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In 2013E.C Biology Note for Grade 9

Unit One
Biology and Technology

1.1 Renowned Ethiopian biologists

A. Dr. Aklilu Lemma ( 1935 – 1983E.C )
 He is the pioneer in the development of biological science in Ethiopia.
 He made soup berry from a local plant called Endod (Phytoleccado decandra) which
used to eradicate snails which is the intermediate host of bilharzia worm.
 The soup berry of Dr. Aklilu Lemma is advantageous over other molluscicide
chemicals because it is cheaper and affordable for more affricans to by use it.
B. Dr Tewolde Birhan G/Egziabher (1940E.C -
 He is the ardent lover of nature because he works on most of time on the
conservation of biodiversity (nature) \
 He wons (devoted) to work: -
 The Right livelihood Award( 2000) for his exemplary work to safeguard
biodiversity and the traditional rights of farmer to their genetic resources
 UN top environmental prize champion of the earth (2006)
 He also participated in various biodiversity meeting such as: -
 Convention on biological biodiversity (CBO) and the food and agricultural
association (FAO)
 Chief negotiator on biodiversity for likeminded group (G – 77) countries.
C. Professor Tilahun Yilma 1943 -
 He develop vaccines against trible cattle disease called rinder pest.
 Rinder pest: - is an acute infectious disease of ruminant animals which caused by
morbillivirus.
 He works on the development of HIV/AIDS vaccines
 He award the highest international award in animal science (2001 – 2002) at UC
D. Professor Yalemtsehay Mekonnen
 The first female professor from Addis Ababa university
 She works on the department of biology for the last 30 years.
 She investigates the researches on: -
 The impact of pesticide chemicals on humans

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 The use of plants as a medicine against animal and human disease.

 She served as:- head of Department of biology
 Director of ALIPB
 She award: - Ethiopian science and technology commission
 Ethiopian agricultural research organization
 British council
 Third world academy of science etc.
E. Dr Melaku Worede
 He is a botanist which is plant genetic researcher
 He works in: - how to save genetic diversity of Ethiopian domestic plants
 Preserve traditional crop varieties
 How to get high yield of crop without using commercial (Artificial)
fertilizers.
 He awarded: - Right lively award in 1989
 National Green award foundation.
F. Dr. Gebissa Ejeta
 He develop strain of sorghum which are resistant to drought and produce high crop
yield
 He also develop strain of sorghum which are resistant to parasitic striga weed which
produce phyto toxins harmful to the host crop which constrain productivity of
staples.
 He award: - “National Hero award of Ethiopia”
- “The world food prize (2009)”
Other Ethiopian renowned biologists
 Professor Beyene Petros - Dr. Zeresenay Alemseged
 Professor Sebsebe Demissew - Tsehaynesh Meselle
 Professor Legesse Negash - Dr. Berhane Asfaw etc

1.2 Biological institution in Ethiopia

A. Armauer Hansen Research Institute (AHRI)
 Setup in 1969 and highly dedicated to patients with leprosy
 Since 1996 AHRI has widened its research on TB, HIV, Leis hamaniasis, malaria
B. Aklilu Lemma Institute of Path biology (ALIPB)
 The Department has been named in honor of professor Aklilu Lemma

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 Carries out the research on five major areas: -

o Microbiology research program on infectious disease
o Vector of disease and how to control
o Human parasitic disease
o Endod and other medicinal plants
o Animal health and disease
C. Ethiopian Health and Nutrition Research Institution (EHNRI)
 Carries out research on: -
o Human health and nutrition
o Immunology and viral disease
o HIV/AIDS
o On the battle against TB
o Nutritional state of mothers and babies as well as infectious disease
D. Ethiopian Institute of Agriculture (EIA)
 There are five main research areas: -
o On crop technology
o Managing animals breeding and feeding programme
o Improving soil and water
o Way of rehabilitation, restoring and conserving forests
o Improving mechanized farming system and harvesting
E. Institute of Biodiversity conservation (IBC or BID)
 Works on: - The conservation of plants, animals and micro organisms
- The management way of:-
o Forests
o Aquatic and medicinal plants
o Animal genetic resources
o Biotechnology and safety
o Ecosystem conservation

UNIT TWO
CELL BIOLOGY
2.1 Microscope
 Is one of the basic tools that used by biologists in order to study living thing and very
smaller microorganisms.
 Abilities of microscope
 Resolution: - is the ability to show detail or separate the scattered parts of an
object or specimen.
 Magnification : -is the ability of microscope to increase or enlarge the size of
an object (specimen) to be viewed

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NB: - The resolution power and wave length is university proportional which mean higher
wave length smaller resolving power.
Total magnification power of microscope = Magnification power of eyepiece lens 
magnification power of objective lens.

Types of Microscope
Basically there are two types of microscope
 Electron microscope
 Light microscope Simple
Compound Monocular
Binocular

Light Microscope Electron Microscope

 Uses beam of light - Uses beam of electron
 Has less magnification - has high magnification and resolution power
and resolution power - magnifies up to 2,000,000
 magnifies up to 2,000 times - resolute up to 2,000,000 times than human eye
 resolute up to 500 times - It is very delicate and expensive
than human eye - images are seen a photographic
 It is cheap than electron screen like a TV screen
 Cell of living thing or parts of
them can be seen directly
Advantage of Light microscope
 It is very important to observe living plants and animal cell directly
 Does not require electricity/ can also be used without electricity
 Relatively smaller and not heavy
 It is moveable easily.
Disadvantage of light microscope
 Their resolving power is limited by weave length of light
 Can’t magnifying cells as much as dead tissue
Advantage of electron microscope
 Have high magnification and resolution power
 Show complicated structure inside cell organelles
 It helps to form 3D picture of specimen

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Disadvantage of electron microscope

 All the specimen are examined in a vacuum because air would scatter the electron
beam
 Expensive
 Take up lot of space and separated room
 Rely a constant source of electricity
Preparing sample for microscopes
 Materials must be prepared in deferent ways depending on what types of microscope are
using.
 There are two techniques of preparation of specimen
i. Mounting: - is a technique of preparation of specimen (objects) for study under
a microscope by water.
ii. Staining: - is the process of adding chemicals / dye/ for clear identification
NB: - Light microscope use staining chemicals (colored dyes) to reflect light
E.g: - Iodine Solution - for plant tissues only
 Acetocarmine - for both animal and plant chromosome
 Haematoxylin - for both plant and animal nuclei
 Methyleneblue - for animal cell only
 Electron microscope use heavy metals used to reflect electron’s
e.g : - Lead
- Uranium
Draw and level part of compound microscope picture on your exercise book with their
function

2.2 The Cell

What is cell? It is a building block and small unit of life
 Structural and functional units in all living cells (organisms)
A. Cell Theory
 Introduced by Matthias Schneider (1838) and Theodore in 1838 – 1859)
States that: -
 All living thing (organisms) are composed of one or more cells
 Cells are a rise from previously existing cell through cellular division
 Cell is basic, structural and functional until of life.
 The seven characteristics of life are carries out by cell such as: -

i. Nutrition: - the process of obtain (providing) food

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ii. Respiration: - the process of getting rid of energy from their food
iii. Excretion: - getting rid of waste products produced cell
iv. Growth:- increase in size and mass using chemicals from their food to build new
material.
v. Irritability: - process of sensitivity (responding) to change in their surroundings
vi. Movement: - the process of moving place to place through different locomtary
structure
vii. Reproduction: - The process of producing new off spring form parent cells.
B. Cell structure and Function
 There are basic similarities between all cells (animal and plants)
e.g: - all cells have – nucleus - mitochondria
- Cell membrane - ribosome’s
- Endoplasmic reticulum - cytoplasm
I. Unspecialized Animal Cell
1. Nucleus: - central parts (except plant cell)which controls all the activities of the cell
 Contains instructional genetic material called chromosome
 Bounded by nuclear membrane in eukaryotic cell, but not bounded in
prokaryotic cell
 Consists four main components. There are: -
 Nuclear membrane
 Nucleo plasm
 Nucleolus
 Chromosome
2. Cytoplasm: - Liquid gel (jelly like) in which chemical reactions takes place
 70% is water
 Contains : - organelles like mitochondria, lysosome, ribosome, etc
 Water
 Enzymes
 Salt and gases
 Amino acids
 Vitamin and sugar
 Excretory wastes
3. Cell membrane
 Called plasma membrane, selective permeable or partially selective membrane
 Then covering found in all organisms cells
 Living parts of a cell covered by cell wall in plant cell
 It controls the movement of material in and out of a cell because it is known as
selectively permeable.
 Made up of proteins covered by two fat layer called lipoprotein

4. Mitochondria
 The power house of the cell because it is the site of cellular respiration
 The central space is filled with fluid called matrix.
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 Have two membrane, smooth and cristae

 The inner membrane is called cristae to increase surface area for the activities of
various enzymes to oxidize sugars
 Important to produce energy from glucose in ATP form

C6H12O6 +O2 Enzyme ATP (energy) +CO2 +H2O

5. Endoplasmic Reticulum (ER)

 Connects the cell membrane and nuclear membrane
 Transport materials from nucleus to cytoplasm and vice – versa
 Two type: - Rough (granular) (RER)
- Smooth (a granular)( SER)
i. Rough ER: - has ribosome’s associate with ER
- Site of protein syntheses
ii. Smooth ER: - has no ribosome
- Concerned with the synthesis of lipids and carbohydrates metabolism
- Site of detoxification
6. Ribosomes
 Site of protein synthesis
 Contain RNA and protein synthesizing enzymes
 Connected to rough endoplasmic reticulum
7. Golgi body (Golgi complex)
 Involved with modifying proteins, packaging and collecting cell products in the
form ready for transport.
 Consists of stacks flattened membranous sacs.
NB: - Organelles that found only in animal cell are: -
i. Lysosomes: - produce digestive enzymes called hydrolytic enzyme.
 Called suicide bag
 Not found in red blood cell
ii. Centrioles: - used to produce spindle fiber during cellular division (mitosis and
meiosis)
II. Unspecialized plant cells
Plant cells have unspecialized cell which listed in the animal cell but have unspecialized cell
which found only in plants cell.
1. Cell wall: -
 made from carbohydrate called cellulose
 Provide shape, support and physical protection
 Is not found in animal cell
 It is fully permeable because it passes water and other material through
plasmodesmata.
2. Plastids: - found only in plant cell and have three layer
i. Chloroplasts: - green in color because it is responsible carrying chlorophyll.
 Site of photosynthesis

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 Mainly found in leaves

ii. Chromoplasts: - yellow or orange pigments
 Give color to fruits and flowers
 Are non – photosynthetic
iii. Leucoplasts: - are colorless
 Serve as starch storage area
 Non – photosynthetic
3. Vacuoles: - watery fluid filled cavities (sacs) called cell sap containing
 Sugar
 Mineral ions
 Other chemical dissolved in water
 Enclosed by vacuolar membrane (tonoplast)
 Large in plant but small in animal cell temporally
 Maintain the turgidity of cell
Draw and Level :-
i. Animal cell
ii. Plant cell diagram

Cell Specialization in humans

 Specialized cells are cells adapted to carry out a particular bodily function.
E.g: - Nerve cell, epithelial cell
 Differentiated cells: - are cells special which carry out specific functions
E.g red blood cell
 Undifferentiated cell: - are cells that have not yet assumed their final functional
characteristics
E.g: - embryonic stem cell
A) Epithelial cell
 Cover the internal and external surface of body (organs)
 Protect the tissue underneath from damage or infection
 Allow diffusion transport materials from one area to another
E.g: - microvillus, Alveoli, fallopian tube etc.
B) Reproductive cell
 Involves in the process of reproduction
 Consists egg (Ova) and sperm cell
i. Egg (Ova) cell: - have large nucleus containing half chromosome genetic
material number from women.
 Covered by protective outer coat
 Contain stored food in cytoplasm for the developing embryo
ii. Sperm cell: - have half chromosome number from men
 Have three body parts :-
o Tail
o Head
o Mid piece
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 Tail – have protein and used for swimming during ejaculation

 Head – contain nucleus with genetic materials
- Produce enzyme in the acrosome which used to produce enzyme to
penetrate the protective coat of ovum.
 Mid piece – have mitochondria to provide energy for tail and cell.

C) Nerve cells: - communicate and control system of the body

o Single neurons have the following structure
i. Denotrite: - receive impulse from
neighboring neurons
ii. Axon: - carry impulse long distance
iii. Myelin sheath: - cover the axon and
impulses to travel faster

D) Muscle cells responsible for movement

 Contain two protein actin and myosin
 Contain lots of mitochondria which provide energy for them to contract
II.3 Cell and its environment
 Exchange of material (in and out) across Cell membrane in three ways
o Diffusion
o Osmosis
o Active transport
i. Diffusion
 Is the net movement of particles from an area of high concentration to an area of lower
concentration
 Rate of diffusion can be affected by: -

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 Temperature
 Concentration
 Density of diffusing molecules
 Solubility in diffusing molecules
 Chemical potential gradient
 Distance over diffusion occur
 Size of diffusing molecule
ii. Osmosis
 Is the net movement of water molecule from a higher concentration to a lower
concentration through semi permeable membrane.
 Is the movement of water from dilute (weak solution) to concentrated (strong
solution)
 There are three ways osmosis takes place
A. Isotonic
 Concentration of the solution on both side of a cell is the same
 No movement of water
 The cell becomes as it is
B. Hypertonic
 Outside concentration is higher than inside concentration
 Water move from inside to outside of the cell \
 The cell becomes shrink
C. Hypotonic
 Outside concentration is lower than inside concentration
 Water moves from outside into inside of the cell
 The cell becomes swell up.
If animal cell: -
 Kept in hypertonic solution the cell: -
 Loss water and shrink
 Cell crenate occur
 Kept in hypotonic solution the cell: -
 Gain excess water
 The cell swell and finally bursts
 Homeostasis occur
If a plant cell: -
 Kept in a hypertonic solution the cell: -
 Loss water and the cell shrink (flaccid)
 Plasmolysis occur
 Kept in a hypotonic solution the cell: -
 Gain excess water
 The cell swell up but not bursts due to cell wall
 Turgor pressure occur

Active Transports

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 The transport (movement) of materials from lower concentration to an area of higher

concentration.
 Require energy
Importance: - For absorption of minerals by root hair cell from soil
o Rapid and selective absorption of nutrient by cell
o Maintaining a membrane potential
o Maintain water and ionic balance.

UNIT THREE
HUMAN BIOLOGY AND HEALTH
3.1 Food and Nutrition
The human diet
 Food: - is the source of nutrient and energy for the body it is important:-
 To provide energy for our cell to carry out all functions of life.
 To provide materials for new biological activities like growth, repair and
replacement.
 To provide maintenance of body health against disease.
 Nutrients: - are substance (chemical) in food needed to live and grow
 Can be classified into two groups
i. Macronutrients: - are a group of nutrients that are needed by the body in a large
amounts.
E.g: - carbohydrates, lipid and protein
ii. Micronutrients: - are a group of nutrients that are needed by the body in a small
amount
E.g: - vitamin, minerals
Generally there are six nutrients in food
 Carbohydrate vitamin
 Lipid mineral
 Protein water
A. Carbohydrate
 Are composed of carbon, hydrogen and oxygen elements provide energy
 Store in the forms of starch and glycogen
 Classified into three classes based on complexity of unit

i. Monosaccride (Simple Sugar): - have one sugar unit

 Have a general formula (CH2O)n where n  3, 3, 7
 Are sweet, soluble in water and diffuse quickly.
E.g:- Glucose, Galactose and Fructose, with a general same formula
C6H12O6

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ii. Disacchride (Double Sugar)

 Compsed of two sugar unit molecule
 Formed by condensation reaction between two monosaccharide
 Have a general formula C12H22O11
 Are colorless, more soluble than monosaccharide
C6H12O6 + C6H12O6 Condensation C12H22O11+H2O
Hydrolysi
E.g – Sucrose = glucose + fructose
Lactose = galactose +glucose
Maltose = Glucose + glucose

iii. Polysaccharide (Complex sugar)

 Compsed of combinationof several hundered simple sugar (long chain)
 Are in soluble in water
 General formula Cn(H2O) n – 1 when n is between 200 – 500
Example: -
 Starch (found in plant)
 Glycogen (found in animal)
 Cellulose (found in plant)
 Chitin (found in insect skeleton)
B. Proteins
 Composed of carbon, hydrogen, oxygen and nitrogen sometimes sulfur and
phosphorus.
 Made up of smallest units called amino acids
 Used for the growth and repair of tissue and also source of energy and formation
of enzymes
 Should make up 20% of a normal diet.
 Some proteins are in soluble in water and are very tough
E.g In tendons and matrix of bone
In silk of spider
In nail, feather, horn etc
 Some proteins are soluble in water which forms antibodies, Enzymes and
hormones.
 Lack of protein causes a disease called kwashiorkor.
C. Lipids (fat and oils)
 Are composed of carbon, nitrogen and oxygen but less oxygen than carbohydrates
 Contain twice as much energy than carbohydrates and proteins
 Made up of simple compounds called fatty acid and glycerol
 Are not soluble in water, but soluble in organic solvent
 Fatty acid can be saturated :-
o Saturated
o Unsaturated
i. Saturated fatty acid : - are solid at room temperature

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 Each carbon atom is joined by single covallent bond

 Are riched in energy E.g stearic acid
ii. Unsaturated fatty acid : - liquid at room temperature
 Each carbon atom is joined by double covalent
 Less chelostrol
E.g : - linoleic acid
Generally lipids have the following importance
 Used as chemical messenger as a hormone in cell membrane
 Structural component of cell membrane
 Insulation layers under skin cell
 Regulate body temperature
4. Minerals
 Are needed in a small amount
 Are important for proper function body in the regulation of metabolic activities
 Are inorganic
Mineral Sources Functions Deficiency
disease
Calcium Milk cheese, fish cereals, Strong bones and teeth Weakness of bone
vegetables and teeth
Iron Liver, egg yolk, meat, Hemoglobin synthesis Anemia
kidney, vegetable
Iodine Table salt, seafood, onion Thyroxin hormone Goiter
synthesis
Phosphorus Milk, dairy product, egg Strong bone and teeth Rickets
cereals
Chlorine Cabbage, table salt HCl formation in Shortage of HCl
stomach
Water balance
5. Vitamins
 Are needed in small amount
 They do not provide energy
 Each enzyme has specific functions
 Some are soluble in fat
E.g Vitamin A, D, E and K
 Some are water soluble
E.g: - Vitamin C and vitamin B groups
Vitamins Sources Function Deficiency disease
Vitamin A (retinol) Carrots, eggs liver,  Skin health  Night blindness
egg yolk  Good vision  Dry skin and poor
growth
Vitamin B1 thiamine Cereals milk, liver,  Normal growth  Beri beri
bean meat  Normal function of  Loss of appetite
heart, muscle and  Disease of heart
nervous system.  Muscle and NS
Vitamin B2 Vegetables, liver milk,  Skin health  Slow growth
Riboflavin meat, pea  Prevent sensitivity  Eye disease
 Sour mouth and tongue
Vitamin B3 Niacin Milk, meat, egg liver,  Prevent pellagra  Pellagra
vegetables  Prevent appetite loss  Loss of energy digestive
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and N system disorder

Vitamin C (Ascorbic Lemon, green paper  Gum health Scurvy
acid) orange, vegetable  Help to heal wound
Vitamin D Fish liver oil, milk,  Calcium and Rickets
(calaferol) egg, sunlight phosphorus
absorption
 Bone formation
Vitamin E Vegetables, milk Fertility in human Sterility
(Tecepherol) butter, cereal
Vitamin K Liver vegetables egg, Blood clouting Failure of blood to clot
(Phyloquinone) cereals

6. Water
 In inorganic substance that is vital for life
 Is a vital solvent
 Is involved in the transport of substances around the body
e.g: - food, hormone, waste product etc
 Is involved in the removal of waste products from the body
e.g: - urine and sweat
 Is a reactant in many important reaction in the body
e.g: - hydrolysis reaction
 Is needed for the osmotic stability of the body.

Balanced diet
 Is a diet which contains sufficient number of KIS and proper amount of all nutrients
 Source of balanced diet and divided into four groups: -
 Group A Milk and cheese
 Group B Fruits and Vegetable
 Group C meat, pulses and legume
 Group D cereals and bread
 Over nutrition : - taking of too much or great food
 Malnutrition: - faulty nutrition due to in adequate or unbalanced intake of nutrients
 Under nutrition: - taking of too little or small food insufficient food

3.2 Digestive system

 Digestion : - is the process which large, complex and insoluble food particles are
changed into smaller, simple and soluble
 There are two reasons of the need for digestion
 Insoluble foods can’t pass through cell membrane into cells
 Most of foods are chemically differ from the substances that makeup body
tissue.
 There are two types of digestion
i. Physical (mechanical) digestion
 Involves breaking down of food (large particle) into smaller particle
 Takes place in mouth

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ii. Chemical digestion

 Involves converting complex and insoluble food particles into simple and
soluble form
 Use hydrolysis rxn and mediated by enzymes
 Starts in mouth and end in different cells.
Enzymes
 Are proteins which is speed up chemical/ biological rxns
 Are called biological catalysts
 Some are works inside of the cell called intera cellular enzyme
E.g: - Respiratory enzyme
 Some are works outside of the cell called extra cellular enzyme
E.g: - Digestive enzyme
 Are very specific which mean one enzyme catalyze one reaction
 Are sensitive to temperature and PH
 Usually but not all ends in – ase
E.g: - amylase
Lipase
Maltase etc
The working of gut
 Gut is a hallow tubular structure which extends from mouth tonus which include the
following pathway
 Mouth esophagus (gullet) Stomach small intestine large intestine Anus.
 In the gut four process occur: - Ingestion
o Digestion
o Absorption
o Egestion/ defecation

Digestion in mouth
 Ingestion and the process of mastication occur.
 Both physical and chemical digestion starts
 Physical digestion is carried out by the grinding and chewing action of teeth and tongue.
Teeth” -
 The hardest parts which use to break down food
There are four type: -
i. Incisor – used to cut the hard lump of food
ii. Canines: - long and pointed used for training and holding food
iii. Premolars
iv. Molars used for grinding and crushing food

Structure of Teeth
 Root:- embedded in a socket in the Jaw bone
 Neck: - an arrow region between root and crown

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 Crown: - exposed portion of teeth which covered by hardest part called enamel.
Layer of teeth
 Enamel: - covers neck and crown of teeth
 It’s hardest structure
 Dentine: - living parts of teeth which consists nerve
 Pulp cavity: - living part of teeth which consists nerve cell, blood vessel
 I is sensitive to heat, pain, etc
NB: - The food which digestion is swallowed and reached into stomach through esophagus

Digestion in stomach
Stomach: - It is the “J” shaped organ used to store and digest food
 Produce protein digestive enzyme called protease
 Produce concentrated solution called HCl
 Protease enzyme consists two types
 Pepsin: - converts protein into peptone (poly peptides)
 Renin: - converts milk (cascinogen) into cogulated milk protein (casein)
 HCl solution: - kill bacteria enter with food
 Indirectly break down protein because pepsin works best in acid.
Digestion small intestine
The thick, grey, soup like mixture of partially digested food called chime, is s quizzed out of
stomach into small intestine through pyloric (spincter).
 Small intestine: - site of both digestion and absorption and assimilation.
- Is the longest canal and have three major parts
i. Duodenum: - it is the upper part
o Receive secretion bile from liver and pancreatic juice from pancreas.
A. Bile: - produced by liver and stored in gallbladder
 Is not enzyme but contain bile salts
 Used for emulsify lipids (fat)
 Used for neutralized the acid by sodium carbonate
B. Pancreatic Juice:- Produced by pancreases
 Consists of – amylase
 Lipase
 Trypsin
Starch amylase Maltose
Peptones Trypsin peptides
Fat droplet lipase fatty acid + glycerol
Fat Bile fat droplet

ii. Jejunum : - it is the short intermediate region

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iii. Ileum : - it is the lower part of small intestine

o Both digestion and absorption takes place
o All digestive processes are completed and the soluble products are
absorbed in to blood stream by villi
o Produce intestinal juice which consist: - erepsin, lipase, maltase, surcease
and lactase
Peptides Erepsin (peptidase) Amino acids
Fats Lipase Fatty acid + Glycerol
Maltose Maltase Glucose + Glucose
Sucrose Sucrose Glucose + Fructose
Lactose Lactase Glucose + Galactose

Large intestine
 Undigested food (cellulose), bile pigments, dead cells and mucus is left in the small
intestine and moved into large intestine
 Water is absorbed back into blood stream by diffusion
 Contains: - appendix, colon, rectum and anus
 Colon – used for water absorption
 Rectum – used for temporary storage of feces
 Anus: - used for defecation (egestion)

Issue of digestive health

 The process of digestion may be affected by different ways
 Can be affected: -
 Constipation
 Diarrhea
 Food hygiene
 Stomach and intestinal ulcer

Draw and level the diagram of human digestive system

3.3 The Respiratory system

Respiration is the process which includes gas exchange and burning of food in cells
 In single cell it is direct respiration
 In multi cellular it is indirect respiration
There are two stage of indirect respiration
i. External respiration exchange of gas between blood and environment
o Takes palce in lungs and gills
ii. Internal respiration: - exchange of gas between blood and cell of the body

Breathing:- the processes of inhalation and exhalation consists nasal cavity, pharynx,
trachea, bronchi, bronchioles and alveoli with in the lungs.

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A) Nasal cavity: - contain epithelial cell with mucus and hair used to trap dust particle
and moist hot air (mucus)
B) Pharynx (throat): - common passage of air and food
C) Epiglottis: - is a flap of cartilage present on glottis which used to prevent the entrance
of food into trachea.
D) Trachea (Wind pipe): - it connects the lung to larynx
- Divided into left and right bronchi
E) Bronchi: - enters into left and right lung
- Divided into bronchioles
F) Bronchitis: - a networking of branching tubes in lungs
- Carry air into and from alveoli
G) Alveoli: - are air sacs at the end of bronchioles
- Site of gas exchanges between blood capillaries and air

Inhalation ( Inspiration) Exhalation (expiration)

 Taking air into lungs - giving out air from lungs
 Ribcage moves upward and out - ribcage moves downward and in
 Diaphragm contracts and flattens - Diaphragm relaxes and move up
wards down wards dome shaped
 Volume of thorax increase - volume of thorax decrease
 Pressure of thorax decrease - pressure of thorax increase
 Less water vapor - high water vapor
 Less heat - high (more) heat
 Lung become inflated and big in size - lung become deflated and small in size
 78% of Nitrogen - 78% of nitrogen
 21% of oxygen - 16% of Oxygen
 0.04% of carbon dioxide - 4% of carbon dioxide

Factors affect breathing rate

 The average breathing rate for a normal adult human is 12/14 breaths per minute
 Rate of breathing: - is the total number of breath per minutes
 Depth of breathing: - the amount of air per breath depend on: -
 Tidal volume – the amount of air breathe in only.
 Vital capacity – maximum amount of air that can be taken into the lungs

 The main factors that affect breathing rate is: -

 Exercise
 Anxiety
 Drugs
 Environmental factors
 Altitude
 Weight
 Smoking
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Draw and level diagram of respirator (breathing) organ

3.4 Cellular respiration

Respiration is the process in which energy is released from food
Energy in the form of ATP
Can be – aerobic respiration
o Anaerobic respiration
C6H12O6 + O2 2C02 + H20 +ATP (energy)
Takes place in the mitochondria
Aerobic respiration Anaerobic respiration
 Use oxygen - doesn’t use oxygen
 Produce high amount of energy - produce less amount of energy 2 ATP
36/38 ATPs from glucose from glucose
 Occurs in the mitochondria - occurs in the cytoplasm
- In plants glucose is converted into ethyl
alcohol and carbon dioxide
- In animal glucose is converted pyruvic acid
into lactic acid
ATP (Adenosine Triphosphate)
 It is the immediate source of energy
 Is composed of adenosine and three phosphate group
 When ATP (three phosphate bond) break and large amount of energy is released
Energy produced
ADP + Pi ATP
Energy required
 When energy is needed, ATP is broken down into ADP and P
ATP +H2O AOP + pi + Energy
 During respiration ATP is made from ADP and P (phosphate)
ADP + pi +Energy ATP + H2O
Importance of ATP
 For building up of molecules (Anabolism) and break down of large molecule
(catabolism)
 For muscular contraction
 For maintenance of body temperature
 Provide energy for active transport of some materials across cell membrane.
NB: - chemical equation of cellular respiration
 Anaerobic respiration in animal
C6H12O6 Enzyme 2C3H6O4 + 4ATP, but net join 2ATP (lactic acid)
2ATP
(lactic acid)
 Anaerobic respiration in plant and yeasts
C6H12O6 Enzyme 2C2H5OH + 2CO2 + ATP, but net is 2ATP
2ATP

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2ATP
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(ethanol)
 Aerobic respiration
C6H12O6 + O2 6CO2 + CH2O + 36/38 ATP

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