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  • Created by: BUSHRA
  • Created on: 03-04-13 18:04



  • A balanced diet gives you all the nutrients you need ; carbonhydrates, fats, protiens, vitamins, mineral salts, fibre and water
  • Malnutrition is caused by having too much or too little of some nutrients in your diet
  • Too little leads to dieficiency illnesses e.g. little iron leads to anaemia
  • Too much nutrients such as carbonhydrates and fats lead to obesity
  • Excess energy is deposited in the adipose tissues which leads to many disease e.g.  CHD, cancer , type 2 diabetes, hypertension e.t.c
  • Energy intake < energy used
  • BMI = mass in kg /  (heightin m)2
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  • Deposition in the coronary artery walls narrows the size of the lumen. This restricts blood flow to the heart muscle, which may cause oxygen starvation


  • Excess salt in your diet will decrease the water potential of your blood. This leads more water being in the blod increasing the blood pressure leading to hypertension that can damage the inner linning of the arteries


  • Saturated fats e.g animal fats are more harmful than unsaturated fats e.g plant oils. Polysaturated and monosaturated fats e.g olive oil are beneficial to our health  
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  • Cholesterol are associated with saturated fats in meat, eggs and dairy products. Cholesterol is made in the liver from saturated fats and too much in the blood is harmful
  • Cholesterol is not soluble so it can be combined with lipids and protiens to be made soluble
  • HDL are mainly protiens that carry cholesterol from the tissues to the liver, in the liver it is broken down or used up in cell metabolism lowering cholesterol levels
  • LDL are mainly lipids that carry cholesterol from the liver to the tissues raising the blood cholesterol levels
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  • Fertilisers replace minerals in soil. These minerals may have been removed by previous crops. Fertilisers containing nitrate, potassium and phosphate. They increase the rate of growth and the overall size of the crops
  • Pesticides are designed to kill organisms that cause diseases in crops. These diseases would reduce the yeild or kill the crop. Many crops are sprayed with fungicides to reduce the effect of fungal growth in the leaves and roots. Animals can be treated with pesticides
  • Infected animals can be treated with antibiotics. These reduce the spread of disease among animals that are intensively farmed and in close proximity to each other. Such diseases could reduce the growth performance of the animals and many impair reproduction
  • Selective breeding reqires isolation, artificial selection and inbreding or line breeding. In this selection you select a pair of animals or plants that display the characteristics you want. This pair is allowed to reproduce. The offsring produced are sorted carefully to select those with the best combination of characteristics and are left to reproduce
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  • Marker assisted selection has been employed. A section of DNA is used as a marker to recognise the desired characteristics. Once offspring have been produced from the selected parents, their DNA is cheecked for the marker. This allows selection at a very early age.


In plants it is possible to:

  • Improve the growth rate of crops
  • Increase the size of yield from each plant
  • Reduce losses of crops due to disease and pests
  • Make harvesting easier by standardising plant size
  • Improve plant responses to fertiliseres

In animals it is possible to:

  • Improve the rate of growth
  • Increase productivity
  • Increase resistance to disease
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  • Microorganisms obtain nutrients from digesting organic matter around them which leads to food spoilages
  • There are 4 main ways that microorganisms spoil food:

(1) Visible growth- Fungi growing on food

(2) Microorganisms use external digestion, they release an enzyme to absorb the nutrients leaving the food sweet smelled and eventually much due to action of enzymes

(3) Toxins being produced- Clostridium botulinum produces toxin botulin

(4) The present of microrganisms can cause infection e.g. samonella bacteria in poultry attacks the lining of the stomach and digestive system

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  • SALTING -This process dehydrates the microorganism by water leaving them via osmosis
  • SUGAR- This process dehydrates the microorganism by water leaving them via osmosis
  • FREEZING - These do not kill the microorganism but ****** enzyme activity so their metabolism, growth and reproduction is very slow
  • IRRADIATION - Ionising radiation kills the microorganism by distrupting their DNA structure
  • PICKLING - This uses an acid PH to kill microorganisms by denaturing their enzyme and other protiens
  •  HEAT TREATMENT/ PASTEURISING -This involves heating to 72'c for 15 seconds and then cooling rapidly to 4'c, killing harmful microorganisms
  • COOKING - The heat denatures enzymes and other protiens and kills the microorganisms
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  • BREAD - Made by mixing yeast ( a fungus) sugar, flour and water into a dough. the yeast turn the sugar into ethanol and carbon dioxide - makes the bread rise
  • WINE - Made by adding yeast to grape juice. The yeast turn the sugar in the grape juice into ethanol ( alcohol) and carbon dioxide
  • CHEESE - Made by adding bacteria to milk. The bacteria turn the sugar in the milk into lactic acid which causes the milk to curdle. An enzyme is then used to turn the curdled milk into curds and whey. The curds are seperated off and left to ripen into cheese
  • YOGHURT - Made by adding bacteria to milk. The bacteria turn the sugar in the milk into lactic acid causing the milk to clot and thicken into yoghurt
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  • Production of protien can be many times faster than that of animal or plant protien
  • Production can be increased and decreased according to demand
  • There are no animal welfare issues
  • They provide a good source of protiens for vegetarians
  • The protien contains no animal fat or cholesterol
  • SCP production could be combined with removal of waste products


  • Many people may not want to eat fungal protien or food that has been grown on waste
  • Isolation of the protein- The microorganism are grown in huge fermenters and need to be isolated from the material on which they grow
  • The protien has to be purified to ensure it is not contaminated
  • Palatablity - The protien does not have the texture or taste of traditional protien sources
  • Infection - Culture can be contaminated with wrong organism  
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  • PARASITES - They are organisms that live in or on another living thing (host), they harm the host by taking all their nutrients e.g Head louse ,Tapeworms
  • PATHOGENS - They are organisms thta cause disease by taking nutrients from their host but also cause damage in the process
  • BACTERIA - They are smaller cells to us and reproduce every 20 minutes and once in the human body they can multiply rapidly. Their presence can cause disease by damaging cells or releasing wsate products that are toxic to us e.g. Cholera is caused by the bacterium Vibrio cholerae
  • FUNGI - Fungi can cause a variety of disease e.g Athlete's food and ringworm are called by a fungus called Tinea
  • VIRUSES - They invade cells and take over genetic machinery and other organelles of the cells. They can cause the cell to manufacture more copies of the virus. The host cell will eventually burst releasing many new viruses e.g HIV/ AIDS, Cold and Influenza
  • PROTOCTISTA - They are caused by animal- like protoctista ( protozoa), they enter host cells and feed on host content as they groe e.g .Malaria parasites
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  • Malaria is spread by vector

(1) A person with malaria

(2) Gametes of plasmodium in blood

(3) Female Anopheles mosquito sucks blood

(4) Plasmodium develops and migrates to a mosquito's salivary glands

(5) An uninfected person is bitten

(6) Plasmodium migrates to liver

(7) Plasmodium migrates to blood

  • Malaria parasites can be trancmitted by careless and unhygenic medical practices, unscreend blood transfusion , unsterilised needles and across placenta into an unborn child
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  • HIV/ AIDS - Caused by the human immunodeficiency virus. The virus enters the body and remains unactive but when it becomes active it destroys T-helper cells in the immune system which reduces the ablity to resist infections. You will be unable to defend yourself against pathogens that may enter your body and may contract a range of OPPORTUNISTIC INFECTIONS
  • HIV can be transmitted by exchange of body fluids such as blood-blood contact, unprotected sexual intercourse, unscreened blood transfusions, use of unsterilised surgical equipment, sharing hypodermic needles, accidents such as needle stick , across placenta or during child birth and from mother to baby during breast feeding
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  • TB is transmitted by droplet infection
  • In many people it is inactive or controlled by thier immune system
  • TB is contracted by overcrowding, poor ventilation, poor health, poor diet , homelessness and living or working with people who have migrated from areas where TB is common


  • Common in sub-saharan africa and other developing countries
  • This is beacuse tehre is limmited acess to healthcare, limited health education, limited equipment to reduce the spread of infection and overcrowded conditions
  • The prevalence of these diseases slow down social and economic development as they increase death rates, reduce productivity, and result in high healthcare costs
  • Studying the global distribution of these disease are important as the information can be used to find out where people are at most risk, any data collected can be used to predict where epidermics are most likely to occur, its important for research e.g how it spreads, it allows organisations to provide aid where it's needed most
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  • THE SKIN - The outer layer of the skin is called the epidermis, it is produced by mitosis and travels to the skin. As they migrate they dry out and the cytoplasm is replaced by a protien called keratin. This process is called keratinisation. Once they reach surface of the skin they are dead and these dead cells slough off forming an effective barrier
  • MUCOUS MEMBRANES - The epithelium layer contains mucus secreting cells called goblet cells.In the airways the mucus lines up trapping pathogens that may be in the air. The membrane contains ciliated cells these sre long hair like structures that waft along . They move the mucus up the trachea where it enters the oesphagus and is swalled into the digestve system where the acidity of the stomach will denature the pathogens enzymes.
  • The eyes are protected by antibodies in the tear fluid
  • The ear canal is lined by wax, which traps pathogens
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  • NEUTROPHILS- They have a multibodied nucleus and are manufactured in bone marrow. They are short lived but they will be released in large numbers as a result of an infection
  • MACROPHAGES - They are larger cells manufactured in bone marrow. They travel as monocytes then settle down in the body organs and develop into macrophages. They play an important role in the specific responses to invading pathogens


  • A phagocyte recognises the antigens on a pathogen. The phagocyte engulfs the pathogen. The pathogen is now contained in a phagocytic vacuole. A lysome fuses with the pagocytic vacuole and digestive enzymes break down the pathogen. The phagocyte presents the antigens to T lymphocytes
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  • Infected cells relese histamines that attract neutrophils , they cause a reponse of making the capillaries more leaky as fluid is leaving, this causes swelling and redness. The tissue fluid passes the lympahtic system leading the pathogens to the macrophages so they can activate the specific response known as immune response which is the activation of lymphocytes in the blood to help fight disease

                                        phagocytosis (



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  • Antigens are molecules that stimulate an immune response. Almost any molecule can act as an antigen.Antigens are large molecules with complementary shape to their antibodies. An antigen is specific to the organism. They usually are protiens or glycoprotiensin or on the plasma membrane. Our own anigens are recognised by our immune system and do not stimulate any response.


  • Four polypetide chains held together by disulfide bridges
  • The variable regions of the antibody form the antigen binding sites. The shape of the variable region is complementary to a particular antigen. The variable regions differ between antibodies
  • The hinge region allows flexiblity when the antibody binds to the antigen
  • The constant regions allow binding to receptors on immune sysytem cells e.g. phagocytes. The contant region is the same in all antibodies
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  • NEUTRALISATION- Antibodies covering the pathogen binding sites preventing then from binding to a host cell and entering the cell
  • AGGLUTINATION - A large antibody can bind many pathogen together. The group of pathogens is too large to enter a host cell
  • PREVENTING THE PATHOGEN BINDING TO HUMAN CELLS - When antibodies bind to tha antigens on the pathogen they may block the cell surface receptors that the pathogens need to bind to the host cell. This means the pathogen can't attach to or infect the host cells.


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  • Communication is acheived through cell surface molecules and through the release of hormone like chemicals called cytokines. In order to detect a signal, the target cell must have cell surface receptors. B lyphocytes and T lyphocytes have receptors that are complementary to the foreign antigen. The antigen may be an isolated protein, it may attach to a pathagen or it may be on the surface of a host cell. When the antigen is detected, the lymphocyte is activated or stimulated. Chemical signals are also dtected by their target cells using specialised cell surface receptors
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  • A T lymphocyte is another type of white blood cell
  • Their surface is covered with receptors
  • The receptors bind to the antigens presented by the phagocytes ( antigen presentation)
  • Each T lymphocyte has a different receptor on its surface
  • When the receptor on the surface of a T lymphocyte meets a complementary antigen, it binds to it so each T lymphocyte will bind to different antigens
  • This activates the T lymphocyte - it divides and diffrentiates into different types of T lymphocytes that carry out different functions ( clonal selection)
  • Some activated T lymphocyes release substances to activate B lymphocytes ( T helper cells)(clonal expansion)
  • Some attach to antigens on a pathogen and kill the cell ( T killer cells)(clonal expansion)
  • Some become memory cells (for immunological memory)*(clonal expansion)
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illustration ( T cell (

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  • B lymphocytes are another type of white blood cells
  • They're covered with proteins called antibodies
  • Antibodies bind to antigens to form an antigen- antibody complex
  • Each B lymphocyte has a different shaped antibody on it's surface
  • When the antibody on the surface of a B lymphocyte meets it's complementary antigen, it binds to it so each B lymphocyte will bind to different antigens
  • This together with substances relaesed from the T lymphocytes activate the B lymphocytes
  • The activated B lymphocytes divides by mitosis and diffrentiate ( clonal expansion)
  • Some become plasma cells so they can manufacture antibodies
  • Some become memory cells for immunological memory
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  • Vaccines contain either whole live microorganisms, a harmless or attenuated version of the pathogenic organism, a dead pathogen, a preparation of the antigens from a pathogen or some harmless toxin
  • Herd vaccination is using a vaccine to provide immunity to all or almost all the population at risk. Once enough people are immune the disease can no longer spread
  • Ring vaccination is used when the disease is a new case. Ring vaccination involves vaccinating all the people in the immediate vicinity os the new case. This may mean vaccinating the people in the surronding houses, or even the whole vilage or town. Ring vaccination is used in many parts of the world to control the spread of livestock disease
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  • The influenza virus is caused by influenza (flu)
  • Proteins ( neuraminidase and haemagglutinin) on the surface of the influenza virus acts as antigens, triggering the immune system
  • These antigens can change regularly, forming new strains of the virus
  • Memory cells produced from vacciantion with one strain of flu will not recognise other strains with different antigens 
  • Every year there are different strains of the influenza virus circulating in the population so a different vaccine has to be made
  • Laboratories collect samples of these different strains, and organisations such as WHO and CDH test the effectiveness of different influenza vaccines against them
  • New vaccines are develpoed and one is chosen every year that is the most effective against the recently circulating influenza viruses
  • Governments and heath authorities then implement of a programme of vaccination using the most suitable vaccine. This is a good example of *** society uses science to inform descisin makeing
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  • Cigarette smoke contains carcinogens
  • Thes carcinogens may cause mutations in teh DNA of lung cells, which could lead to uncontrolled cell growth and the formation of malignant tumour
  • Malignant tumours grow uncontrollably blocking air flow to areas of the lung
  • This decreases gas exchange and leads to a shortness of breath because the body is struggling to take in enough oxygen
  • The tumour uses lots of nutrients and energy to grow, which causes wieght loss


  • Chronic bronchitis is inflammation of the lungs
  • The upper respiratory tract is lined with goblet cells that produce mucus to trap microorganisms. The tract is also lined with cilia that beat to move the mucus towards the throat so it can be removed
  • Cigarette smoke damages the cilia and causes the goblet cells to produce more mucus
  • The mucus accumulates in the lungs which causes increase coughing to try and remove the mucus
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  • Microorganisms multiply in the mucus and cause lung infections that lead to inflammation which decreases gas exchange
  • Chronic bronchitis is a type of chronic obstructive pulmonary disease ( COPD), COPD is a group of disease that involve permanent airflow reduction


  • Emphysema is a lung disease caused by smoking or long term exposure to air pollution - foriegn particles in the smoke (or air) become trapped in the alveoli
  • This causes inflammation which encourages phagocytes to the area. The phagocytes produce an enzyme that breaks down elastin
  • The alveolar walls are destroyed and the elasticity of the lungs is lost
  • This reduces the surface area of the alveoli so the rate of gaseous exchange decreases
  • Symtoms of emphysema include shortness of breath and wheezing. People with emphysema have an increased breathing rate as they try to increase the amount of air ( containg oxygen) reaching their lungs
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  • When damage occurs to the linning of an artery, white blood cells move into teh area
  • Over time more white blood cells, lipids, and connective tissue build up and harden to form a fibrous plaque at the site of damage- an atheroma
  • The atheroma partially blocks the lumen of the artery and restricts blood flow
  • Atherosclerosis is teh hardening of the arteries due to the formation of atheromas
  • Cigarettes smoke contains nicotine, which causes increase in blood pressure. Increased blood pressure can cause damage to the arteries, leading to formation of more atheromas


  • CHD is when the cornary arteries have lots of atheromas in them. This restricts blood flow to the heart
  • A reduction in blood flow reduces the amount of oxygen an area of the heart gets. This can cause pain (angina) or a heart attack
  • Smoking increases the risk of CHD because carbon monoxide irreversibly combines with haemoglobin reducing the amount of oxygen transported in the blood , reducing amount of oxygen available to tissues including the heart
  • Also nicotine in cigarette smoke makes platelets sticky, increasing the chance of blod clots forming. If cotting happen in teh cornary artries it could cause a heart attack
  • The presence of atheromas also increases the risk of blood clots forming   
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  • Also nicotine in cigarette smoke makes platelets sticky, increasing the chance of blod clots forming. If cotting happen in teh cornary artries it could cause a heart attack
  • The presence of atheromas also increases the risk of blood clots forming


  • A stroke is a rapid los of brain function due to distruption in the blood supply to the brain
  • This can be caused by blot clot in an artery leading to the brain which reduces the blood supply so therefore oxygen that can reach the brain
  • Nicotine increases risk of stoke as it increases the risk of blood clotting
  • Carbon monoxide also increases teh risk of strok beacause it reduces the amount of oxygen available to the brain by combining with haemoglobin


  • A blood clot is known as a thrombis. Nicotine increases the risk of clot as it causes stickness of the platelets. A clot stops flow of blood in the arteries and sometimes the clot can brak free and flow around the body till it raches a narrow artery and blocks blood flow.












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  • Atherosclerosis
  • Coronary heart disease (CHD)
  • Stroke


  • Carbon monoxide can damage the inner linning ( endothelium) of the arteries. If the person also has high blood pressure this will add to such damage.The damage is repaired by the action of white blood cells ( phagocytes). These encourages the growth of amooth muscle and the deposition of fatty substances. The deposits include cholesterol from LDL's. High blood pressure also increases the deposition of cholesterol. The deposistes or atheromas may also include fibres, dead blood cells and platelets. The process of deposition is called atherosclerosis. This build up of atheromas occurs under the endothelium, in the walls of the atrery. It may grow enough to break through the inner linning of the artery. The atheroma eventually forms a plaque which sticks out into the lumen of the atrery. This leaves the atrety wall rougher and less flexible than in a healthy artery. It also reduces the size of the lumen of the artery which reduces blood flow 
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Bethany Cunningham


This is definitely getting saved to my favourites, it is great in detail. Well done!

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