BIOLOGY FORM 4 NOTES CHAPTER 6 : NUTRITION

CHAPTER 6: NUTRITION

6.1          TYPE OF NUTRITION

Nutrition =   process by which organisms obtain nutrients and energy from food.

Type of nutrition	Definition	Examples
Autotrophic Nutrition
Photosynthesis
Chemosynthesis
Heterotrophic Nutrition
Holozoic Nutrition
Saprophytism
Parasitism

6.1          BALANCED DIET

1.    A balanced diet contains the main nutrients which include carbohydrates, fats, proteins, vitamins, minerals, water and roughage in the correct proportions to meet the body’s daily requirements.

2.    The importance of a balanced diet:

(a)   to allow the organism to function efficiently by providing daily energy requirement

(b)   for metabolism and maintain a healthy life

(c)   for growth and repair damage tissues

(d)   to supply essential nutrients

6.1.1      Daily energy requirement

1.    Energy can be obtained from carbohydrates and fats. Proteins are only used if there is a shortage of carbohydrates and fats.

2.    Energy requirement vary according to:

(a)  Age

-          Children and teenagers require more energy because they have a higher metabolic rate

(b)  Sex

-          A male adult need more energy because they usually have relatively less fatty tissues as heat insulator and a higher rate

(c)  Body size and weight

-          People with bigger body size and weight will require more energy for their basal metabolism

(d)  Occupation and lifestyle

-          A woman who does heavy work will need more energy than a person who only moderately active, and thus requires more energy than a sedentary worker.

(e)  Pregnancy and lactation

-          Pregnant women and breast-feeding mothers require more energy.

(f)   Climate

-          A person who lives in a cold country needs more energy to maintain his body temperature than a person living in the tropics.

3.    Determination of energy value in food samples

Energy value of food =

     Definition of energy value:

4.    Food Test

Test For	Food test	Observation
Starch	Iodine test
Reducing sugar	Benedict’s test
Protein	Millon’s test
	Biuret’s test
Lipid	Ethanol-emulsion test
	Grease spot test
	Sudan III test
Vitamin C	DCPIP test	Percentage of Vitamin C in fruit juice = Concentration of Vitamin C in fruit juice =

1.    Vitamins and Minerals --- Refers to Reference Book

2.    Dietary Fibre (Roughage)

-          Functions:

(a) stimulates peristalsis and assists the movement of food in the intestine

(b)  helps to prevent constipation

(c)  may protect colon cancer

(d)  contains less fat and cholesterol which may decreases the risk of cardiovascular diseases

3.    Selection of an appropriate balanced diet:

Target group	Appropriate balanced diet
Pregnant women
Infants
Children
Teenagers
Target group	Appropriate balanced diet
Athletes
The aged
Vegetarians
People with specific diseases

6.1          MALNUTRITION

1.    Malnutrition is failing health that results from not eating a balanced diet over a long period of time.

2.    Malnutrition refers to:

(a)  undernutrition: resulting from inadequate consumption or excessive loss of nutrients

(b)  overnutrition: resulting form overeating or excessive intake of specific nutrients

3.    Effects on malnutrition

(a)  Kwashiorkor

-          caused by protein deficiency

-          symptoms:

(i)            swelling legs

(ii)           underweight

(iii)          ‘moon face’

(iv)         swollen abdomen

(v)          thin muscles but fat present

(vi)         dry, sparse, thin hair

(vii)        apathetic, little interest in his surrounding

(viii)       stunted growth

(b)  Marasmus

-          caused by deficiency of energy and protein foods in children

-          symptoms:

(i)            underweight

(ii)           ‘old man face’

(iii)          thin muscles, thin fat

(iv)         stunted growth

1.    Effects of Excessive Intake and Deficiency in Nutrients on Health

Nutrient	Effects of excessive intake	Effects of deficiency
Carbohydrate
Lipid
Protein
Vitamins
Minerals

6.1          FOOD DIGESTION

6.1.1      Human Digestive System

1.    Basic functions of human digestive system:

(a)  Ingestion:

-    taking food into the body

(b)  Peristalsis

-          food substances moved along the alimentary canal by muscular contractions

(c)  Digestion

-          mechanical digestion by physical breakdown of food and chemical digestion by enzymes

(d)  Absorption

-          Absorption of soluble food into the bloodstream

(e)  Egestion

-          Elimination of undigested food from the body

2.    Digestion of Carbohydrates, proteins and lipids

(a)  In the mouth

-          Digestion of food begins in the mouth

-          Includes:

(i)            Mechanical digestion:

·         Involves the chewing of the large pieces of food into small pieces. This makes it easier to swallow the food and increases the surface area for digestive enzymes

(ii)           Hydrolysis of starch to maltose

·         Saliva contains salivary amylase to hydrolyse starch to maltose.

-          The food particles are rolled into small ball called bolus. During swallowing, the bolus is forced into pharynx and then into the oesophagus

(b)  Oesophagus

-          Food bolus is moved down the oesohagus by peristalsis

-          Mucus is secreted by the oesohagus wall to lubricate the passage of the bolus.

-          When the cardiac sphincter relaxes, the food bolus enters the stomach.

(c)  Stomach

-          The gastric glands presented in the epithelium of the stomach wall secrete gastric juice containing:

(i)            Hdyrochloric acid

·         privides an optimum pH (1.5 – 2.0) for pepsin and rennin

·         kills bacteria in the food

·         stops the action of salivary amylase

(ii)           Enzyme pepsin

·         Hydrolyses the protein into polypeptides

(iii)          Enzyme rennin

·         Converts caseinogen into casein

-          Food remains in the stomach for 2 to 4 hours.

-          The semi-liquid food is called chime.

-          The pyloric sphincter relaxes to allow the chime to enter the duodenum.

(d)  In the small intestine

-          consists of duodenum, jejunum and ileum

(i)            Duodenum

·         The presence of food in the duodenum stimulates the pancreas to release pancreatic juice and the liver to produce bile.

·         Bile is produced in the liver and stored in the gall bladder.

·         The function of bile:

Ø  Bile contains bile salts which emulsify the lipids and breaks them into smaller droplets.

·         Pancreas secretes pancreas juice to the duodenum. Pancreas juice contains sodium hydrogen carbonate, pancreatic amylase, trypsin and lipase

·         Bile and pancreas juice neutralize the acidic chime from the stomach and provides an optimum alkaline medium for digestive enzyme in the duodenum.

·         In the duodenum:

1.    Pancreatic amylase hydrolyses the starch to maltose

2.    Trypsin hydrolyses polypeptides into peptides

3.    Lipase hydrolyses lipids into glycerol and fatty acids

(ii)           In the intestine:

·         The epithelial cells in the villi of the small intestine contain enzymes to complete the digestion of food

1.    Maltase hydrolyses maltose to glucose

2.    Sucrase hydrolyses sucrose to glucose and fructose

3.    Lactase lactose to glucose and galactose

4.    Eripsin hydrolysespeptides into amino acids.

·         At the end of the digestion:

Ø  The complex carbohydrates are broken into simple sugars

Ø  Proteins are broken into amino acids

Ø  Lipids are broken into glycerol and fatty acids

·         This soluble food in the small intestine is known as the chyle.

Summary:

Site of action	pH	Enzymes	Reaction
Mouth
Stomach
Duodenum
Small intestine

6.1.1      Digestion of Cellulose in Ruminants and Rodents

1.      The alimentary canals of herbivorous mammals such as ruminants and rodents contain microorganism that can produce cellulase to digest cellulose.

2.      Ruminants

-                Ruminants are herbivores characterized by a four-chambered stomach (rumen, reticulum, omasum and abomasums)

-                Examples: cows, sheep and goats.

-                The digestion of cellulose by a ruminants:

(i)            The grass is mechanically digested by grinding action of the teeth

(ii)           The partially macticated food is passes to the rumen (the largest compartment).

·         Fermentation occurs.

·         The anaerobic bacteria and protozoa partially break down the cellulose into glucose and organic acids.

(iii)          The partially digested food enters the reticulum and undergoes further fermentation.

(iv)         The food is then regurgitated to the mouth for further grinding.

(v)          The chewed food is swallowed into the omasum where water and some nutrients are absorbed.

(vi)         Then, the food is channeled to the abomasums (the true stomach) for digestion of proteins.

1.      Rodents

-          Rodents are mostly herbivores or omnivores

-          Examples: rabbits, rats and mice

-          They have a large caecum containing symbiotic bacteria and protozoa. These microorganisms secrete cellulase to digest cellulose.

-          Food is digested two times in the alimentary canal:

(i)    The first faecal pellets produced at night contain partially digested food and are moist and soft.

(ii)   Rodents eat pellets directly from the anus. The faecal pellets pass through the alimentary canal again to be more fully digested.

(iii)  The second fry, hard faecal pellets produced during the day are not eaten.

Similarities and differences between the digestive process in human, ruminants and rodents:

6.1.1      Problems associated with food digestion

1.    Incomplete digestion of food

-          Causes: excessive eating, drinking or an inability of the body to digest the ingested food

-          Symptoms: nausea, vomiting, abdominal pain and a bloated stomach

-          Preventive measures: proper chewing of food, eating moderately and following a balanced diet

2.    Gallstones

-          Causes: eating high cholesterol diet, obesity and aging

-          Symptoms: fever, pain in the upper right abdomen, nausea, vomiting and jaundice

-          The presence of large stones block the bile duct. The lipids are not emulsified and lipid digestion is less effective.

-          Treatment: In severe cases, the gall bladder may be removed by surgery or laparoscopy

3.    Reduced production of specific digestive enzymes

-          Example:

·         Decreased production of lactase causes lactose intolerance in some babies and older adults.

·         If a person with lactose intolerance eats dairy products containing lactose, diarrhoea may result. The bacteria in the colon ferment the lactose. The gas and organic acids produced cause bloating of the abdomen.

6.2          PROCESS OF ABSORPTION AND ASSIMILATION OF DIGESTED FOOD

1.    The adaptive features of small intestine to aid absorption of nutrients:

(a)  It is 5-6m long in an adult. This gives a longer time for food digestion and more nutrients to be absorbed.

(b)  It has a lot of villi and microvilli to provide a large surface area for more rapid absorption.

(c)  It has a thin (one-cell-thick) epithelium to allow digested food to pass easily through it into the blood capillaries or lacteals.

(d)  It has a moist surface.

(e)  It is richly supply with blood capillaries to absorb and to transport the absorbed nutrients.

2.    Absorption and transportation of digested food:

(a)  Glucose, amino acid, mineral ions, water soluble vitamins B and C

-          are absorbed and enter blood capillaries

-          are transported by blood vessels to the hepatic portal vein to the liver.

(b)  Fatty acids, glycerol and fat soluble vitamins A, D and E

-          are diffuse into the lacteals.

-          Are transported from lacteals to lymphatic vessels then return to the blood circulatory system.

(c)  Water and remaining mineral ions

-          are absorbed from undigested food in the colon together with Vitamin K synthesized by bacteria in the colon.

3.    The functions of liver

(a)  Regulation of blood glucose level

-          When the blood glucose level is high, hormone insulin promotes the conversion of excess glucose to glycogen for storage in the liver

-          When the blood glucose level is lower than the normal, hormone glucagon promotes the conversion of glycogen to glucose.

(b)  Deamination

-          Excess amino acids cannot be stored and are transported to the liver.

-          Liver converts the amino group (-NH₂) to ammonia (through a process called deamination) then into urea which is then excreted through the urine.

-          The remaining amino acid portion may be converted to carbohydrate or fat.

(c)  Storage function

-          The liver stores:

(i)    fat soluble vitamins A and D, and the water soluble vitamin B₁₂.

(ii)   Some mineral ions: iron, potassium, cobalt, zinc and copper

(d)  Detoxification

-          Toxins carried by the blood to the liver are chemically modified into nontoxic substances and are eliminated.

(e)  Production of bile

-          Bile is produced in the liver and stored in the gall bladder. It is transported to the duodenum to emulsify the fats into small droplets to increase the surface area for digestion by lipase.

(f)   Synthesis of plasma protein

-          The liver synthesis plasma protein such as fibrinogen and prothrombin that are needed for blood clotting.

4.    Assimilation

(a)  Assimilation refers to how a living organism utilizes the absorbed food substances for growth, development, reproduction or repair.

(b)  Glucose

-          Glucose is used as main respiratory substrate. It is oxidised to release energy, water and carbon dioxide.

-          Excess glucose is converted to glycogen and stored in the liver

-          Further excess is converted into lipids

-          When the blood glucose level decreases below the normal level, glycogen is converted back into glucose.

(c)  Lipids

-          Lipids are used

o   as a respiratory substrate, a major energy reserve in the body.

o   to form the phospholipids components of plasma membrane.

-          Excess fats are stored in adipose tissue under the skin, and around the internal organs.

(d)  Amino acids

-          Amino acids are used:

o   in protein synthesis for the production of new protoplasm, growth and repair

o   in the formation of enzymes and some hormones

o   in the formation of protein part of haemoglobin part of the red blood cells

-          Excess amino acids are deaminated to form urea which is excreted in the urine.

6.3          FORMATION OF FAECES AND DEFECATION

Defaecation is important for discharging waste and unwanted toxic substances from the colon.

6.3.1      The process of defaecation

6.1.1      Role of microorganisms in the colon

-          There are symbiotic microorganisms living in the human colon such as Escherichia coli.

-          The symbiotic bacteria synthesis Vitamin B₁₂ and Vitamin K that can be absorbed in the colon.

-          Consumption of antibiotics can kill and decrease the microbial population in the colon. Consequently, Vitamin B₁₂ and Vitamin K cannot be obtained from the colon.

6.1.2      Problems related to defaecation

1.    Constipation

-          Constipation is the difficulty or infrequent evacuation of the bowels.

-          Reasons:

·         Too much water is removed by the colon

·         Faeces moving too slowly through the colon

·         The rectum is unable to expel faeces

-          Preventions:

·         Taking a diet rich in roughage

·         Consume more liquids

·         Visit toilet regularly

·         Exercise daily

2.    Haemorrhoids

-          Haemorrhoids are a condition in which the veins around the anus or lower rectum are swollen and inflamed.

-          Reasons:

·         Caused by prolonged constipation or diarrhoea

-          Preventions:

·         Drink a lot of water and eating a high fibre diet

·         Empty your bowel as soon as possible when urge occurs

·         Exercise regularly

3.    Colon cancer

-          Colon cancer is a type of cancer that develops in the tissues of the colon.

-          Reasons:

·         Carcinogens produced by colon bacteria

·         Eating a high fat , low fibre diet

-          Preventions:

·         Eating a high fibre diet

6.2          EVALUATING EATING HABITS

1.    Eating habits refer to:

-          The type of food we eat, and

-          Frequency and time we eat

2.    Good eating habits:

(a)  taking meals at the appropriate time

(b)  refraining from overeating or eating too little during a meal

(c)  eating a variety of food

(d)  eating a balanced diet

(e)  eating  sufficient amount of fibre

(f)   drinking a least  2 to 3 liter of water daily

(g)  avoid excessive fatty and sweet food

3.    Health problems related to eating habits:

Health problems	Gastritis	Obesity	Anorexia nervosa	Bulimia
Definition
Symptoms
Causes
Health risks

1.    When choose food, we must consider:

(a)  the nutritional contents of food

(b)  freshness of food

(c)  presence of food additives (Flavoring, colouring and preservaties)

6.1          IMPORTANCE OF HEALTHY DIGESTIVE SYSTEM

1.    A healthy digestive system is essential for:

·         Proper digestion of complex food into small soluble molecules for the absorption and assimilation of nutrients in the cells

2.    Ways to take care of the digestive system:

(a)  having good eating habits

(b)  avoiding junk foods

(c)  cutting down on sugar intake and sweetened food

(d)  reducing intake of fatty food

6.1          MACRONUTRIENTS AND NICRONUTRIENTS IN PLANTS

·         Mineral elements = essential chemical elements required by plants to achieve optimal growth and development.

·         The functions and effects of nutrients deficiency in plants

~ refers text book and reference book

·         Experiment: Studying the effects of macronutrient deficiencies in plant

~ refers text book and reference book

6.1          PHOTOSYNTHESIS

6.1.1      A brief history of the discovery of photosynthesis

~ refers text book and reference book

6.1.2      Leaf structure and function

The physical adaptation of leaves for photosynthesis

Structure	Adaptation	Explanation
Lamina of the leaf	Bloat, flat and thin	§  The broad and flat shape provides a large surface area for the maximum absorption of sunlight and carbon dioxide. §  Thin leaf allows light to penetrate and reach the cells. It also allows carbon dioxide to diffuse rapidly to the cells in the leaf.
Position of the leaf	Leaf is positioned at right angle to rays of sunlight	§  To absorb maximum sunlight.
Arrangement of the leaf	Leaves are arranged in mosaic pattern so that they do not overlap.	§  To absorb maximum sunlight.
Upper epidermis	Translucent	§  Allows sunlight to pass through easily.

The adaptation of the structure of a leaf for photosynthesis

Cross section of a leaf

1.    Cuticle

·         A waxy covering which protects the leaf

·         Functional adaptation:

-          Waterproof: to prevent excessive water loss

-          Transparent: to allow sunlight to penetrate the leaf

2.    Upper epidermis

·         Covers the upper surface of a leaf

·         Does not contain chloroplast

·         Functional adaptation:

-          Thin and transparent: to allow sunlight to penetrate the leaf and reach the light-trapping chloroplast

3.    Palisade mesophyll

·         These cells are packed tightly together in an upright arrangement right beneath the upper epidermis

·         These cells are cylindrical and have a high density of chloroplasts

·         The cell walls are coated with a film of water

·         Functional adaptation:

-          Packed tightly together: to allow the cells to receive the maximum amount of light

-          Have a high density of chloroplasts: to carry out maximum absorption of sunlight

-          Coated with a film of water: to facilitate the diffusion of carbon dioxide into the cells

4.    Spongy mesophyll           

·         Have irregular shape

·         Contain chloroplasts but fewer than palisade cells

·         Have air space that connect the mesophyll to the stomata

·         The cell walls are coated with a film of water

·         Functional adaptation:

-          Irregular shape: to increase the internal surface are of gaseous exchange

-          Contain chloroplasts: to carry out photosynthesis

-          Have air space: to allow easy diffusion of water and carbon dioxide

-          Moist surface: to allow gaseous exchange to take place efficiently in the cells

5.    Vascular bundle

·         Consists of xylem and phloem

·         Functional adaptation:

-          Xylem: transport mineral ions and water from the root to the leaf

-          Phloem: to transport the products of photosynthesis from the leaf to the other parts of the plants

6.    Lower epidermis

·         Forms the lower protective boundary of the leaf

·         Consists of guard cells and stomata

·         Functional adaptation:

-          Guard cells: control the opening and closing of stomata

-          Stomata: allow carbon dioxide from the atmosphere diffuses into the leaf and oxygen diffuses out of the leaf

6.1.1      Adaptation of plants from different habitats to carry out photosynthesis

1.    Land plants

·         Most stomata are located on the lower epidermis

-          To allow maximum carbon dioxide absorption

-          To prevent excessive evaporation and water loss

·         Most of the chloroplasts are found in the palisade mesophyll cells and the spongy mesophyll cells

-          To facilitate maximum absorption of sunlight

2.    Floating plants

·         The stomata are mostly distributes on the upper epidermis which is covered by a thick and waxy cuticle

-          To repel water and keep the stoma open

·         Chloroplasts are found mainly in the upper epidermis

-          To maximize the absorption of sunlight

3.    Desert plants

·         Leaves contain very few stomata and some have embedded stomata (sunken stomata)

-          To prevent excessive loss of water

·         Chloroplasts are found all over the plant

-          To maximize the absorption of sunlight

4.    Aquatic plants

·         Stomata are not found on the leaves

-          The cells on the surface are able to absorb water, nutrients and dissolved gases directly from the surrounding

·         Chloroplasts are found all over the surface of the plant

-          To maximize the absorption of sunlight

6.2          MECHANISM OF PHOTOSYNTHESIS

Chloroplast: The site of Photosynthesis

Photosynthesis is a two-stages process:

(a)  Stage 1: the light reaction, occurs in the grana

(b)  Stage 1: the dark reaction, occurs in the stroma

The Light Reaction

1.    When chlorophyll absorbs light, it becomes activated and this energy is used to:

(i)    split up the water molecule into hydrogen ion and hydroxide ion.

(ii)   excite the chlorophyll to release electrons.

2.    Each hydrogen ion receives an electron from the chlorophyll and becomes a hydrogen atom.

3.    The hydrogen atom then enters the dark reaction, where it is combined with the carbon dioxide to form carbohydrates.

4.    Hydroxide ions release their electron to the chlorophyll to restore its neutrality. Hydroxyl groups are formed, which then combined to form water and oxygen.

Summary:

The light reaction involves the breaking of water molecule into hydrogen and oxygen in the presence of light.

This process is called photolysis of water.

The Dark Reaction

1.    Carbon dioxide which had diffused into the leaves are combined with hydrogen atom from the light reaction.

2.    (CH₂O) is the basic unit for the formation of glucose. Six units of CH₂O will combine to form a molecule of a glucose.

General Equation of Photosynthesis

6.3          SYNTHESISING FACTORS AFFECTING PHOTOSYNTHESIS

The rate of photosynthesis is affected by

(c)  Light intensity

(d)  Concentration of carbon dioxide

(e)  Temperature

(f)   Water

(a) The effect of light intensity on the rate of photosynthesis

§  The higher the light intensity, the higher the rate of photosynthesis.

§  As the light intensity increases, the rate of photosynthesis increases up to a saturation point (P)

§  A further increase in the light intensity (beyond point P) does not increase the rate of photosynthesis because of the limiting factors such as concentration of carbon dioxide and temperature.

§  At very high light intensity, the rate of photosynthesis slow down because the pigment chlorophyll is damaged by ultraviolet rays.

(b) The effect of concentration of carbon dioxide on the rate of photosynthesis

§  The higher the concentration of carbon dioxide, the higher the rate of photosynthesis.

§  As the concentration of carbon dioxide increases, the rate of photosynthesis increases up to a saturation point.

§  A further increase in the concentration of carbon dioxide does not increase the rate of photosynthesis because light intensity acts as a limiting factors.

(c) The effect of temperature on the rate of photosynthesis

§  Changes in temperature will affect the rate of photosynthesis because the dark reaction of photosynthesis is catalysed by the photosynthetic enzymes.

§  An increase of 10 ⁰C in the surrounding temperature will double the rate of photosynthesis

§  The optimum temperature for most of the plants is 25 ⁰C - 30⁰C

§  When the temperature is too high, the photosynthesis will stop because the photosynthetic enzymes are denatured.

(d) The effect of water on the rate of photosynthesis

§  If the water is not supplied, wilting occurs. This results in the the closing of stomata and prevents the diffusion of carbon dioxide into the leaves.

§  As a result, the rate of photosynthesis decreases because of the lower concentration of carbon dioxide.

6.4          PRACTICING A CARING ATTITUDE TOWARDS PLANTS

1.    The importance of photosynthesis

(iii)  Through photosynthesis, green plants convert the energy from sunlight into chemical energy and store this energy within organic molecules. These organic molecules provide fuel for other organisms that eat the plants.

(iv) During photosynthesis, plants remove carbon dioxide from the air, and at the same time produce oxygen.

6.14 TECHNOLOGY IN FOOD PRODUCTION

1. The effort by various agencies to diversify food production

(a) Consuming Ulam

Ø  Ulam are vegetables salad consists of fresh leaves, fruits and other plant parts which are eaten raw.

(b) Consuming Various Sources of Proteins

Ø  Rabbit meat: rich in proteins, low in fats and cholesterol

Ø  Ostrich meat: rich in proteins and low in fats

Ø  Fresh water fish: rich in proteins and low in fats

(c) Consuming Mushrooms

Ø  Example: button mushrooms, abalone mushrooms, shitake mushrooms

Ø  To boost body’s immunity

2. Methods to improve the quality and quantity of food production

Direct seeding

Ø  Seeds are sown direetly into soil by using special drilling machine.

Ø  Advantages:

1.    Less damage compared to transplanting seedlings.

2.    Faster,easier,less labour is needed, lower down the production cost.

3.    Have earliear crop maturity.

Hydroponics

Ø  Grows plants in a nutrient solution(not in soil)

Ø  2 main methods:

1.    Water culture – plant roots are placed in water containing correct amount of nutrient for growth. The culture solution is aerated to provide oxygen to plants. It is recycled by a pumping system and is changed periodically to prevent depletion.

2.    Aggregate culture – the roots are placed in sand, pebbles or some inert medium to anchor the plant. Nutrient solution is supplied from below the roots or sprayed above.

Ø  Usually carried out in places where light, temperature and water supply can be controlled(greenhouse)

Aeraponics

Ø  Vegetables are grown with their roots suspended in the air in greenhouse (soil medium is not required).

Ø  Seedlings are anchored into planting holes through a polystryrene panel on a growing trough.

Ø  Plant roots are periodically sprayed with a fine mist of nutrient solution through a sprinkle system. The nutrients are readily absorbed by the roots.

Advantages of Hydroponics and Aeroponics:

Ø  Soil-medium is not required

Ø  Plants are less infected by pathogens

Ø  No herbicides or pesticides are required

Ø  Environment factors can be well-controlled for maximum growth

Ø  No cultivation is required

Ø  Plants grow more healthily and give higher yields in a shorter time

Ø  The growth of plants is uniform

Ø  Plant can be grown all year round

Ø  Large scale production of different commercial crops can be carried out

Ø  Less space is needed

Ø  Low labour cost

Plants breeding

Ø  Different plant species with certain beneficial characteristics are selectivelybred.

Ø  The resulting varieties of plant inherit the characteristics of both parent plants and they may have

(a)  Increased nutritional value

(b)  Higher yields

(c)  Greater resistance to disease and climatic changes

Ø  The most widely planted variety of oil palm is Tenera sp. (crossing of Dura sp. and Pisifera sp.  )

Ø  Palm oil can be extracted from the kernel and mesocrap of the oil palm.

Animal breeding

Ø  Involve the cross-bleeding of two different breeds of animals.

Ø  Function:

-          To change the yields of milk, meat and other farm products.

Ø  Examples: hybrid cattle called Mafriwal is bred for its milk (crossing of Friesian cow and Sahiwal bull) goats, sheep, chickens, ducks.

Tissue culture

Ø  Technique which plant can be regenerated from cell / tissue of parent plant in a sterile culture medium which contain nutrients and growth hormone.

Ø  Plantlets produced can be transplanted to nurseries.

Ø  Advantages:

(a)  Enables commercial propagation of clones

(b)  Increase the agricultural yield of crops plant such as papayas, pineapples, and starfruits.

Soil management

1.    Proper soil management includes:

(a)  A knowledge of physical, chemical and biological properties of the soil.

(b)  The application of the properties of the soil and the type of crop to be grown.

2.    Some of the steps to maintain soil fertility include:

(a)  Ploughing to improve drainage and aeration of the soil.

(b)  Practicing crop rotation which includes a leguminous crop to prevent depletion of soil nutrients

(c)  Introduction of plant covers to prevent soil erosion and leaching.

(d)  Maintenance of organic matter, for example, adding organic manure to increase nutrients and improve soil texture.

(e)  Preventing over-grazing of farm land.

(f)   Avoiding excessive use of herbicides and pesticides.

(g)  Practicing terracing or countour-ploughing on sloping and to prevent soil erosion.

Genetic engineering

(a)  Is a technique that can increase the quality and quantity of food production tremendously .

(b)  Enables the characteristics of an organism to be altered by changing the genetic composition of the organism.

(c)  Involves the transfer of a segment of DNA which carries the genetic information or beneficial genes from one organism to another.

(d)  Examples : genes from plants can be inserted into the DNA of animal cells and vice versa.

(e)  The genetically modified organism (GMO) is called a transgenic organism.

(f)   Development of this genetic engineering have enabled transgenic crop plants.

(g)  Contain genes from other organisms to enhance their growth or nutritional properties.

(h)  Example: Golden rice is a transgenic rice in which the gene that codes for the synthesis of beta-carotene has been transferred from the daffodil plant.

Biological control

(1)  In biological control, a pest is controlled by using its natural enemy or predator.

(2)  Example include:

(a)  Ladybirds, used to prey scale insects which kill circus fruit trees.

(b)  Owls and snakes, used to control rats in oil palm plantation.

(c)  A female Ichneumon wasp, which lays eggs inside the caterpillar of the rice stem borer (pest of paddy plant). The larvae feed on the caterpillar on the stem borer and kill it.

(3)  Biological control is an environmentally friendly method. By using the method, the use of toxic chemical pesticides can be reduced.

6.5          TECHNOLOGICAL DEVELOPMENT IN FOOD PROCESSING