Chapter 6 NutritionOng Yee Sing

2017

Content

• Type of nutrition

• Balanced diet

• Malnutrition

• Food digestion

• Formation of faeces and defaecation

• Evaluating eating habits

• The importance of a healthy digestive system

UEC C5

UEC C5

UEC C5

• The importance of macronutrients and micronutrients in plants

• Photosynthesis

• The mechanism of photosynthesis

• The factors affecting photosynthesis

• A caring attitude towards plants

• Technology used in food production

• Technological development in food production

UEC C5

UEC C5

6.1 Type of nutrition

• Nutrition 营养作用

• Nutrients 营养素

• Autotrophic nutrition 自身营养• Autotroph 自养生物• Photosynthesis 光合作用

• Photoautotroph 光养生物

• Chemosynthesis 化能合成• Chemophototroph化能生物

• Heterotrophic nutrition 异生营养• Heterotroph 异养生物

• Holozoic nutrition 全动物式营养

• Saprophytism腐生营养• Saprophyte 腐生生物

• Parasitism 寄生营养• Parasite 寄生物

• Host 宿主

6.2 Balanced diet

• The necessity for a balanced diet

• Daily energy requirement

• Nutrient content in food

• Selection of an appropriate balanced diet

The necessity for a balanced diet• Living organisms obtain nutrients from their diets.

• The foods that constitute a balanced diet should contain the major nutrients which include:• Carbohydrates• Proteins• Lipids• Vitamins• Minerals• Roughage or dietary fibre• Water

• These nutrients must be taken in the correct proportion• To meet the daily energy requirement of an individual• To provide the necessity nutrients for growth and tissue repair• For maintaining health

Daily energy requirement

• A balanced diet is able to fulfil the daily energy requirement.

• This energy is generated by the oxidation of molecules obtained from the food during respiration.

• The energy content of a substances can be determined by burning a known mass of food in the presence of oxygen in a bomb calorimeter.

Energy content in food

• The energy value of the food is the amount of heat generated from the combustion of one gram of food.

• The unit of energy value is joule per gram (J g-1).

• 4.2 joules of energy are needed to raise the temperature of 1 g of water by 1°C.

• The energy value of nutrient• Carbohydrates – 16.7 kJ/g

• Protein – 22.2 kJ/g

• Lipid – 37.6 kJ/g

Factors that effecting the daily energy

•Age• Growing children and adolescents

require more energy compare to adults

•Sex• Adult males require more energy

than adult female.Men generally are physically more active and have less body fat.

•Occupation• People that involve heavy physically

work require more energy than those who are physically inactive.

•Climate• People who live in cold countries

require more energy to keep their body warm,compare to those in the tropics.

• Body size/weight• An individual of bigger size require

more energy than another of smaller size.

• Lifestyle• People who indulge in sports

activities require more energy than those who lead a sedentary life.

Vitamins • The group of a complex non-

protein organic compounds which are needed in relatively small quantities by living organism.

• Provide no energy but are essential for maintenance of good health and efficient metabolism.

• Can be divided into:

water-soluble vitamins : B and C• cannot be stored in the body• have to be constantly supplied in the

daily diet

Fat-soluble vitamins : A,D,E and K• can be stored in the body fat

VITAMINS SOURCES FUNCTIONS

A EGG, MILK,CARROT, PAPAYA •For growth and promote healthy skin•For good night vision

B EGG, YEAST, LIVER, NUTS, TOMATO •Promotes the effective functioning of the nervous system•Controls the supply of carbohydrates to the muscle and nerve cells

C GREEN VEGETABLES, TOMATO, LIME •Increases immunity against diseases•Promotes healthy skin

D EGG, MILK, COD LIVER OIL •Helps in the absorption of calcium and phosphorus in the small intestines

E VEGETABLE OIL, EGG, LIVER, MILK,PALM OIL •Maintains a healthy reproductive system

K SUNFLOWER SEEDS, MAIZE •Necessary for the clotting of blood

Minerals

• Simple inorganic nutrients which must be obtained through the diet, either from food or dissolved in drinking water.

• Provide no energy but are vital for the maintenance of good health.

• Macrominerals/major minerals are required in relatively large quantities.• Calcium, phosphorus, sodium, potassium, chlorine

• Microminerals are required in trace amounts of less than 20mg per day.• Ferum, iodine, zinc

MINERALS SOURCES FUNCTIONS

CALCIUM MILK, ANCHOVIES, CHEES, EGG • Formation of strong bones and teeth

• Helps in clotting in blood

SODIUM COMMON SALT • Necessary constituent of blood plasma

IRON MILK, LIVER, MEAT, EGG • Builds haemoglobin of red blood cells

IODINE SEAFOOD • Necessary for the functioning of the thyroid gland

PHOSPHORUS MILK, FISH, EGG • Formation of strong bones and teeth

POTASSIUM MILK, EGG • For muscles contraction• Helps to maintain the balance

of blood and tissue

Roughage/dietary fibre

• Refer to the parts of plants that cannot be digested.

• The sources of roughage are vegetables, fruits, nuts and wholemealgrains.

• Functions • Helps to stimulate peristalsis and the muscle movement of the small and big

intestines

• Helps to lower blood cholesterol

• Prevent obesity, diabetes mellitus and heart diseases

• Deficiency of roughage in our diet causes constipation and other disorders of the large intestine.

Human require ~ 25 – 50 g of roughage per day.

Water• Water is very essential to the survival of

human as all metabolic reactions take place in solution.

• Water makes up about 70% off the total body weight.

• Functions of water• Controlling the body temperature• Removing excretory products• Controlling the concentration of blood• Transporting foods during digestion• As a lubricant• As a medium for biochemical reactions in the

body

• Failure to replace the lost water results in dehydration. A series loss of water can be fatal.

Selection of an appropriate balanced diet• Athletes

• CARBOHYDRATES: provide extra energy

• PROTEINS :build up muscles

• Reduce intake of fats

• Vegetarians• Eat a variety of vegetables, fruits,

cereals and beans

• Take a vitamin B12 supplement as it only found in animal sources

• Pregnant women• PROTEINS: the building of the foetal tissue

• CALCIUM & PHOSPHORUS: build the bones

• IRON: for the foetus to make red blood cells

• Cut down on sugar and fats

• Infants• PROTEINS: build soft tissue• CALCIUM & PHOSPHORUS: build bones and

teeth

• CARBOHYDRATES: provide energy for growth

• Breast milk is the best food

• Children • Need energy-rich food• PROTEINS, IRON, CALCIUM &

PHOSPHORUS : for their rapid growth

• Teenagers• GIRLS: IRON: making red blood cells to replace

those lost during their menstrual periods• Cut down on oil-rich food

• A diet of cereals, lean meat, fish, vegetables and fruits

6.3 Malnutrition

• Results from taking an unbalanced diet in which certain nutrients are lacking , in excess, or in the wrong proportions.

• Malnutrition leads to health problems and diseases.

The effect of malnutrition

• Kwashiorkor恶性营养不良: Stunted growth , muscles that waste away, diarrhoea ,oedema which causes the belly to swell, loss of appetite and apathy.

• Marasmus消瘦: lacks of energy-providing too .The child become very thin and looks old for his age.

DEFICIENCY IN PROTEINS

• Rickets佝偻病Gōulóubìng: CALCIUM & PHOSPHORUS. The child’s bones are soft and can bend out of shape.

• Osteoporosis 骨质疏松: CALCIUM,VITAMIN D & PHOSPHORUS. The elderly ’s bones become porous and break easily.

DEFICIENCY IN MINERALS

• Rickets佝偻病: VITAMIN D.

• Scurvy坏血病: VITAMIN C .Symptoms: bleeding and swollen gums.

• Sterility不育症: VITAMIN E.

• Night blindness 夜盲症: VITAMIN A

DEFICIENCY IN VITAMINS

DEFICIENCY IN PROTEINS DEFICIENCY IN MINERALS

DEFICIENCY IN VITAMINS

• Obesity痴肥: An obese person is at higher risk of developing high blood pressure and heart problems.

• Atherosclerosis动脉粥样硬化: A person leads to high blood pressure, puts a strain on the heart and increase the risk of stroke.

EXCESSIVE INTAKE OF LIPIDS

• Obesity

• Diabetes mellitus糖尿病: A higher risk of stroke, heart diseases and kidney failure.

EXCESSIVE INTAKE OF CARBOHYDRATES

• Gout痛风: Raise the level of uric acid in the blood.EXCESSIVE INTAKE OF PROTEINS

• The liver and kidney will be damaged : VITAMIN A,D,E & K

• an upset stomach : VITAMIN C

EXCESSIVE INTAKE OF VITAMINS

• High blood pressure : COMMON SALT

• Damage the liver and kidneys : IRON

• Bone formation in soft tissues & promotes formation of kidney stones : CALCIUM

EXCESSIVE INTAKE OF MINERALS

Ways to reduce the chance of contracting certain health problems due to one’s diet• Cutting down on the intake of saturated fats,red meat and organs.

• Cutting down on the intake of salt.

• Taking enough dietary fibre, which can help lower blood cholesterol level.

• Having enough sleep daily.

• Managing stress well.

• Exercising regularly.

• Abstaining from smoking and alcohol, which cause high blood pressure.

6.5 Food digestion

• Refer UEC Chapter 5

• Extra vocab:• Bolus 食团: a ball-like mixture of food and saliva that forms in the mouth

during the process of chewing

• Chyme食糜: the semi-fluid mass of partly digested food that is expelled by the stomach into the duodenum

• Erepsin肠肽酶: enzymes that digest peptones into amino acids

• Cud 反刍的食物: a portion of food that returns from a ruminant's stomach to the mouth to be chewed for the second time

6.6 Formation of faeces and defaecation• Function of colon:

• Expel faeces through peristalsis.• Faeces contain water, undigested food substances, indigestible fibre (cellulose), dead

cells, waste products (bile pigments, toxic).

• Provide a habitat for bacteria that maintain homeostasis in the alimentary canal.

• Defacecation is the process of elimination of faeces. • Controlled by the muscle around the anus• Due to increase pressure on the rectum

• Problems related to defaecation• Constipation 便秘• Haemorrhoids痔核• Colon cancer 结肠癌

6.7 Evaluating eating habits

• We should practice good eating habit and follow a balanced diet.

• Processed food contain food labels that provide information on the nutrition content.

Health problems related to eating habits• Obesity 痴肥

• Gastritis 胃炎• Gastric ulcer 胃溃疡

• Anorexia nervosa 神经性厌食症

• Bulimia 贪食症

Obesity 肥胖症• Excessive amount of body fat

• Result from lack of balance between food intake and energy expenditure

• May lead to cardiovascular disease 心血管疾病, diabetes mellitus

Gastritis 胃炎• Inflammation of the epithelium of the stomach

• Result from irregular food intake that leads erosion of the mucosal covering of the epithelial tissue by the gastric juice

• May lead to gastric ulcer 胃溃疡: open sores疮that develop on the lining of the stomach

Gastritis (this micrograph shows a result of Helicobacter pylori infection)

Normal

Anorexia nervosa神经性厌食症

• A psychiatric diagnosis that describe an eating disorder characterized by a low weight, fear of gaining weight, a strong desire to be thin and food restriction.• Voluntary starvation, purging 净空行为, vomiting, excessive exercise, drugs

• May lead to disturbed electrolyte balance (esp. phosphate – heart failure, muscle weakness, immune dysfunction, death), stunted growth, low essential hormones, chronically increased cortisol levels, osteoporosis.

Bulimia nervosa 贪食症/暴食症

• A psychiatric diagnosis that describe an eating disorder characterized by recurrent binge eating 暴饮暴食 followed by purging 净空行为 (e.g. vomiting, fasting, taking laxatives, enemas, excessive exercise).

• May lead to organ damage, teeth damage etc.

6.4 The importance of macronutrients and micronutrients in plants• Mineral nutrients are essential chemical elements

required by plants.

• Macronutrients 主要营养物质 are required in larger amount than micronutrients 微量营养物质.

• Deficiency in macronutrients that can be obtained from the air such as oxygen, carbon, and hydrogen rarely occurs.

• Determination of the requirement of nutrients of a plant seeding can be carried out through the Knop’s solution by eliminating it from this solution.

MacronutrientElements Functions Deficiency Symptom

Potassium (K) • Helps in the building of protein, fruit quality and reduction of diseases.• A cofactor for many enzymes.• Maintain turgidity in plants.

• Reduced protein synthesis.• Yellow-edges leaves.• Premature death of plants.

Calcium (Ca) • Synthesis of middle lamella.• Formation of spindle fibres.

• Stunted growth.• Distorted and cupped leaves.• Yellowing in the regions between the veins.

Magnesium(Mg)

• Magnesium is part of the chlorophyll.• It also helps activate many plant enzymes.• It involves in carbohydrate metabolism.

• Yellowing in the regions between the veinsof mature leaves.

• Red spot on leaf surfaces.• Leaves become cupped.

Nitrogen (N) • Nitrogen is a part of all living cells and is a necessary part of allproteins, enzymes and metabolic processes involved in the synthesisand transfer of energy.

• Nitrogen is a part of chlorophyll, the green pigment of the plant that isresponsible for photosynthesis.

• Helps plants with rapid growth, increasing seed and fruit productionand improving the quality of leaf and forage crops.

• Chlorosis褪绿 - general yellowing of older leaves (bottom of plant) due to inhibition of chlorophyll synthesis

• The rest of the plant is often light green

Phosphorus (P) • Synthesis of nucleic acids, ATP and phospholipids.• Acts as a coenzyme in photosynthesis and respiration.

• Poor root growth.• Formation of dull, dark green leaves.• Red or purple spot on old leaves.

Sulphur (S) • Components of certain amino acids, vitamin B and some coenzymes. • Yellowing of the affected leaves or entire plants.

MicronutrientElements Functions Deficiency Symptom

Copper (Cu) • Enzyme component.• Nitrogen metabolism and photosynthesis.• Reproductive growth and flower formation in plants.

• Death tips of young shoots.• Brown spot on terminal leaves.• Stunted growth.

Iron (Fe) • Cofactor in synthesis of chlorophyll.• Essential for young growing parts.

• Yellowing of young leaves.

Manganese(Mn)

• Activator of enzymes in photosynthesis, respiration of nitrogenmetabolism.

• A network of green veins on a light greenbackground.

• Brown or grey spots between the veins.

Molybdenum(Mo)

• Nitrogen fixing.• Reduction of nitrates during protein synthesis.

• Chlorosis in the areas between the veins of mature leaves.

• Pale green leaves.• Reduction in crop yield.

Zinc (Zn) • Leaf formation.• Synthesis of auxin (growth hormone).• Cofactor in carbohydrate metabolism.

• Mottled leaves with irregular areas ofchlorosis.

• Retarded growth.

Boron (B) • Aid in calcium ions uptake by roots, translocation of sugars,carbohydrate metabolism, germination of pollen grains.

• Required for normal mitotic division.• A cofactor in chlorophyll synthesis.

6.10 Photosynthesis

• Brief history

• Leaf structure and function

• Adaptation of plants from different habitats to carry out photosynthesis

Leaf structure• Leaf mosaic 叶镶嵌 is a growth arrangement where the cells overlap

each other as little as possible to receive as much light as possible to optimize photosynthesis

Air space

角质层

下表皮

上表皮

栅栏叶肉

海绵叶肉

角质层气孔保护细胞

维管束鞘木质部

韧皮部叶脉

气室

中脉

叶片

气孔

叶脉叶柄

Leaf Functions

• Air space - intercellular gaps within the spongy mesophyll. These gaps are filled with gas that the plant uses (carbon dioxide - CO2 ) and gases that the plant is expelling (oxygen - O2, and water vapor).

• Chlorophyll - a molecule in leaves that can use light energy from sunlight to turn water and carbon dioxide gas into sugar and oxygen (this process is called photosynthesis). Chlorophyll is magnesium-based and is green.

• Cuticle - the waxy, water-repelling layer on the outer surface of a leaf that helps keep it from dying out (and protect it from invading bacteria, insects, and fungi). The cuticle is secreted by the epidermis (including the guard cells) and is often thinner on the underside of leaves. The cuticle is generally thicker on plants that live in dry environments.

• Epidermis - the protective, outler layer of cells on the surface of a leaf. The guard cells (and stoma) are part of the epidermis. The surface of many leaves is coated with a waxy cuticle which is secreted by the epidermis.

• Guard cell - one of a pair of sausage-shaped cells that surround a stoma (a pore in a leaf). Guard cells change shape (as light and humidity change), causing the stoma to open and close.

• Palisade mesophyll - a layer of elongated cells located under the upper epidermis. These cells contain most of the leaf's chlorophyll, converting sunlight into usable chemical energy for the plant.

• Spongy mesophyll - the layer below the palisade mesophyll; it has irregularly-shaped cells with many air spaces between the cells. These cells contain some chlorophyll. The spongy mesophyll cells communicate with the guard cells (stomata), causing them to open or close, depending on the concentration of gases.

• Stoma - (plural stomata) a pore (or opening) in a plant's leaves where water vapor and other gases leave and enter the plant. Stomata are formed by two guard cells that regulate the opening and closing of the pore. Generally, many more stomata are on the bottom of a leaf than on the top.

• Vein (vascular bundle) - Veins provide support for the leaf and transport both water and minerals (via xylem) and food energy (via phloem) through the leaf and on to the rest of the plant.

Leaf Functions

Adaptation of plants from different habitats to carry out photosynthesis• Plans adapted to extreme environmental condition may have

modification in the distribution of stomata and chloroplasts.Examples Habitat Distribution of stomata Distribution of

chloroplasts

Mesophytes 中生植物e.g. hibiscus

Terrestrial environment that are neither particularly dry nor particularly wet

Many stomata on the lower surface of the leaf

Many chloroplasts in the palisade mesophyll cells, spongy mesophyll cells and guard cells.

(Succulent 多肉植物) xerophytes 旱生植物e.g. cacti

Terrestrial environment that have little liquid water available

Reduced leaves with sunken stomata.

The stem have many chloroplasts.

Hydrophytes 水生植物e.g. water lilies, Hydrilla sp.

Aquatic environment Stomata are found on the upper surface of the leaf or no stomata in submerged plants.

Many chloroplasts in the palisade mesophyll or in all parts of the plants in a submerged plants.

Mesophytes中生植物

Succulent xerophytes 多肉旱生植物

Hydrophytes 水生植物

Floating plants

• Floating leaves are generally tough because they have to withstand the weather and water movement.

• The chloroplasts are restricted to the upper surface of the leaves which are the only surface to be well lit.

• Stomata are also found only on the upper surface of the leaf.

• This upper surface often has a thick waxy cuticle to repel water and help to keep the stomata open and clear.

• Air-filled internal cavities are also often present.

• Weak stems produce a massive floating canopy of leaves as water provides all the necessary support.

Submerged plants• The presence of little or no mechanical

strengthening tissue in stems and leaf petioles.

• The epidermal (outermost) layer shows very little, if any, sign of cuticle formation. All the surface cells appear to be able to absorb water, nutrients and dissolved gases directly from the surrounding water.

• Xylem is often greatly reduced, if not absent.

• There are also no stomata on the leaves.

• Roots are often also reduced and their main function is anchorage. The root hairs which function in absorption are often absent and roots themselves may be entirely dispensed with (e.g. Bladderwort).

• The submerged leaves are often highly dissected or divided to maximise surface area for absorption and photosynthesis and minimises water resistance.

• Air-filled cavities often extend throughout the leaves and stems of aquatic plants, providing an internal atmosphere.

Floating and submerged plants

6.11 Mechanism of photosynthesis

COMPARISON OF LIGHT REACTION & DARK REACTION

LIGHT REACTION 光反应 DARK REACTION 暗反应

SIMILARITIES

•Both occur in the chloroplast

•Both involve chemical reactions

•Both are reactions related to photosynthesis

•Both occur during the day

DIFFERENCES

Occurs in granum Occurs in stroma

Requires sunlight Does not require sunlight

Involves photolysis of water Involves reduction of carbon dioxide

Produces water & oxygen Produces glucose

Substance required in reaction is

water

Substance required in reaction is

carbon dioxide

6.12 The factors affecting photosynthesis• Light intensity

• Concentration of carbon dioxide

• Temperature

• Photosynthesis rate will be different throughout the day and the year.

• There factors can be controlled artificially in green houses.

6.13 A caring attitude towards plants

• The importance of photosynthesis• Carbon fixation

• Coal

• Oxygen

6.14 Technology used in food production • To improve the quality & quantity

of food production in Malaysia through :• Direct seeding

• Hydroponics

• Aeroponics

• Selective breeding

• Tissue culture

• Genetic engineering

• Soil management

• Biological control

• Direct seeding 通过植被直接进行植物播种• Sow the seed directly into

undisturbed soil.

• Plants grow faster as roots are not damaged during transplantation.

• Hydroponics 水耕栽培

• Grow of plant using aerated culture solution which contain all requirednutrients.

• Less space and pesticides are required.

• Aeroponics 气耕• A modification of hydroponics

where the culture solution is sprayed directly to the roots of the plants.

• Less space and pesticide is required.

• Selective breeding 优育• Selection of parents that can

produce offspring which desirable traits.

• Produce crops and offspring with better quality and quantity.

Big kernalThick mesocarpThin endocarp

Big kernalThick mesocarpThin endocarp

• Tissue culture组织培养• Growth of tissue

and/or cells on a growth media.

• Mass production of desirable strain and clones

• Genetic engineering基因工程• The deliberate modification

of the characteristics of an organism by manipulating its genetic material.

• Quick incorporation of desirable traits.

• Soil management土壤管理• All activities used to

protect soil and enhance its performance

• Reduce soil erosion, leaching

• Biological control生物防治• The control of a pest by the

introduction of a natural enemy or predator.

• Cost-effective and do not pollute the environment.

Ladybird eating Aphid

6.15 Technological development in food processing• The necessity for food processing:

• Destroying microorganisms

• Extending the lifespan of food

• Avoiding food wastage

• Diversifying the uses of food, like milk and dairy products

• Ensuring sufficient food supply because processed food can last longer

• Food can be easily sent to places with insufficient food supply

Food processing methods• Cooking

• to kill the bacteria

• Using salt, sugar & vinegar • Osmosis for dehydration – condition

unflavourable for bacteria growth

• Fermentation 发酵• yeast turns glucose into ethanol + CO2

• Drying • dehydration

• Pasteurisation巴氏杀菌• heated to certain temperature and rapid

cooling

• Canning • sterilised at high temperature >120 °C in

vacuum - kill bacteria and prevent bacteria from growing

• Refrigeration • temperature low -15°C - slow down the

action of microorganism