrient medium which is extracted from red algae
Broth: is a liquid nutrient medium 26
Antibiotics
 Drugs which kill bacteria but do not harm human cells
 Penicillin was the first antibiotic to be discovered
 Artificial immunity
Our body has its own natural ability to protect itself against artificial disease, however if the immune
system of the body fails to defend some dangerous disease it will be treated by artificial immunity.
Artificial immunity is given in the form of vaccine
Artificial active immunity: involves introduction of weakened or dead pathogen in the body which
stimulates the body to produce its own antibodies.
It can be natural from mother to child (natural passive) until the child produces its own natural
active immunity
Artificial passive immunity: it involves giving specific antibodies in the form of infection. It
provides a high type of resistance but last only for short time.
Natural active immunity;- acquired from exposure to the disease organism through
infection with the actual disease.
Vaccination (immunization):
 is the use of dead or weakened strains of pathogens to produce immunity to dangerous
diseases
 the vaccination work through the following ways
a weak or dead form of the infecting organism is put into the body by injection or by mouth
once in the body, the white blood cells respond by producing antibodies
If the living micro-organism enters the body in the future, antibodies are produced very rapidly
to destroy it and so the disease does not develop.
4.2. Diseases
Disease is any form of disorder in or on the body distorts its normal functioning
Some of the most commonly known diseases which are caused by pathogenic organisms
among them include:
i. Tape worm (cestoda)
Flat shaped worm that parasitizes the wall of intestine of humans
They have no digestive system & but have cuticle to absorb nutrients
The most common are beef tape worm(Taenia saginata) & the pork tapeworm(Taenia solium)
They have complex life cycle which involves at least two different hosts.
Transmission: eating improperly cooked or raw meat
Symptoms: feeling weakness, weight loss, segments of tape worm in feaces
Control & prevention: avoid eating raw meat, use antiworm drug & proper disposal
of feaces
Life cycle of beef tape worm
Cows raised in unsanitary conditions may contain cysticerci ‗bladder worms‘ embedded in their muscles.
These consist of a capsule containing a scolex. When a bladderworm is ingested (e.g. in undercooked
beef), The scolex turns inside out and attaches by suckers and hooks to the wall of intestine.
It then begins to produce buds, called proglottids, which remain attached to each other for a time and, as
they mature, each develops both male and female sex organs.
The most mature proglottids eventually break loose and are passed out in the faeces. If conditions are
such that cows get access to the human faeces, they take in the eggs and the whole cycle starts again.

ii. Tuberculosis
 It is caused by a bacterium called Mycobacterium tuberculosis
 It can affect anyone of any age, but People with weakened immune systems (such as people
suffering from HIV/AIDS) are at increased risk 27

Transmission :
 Droplet infection, but need prolonged exposure to someone with TB for infection to
 occur. work in overcrowded conditions
Symptoms
 Some people may not have obvious symptoms (asymptomatic), however the symptoms of TB
include:

a low-grade fever fatigue a persistent cough

Night sweats weight loss and
Control and prevention
In social terms avoiding overcrowded conditions Covering the nose &mouth during coughing
Good ventilation vaccination
Treatment
People with active TB disease must complete antibiotic for four months or more
The role of vectors in disease:
A vector is an organism that transmits disease-forming micro-organisms from one host to another
well-known example is the Anopheles mosquito, which carries the malarial parasite
iii. Mosquitoes and malaria
Malaria is a disease where mosquitoes are the vector
The mosquito vector is the female Anopheles mosquito
The disease itself is caused by the single-celled parasite Plasmodium
It spends part of its life cycle in a mosquito and part in the human body
Life cycle
√ Female needs two meals of human blood to provide protein for her developing egg and this
is when she passes on her load of malarial parasites.
√ If the first feed the mosquito takes is from someone infected with malaria, the Plasmodium
parasites called Plasmodium falciparum remain in her mouthparts
√ the next time she feeds, the Plasmodium parasites pass into the blood of the victim along
with the saliva - and someone else is infected with malaria
Symptoms: These include fevers, chills, and sweats
Control and prevention: Methods of controlling malaria must involve controlling the Anopheles
mosquitoes. This can be done by: Using mosquito repellents
having screens on doors and windows
insecticide-treated mosquito nets
Proper disposal of sewage‘
Minimize any opportunities for the mosquitoes to breed

iv. Gastroenteritis/acute watery diarrhea (AWD)

Intestinal infection causing acute watery diarrhea
Some of the causative organisms include rotaviruses, the bacteria Salmonella and
Escherichia coli (E. coli), or the protoctists Giardia and Amoeba.
Transmission
eating contaminated food or water
prepares or handles food without washing their hands after going to the toilet
poor sanitation
poorly cooked and raw eggs if they are infected with bacteria such as Salmonella
symptoms
28
violent abdominal cramps and pain
feeling nauseous, vomiting or often both
watery diarrhoea which does not usually have blood in it
 slight fever
general muscle aches and headache
Control and prevention
Good personal hygiene Avoid eating undercooked or raw food
v. Cholera
√ It is caused by bacteria called Vibrio cholera & it infects intestine
Transmission: eating or drinking food or water contaminated by the faecal waste of an infected person
Symptoms: include the pale, watery diarrhea, vomiting and dehydration, muscle cramps
Treatment: taking more fluid to replace the lost through diarrhea &antibiotics, rehydration salt (ORS)
Control and prevention: avoid consumption of uncooked food
Proper disposal of feaces ,
Good personal hygiene and environmental sanitation
Taking cholera vaccine
vi. Typhoid (Typhoid fever)
is a bacterial infection caused bacterium called Salmonella typhi - typhoid only affects humans
transmission : Like other diarrhoea diseases they are spread by eating foods or drinking water
contaminated by faeces from an infected individuals
symptoms: it may include :A very high fever - 39-40 °C, A painful abdomen
Sore throat and headache, an enlarged spleen and liver , Constipation or diarrhoea
Treatment: antibiotics are used as a very effective treatment. Plenty of fluids to replace the ones they
lose
Control and prevention: careful hand washing after toilet visits,
clean drinking water and good sewage disposal
good food hygiene in kitchens and care in eating raw or lightly cooked foods
vii. Sexually transmitted diseases (STDs)
STDs are Infectious diseases spread by sexual contact it is also known as venereal diseases (VD)
are a growing problem in Ethiopia -partly because sexual activity often starts relatively young
the most commonly known STDs are:
A. Gonorrhea (gonococcal infection)
o Is caused by the bacterium Neisseria gonorrhoeae.
o Gonorrhea germs are found in the mucus areas of the body (the vagina, penis, throat and rectum).
o Transmission :It is spread through sexual contact, Having unprotected sex, having many sexual partner o
Symptoms: burning sensation while urinating and a yellowish-white discharge from the genital organ
 If a pregnant woman has untreated gonorrhea, she can pass the infection on to her baby result in
blindness
Treatment: it can be treated effectively in the early stages using antibiotic o
Prevention& control:
Infected individual do not have sex until your course of treatment is completed.
Use a male or female condom
Be faithful to sexual partner.
B. Syphilis
√ Is bacterial infection, caused by the spiral-shaped Treponema pallidum
√ Any sexually active person can be infected
Transmission: like gonorrhea It is spread through sexual contact
It is congenital syphilis, which is spread from mother to foetus. This can cause very serious problems
29
for the baby when it is born.
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Structure of Treponema pallidum

Symptoms: Syphilis progresses in distinct stages
The symptoms occur in stages called primary, secondary and tertiary (late)
Primary stage (the first six weeks): painless sores around reproductive organ, rectum, & mouth
Secondary stage (six weeks after): The most common symptom during this stage is a rash.
Other symptoms can include:
Tiredness sore throat hoarseness patchy hair loss
Fever headaches loss of appetite
swollen glands
Untreated the disease then goes into a long quiet phase
Tertiary stage (late syphilis):
Involve illness in the skin, bones, central nervous system and heart.
It causes severe and irreversible problems that cannot be treated successfully.
If a pregnant woman has untreated syphilis she may transmit the disease to her unborn child. This may
result in death or deformity of the child.
Treatment: It is treated easily with antibiotics such as penicillin or tetracycline
Pregnant women can be treated with antibiotics to cure them and protect their baby
Prevention& control: similar with gonorrhea
C. Chancroid
It is a bacterial STD that is caused by the bacterium Haemophilus ducreyi
It is more commonly seen in men than in women.
Transmission: having sex with an infected person & increase risk of becoming HIV-positive
Symptoms:
The first symptoms of chancroid are sore ulcerations on the genitals, particularly penis, it is soft and
filled with pus.
The second stage of the infection is that the lymph glands in the groin also become infected,
Permanent loss of penis
Treatment: it can be treated easily with a dose of antibiotics
Prevention & control:
be faithful sexual partner
Use a male or female condom
Good genital hygiene & male circumcision
Using medicines correctly
Traditional medicines are very &alternative form medicine in developing countries like Ethiopia
o It is often holistic, based on treating the whole patient, but limiting their dose is very important.
o It is based on extracts of plants including herbs and spices.
Modern medicines: are responsible for cure various diseases &made in very carefully controlled doses
The most common include: antibiotic & vaccine
However care should be taken while using modern medicine: so the following precaution should
be considered: 30
Do not take more than you are prescribed,
Do not take less than you are given
 Make sure you finish taking all the medicine
Follow the instruction if not antibiotic-resistant bacteria may evolve which can be very
serious indeed
4.3. HIV and AIDS
Acquired Immune Deficiency Syndrome (AIDS) is the medical term for a combination of illnesses
that result when the immune system is weakened or destroyed.
It is caused by Human Immuno deficiency Virus (HIV), a virus that attacks the immune system.
Transmission:
 sexual intercourse which is un protected
 It can pass from a mother to her baby in the womb, during birth or when she breastfeeds
 Infected blood on needles used for injecting illegal drugs, or knives used for female genital
mutilation.
Symptoms
Patients often have few symptoms to begin with but eventually their weakened immune system means
they get many diseases.
Treatment
Antiretroviral drugs can slow down the progress of HIV/AIDS and protect unborn babies from
infection.
 The sooner people can start taking antiretroviral after infection, the longer they will stay healthy.
Prevention & control
It can be controlled by ABC rule means that:
A: abstain from sex
B: be faithful to sexual partner JOIN ON Telegram
C: condom use
@QesemAcademy
HIV and the immune system
How does HIV attack the immune system?
There are two main types of white blood cells in the immune system. These are:
1. T-cells actually bind to the antigens on the invading micro-organism and destroy it.
2. B-cells make antibodies which bind to the antigen and destroy it.
HIV attacks the T-cells of immune system. It gets inside them and so they can no longer work.
As more T-cells are invaded by the virus, the immune system is less and less effective.
This is why people with HIV/AIDS get so many other infections
Stigma and discrimination
Stigma is a mark of disgrace on people with HIV, while discrimination is an act of
neglecting some from the group or other.& are the most serious cases that affects people living
with HIV/AIDS
Care and support
It is important for people living with HIV/AIDS since it helps them live longer & healthier
Unit 5:
Classification
5.1. Principles of classification
On Earth today there are many types of living things. This great variety of life is called biodiversity.
Classification: is grouping of similar living things.
Taxonomy: is study of classification of organisms (Greek, taxis-to arrange, nomos-law) 31

Need for classification

Biologists classify living things for the following reasons:
 To simplify their study
To bring order out of chaos or confusion
To try to understand how life originated
What is a species?
 A group of organisms that can breed successfully with one another to produce fertile offspring.

How are living things classified?

Living things are classified according to how similar they are
One example is animals that are put in a group together because their limbs are built on the same basic
plan.
The limbs of a bat, horse, bird, human and whale all have the same basic pattern though they are used in
different ways these limbs are called homologous structures. (Similar structure with d/t function)
Today there are more sophisticated ways of comparing organisms. The fundamental chemicals of life -
such as DNA, RNA and proteins - are found in almost all organisms
The classification system
▲ Taxonomy: is the process of classifying living organisms‘
▲ Taxa: category in classification
▲ The main taxonomic categories are kingdom, phylum (or for plants, division), class, order,
family, genus and species.
The largest groups into which living organisms are divided are the kingdoms.
Kingdoms are subdivided into phyla,
Each phylum into classes, each class into orders,
Each order into families, each family into genera and each genus into species.
The species is the smallest unit of classification
Naming living things
Different method of classification was introduced by different biologists at different times:
Aristotle: Greece a philosopher .who tried to create a classification system for the living world, and
grouped animals by: animals that live on land‘ and ‗animals that live in water
The modern classification method is introduced by Swedish botanist Carl Linnaeus in 18th century.
He developed the binomial system of nomenclature for organisms
He published in a book called The System of Nature
Binomial means two names. The two names of an organism are in Latin
Simple rules for writing scientific names
The first name is the name of the genus name & it is starts with capital letter. e.g. Homo sapiens,
The second name is the name of a species & it is written with a small letter.
The two names are underlined when handwritten or in italics when printed.
Table 5.1 Examples of scientific names of some common organisms

common name Scientific name

Human beings Homo sapiens
A dog Canis familiaris
A housefly Musca domestica
Domestic cat Felis domesticus
Maize Zea mays
Bean Phaseolus vulgaris
Lion Panthera leo
Living things are classified and named for the following main reasons.
To create an internationally accepted way of referring to a particular living thing. 32
To avoid confusion created by different languages.
To help in simplifying classification and study of living things.
 Human Honeybee Teff Mushroom
Kingdom Animalia Animalia Plantae Fungi
Phylum Chordata Arthropoda Angiospermophyta Basidiomycot
Class Mammalia Insecta Liliopsida Basidiomycetes
Order Primates Hymenoptera Cyperales Agaricales
Family Hominidae Apidae Poaceae Agaricaceae
Genus Homo Apis Eragrostis Agaris
Species sapiens mellifera teff campestris
Table 5.2 Hierarchy of groups
5.2. The five kingdoms
▲ A kingdom is the largest taxon and consists of all the other taxa. In the modern classification, there
are five kingdoms namely:

1 Kingdom Monera 4 Kingdom Plantae

2 Kingdom Protista 5 Kingdom Animalia
3 Kingdom Fungi
This system of classification is known as the five-kingdom system
Viruses are not classified in any of the above kingdom. This is because viruses do not have all the
seven characteristics of life, although most scientists now classify them as living organisms.
1. Kingdom Monera
The representative groups are Eubacteria (true bacteria) & the blue-green algae (Cyanobacteria).
They are unicellular & prokaryotic (have no distinctive nucleus).
They are all microscopic and they reproduce by simply splitting in two (binary fission)
They have either autotrophic or heterotrophic mode of nutrition
Examples include Mycobacterium tuberculosis and Haemophilus ducreyi which are pathogenic while
others are useful.
2. Kingdom Protista
Consists usually unicellular & eukaryotic (do have nucleus)
They include plant-like organisms that can move around and animal-like organisms that cannot move
Representative groups of this kingdom are subkingdom protozoa& subkingdom algae
A. Subkingdom protozoa
They are microscopic & have no chloroplasts
They live as parasite or free living
Have locomotory structure. e.g. Amoeba- pseudopodia , Paramecium:-cilia
B. subkingdom algae
They are photosynthetic & eukaryotic
They live either in aquatic habitat or on land
They have undifferentiated body called thallus.
E.g. Dinoflagellates, red algae, & green algae
3. Kingdom Fungi
Fungi are eukaryotic and usually multicellular.
They are heterotrophic
Many fungi are saprotrophs, which means they feed on dead material.
They play a vital role within ecosystems as decomposers
Examples of this type of fungus are Rhizopus ,Mucor and Penicillium 33
They can be parasites, feeding on living organisms. Such as Candida albicans (thrush) and
Tinea pedis (athlete‘s foot) affect people and other animals.
Some fungi are mutualists. This means they live in close association with another organism
 and both benefit. Examples are lichens, which are a combination of a fungus and green algae
Mycorrhizae, an association between a fungus and the roots of a plant.
There are also single celled fungi like yeast.

4. Kingdom Plantae

The plants - includes a great variety of organisms, which range from tiny mosses to giant trees &
80% of these are flowering plants
The main characteristics of all plants include
They have eukaryotic cells.
They are multicellular organisms
They contain chlorophyll and carry out photosynthesis.
They are predominantly land dwelling.
Their cell wall composed of cellulose
Most have a waxy cuticle that helps to prevent drying out
The kingdom is split into a number of divisions. Plant divisions are the same as animal phyla. The
four most important divisions are:
A. Division Bryophyta (mosses and liverworts)
They are the simplest land plants.
They do not have a true leave , stem & root system
They are non-vascular (do not have xylem and phloem).
The best examples of bryophytes are mosses like Etodon concinnus,and Funaria species.
A moss plant:
has a simple, slender stem.
They also have thin simple leaves
also have simple root-like structures called rhizoids and attach the mosses to the
soil & used for absorption of water.
The other example is the liverworts, which only grow in very wet places.
Bryophytes are commonly found in rainforests and at high altitudes on mountains

B. Division Pteridophyta (Filicinopyta)-ferns

 They have true leaves, stems, and roots.
 Fern stems have rhizomes, which grow horizontally just below the surface of the soil.
 They have vascular tissue
 They have large prominent leaves called fronds
 Their spore produced in the fronds &dispersed by wind 34
 They reproduce by alternation of generation(the sporophyte is well developed their gametophyte
stage is reduced)
 most ferns live in damp, shady places - they are very common in tropical rainforests
  However, some ferns - such as Pteridium spp (commonly known as bracken) can grow and do well in
full sunlight.
 Another example of a pteridophyte is the fern Dryopteris spp.

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Ferns

C. Spermatophytes(seed-bearing plants )
They are the most successful because of the following characteristic features that they possess:
They have well-developed roots, stem and leaves.
They have well-developed vascular tissues.
The male gametes are contained within pollen grains and female gamete is contained within the
embryo sac.
The product of fertilisation in sexual reproduction is a seed that may or may not be enclosed in a
fruit.
The spermatophyta are divided into two divisions. These are:
i. Division Gymnospermae(coniferopyta)- non-flowering plants
ii. Division Angiospermae(flowering plants
i. Division Gymnospermae(coniferopyta)- non-flowering plants
These are more commonly known as the conifers or ‗naked seed plants‘. Pine trees, spruces and
cedars
▲ The main characteristics of the gymnospermae are:
Their seeds are not enclosed in fruits.
They have small needle-shaped leaves with a thick waxy cuticle that reduces water loss and
minimises damage by excess heat or cold.
They are evergreen so they can photosynthesize all year long
The reproductive structures are found in cones.
They different types of cone. The male cone forms huge numbers of pollen grains that are blown by
wind to a female cone.
Fertilisation results in a small winged seed.
The genus Pinus (for example, Pinus sylvestris, Pinus resinosa,) is a good example of a conifer

35
 ii. Division Angiospermae(flowering plants)
 They are the biggest group of land plants on the Earth.
The main characteristics of the angiosperms are
They have flowers as reproductive organs.
They have their seeds enclosed in a fruit.
They have well-developed xylem and phloem tissue
Angiosperms are subdivided into two main classes according to the number of cotyledons they have
in their seeds. These are:
I. Class Monocotyledons (monocots)
 are a group of enormous importance because they are cereal plants that form the staple diet
The main characteristics of the monocotyledons are:
The embryo has a single seed leaf (cotyledon).
Leaves are generally long and thin with parallel veins.
The stem contains scattered vascular bundles.
They do not reach great sizes (palms are the exception to this).
They are often wind pollinated
Example grasses, orchids and maize. Maize& Teff

II.Class Dicotyledons (dicots)

They make up most of the trees, as well as many vegetable plants.
The main characteristics of the dicotyledons are:
The embryo has two seed leaves (cotyledons).
The leaves are often relatively broad and have a network of veins.
The stem contains a ring of vascular tissue.
Some dicots reach great sizes.
They are often insect pollinated.
 Some common examples of dicots include sunflowers, peas, roses and beans. Most trees, such as
Jacaranda, Eucalyptus, Cassia and mangos are dicotyledons. Shrubs include Hibiscus, Lantana camara,
Bauhinia and oranges
5. Kingdom Animalia
This kingdom includes the animals. There are at least two million species of animals alive today.
They are multicellular, eukaryotic and heterotrophic 36
They exhibit locomotion, that is, can move their bodies from one place to another, and
Their cells do not have cell walls.
 They have nervous systems so they are sensitive to their surroundings.
They are either invertebrates (not have a backbone.) or the vertebrates( - all
the animals which have a spinal cord enclosed in a backbone of vertebrae)
There are33 animal phyla but the main ones are
1. Phylum Porifera (the sponges)
They are the simplest invertebrates. Most of them are hermaphroditic
They have hollow filter feeders, and the body cavity is connected to its external environment by pores.
There is little co-ordination or control.
They range in size from a few millimetres to two metres and are supported by a calcareous spicules.
 Sponges are an evolutionary dead end and have no other close living relatives

2. Phylum Coelenterata(cnidaria)
They include some exceptionally beautiful creatures and also
Some very poisonous ones. Sea anemones, hydra, jelly fish and coral are among the members of this
phylum.
They have soft bodies with a ring of tentacles for capturing prey.
They have stinging cells on their tentacles for poisoning or immobilising prey and predators.
They have two layers of cells in their bodies that surround a central cavity.
They have only one opening, the mouth, and their bodies have radial symmetry
Radial symmetry : is a body that can be divided into many halves.
3. Phylum Platyhelminthes - flatworms
 They show a relatively high level of organization
 They have flattened bodies with a mouth but no anus.
 They have no body cavity and rely on diffusion for everything.
 They are hermaphrodites
 They live in other animals as parasites or are free-living in fresh water.
Examples of Platyhelminthes include Planaria spp, which live in fresh water, tapeworms and liver flukes
like Fasciola hepatica
4. Phylum nematoda(round worm)
They have narrow, thread-like bodies,
Their bodies are not segmented and are round in cross-section.
They don’t have a circulatory system but they do have a complete digestive system.
Bilaterally symmetrical.
They contains many important parasites, such as Ascaris, which infects the guts of both humans and pigs, and the
family Filariidae -which cause elephantiasis
5. Phylum Annelida(segmented worm)
They have segmented body.
They have a closed blood circulatory system.
They are hermaphrodites, with male and female reproductive organs and
37
They have bristle like structures called chaetae to help them move.
They are found in moist soil and water and most are free-living.
The common earthworm, Lumbricus terrestris,& leech
 Earthworm Snail (mollusc) e.g. of Echinoderms
6. Phylum Mollusca
The most intelligent of the invertebrate species.
Octopi and squid have well developed brains.
They may have shells or be shell-less, live in the sea, or in fresh water or on land.
They have a soft muscular foot with a soft body
Their bodies are divided into head, foot and visceral mass and they are not segmented.
They breathe through gills. Examples of molluscs include slugs and snails.
7. Phylum Echinodermata
They are spiny skinned animals
they have a mouth, a gut and an anus
They are all marine animals, and move around using tube feet.
The adults have five arms, but the larval stages do not.
Examples include Asteris, the common starfsh, Echinus, the common sea urchin and
Paracucumana tricolor, a brightly coloured sea cucumber known as a sea apple.
8. Phylum Arthropoda
This phylum gets its name from two Greek words, arthron - joint, and podos - foot.
They have an external exoskeleton made of chitin that prevents excessive water loss.
They are animals with segmented bodies and jointed limbs.
They have a well-developed nervous system and a complete gut from the mouth to anus.
They divided into a number of classes according to the number of limbs, presence and number of
antennae and number of body parts.
Class insecta
They live almost everywhere although most are land-based.
They have a body divided into three body parts; head, thorax and abdomen.
They have three pairs of jointed legs on the thorax along with one or two pairs of wings.
On their head they have a pair of antennae and one pair of compound eyes.
Insects include flies, butterflies and moths, beetles, wasps and bees and many other common groups.

Class crustacea
They are mainly aquatic.
They vary in size from very small, for example water fleas, to quite large, for e.g. lobsters and crabs.
Their body is made up of two parts - a cephalothorax (head fused with thorax) and abdomen.
The body is often protected by a tough covering called a carapace.
They have more than four pairs of jointed legs, two pairs of antennae and simple eyes.
They include Daphnia, crab, prawn, shrimp, barnacle, water flea, lobsters, woodlice and crayfish.
38
Class chilopoda ( the centipedes )and the diplopoda (the millipedes)
They both have long bodies with many segments and lots of leg
 Centipedes Millipedes
Have flattened bodies Cylindrical bodies
Have brightly coloured bodies Dull-coloured bodies
Have few or less segments Have more segments
Have one pair of limbs per segment Have two pairs of limbs per segment
Carnivorous (feed on other animals) Herbivorous
Have poisonous claws for paralysing their prey Have claws for biting and chewing plant material
Table 5.3 Differences between centipedes and millipedes
Class Arachnida (the spiders)
They are mainly terrestrial although some are aquatic.
They have two body parts - a cephalothorax and the abdomen - with no antennae.
They have eight legs in four pairs.
They have simple eyes
Spiders spin silken webs. Examples of arachnids include spiders, ticks, scorpions, and mites.
9. Phylum Chordata
The term Chordata is derived from the term notochord
Notochord flexible rod like structure of cartilage running along the dorsal side of the body.
They have the following three features in common:
They have a notochord at some stage of their lifecycle.
They have a hollow nerve cord
They have gill slits during early stages of development that are later replaced by lungs and gills.

Vertebrates
The chordates, the best known of which are the vertebrates (animals with vertebral
column/backbone)

In addition, they also have the following features:

An internal skeleton (endoskeleton) made of bone or cartilage.
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A well-developed nervous system.
Two pairs of limbs.
Kidneys as excretory organs
Phylum Chordata divided five classes

i. Class pisces- fishes

They are aquatic
They have streamlined bodies with scales on their skin.
They use gills for gaseous exchange and have fins for swimming
They are ectothermic - they rely on heat from their environment to regulate their body temperature.
Table 5.5 Differences between bony fish and cartilaginous fish
Bony fish (teleosts) Cartilaginous fish(elesmobranches)
Have bony skeleton Have cartilaginous skeleton
Have round-shaped scales Have scales that are not round shaped
Have opercula (gill covers) covering their gills Have no opercula (gill covers) but have gill slits
Have homocercal tails (even size fins) Have heterocercal tails (one part is larger than the other)
Are usually smaller in size Are usually larger in size
e.g. Tilapia, Nile perch, mackerel and catfish E.g. Sharks, skates and rays.
ii. Class Amphibia
 Spend part of their lives in water and part of it on land.
 They were the first vertebrates to colonise the land. 39
 They have simple sac-like lungs (which are not very efficient) and smooth, moist skin
 Their lifecycle includes metamorphosis, and they need water for successful reproduction as fertilization
is external and the larval form (tadpole) is aquatic.
  Gills are only present in the larval forms & they are ectothermic Example: frogs, toads, newts and
salamanders
Frog Toad
Has a smooth skin Has a rough skin
Has a moist skin Has a dry skin
Has more webbed feet Has less webbed feet
Has a brightly coloured body Has a dull-coloured body
Has a more streamlined body Has a less streamlined body
Has extra-long hind legs Has hind legs that are not extra long
Table 5.6 Differences between a frog and a toad
iii. Class Reptilia
The reptiles are mainly terrestrial animals
They have bony skeleton
They have dry skin with scales and their gas exchange takes place exclusively in the lungs
They have developed internal fertilisation
Some reptiles even keep the eggs within their body and give birth to fully developed young.
They are poikilothermic (ectothermic) & have no external ears
Examples , snakes, crocodiles
Two pair of pentadactyl limbs usually present

iv. Class Aves(birds)

Have skin that bears feather & scales on legs.
Have bony skeleton
Two pairs of pentadactyl limbs, front pair forms wings
They are homoeothermic (endothermic)
Example: domestic fowl, the wattled ibis, white collared pigeon and the Ethiopian eagle owl.
v.Class Mammalia
They are the best known of all animals
Their skin bears hair , the skin consists of glands like sebaceous& sweat
They produce live young which have developed for a time within the body of the
mother in a structure called the uterus
They have bony skeleton & Have external ear
Have two pairs of pentadactyl limbs
They use lungs for gas exchange
A true mammal produces milk for its young in mammary glands
Subdivisions of mammals
Mammals are classified according to the way their young are produced. There are three sub-classes of
mammals:
i. Egg-laying mammals - lay eggs, e.g. duck-billed platypus.
ii. Marsupials - produce immature young, which are nourished by milk in the pouch,
E.g. Kangaroo, koala bear, opossum
iii. Higher mammals - produce fully developed young, which are nourished by milk from the mammary
glands, e.g. cows, elephants, cats, monkeys, and humans.
 There are even flying mammals, as bats have been adapted to fly through the air on their
leathery wings!
UNIT 6
ENVIRONMENT
6.1. Ecosystems
Ecosystem: all the animals and plants that live in an area along with the things that affect them. It is the
home or habitat of the living organisms within it
 Habitats may be on land - when they are known as terrestrial habitats 40
or they may be in water, when they are called aquatic habitats.
  There are two main types of aquatic habitat - the marine habitat, which is the salt water of the seas and
oceans, and the freshwater habitat of lakes, ponds, rivers, and streams
- They are affected by both the abiotic components and the biotic components of the ecosystem
A. Abiotic components
o Abiotic factors are the non-living elements of an ecosystem
o The climate and weather produce several important abiotic components. They include the amount of
sunlight, and the amount of rainfall.
o Temperature is a factor which often affects whether animals and plants can survive in an ecosystem.
o Other abiotic factors include the type of soil and rocks, the drainage of the soil and the pH (acidity).
B. Biotic components
o Are factor of the living organisms within an ecosystem which affect the ability of an organism to survive
o Each organism is the part of another organisms environment thus they interact in various ways: these are:
I. Intraspecific: occur between members of the same species, such as Competition for food,
territory, & finding mate.
II. Interspecific f: occur between members of different species. This include predator-prey relationship
& symbiosis
Predator-prey relationship (predation): in which predator animal like lion, tiger feed on other animal
(prey) like buffalo, rabbit, etc.
Symbiosis: is relationship between two organism of different species in which one or both get
benefited from the relationship: this can classified as:
Commensalism: is the relationship in which one organism is benefited while the other is
neither benefited nor harmed. E.g. The r/ship between big trees& epiphytes
Mutualism: is relationship in which get benefited & it‘s an obligatory relationship
For example: lichen (algae & fungi).
Parasitism: is the relationship in which one organism is benefited (the parasite) & another
organism is harmed (host). e.g. R/ship between human & parasite like tape worm.
Protocooperation: the relation which both organism are benefited but it is not an obligatory
relationship. e.g. the r/ship between teeth cleaning bird & crocodile
6.2 Food relationships
According to their mode of nutrition organism can be classified as: autotrophs and heterotrophs
A. Autotrophs: organism that can synthesize their own food to release energy from the raw material
in their surrounding environment. they can be classified as :
▲ Phototrophs: organisms that feed off light to synthesize their organic food .This group of
organisms are called producers. E.g. green plants, algae,& photosynthetic bacteria.
▲ Chemotrophs: organisms that get energy from the breakdown of inorganic chemical
E.g . Nitrifying bacteria
B. heterotrophs: organisms that rely on eating other organisms. They cannot produce their own
food so they are called Consumer. They can be grouped as:
Herbivores: animals that eat plants only. E.g. cow, buffalo, sheep, etc.
Carnivores: animals that feed on other animals only. e.g. tiger ,lion
Omnivores: animals whose diet includes both plants and animals. e.g., human
Decomposers: organism that break down the remains of animals and plants and return the
mineral nutrients to the soil e.g. bacteria & fungi
Food chains
Food chain: is simple & direct feeding interrelationship which involves transfer of energy & nutrients
from one organism to another.
41
in a food chain energy flow is unidirectional (from producer to consumer)
Each organisms occupies particular tropic level within a food chain
 Trophic levels: levels in a food chain to which an organism belongs.
The main tropic levels are:
i.Producer (first tropic level): are green plants & algae.
All organisms depend directly or indirectly on producer.
The sun is ultimate source of energy for all food chains.
ii. Primary consumers (second trophic level): includes herbivores & omnivores.
iii.Secondary consumers (third tropic level): are carnivores which mostly eat herbivores &omnivores.
iv. Tertiary consumers (fourth tropic level): are carnivores (sometimes called top carnivores) which
mostly eat other carnivores
 Decomposer are found at the of each food chain
 Many aquatic food chains start with the microscopic photosynthetic organisms known
as phytoplankton (plant plankton).
 These tiny organisms are eaten by the equally microscopic zooplankton (animal plankton) and
these two groups of organisms underpin food chains which involve almost every animal in the water,
from tiny shrimps to enormous whales.
Examples food chain
Oak (Leaves) → grasshopper → rodent → leopard
ndary
Producer primary consumer 2 consumer tertiary consumer
Grass → zebra → lion
Phytoplankton → zooplankton →fish →man
Food web
 Food web is network of food chains
 In a food web the interactions between many different food chains can be shown
Example of food web

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Pyramid of Biomass
Biomass: Is a term that describes all the organic material produced by living organisms.
It all comes originally from plants as they photosynthesize at the beginning of all food chains.
 This biomass is then passed on through a food chain or web into the animals which eat the
plants and then on into the animals which eat other animals.
 The total amount of biomass in the living organisms stage of the food chain can be drawn to
scale and shown as a pyramid of biomass
 The biomass supported at each trophic level decreases as it goes from one tropic level to the
next.
 At each tropic level biomass is lost in various forms: heat from respiration, urine, feaces, to 42
provide energy
Pyramid of numbers
 The number of organism decreases it moves from one tropic level to the next.
  In most ecosystems producers contain large number of organisms than consumer,
however sometimes this may not work
For e.g. the breadfruit tree can grow to around 20 m tall, yet it can be attacked by mealybugs. They in
turn are eaten by ladybirds. However, the pyramid of numbers for this food chain doesn‘t look like a
pyramid at all.
Pyramid of energy
 In ecosystem there is always be transfer of energy from one tropic level to the next tropic level
 There is progressively less energy available for organisms further down a food chain.
Energy is cannot be recycled in an ecosystem; it always flows in one directly.

6.3 Recycling in nature

 Living things are constantly removing materials from the environment.
 The recycling of substances provide an important link between the biotic and abiotic component.
 The materials are returned to the environment from the waste products of animals and the dead
bodies of plants and animals.
 Nutrient in organisms are back into the soil by action of group of organisms known as the
decomposer. Decomposer(bacteria & fungi) play a huge role in recycling of nutrients :
Important of decomposers
They are important in various ways to the environment:
Break & digest dead bodies of plants, animals & waste materials or dropping of animals & add them
into the soil. This increases the fertility of the soil which is useful for plants.
Removes unpleasant waste materials from an environment
Used to make compost in garden
Recycling of substances in an ecosystem includes chemical, physical, & biological processes.
i. The nitrogen cycle
▲ Nitrogen is a vital part of the structure of amino acids and proteins, DNA and RNA
▲ It involves the conversion of nitrogen gas by various processes into usable form by plants
▲ Green plants absorb nitrogen in the form of nitrates dissolved in the soil water.
▲ They use these nitrates to make proteins, and then this protein is passed along the food chain.
▲ The atmospheric nitrogen is fixed by microorganisms living in a symbiotic relationship certain plants,
specially legumes, it includes pea, beans and clover - have nodules on their roots which are full of nitrogen-
fixing bacteria
The nitrogen cycle involves the following bacteria
A. Nitrogen fixing bacteria-convert free atmospheric nitrogen into nitrate
Note: lightning has also a role in fixing atmospheric nitrogen
B. Nitrifying bacteria : convert ammonium to nitrite then to nitrate
Ammonium Nitrite
Nitrite Nitrate
C. Putrefying (amonifying) bacteria: they convert protein in the dead bodies & decay of plants into
ammonium compounds.
D. Denitrifying bacteria -are bacteria that convert nitrates into free atmospheric nitrogen
ii. The carbon cycle
Carbon cycle: cycling of carbon compounds between the living and the nonliving world.
 The main molecules of life are based on carbon atoms.
 It mainly involves the conversion of the inorganic molecule carbon dioxide to form organic
molecules which are formed within the tissues of organisms.
 Carbon dioxide is removed from the air by green plants in the process of photosynthesis.
 Then when the plants are eaten by animals the carbon is passed on and becomes part of the
animal bodies
 when animals respire they release carbon dioxide as a waste product into the air 43
 Finally when both plants and animals die, their bodies are broken down by the action of
decomposers.
 Carbon dioxide is also released into the atmosphere in the process of combustion.
  This build-up of carbon dioxide gas in the atmosphere is generally believed to contribute to the
greenhouse effect, also referred to as global warming
 Methane is another greenhouse gas which causes air pollution and the levels of this gas are rising
too.
6.4 Adaptation
 Features organisms develop which make it possible for them to survive in particular habitats.
 Organisms in different climatic condition have different adaptation mechanisms to survive in their
ecosystem.
I. Animals in cold climates
Animals in very cold climates have other adaptation:
 Thick layer of fat under the skin to keep to store more internal heat &a thick fur coat on the outside
 Reduced surface area to volume ratio
 Usually have Very small ears
 camouflage of an Arctic animal in summer would stand out against the snow in winter
 E.g. Arctic fox change the greys and browns of their summer coats for pure white in the winter.
II. Adaptation in dry climates
Many animals which live in hot or dry conditions have other adaptations for cooling down
They are often most active in the early morning and late evening
They often have large, thin ears as well to increase their surface area for losing heat
They don‘t have much fur & relatively little body fat stored under the skin.
III. Some adaptation of plants
Plants take in water through their roots in the soil & lose water all the time through their leaves.
There are small openings called stomata in the leaves of a plant. These open to allow gases in and
out for photosynthesis and respiration.
When it is hot and dry, photosynthesis and respiration take place fast
most plants that live in dry conditions have reduced the surface area of their leaves so they lose less
water e.g. cacti
plants can cope with dry conditions to store water in their tissues
Plants which store water in their fleshy leaves, stems or roots are known as succulent
Animal dispersed plants have seeds which have hocks & spines
IV. Some animal adaptation
Carnivores animals have sharp & pointed canines to tear flesh.
Porcupine has skin surface which is covered with long stiff parts like needle called quills,
which it can raise to protect itself when it is attacked by enemy
6.5 Tree-growing project
Ecosystem our country has been changing dramatically because of deforestation. Now Only 3% of land
is covered with forests.
Trees produce oxygen and remove carbon dioxide from the air. They help to reduce the effects
of air pollution and also reduce global warming.
It hold the soil in place and without them our soil is becoming unstable and blowing away.
it also help absorb water - they prevent soil erosion and help to prevent the formation of great areas of
Desert
Tree planting procedure
To plant a tree successfully:-
I. The soil must be prepared,
II. a big hole must be dug and
III. Water must be put into the hole before the tree is planted.
IV. Once the sapling is in place, the soil must be pressed very firmly around it and
V. Often a stake is used to support the young tree as it starts to grow and get established. 44
VI. The young trees need to be cared.
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Biotechnology is the use of micro-organism to make things that people want

Or the use of living organisms to make what people want, often involve industrial production.
-It helps to make and preserve food and alcoholic drinks.
Example: - - brewing beer
-making wines Traditional application of
-Making bread biotechnology
-making cheese (ayib)
- making yoghurt (irgo)
-Change gene of crop and animals
-produce new medicine Modern application of
-produce new energy sources biotechnology
→Biotechnology is based on microbiology. i.e. the study of micro-organisms and their effects on human.
-Bacteria and fungi are the main micro-organisms used in biotechnology.

1.2. TRADITIONAL TECHNOLOGY USING YEAST.

Yeast: - Is the single cell.

-Has nucleus, cytoplasm, cell membrane, and cell wall.

- 1gram of yeast contains about 25 billion cells. This expresses that how much they are small.
-Yeast can respire aerobically and anaerobically.
-yeast reproduces by asexual budding (split in to two)

Aerobic -which uses oxygen to

break down food
Cellular
respreation
Anaerobic - which break
down food without oxygen

Aerobic respiration of yeast – produce more energy.

Sugar + oxygen → water + carbon dioxide + energy.
Anaerobic respiration of yeast- it is called Fermentation (anaerobic).
Fermentation converts sugar into acid such as lactic acid, alcohol, and co2 using yeast and bacteria, under anaerobic
conditions.
Sugar → ethanol + Carbon dioxide + energy
→ Yeast can respire aerobically in bread making, but must respire anaerobically to make alcoholic drink.
-too much alcohol kills yeast and stops fermentation. 45
- Yeast is used in making – injera, bread, tell, tej …etc.
Food production using bacteria