biology spm chapter 6 form 4

CHAPTER 6CHAPTER 6

NUTRITIONNUTRITION

What is Nutrition?What is Nutrition?

The entire process by which organism obtain energy from food for growth, maintenance and repair of damaged tissues

Nutrient – the substances that are required for the nourishment of an organism

6.1 Type of Nutrition6.1 Type of Nutrition

Two main types:1. Autotrophic2. Heterotrophic

1. Autotrophic 1. Autotrophic

A process in which organisms synthesise organic substances from inorganic substances

Autotroph = Auto – self, trophos – feed (organism which can make their own food)

The source of energy for synthesising food can be either light energy or chemical energy.

The synthesis of food using light energy – photosynthesis (photo – light)

Photoautotroph – organisms which produce organic molecules from carbon dioxide and water using sunlight as a source of energy

Example: green plants

The synthesis of food using chemical energy – chemosynthesis (chemo – chemical)

Chemoautotroph – organisms which synthesise organic compound by oxidising inorganic compound (hydrogen sulphide and ammonia)

Example: certain bacteria (Nitrosomonas sp. and Nitrobacter sp.)

2. Heterotrophic2. Heterotrophic

A type of nutrition in which organism obtain energy through the intake and digestion of organic substances.

Heterotroph =Hetero – other, trophos – feed (organism that cannot synthesis their own nutrients but obtain the nutrients from other organisms)

They may practice a) Holozioc nutrition, b) Saprophytism c) Parasitism

- holo –like, zoon – animal- The organism feeds by ingesting

solid organic matter which is subsequently digested and absorbed into their bodies

- Examples: humans, herbivores, carnivores and some carnivorous pitcher plants and Venus fly-traps

a) Holozoic nutritiona) Holozoic nutrition

- The organism called saprophytes- Feed on dead and decaying

organic matter- Digest their food externally

before absorbing the nutrients into their bodies

- Examples: bacteria, fungi

b) Saprophytismb) Saprophytism

- The organism called parasite- Obtain nutrient from living on

(ectoparasites) or in (endoparasites) the body of another living organism (host)

- They absorbs readily digested food from its host

- Examples: fleas (ectoparasites), lice, worms (endoparasites), Rafflesia plant

c) Parasitismc) Parasitism

Test YourselfTest Yourself

1. Differentiate between autotrophic and heterotrophic nutrition.

A: Autotrophic nutrition – A process in which organisms synthesise organic substances from inorganic substances Heterotrophic nutrition - A type of nutrition in which organism obtain energy through the intake and digestion of organic substances.

1. Name two types of autotrophic nutrition.

A: Photosynthesis and chemosynthesis


1. Name three types of heterotrophic nutrition.

A: Holozoic nutrition, saprophytism and parasitism


1. Name the nutritional habits of the following organisms;a) Pitcher plants

A: holozoic nutritionb) Green algae

A: photosynthesisd) Tapeworm

A: parasitism


DietDietfats-sweets group

protein-rich group

dairy products group

fruits group

vegetables group

grain products group

Diet

Food Food GroupGroup Foods in the GroupFoods in the Group NutrientsNutrients

Grain Grain productsproducts

Products made with whole grains or enriched flour.

Mostly carbohydrates and fibres, Vitamin B, iron and protein.

Fruits and Fruits and vegetablesvegetables

Dark green vegetables (broccoli, spinach) and deep yellow vegetables

(carrots).

Most carbohydrates and fibre. Various vitamins and minerals

Protein-rich Protein-rich foodfood

Poultry, eggs, fish, red meat, organ meat such as

kidneys and liver. Legumes, nuts and seeds.

Rich in proteins, Vitamin B and minerals such as magnesium and zinc.

Dairy Dairy productsproducts

Milk and milk products such as yoghurt and cheese.

Protein, Vitamins A, B and B2. Main source of calcium.

Fats-sweets Fats-sweets foodfood

Candy, pastries, salad dressing, coffee and

cooking oil.

Supplies fats and sugar. Low in nutrient value.

A balanced diet is a diet which supplies all the essential nutrients in the correct proportions.

A balanced diet must contain enough: Protein to provide all the essential amino acids for

growth and repair for the body Energy-food to meet the energy requirements of

the individual Minerals and vitamins to maintain good health Roughage or dietary fibre to stimulate peristalsis Water to aid the chemical reactions in the body

DietBalanced Diet

Basal metabolic rate and physical activity determine energy needs.

Basal metabolic rate varies with sex, age and state of health of a person.

Diet

1.climate ~living in colder,less humid countries would result in a tendency to actually lose more energy to a person’s surrounding.~this is due to the body needing more energy to regulate its body temperature.~those living in hot,wet areas do not use as much energy to maintain their body temperature.~people living in cold temperature regions would actually have a much higher basal metabolic rate than people living in the tropics.

2.body size ~the difference in body size also contributes to a person’s basal metabolism.~it is estimated that people with a larger build would have a higher basal metabolic rate than another person with a smaller build.

3.age ~growing children usually have higher basal metabolism rates than older people simply because of the fact they are growing.~for growth to take place,increased energy is also needed.~adults tend to have a decresing basal metabolic rate throughout their lives.

Factors affecting the daily energy requirement of the Human body

4.gender ~men normally have higher heat production than woman of the same size and age,because men usually have less fatty tissue in their body.~fat healps to conserve heat,and thus,men with less fat would lose heat a a quicker rate than women.~the result in men having a higher basal metabolic rate than women.

5.health ~the function of the thyroid galand is to control the metabolic rate by secreting a hormone known as thyroxin.~an underactive thyroid gland would result in insufficient number of the hormone being created,thereby causing a lower metabolic rate in the person.~an overactive thyroid,however,may produced too many of these hormones,thereby speeding up the metabolic rate.

6.occupation ~a person who is very active and does heavy labour is only moderately active.

Energy value in food Energy value in food samplessamples

carbohydrates , fats and protein are our main supplier of energy.

the same amount of these foods store different amount of energy.

the amount of stored energy in food is found by burning a known mass of the food to heat a certain amount of water in a food calorimeter.

the amount of heat released from the burning of a fixed mass of food is equal to the amount of stored energy in the food.

this is known as its energy value.

MalnutritionMalnutrition•Kwashiorkor

•Marasmus•Cardiovascular diseases

•Rickets

KWASHIORKORKWASHIORKORDo you know what Kwashiorkor

is???Kwashiorkor is a form of malnutrition caused by inadequate protein intake in the presence of fair to good energy (total calories) intake.

KWASHIORKORKWASHIORKORWhat are the symptoms?

•Failure to gain weight and failure of linear growth •Irritability •Lethargy or apathy •Decreased muscle mass •Swelling (edema) •Large belly that stick out (protrudes) •Diarrhea •Dermatitis •Hair changes -- hair colour may change, often lightening or becoming reddish, thin, or brittle •increased and more severe infections due to damaged immune system •Shock (late stage) •Coma (late stage)

MarasmusMarasmusMarasmus is…

a form of severe protein-energy malnutrition characterised by energy deficiency

A child with marasmus looks emaciated and the body weight may reduce to less than 80% of the normal weight for that height.

Marasmus occurrence increases prior to age 1 whereas Kwashiorkor occurrence increases after 18 months.

Symptoms??Symptoms?? dry skin, loose skin folds hanging

over the glutei, axillae, etc Drastic loss of adipose tissue

from normal areas of fat deposits like buttocks and thighs

pigmented and depigmented hair flaky paint appearance of skin

due to peeling.

Cardiovascular DiseasesCardiovascular Diseases

What Are They??

A collection of diseases and conditions affecting :

•The heart (cardio)

•Blood vessels (vascular) – arteries, veins, and capillaries

Cardiovascular DiseasesCardiovascular Diseases

Coronary Artery Disease – a disease of the arteries that supply the heart muscles with blood

Heart attack – a sudden heart failure

Stroke – the sudden death of brain cells when blood supply to the blood cells is cut off.

High blood pressure – the excessive force of blood pumping through the blood vessels.

RicketsRicketsApa itu Rickets (What is Rickets)?

Rickets is a softening of the bones in children potentially leading to fractures and deformity. Rickets is among the most frequent childhood diseases in many developing countries. The predominant cause is a vitamin D deficiency, but lack of adequate calcium in the diet may also lead to rickets.

Symptoms ofSymptoms of RicketsRickets Bone pain or tenderness dental problems muscle weakness (

rickety myopathy or "floppy baby syndrome")

increased tendency for fractures (easily broken bones),

Skeletal deformity Growth disturbance Hypocalcaemia (low level of

calcium in the blood), and Tetany (uncontrolled muscle

spasms all over the body). Craniotabes (soft skull)

http://en.wikipedia.org/wiki/Tooth

http://en.wikipedia.org/wiki/Muscle

http://en.wikipedia.org/w/index.php?title=Rickety_myopathy&action=edit

http://en.wikipedia.org/wiki/Fracture

http://en.wikipedia.org/wiki/Hypocalcaemia

http://en.wikipedia.org/wiki/Tetany

http://en.wikipedia.org/wiki/Craniotabes

The Digestiv

e System

The Digestive The Digestive SystemSystem

Which parts of the Which parts of the body are involved body are involved

in digestion?in digestion?

• Consists of the alimentary canal and the glands and organs associated with it.

• The alimentary canal is like a tube that extends from the mouth to the anus.

• Most of its length is coiled in the abdominal cavity.




salivary gland

stomach

pancreaspyloric sphincter

descending colon

rectumanus

mouthteeth

oesophagus

liver

Gall bladder

duodenum

ileumascending colon

caecumappendix

pharynx

The Digestive System - The Digestive System - MouthMouth

Food enters the body through the mouth.

The mouth leads to the buccal cavity.

The Digestive System - The Digestive System - MouthMouth

What do you find in the mouth?:

Teeth: chewing action (mastication) breaks down large pieces of food into smaller pieces. This increases surface area to volume ratio of the food for enzyme action.

Salivary glands: secrete saliva into the mouth via ducts.

Tongue: helps to mix food with saliva. Taste buds help one to identify and select suitable foods.

salivary gland

mouth

teeth

Process of nutrition??

The Digestive System - The Digestive System - PharynxPharynx

Connects the buccal cavity to the oesophagus and larynx (voice box).

Leads to the trachea.

Both food and air must pass through the pharynx then they enter the body.

Air will pass to the trachea, while food will go into the oesophagus.

trachea (windpipe)

glottis

pharynx

oesophagus

larynx (voice-box)

air

trachea (windpipe)

glottis

pharynx

oesophagus

larynx (voice-box)

air

The Digestive System - The Digestive System - PharynxPharynx

The epiglottis is above the larynx, and it prevents food from going the wrong way.

During swallowing, the larynx moves up and the epiglottis moves downwards so that the epiglottis covers the larynx.

If food or water enters the trachea, it induces coughing to force the food/water particles out and prevent choking.

pharynx

trachea (windpipe)

oesophagusglottis

epiglottis

food particles

larynx (voice-box)

pharynx

trachea (windpipe)

oesophagusglottis

epiglottis

food particles

larynx (voice-box)

The Digestive System - The Digestive System - OesophagusOesophagus

Also known as the gullet.

A narrow, muscular tube.

Passes through the thorax (chest) and the diaphragm to join the stomach.


Made up of 2 layers of muscles, present from the oesophagus to the rectum: Longitudinal muscles

(outer layer) Circular muscles

(inner layer) These muscles are

antagonistic muscles – when one contracts, the other relaxes

circular muscles

Part of the gut walllongitudinal muscles


The muscles cause peristalsis – rhythmic, wave-like contractions of the gut walls.

It helps to move food along the gut while mixing the food with digestive juices.

circular muscles

Part of the gut walllongitudinal muscles




mouthteeth

oesophagus

salivary gland

food mass

circular muscleslongitudinalmuscles


PERISTALSIS When circular muscles contract, longitudinal

muscles relax. The gut wall constricts (becomes narrower and longer). Food is squeezed or pushed forward.

When longitudinal muscles contract, circular muscles relax. The gut wall dilates (becomes wider and shorter). This widens the lumen for food to enter.

wall constricts to push food forward

wall dilates to allow food to

enter


PERISTALSIS When circular muscles contract, longitudinal

muscles relax. The gut wall constricts (becomes narrower and longer). Food is squeezed or pushed forward.

When longitudinal muscles contract, circular muscles relax. The gut wall dilates (becomes wider and shorter). This widens the lumen for food to enter.


The Digestive System - The Digestive System - StomachStomach

The stomach is a distensible (muscular) bag.

The muscles of the stomach wall are thick and well-developed.

When fully stretched, it sends signals to the brain to indicate that it is full.


The stomach wall has many pits which lead to gastric glands.

They secrete gastric juices into the stomach.What is

one enzyme found in gastric juice? pits


The stomach stores food for a few hours. It digests food to become chyme.

Food stays in the stomach because of the pyloric sphincter – a ring of circular muscle located between the stomach and duodenum. Contracts: stomach exit

closes Relaxes: stomach exit

opens, food leaves the stomach.

Where else can we find

circular muscles?


The Digestive System – Small The Digestive System – Small IntestineIntestine

Consists of 3 parts:Duodenum Jejunum Ileum

progressively more coiled

The Digestive System – Small The Digestive System – Small IntestineIntestine

Wall of small intestine has 2 functions:Contains glands

which secrete intestinal juice. It contains digestive enzymes.

Wall is adapted to absorb digested food products and water.Process of nutrition??

The Digestive System – Large The Digestive System – Large IntestineIntestine

The large intestine is about 1.5 m longShorter and wider

than the small intestine

Consists of 2 parts:ColonRectum

large intestine

small intestine

rectum

colon


Only undigested food enters the colon.

It absorbs water and mineral salts from the food.

No digestion occurs in the colon. colon


The rectum temporarily stores faeces.

When it contracts, faeces is expelled through the anus.

rectum


Between the small and large intestines lie the caecum and appendix.

The caecum has no function in humans.

The appendix contains bacteria that are useful to the body.

caecum

appendixProcess of nutrition??







salivary gland

stomach

pancreaspyloric sphincter

descending colon

rectumanus

mouthteeth

oesophagus

liver

Gall bladder

duodenum

ileumascending colon

caecumappendix

pharynx

The Digestive System - The Digestive System - LiverLiver

The largest internal organ in the body

There are 3 important blood vessels attached to the liver: Hepatic vein Hepatic artery Hepatic portal vein

liver

gall bladder bile duct


It is also the largest gland in the body. Secretes bile into the

duodenum Properties of bile:

Alkaline Greenish-yellow Contains bile salts and

bile pigments Produced in the liver,

stored in the gall bladder

Why alkaline?


Functions of bile: Neutralize acid in

chyme Activate intestinal

enzymes Speed up fat digestion Gives faeces its colour

When the gall bladder contracts, bile is secreted into the duodenum via the bile duct.

liver

gall bladder bile duct


The Digestive System - The Digestive System - PancreasPancreas

Connected to the duodenum via the pancreatic duct

Secretes pancreatic juice which contains digestive enzymes.

Also secretes hormones which control blood glucose level.


Definition of Definition of DigestionDigestion

Digestion is the process by which the body breaks down carbohydrates, fats and proteins into simpler substances

that cells can absorb and use.

What is What is Digestion?Digestion?

Physical digestionThe mechanical break up of

food into small particles.

Chemical digestion The breaking down of large

molecules in food into small, soluble molecules which can

be absorbed.

Chemical digestion involves hydrolysis catalyzed by digestive enzymes.

Physical Physical DigestionDigestion


• Physical digestion breaks down food into smaller particles.

• Purpose: to increase surface area to volume ratio of the food to aid enzyme action.

• Food substances are not chemically changed during physical digestion.

• Where does physical digestion occur?– In the mouth– Along the alimentary canal– Physical digestion of fats in the small intestine

chewing / masticationperistalsis

emulsification

Physical Physical DigestionDigestion


EMULSIFICATION• Fats do not dissolve in water

– they tend to clump together.

• This reduces the surface area for enzymes to work, slowing down fat digestion.

• Bile molecules place themselves in between the fat and water – half the molecule is hydrophilic, half is hydrophobic.

• This prevents the fat from clumping together.

• Surface area of fat molecules is increased, speeding up enzyme action.

Picture taken from http://www.colorado.edu/eeb/web_resources/cartoons/bile.html

• Breaking down of large molecules in food (starch, protein, fats) into small soluble molecules which can be absorbed.

• Hydrolytic reactions – catalysed by ENZYMES

• Three groups of enzymes:

• Chemical digestion occurs mainly in 3 parts of the alimentary canal:– Mouth, stomach, small intestine

Carbohydrases ProteasesLipases


Chemical Chemical DigestionDigestion



In the mouth...• Food in the mouth stimulates the salivary

glands to secrete saliva.• Saliva is mixed with food. Mucin in saliva

softens the food.• Salivary amylase is found in saliva:

– Digests to • The optimum pH of salivary amylase is pH 7.

– The pH of saliva is neutral. • The tongue rolls the food into small, slippery,

round masses called boli (singular: bolus).• The boli are swallowed and passed down into

the oesophagus.

starch maltose



In the stomach... The presence of food in the stomach

stimulates the gastric glands to secrete gastric juice into the stomach.

Gastric juice contains 3 substances:– Hydrochloric acid– Pepsinogen– Prorennin



In the stomach... Action of Pepsin Pepsinogen is activated to pepsin by

hydrochloric acid. Pepsin then digests protein to polypeptides.

pepsinogen

pepsin

hydrochloric acid

proteins

polypeptides

pepsin



In the stomach... Action of Rennin Prorennin is activated to rennin by

hydrochloric acid. Rennin curdles milk proteins by converting

soluble protein caseinogen into insoluble casein.

– Soluble caseinogen would pass through the stomach as easily as water and not be digested.

– Insoluble casein can remain in the stomach to be digested.

prorennin

rennin

hydrochloric acid

caseinogen

casein

rennin

casein polypeptides

pepsin



In the stomach... Purpose of Hydrochloric Acid

Stops the activity of salivary amylase by it

Activates pepsinogen and prorennin to form and respectively

Provides acidic medium for the action of pepsin and rennin

Kills harmful microorganisms in food

denaturing

pepsinrennin



In the small intestine... When chyme enters the small intestine, it

stimulates 3 glands:– Intestinal glands secrete intestinal juice,

which contains enzymes sucrase, maltase, intestinal lipase, lactase, enterokinase, and erepsin.

– Pancreas secretes pancreatic juice, which contains pancreatic amylase, pancreatic lipase, and trypsinogen.

– Gall bladder releases bile. It does not contain enzyme

SMILEE!

ALT



In the small intestine...

All 3 fluids are alkaline:– Neutralize acidic chyme– Provide suitable pH for the action of

pancreatic and intestinal enzymes



In the small intestine... Carbohydrate digestion

starch

maltose

pancreatic amylase

lactose glucose + galactose

sucrose

glucose + fructose

glucose

maltase

lactase

sucrase



In the small intestine... Protein digestion

trypsinogen

trypsin

enterokinase

proteins polypeptides

trypsin

polypeptides

amino acids

erepsin



In the small intestine... Fat digestion

fats

fatty acids + glycerol

lipase

Recall: What process

speeds up fat digestion in

the small intestine?

Digestive Digestive EnzymesEnzymes


starch

maltose

pancreatic amylase

lactose glucose + galactose

sucrose

glucose + fructose

glucose

maltase

lactase

sucrase

Carbohydrate digestion

starch

maltose

salivary amylase

mou

thsm

all in

testi

ne

Digestive Digestive EnzymesEnzymes


Protein digestion

sm

all

inte

sti

ne trypsinog

entrypsin

enterokinase

proteins polypeptides

trypsin

polypeptides

amino acids

erepsin

prorennin

rennin

hydrochloric acid

caseinogen

casein

rennin

casein polypeptides

pepsinsto

mac

h

AbsorptionAbsorptionWhat happens to What happens to

food after food after digestion?digestion?

• Where does absorption occur?

In the small intestine and large intestine

• What nutrients are being absorbed?

Simple sugars

Amino acids

Fatty acids and glycerols

Water and mineral salts

AbsorptionAbsorptionWhat happens to What happens to


How does absorption take place in the small intestine?

• Glucose and amino acids:– Absorbed by into blood

capillaries of the villi.– Absorbed by when there is

lower concentration of digested food substances in the small intestine than in the blood capillaries.

• Fatty acids and glycerol:– Absorbed by into the epithelium– Combine to form fat globules which enter the

lacteals• Water and mineral salts:

– Absorbed by the and – Most of the water is absorbed by the ileum

diffusionactive

transport

diffusion

small intestine

colon

Absorption: Small Absorption: Small IntestineIntestine

What happens to What happens to food after food after digestion?digestion?

Adaptations of the Small Intestine for Absorption

• The rate of absorption of digested food substances depends on 3 factors:1.Surface area2.The thickness of

cell membranes4.Concentration

gradient



1. Surface Area• The surface area of the small intestine is

increased for absorption in 4 ways:1. Inner walls have folds2.The surface of the folds are lined with

numerous villi (singular: villus), which are minute finger-like projections.

3.The epithelial cells of the villi have numerous microvilli.

4.The small intestine is long, providing large surface area and ample time for absorption.







2. Thickness of Cell Membranes• The villi have very thin membranes: the

epithelium is only one-cell thick.

3. Concentration Gradient• In each villus is a lacteal (lymphatic

capillary) surrounded by blood capillaries.• The lacteal continually transports away

from the villus, while the blood capillaries transports and away.

• This maintains the concentration gradient needed for the absorption of food substances.

fatssugars

amino acids

EgestionEgestionWhat happens to What happens to


• Some food substances cannot be digested and remain unabsorbed in the large intestine.

• These are stored temporarily in the rectum.• When the rectum is full, they are discharged

as faeces through the .• This process is known as egestion or

defecation.

anus

Transport and Transport and AssimilationAssimilation


Transport of Simple Sugars• After absorption, the blood in the villi is rich

in sugars.• Blood capillaries unite to form the hepatic

portal vein.• The hepatic portal vein transports sugars to

the liver.



Assimilation of Simple Sugars• In the liver, most sugars are converted to

glycogen and stored.• Glucose leaves the liver and is distributed

around the body by the bloodstream.– Used during respiration to provide energy for

cells.

• Excess glucose is returned to the liver– Hormone insulin (produced by Islets of

Langerhan in the pancreas) stimulates the liver to convert glucose to glycogen for storage.

– When more glucose is required, the liver will convert glycogen back to glucose.



Transport and Assimilation of Amino Acids

• Amino acids pass through the liver before they are transported to the rest of the body.

• How are amino acids used?– Converted to protoplasm by cells, used for

growth and repair of body parts– Used to form enzymes and hormones

• Excess amino acids are deaminated.

Functions of the Functions of the LiverLiver


The Liver has 7 Functions2.Regulation of blood glucose concentration3.Production of bile4.Protein synthesis5.Iron storage6.Deamination of amino acids7.Detoxification8.Heat production



1. Regulation of Blood Glucose Concentration

• Blood normally contains about 70-90 mg of glucose per 100 cm3 of blood.

• After a meal:– Amount of glucose in the blood rises– Stimulates Islets of Langerhans in the

pancreas to secrete insulin into the bloodstream

– Insulin is transported to the liver.– Insulin stimulates liver to convert excess

glucose to glycogen for storage.– Blood leaving the liver contains a constant

amount of glucose.

What about adrenaline??




• When body cells need glucose:– Glucose level in the blood drops.– Islets of Langerhan are stimulated to secrete

hormone glucagon.– Glucagon stimulates liver to convert stored

glycogen to glucose.– Glucose enters the blood; blood glucose level

returns to normal.




• If we have not eaten for a long time:– Glucose level in the blood drops below

average.– Blood that is low in glucose reaches the

hypothalamus in the brain.– Brain sends signals to the stomach.– This causes strong contractions and we feel

hunger pangs.– After eating, the blood glucose level rises.

The hypothalamus signals to the stomach to stop contracting.



1. Regulation of Blood Glucose Concentrationhigh blood

glucose concentratio

n

normal blood glucose concentration

low blood glucose

concentration

pancreas secretes insulin

pancreas secretes glucagon

converts glucose to glycogen

converts glycogen to

glucose



2. Production of Bile• The liver produces bile which is stored in the

before use.• Bile is used in the of fats.

3. Protein Synthesis• Blood plasma contains amino acids from the

diet.• The liver synthesizes these amino acids to

form proteins, e.g.:– Albumins, globulins, fibrinogen (for blood

clotting)

gall

bladder emulsifica

tion



4. Iron Storage• Red blood cells contain a iron, which is

involved in the transportation of oxygen around the body.

• These cells become worn out after some time.

• They are destroyed in the spleen, a gland near the liver.

• Haemoglobin from red blood cells is brought to the liver.

• Haemoglobin is broken down, forming iron and bile.

• Iron is stored in the liver.



5. Deamination of Amino Acids• Excess amino acids are transported to the

liver.• The amino groups are removed and

converted to urea.• Urea leaves the body in urine.• The remains of the amino acid are

converted into glucose.• Excess glucose is converted to

.

glycogen



6. Detoxification• This is the process of converting harmful

substances into harmless ones.• Breaks down alcohol to acetaldehyde by the

action of alcohol dehydrogenase• Acetaldehyde can be broken down to

compounds which can be used in respiration.

• Excessive alcohol consumption stimulates acid secretion in the stomach, increasing the risk of gastric ulcers.



6. Detoxification• Prolonged alcohol use can lead to cirrhosis

of the liver.– Liver cells are being destroyed and replaced

with fibrous tissue– Cells are less able to function– Can lead to liver failure and death



7. Heat Production• There are many chemical reactions taking

place in the liver.• Heat is produced from these reactions.• The heat is distributed by the blood to other

parts other body.• Helps to maintain body temperature.

Bowel movements are difficult and do not occur often enough.

It is caused by a lack of exercise, emotional distress or misuse of laxatives, and/or a diet low in dietary fibres.

Due to constipation, abdominal pressure causes blood vessels in the rectum to enlarge, producing haemorrhoids.

Evaluating Eating HabitsConstipation

Anorexia nervosa is characterised by constant dieting, rapid weight loss and feeling too fat in spite of the weight loss.

Bulimia is characterised by eating too much food through vomiting or the use of laxatives; tend to gain weight easily and live in constant fear of becoming obese. Bulimics often have mouth and throat problems due to repeating vomiting.

Both anorexics and bulimics have a constant fear of being fat and fear rejection

Evaluating Eating HabitsEating Disorders

PhotosynthesisPhotosynthesis

PhotosynthesisPhotosynthesisThe synthesis of organic compounds

From the splitting of water (photolysis) in the light dependent reaction

And from the reduction of carbon dioxide in the light independent reaction

PhotosynthesisPhotosynthesis

LIGHTLIGHT

HH22OO

OxygenOxygen

2H+2H+

ATPATP

COCO22CarbohydrateCarbohydrate

Leaf structureLeaf structureThe leaf is the main site for

photosynthesis in plantsIt has several special features

which help it carry out this role;Flattened shape – increasing surface

areaThin – so that gases can diffuse

quicklyA vascular system – to supply water

& take away the productsStomata – To allow gas exchangeChloroplast containing cells – to

capture light energy

Leaf structureLeaf structure

CuticleUpper epidermis

Palisade

Vascular tissue

Spongy mesophyll

Lower epidermisAir space Stoma Guard cell

Palisade cell structurePalisade cell structure

Chloroplast

Cell surface membrane

Vacuole

Tonoplast

Starch grain

Cytoplasm

Nucleus

Cellulose cell wall

Cytoplasm

Chloroplast structureChloroplast structure

Chloroplast structureChloroplast structureOil droplet

RibosomesThylakoid membranes

DNAStarch grain Intergranal membrane

Stroma

Granum

Factors Affecting Photosynthesis

Light Intensity

Concentration Of Carbon Dioxide

Temperature

Water Supply

LIGHT INTENSITYLIGHT INTENSITY

Light is essential during the light reaction of photosynthesis.

When the concentration of carbon dioxide and temperature are controlled at constant level, the rate of photosynthesis is directly proportional to light intensity up to a certain point.

Light intensityLight intensity

Light intensityRat

e of

pho

tosy

nthe

sis

Concentration of carbon Concentration of carbon dioxidedioxide

Carbon dioxide is needed in the dark reaction as a raw material used in the synthesis of glucose if there is no other factors limiting photosynthesis and increase in the concentration of carbon dioxide results in an increase in the rate of photosynthesis.

At a very high light intensity, the rate of photosynthesis slows down because the pigment chlorophyll is damaged by ultra-violet rays.

Carbon dioxide Carbon dioxide concentrationconcentration

Light intensity

Rat

e of

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0.035% CO2

1% CO2

WATER SUPPLYWATER SUPPLYWater is needed for photosynthesis, however water is rarely the limiting factor in photosynthesis because the amount of water required is small.If water is not supplied, wilting occurs and the stomata is closed.This prevents the diffusion of carbon dioxide into the leaves.As a result the rate of photosynthesis decreases as the lower concentration of carbon dioxide becomes the limiting factor.

TemperatureTemperatureThe dark reaction of photosynthesis is catalysed by the photosynthetic enzyme and therefore changes in temperature will affect the rate of photosynthesis.

Generally, an increase of 10 degree Celsius in the surrounding temperature will doubled the rate of photosynthesis.

The optimum temperature for most of the plants are between 25-30 degree celcius.

However, when the temperature is too high the photosynthetic enzyme are destroyed and photosynthesis stops altogether.

TemperatureTemperature

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Temperature

25ºC

Increasing KE

Enzymes denatured

Carring attitude towards Carring attitude towards plantsplants……

THE NEED TO TAKE CARE OF PLANTS. Sustains lifed) Green plans produce and generates the supply of oxygen that all

living things need.

Air qualityf) Plants influence the quality of the air that we breathe.

g) Plants stop the movement of dust and pollutants.

h) Plants reduce the greenhouse effect caused by burning of fossil fuels by absorbing and removing large amounts of carbon dioxide from the atmoshere.

Climatej) The type of plant cover influences regional climates.

k) The destruction of forest causes drought and turns fertile land into desert.

Water qualityb) Forests are important in maintaining healthy watercatchment

areas.

c) Forest hold sil in place,and filtering sediments from water flowing into streams,rivers and lakes.

Control of erosione) Plants and trees help to protect the soil from erosion caused

by heavy rains.

f) Uncontrolled felling of trees and clearing of plants and clearing of plants can cause landslides.

Fish and wildlife habitath) Plants provide the necessary habitats for wildlife and fish

populations.

Ecosystemb) Humans,plants and animals all live together supporting each

other.

c) Each species serves an important role in the ecosystem.

Foode) Humans use about 3000 species of plants as food.

Medicineg) Plants have been providing humans with medicines thoughout

human history.

h) About 80% of all medicinal drugsoriginate from wild plants and there are many important drugs yet to be discovered from plants.

Industrial productsb) We use fibres from plants to provide clothing.

c) We build our houses and furniture using wood from plants.

d) We produce fuel products are made from plants,palm oil bodies,soy diesel and ethanol made from corn.

Recreationf) Our forests provide many recreational activities like

hiking,fishing,hunting,nature observation and ecotourism.

Aestheticsh) We use plants to enchance the beauty of our homes,gardens

and roads which are important for us to seek peace,rest and beauty from nature.

TECHNOLOGICAL TECHNOLOGICAL DEVELOPMENT IN DEVELOPMENT IN

FOOD PROCESSINGFOOD PROCESSING

Food processing is the process of preparing food to make it more attractive, more palatable and to last longer

Food has to be processed so that it can withstand long periods of transportation and storage

One of the main purpose of food processing is to preserve food by overcoming the factors that cause food spoilage

Food spoilage is caused by : *the action of microorganism in

food, especially decomposing bacteria and fungi which act on carbohydrates and proteins in food to produce carbon dioxide, water, ammonia, hydrogen sulphide and other organic substances. The presence of these substances spoil the food and sometimes make it toxic

The oxidation of food due to the oxygen reacting with enzymes and chemical released by the cells in the food. Oily food can also become rancid, smell and taste different as a result of oxidation. Rancid food is harmful to the body

Food has to be processed : *to extend their lifespan so that

they can be stored for future use *to avoid wastage *to prevent the spread of

diseases due to contamination of food, which can cause food poisoning

*to ensure there will be the continuous supply of food for the population

*to increase their commercial value *to prevent the bacteria and fungal

decay *so that they can withstand long

periods of transportation and storage *so that food can be supplied to the

local or global market all year round in good condition

To diversify the uses of food substances. For example , milk has been processed to produce a variety of dairy products such as cheese, yogurt, ice cream, butter and chocolates

RELATING THE FOOD RELATING THE FOOD PROCESSING METHODS PROCESSING METHODS WITH FACTORS CAUSING WITH FACTORS CAUSING

FOOD SPOILAGEFOOD SPOILAGE Microorganisms require nutrients,water,oxygen and a suitable temperature for optimal growth and reproduction

Microorganisms can only survive in condition with optimum pH and solute concentrations as these will not destroy them

Hence,food can be preserved by destroying the microorganisms present in the food or by stopping their activities

A few methods of processing and preserving food that have been practised since the early days are cooking,fermentation and drying of food

COOKINGCOOKINGCooking at high temperatures or

boiling for at least five minutesHeating food to high

temperatures can kill microorganisms and denature the enzymes that cause the breakdown of food.

Certain bacterial spores may also be killed. However toxins produced by bacteria are not always destroyed.

E.g. Meat, vegetables and fish

FERMENTATION PROCESSFERMENTATION PROCESS

Yeast is added to fruit juices or other food substances. Fermentation produces ethanol which at high concentrations, stops the activity of bacteria that causes food spoilage. The ethanol produces also has a great commercial value. E.g. Fruit juices and tapai.

DRYINGDRYINGDrying under the hot sun, in hot air

or in the oven.Drying removes water from food.

This prevents microorganisms from growing as microorganisms cannot live without water.

The enzymatic activity in food also stops.

The ultraviolet rays from the sun also kill bacteria and many other harmful microorganisms.

E.g. Fish, meat and fruit

PICKLING FOODPICKLING FOODFood is soaked in an acidic

solution such as vinegar.Most organisms cannot lives in

low pH conditions.E.g. Chillies, ginger, onions and

mangoes

TREATING FOOD WITH TREATING FOOD WITH SALT AND SUGARSALT AND SUGAR

Food is soaked in a concentrated salt solution or boiled with sugar.

Microorganisms lose water through osmosis in a hypertonic solution.

E.g. Meat, vegetables and ducks’ eggs

Milk is preserved by pasteurisation to destroy bacteria which cause diseases such as those which cause tuberculosis and typhoid.

In this process,milk is heated to a) 63 for 30 minutes b) 72 for 15 seconds and then rapidly cooled to below 10

While maintaining the nutrient content The purpose of pasteurisation is to kill microorganisms and natural flavour of the milk

Nutrient like vitamin B are not destroyed. Pasteurisation is unable to kill all types of

bacteria.Therefore,pasteurised milk needs to be stored in the refrigerator because of its short shelf life.This is to prevent those microorganism active again.

Fruit juices and soup can also preserved using this method.

Canning uses the heat sterilisation method to kill microorganism and their spores.

The food is packed in cans and steamed at a high temperature and pressure to drive out all the air.

The cans containing food are then sealed while the food is being cooled.

The airtight containers all the vacuum created within the cans prevent the growth of microorganisms.

Pathogens and food-spoiling bacteria are destroyed and the enzymes in the food are inactivated.

Canning keeps food sterile for long periods hence,the shelf life of canned food is usually longer although the cans may eventually corrode.

However,if the food is not thoroughly cooked,there is a danger contamination by spores of Clostridium botulinum.

This bacteria can survive in food which is mildly heated and stored at room temperature.Under these conditions,the bacteria produce a toxin which can kill human at very low concentrations.

Consequently,because canned food needs to be thoroughly cooked,it is low in quality.

Refrigeration is a common method used by household to prevent food spoilage.

Food stored at temperatures below 0 can remain fresh for a long period of time.

Meat,fish and meat products can be preserved this way.

The extremly low temperatures prevent growth of microorganisms or germination of spores because enzymatic reactions stop at low temperatures.

The End!!!The End!!!Bubye..Bubye..

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