Biology F212 Food and Health

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  • Created on: 25-05-15 12:18


A balanced diet- A diet in which all nutrient required for health and growth are proved

How an unbalanced diet leads to malnutrition: Obesity is consuming more energy than needed and the excess energy is deposited as fat. Obesity is when excess fat impairs health. We usually define obesity as when a person has a BMI of 30 or over. Which is where the body is composed of 20% or more above the weight recommended for the height.

Mass (Kg)

-------------   = BMI

Height (M)^2

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Health related diseases

Diet and CHD: Excess salt in the diet decreases the water potential of the blood. As a result, more water is held in the blood by osmosis, so therefore the blood pressure increases causing hypertension, which can damage the inner lining of the arteries, which is an early stage in the process of otherosclerosis. Sat fats can cause damage to the heart.  

Effects of high blood cholesterol on the heart and circulatory system: Cholesterol is moved around the body in the form of lipoproteins

HDLs, are combinations of unsaturated fats, cholesterol and protein. They move cholesterol from the body tissue to the liver, where cholesterol can be broken down. HDLs reduce cholesterol in artery walls.

LDLs, Produced by the combination of saturated fats, cholesterol and protein. They tend to carry cholesterol from the liver to body tissue. High conc. of HDLs causes deposits in the artery wall. Sat fats decrease the activity of LDL receptors, so as more LDLS enter the blood, less is removed.

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Animals relying on Plants

Plants carry out photosynethesis, converrting light energy into chemical energy. Also absorbing nitrogen and can therefore make more organic molecules. Herbivores normally use these biological molecules when they eat and digest food. Humans eat both plants and herbivores, gaining our nutrition directly and indirectly.

Selective breeding: A pair of plants which show desirable traits will be allowed to reproduce, then their offspring are sorted into those with the same desirable traits. If this is continued through multiple generations, the traits become more distinct.

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Use of fertiliser, pesticides and antibiotics

Fertilisers: Replaces minerals in the soil which have been removed by other crops, they contain nitrates, phosphates and potassium. They increase the rate of growth.

Pesticides: Kills organisms which cause harm and disease to crops. The use of pesticides increases the yield, because pesticides kill organisms which would otherwise kill the crop.

Antibiotics: Infected animals can be treated with antibiotics to reduce the spread of disease in animals which live close together. Disease normally reduces the growth performance of animals.

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Use of microorganisms

Advantages: production of protein can be many times faster than that of animal or plant protein.

Production can be increased or decreased to support demand

No animal welfare issues

They provide a source of protein for vegatarians

No animal fats or cholesterol

Disadvantages: Many people may not want to eat fungal protein, no taste and no texture

The microorganisms are grown in large fermenters and need to be isolated from the material on which they grow.

The protein has to be purified to avoid contamination

Conditions to grow are ideal for pathogens

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Methods of preserving foods

Salting: Dehydrates the organisms as water leaves by osmosis

Adding sugar: Same principle as 'Salting'

Pickling: Acid pH denatures the mircoorganisms proteins and enzymes

Freezing: Slows down enzymes in mircoorgansims so that their metabolism slows down, so that reproduction and growth is slowed

Heat treatment: Kills harmful microorganisms

Irradiation: Kills organisms by altering the structure of DNA till it is unusable

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Health and Disease

Health: A state of mental, physical and social well being

Disease: A departure from good health caused by a malfunction of the mind or body.

Parasite: An organism which lives on or in another organism causing harm to its host

Pathogen: A organism which causes disease

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Cause and means of Transmission of Malaria

Malaria: If the host has malaria, the femal anopheles mosquito will **** the parasite gametes into its own stomach

The gametes fuse and the zygote develops in the mosquito's stomach

Infective stages are formed and these move to the mosquito's salivary glands.

When the mosquito bites another person, it injects a little saliva as an anticoagulant

The saliva contains the infective stage of the parasite

In the human host, the infective stage enters the liver where they multiply before pssing into the blood again

In the blood they enter red blood cell, where gametes are produced.

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Cause and means of Transmission of HIV/AIDs

HIV-Human Immunodefciency Virus

AIDS- Aquired Immuno Deficiency Syndrome

The virus enters the body by-

Exchange of bodily fluids such as blood to blood contact, Unprotected sex, Unscreened blood transfusions, Use of unsterilised surgical equipment, Sharing hypodermic needles, Accidents such as 'needlestick', Across the placenta or during childbirth, From mother to baby during breastfeeding

It can remain unactive in the body for many years. Once the virus becomes active it attacks and destroys T helper cells in the immune system, effectively rendering the immune system useless

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Cause and means of Transmission of Tuberculosis

The bacteria (Mycobacterium Tuberculosis) are contained in tiny droplets of liquids which are released when an infected person coughs, sneezes or talks. But it takes close contact with an infected person over a long period of time to contract the disease. There are a number of conditions which make contraction and spread more likely.


Poor ventalation

Poor diet

Poor health


Living in areas where TB is common

TB can also be contracted from the milk or meat of catte

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Immune response

Immune response- The specific response to a pathogen, which involves the action of lymphocytes and the production of antibodies.

Antigen: Molecules that stimulate immune response

Antibodies: Protein Molecules that can be identify and neutralise antigens

Primary Defenses:

Skin- The outer layer is the epidermis, which consists of layers of cells.

Mucous membrane- Oxygen and nutrients must enter our blood, so the body can be exposed to infection as they may harbour microorganisms. So th airways, lungs and digestive system are protected by mucous membranes. In the airway, mucis lines the passages and trapsany pathogens that may be in the air. The epithelium is also ciliated cell. The ciliated cells move in a coordinated fashion to waft layers of mucus up to the top of the trachea where it can enter tha oesophagus. Most of these then enter the stomach which has digestive juices and a pH of about 2.

HCl is the stomach acid

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The pathogens attaches to the phagocyte by antibodies and surface receptors

Pathogen is engulfed by infolding of phagocytemembrane


Lysosome release lysins into the phagosome (a vacuole with the pathogen trapped inside)

Harmless product of digestion are absorbed.


Any other unused substances are exocytosed out of the cell.

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Structure of a antibody

Four polypeptide chains held together by disulfide bridges

Y- Shaped

A constant region, which is the same on all antibodies. This enables the antibody to attach to the phagocytic cells and help the proces of phagocytosis

A variable region which has a specific shape and differs from the one type of antibody to the next. It ensure that the antigen can attach only to the correct antigen.

Hinge region, which allows a certain degree of flexibility. They allow the branches to move further apart to allow attachment to more than one antigen.

They attach to the antigen on a pathogen. The pathogen may use these antigens as a binding site, for example, which would bind to the host cell. if the antibody blocks the binding site, the pathogen cannot bind to its host cell- neutralisation

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Cell signalling

The immune response involves a coordinated response between a wide range of cells.

A body cell is infected with a pathogen

Lysosomes will attempt to fight the invader

The pathogen will often be damaged, and parts of the pathogen may be presented on the plasma memebrane of the infected cell. This has two effects : Acts as a distress signal and can be detected by cells from the immune system. Or. Acts as amrkers to indicate that the host cell is infected- T killer cells recognise that the cell is infected and must be destroyed.

Pathogen engulfs by macrophage cells from the immune system, removal of antigens from pathogen, Antigens presented on surface of engulfed cells: They then find the lymphocytes that can neutralise the particular antigen. Selection of correct T Killer cells and T Helper cell:

Either Reproduction of T helper cells, release of interleukins, activation of B cells, Reproduction of B cells

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Selection of correct T Killer cells and T Helper c

1) Reproduction of T helper cells, Release of interleukins, Activation of B cells reproduction of B cells

a) Some B cells differentiate to make plasma cells, Plasma cells manufacture antibodies

b) Some B cells differntiate to make B memory cells

2) reproduction of T killer celss, T killer cells search for infected cells, T killer cells attach to infected cells, T killer cells secrete toxic substances (hydrogen peroxide) into infected cell to kill cell and the pathogen it contains.

There are a range of cytokines release by cells: Macrophages release monokines that, attract neutrophils, stimulate B cells to differentiate and release antibodies

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Memory cells

Circulate the body for a number of years, so that if a pathogen presenting in the same antogen returns, the memory cells can stimulate the production of plasma cells and antibodies much more quickly.


White blood cells with a large nucleus and specialised receptors on their plasma membranes

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Primary and Secondary Response


When the infecting agent is first detected, the immune system starts to produce antibodies, but it takes a few days before the number antibodies in the blood rises to a level that can fight th infection.


The immune system recognises the pathogen if the body is infected agian, so the immune system can swing into action more quickly.

The production of antibodies rises sooner and reaches a higher concentration.

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Natural and Artificial Immunity


Passive- Antibodies provided via the placenta or breast milk. This makes the baby immune to diseases the mother is immune to. It is very useful in the first year of the baby's life, when the immune system is developing.

Active: Immunity provided by antibodies made as a result of infection. A person suffers from disease once and is then immune (e.g. immunity to chicken pox)


Passive- Immunity provided by injection of antibodies made by another indivual (e.g. tetanus)

Active- Immunity provided by antibodies made in the immune system as a result of vaccination. A person is injected with a weakned, dead or similar pathogen, or with antigens, and this activates his/her immune system (e.g. immunity to TB and influenza)

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Vaccinations provide immunity to specific diseases. A person who has been vaccinated has artifiacial immunity. This is created by the deliberate exposure to antigenic material that has been rendered harmless. The immune system treats the antigenic material as if it was a real disease. As a result, the immune systm manufactures antibodies and memory cells. The memory cellx provide the long-term immunity.

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Effect of smoking on the gas exchange system

Short term:

Tar is a combination of chemicals which settles on the inner lining of the airways and alveoli. This increases the diffusion distance for oxygen entering the blood and for carbon dioxide leaving the blood.
The tar paralyses or destroys the cilia on the surface of the airway so they are unable to move the layer of mucus away and up to the back of the mouth. The tar also stimulates the goblet cells and mucus secreting glands to enlarge and release more mucus. The mucus collects in the airways.
Bacteria and viruses that become trapped in the mucus are not removed. They can multiply in the mucus and eventually a combination of mucus and bacteria may block the bronchioles.
The presence of bacteria and viruses means that the lungs are more susceptible to infection. Smokers are more likely to catch diseases such as influenza and pneumonia. 

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Effect of smoking on the gas exchange system

Long term:

The mucus and bacteria irritates the airways, and they need to be cleared to get oxygen into the alveoli. This leads to smokers cough to try and shift the bacteria-laden mucus.
This constant cough damages the lining of the alveoli and airways. This lining will eventually be replaced by scar tissue which is thicker and less flexible. The layer of smooth muscle in the bronchioles also thickens. This reduces the lumen of the airway, and the flow of air is restricted.

Frequent infections as a consequnce of bacteria and viruses in the mucus inflames the lining of the airway, which damages it. This attracts white blood cells which release enyzymes to get out of the blood and into the airways. The enzyme digests part of the lining of the lungs. The enzyme elastase is used which damages the elastic tissue of the lining the lungs. Loss of the elastic tissue in the alveoli can reduce the elasticity of their wall, so the alveolus wall does not push out as exhale. The bronchioles collape, trapping air in the alveoli. This can cause the alveoli to burst as pressure in the lung increases.

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Effect of smoking on the gas exchange system

Chronic Bronchitis:

Inflamation of the lining of the airway, damage to the cilia and overproduction of mucus

Symptoms- Irritation of the lungs, Contiual Coughing, Coughing up mucus that is oftn filled with mucus and white blood cells.

Emphysema :

The loss of elasticity in the alveoli which causes them to burst

Symptoms- Shortness of breath, especially when exerting themselves. The loss of elasticity making it harder to exhale. Breathing becomes shllower and more rapid. The blood is less well oxygenated and fatigue occurs.

Lung Cancer: Continual coughing, shortness of breath, pain in chest, blood coughed up in the sputum.

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Effects of nicotine and carbon dioxide on heart


Causes addiction. Mimics effects of ACh at synapses between nerves, this makes nervous system more sensitive and smokers feel more alert. Causes adrenaline to be released. Causes constriction of the arterioles leading to the extremities of the body. Makes platelets sticky, this increase the risk that a blood clot or thrombosis may form.

Carbon Monoxide:

Haemoglobin has a higher affinity for CO than for O2. Carbon monoxide combines with haemoglobin, which is very stable. This reduces the oxygen carrying capacity of the blood. Smokers feel this when they exercise. The body will detect lower levels of oxygen and the heart rate will rise.

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Effects of nicotine and carbon dioxide on heart

Atherosclerosis: Carbon monoxide can damage the endothelium of the artreies. The damage is repaired by phagocytes. This encourages the growth of smooth muscles and the deposition of fatty substances. The deposits include cholseterol from LDLs. These deposits (atheromas) may also include fibres, dead blood cells and platelets. Atheroma eventually forms a plaque which sticks out into the lumen of the artery. This leaves the artrey wall rough and less flexible. It also reduces the lumen of the artery, reducing blood flow.

CHD: The coronary arteries carry blood to the heart muscles. They carry blood at high pressure which makes them prone to damage and atheroclerosis. When the lumen of a coronary artery is narrowed by plaques, there is less blood flow to the heart muscle, so they recieve less oxygen for respiration. 

Angina, severe pain in chest which may extend down the left arm or up the neck. Heart attack/ Mycocardical infaction- the death of part of the heart muscle, usually caused by clots in the coronary artery blocking the flow of blood to the heart muscle. Heart failure, when the heart cannot sustain pumping action; this can be due to the blockage of a major artery, but there are other types and causes.

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Effects of nicotine and carbon dioxide on heart


Death of part of the brain tissue due to loss of blood flow to that part of the brain.

Two possible causes:

A blood clot floating around in the blood blocks a small artery leading to part of the brain.

Artery leading to the brain bursts.

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Links between smoking and disease

Epidermiolgical: A regular smoker is three times more likely to die premature than a non smoker

50% of regular smokers are likely to die of smoking related diseases

The more cigarettes a person smokes a day, the more likely to die of lung cancer than a non-smoker

Chronic Obstructive Pulomonary Disease is rare in non-smokers

It is not easy to link smoking with cardiovascular disease because there are so many other factors that can contribute to cardio-vasular disease.

Experimental: In 1960s there were experiments on dogs.

Some dogs were made to breathe smoke from unfiltered cigarettes. They developed changes in their lungs that were similar to those of COPD. They developed early signs of lung cancer. Some dogs were mader to breathe smoke from filtered cigarettes. These dogs remained healthier, but their lungs still shoed early signs of lung cancer.

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Species- A group of individual organisms which are very similar in appearance, anatomy, physiology, biolochemistry and genetics, whose memebers are able to interbreed freely to produce ferile offspring.

Habitat- The place where an organisms lives

Biodiversity- The range of organisms to be found

How biodiversity is considered as differnt levels: 

Habitats- The range of habtats in which different species live

Species The difference between speices

Genetics- genetic variation between indiviuals of a species

Human activity affects the enviroment in a variety of ways. Unless we study these affects, we cannot assess the impact that we have. Enviromental impact assessments are very importat parts of planning processes, and they are sued to estimate the effects of a planned development on the enviroment

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Methods of measuring Biodiversity

Taking random samples at reegular distances aross the habitat

Using random numbers to plot coordinates within the habitat

Selecting coordinates from a map and then using GPS to find the position inside the habitat

Random Quadrats:

The quadrat is placed at random on the habitat and the plants within the quadrat are identified. Their abundances then measured in one of three ways- An abundance Scale, Percentage Cover, Point frame (The pointy needle thing in a line)

Transect: A long rope of tape is stetched across the habitat, and samples are taken along the line.

Line transect- Record plants the line at set intervals

Interrupted belt transect- A quadrat is used at a set intervals along the line

Continuous belt transect- A quadrat is used continuously along the transect

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Methods of measuring Biodiversity (Animals)

Sweeping netting:Sweeping through vegetation. Any organism caught are released into a white sheet and counted

Collecting from trees: A white sheet is held under a branch, and the branch is knocked, so any small animals drop on to the sheet.

Pitfall trap: A container buried in the soil so that it is just below the surface. Any animals moving through the plants or leaf litter will fall into the container

Tullgren Funnel: Leaf litter is placed in a funnel. A light above the leaves drives the animals downwards as the laf dries out and warms up. They fal throught the mesh screen into the jar below.

Light Trap: An ultraviolet light attracts the insects, which eventually fall into the vessel of alcohol below.

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Measurements of Biodiversity

Species Richness- The number of species in a habitat

Species Eveness: The relative abundance of indivduals in each species

-Large animals, observed and counted

-Small animals, ((C1)*(C2))/(C3)

Simpson's index of diversity: (1- Sum of (n/N)^2)=D

High SID= a more diverse habitat (can handle more change)

Low SID= a less diverse habitat (can handle less change)

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Classifiaction: The process of sorting living things into groups

Phylogeny: The study of evolutionary relationships between organisms

Taxonomy: The study of the principles of classification

Related species are put together, by knowing the relationship between species we can put them in correct groups.

Taxonomy Hierarchy:(Domain) Kids Prefer Cheese Over Fried Green Spinach

(Domain) Kingdom Phylum Class Order Family Genus Species

Species are the basci unit of classification. All of the members show some variation, but are essentially the same. As you rise through the ranks of taxa, the individuals show more diversity. There become fewer similarities.

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Taxonomy and Classification

The five kingdoms:

Animalia- Eukartotes, Multicellular, Heterotrophic, Able to move around, have fertilised eggs called blastula.

Plantae: euyaryotes, Multicellualr, Surrounded by a cellulose cell wall, produce multicellular embryos from ferilised eggs

Fungi: Eukaryotes, Have mycelium which consist of hyphae, Walls made of chitin,Cytoplasm is multi-nucleatic, mostly free living

Protoctista: Eukaryoyes, Single cell, Variety of forms, Various Plant and Animal like features, Auto and hetero

Prokaryotes: No nucleus, naked DNA, No membrane bound organelles, Smaller ribosomes, Free living or parasitic

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Classifying species

The binomial system is latin to avoid confusion by using common name, so it is universal to all countries.

Orginally species were organised into animal or plant until it was discovered that some acted like both, or neither (e.g. fungi, do not photosythesis or move)

Links between the reaction in their metabolism

The domain system was suggested after a detailed study of RNA. The scientists believed that two groups of bacteria and all eukaryotes had seperate orginsand these groups were given the taxnomy structure of domains to support this. They are above the kingdom level.

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Variation-The presence of variety

Variation between hair colour e.t.c shows variation in the same species

Continuous- Two extremes and and a full range of values in the middle. Most individulas are close to the means, i.e. height

Discontinous- Distinct categories in which there are no intermediate values, i.e. sex, blood group

Cause of variation:

Genetics, We inherit combinations of alleles from our parents because they are demed vital to our survival, however random mutation can chnage the alleles.

Enviroment, The idea that we survive relative to our surroundings, i.e. a tree in a small amount of soil will not grow tall.

There are Physiological (Biochemistry), Behavoural and Antomical (The structure of the organism)

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Darwin and his four observation

Offspring appear gentically similar to their parents

No two individuals are identical

Organisms have the ability to produce large numbers of offspring

Populations in nature tend to remain fairly stable in size


There is a struggle for survival

Better adpated indivuals survive and pass on their charcteristics

Over time, a number of changes may give rise to a new species

Speciation- The formation of a new species

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Evidence of Evolution

Fossils: Showing similar organisms over a long period of time. They chage slowly and show different adaptations to better suit their enviroment. There are also many modern species hat ar similar to fossils.

DNA: Genes can be compared by sequencing the bases in DNA. Most distantly related sppecies have more differences in their DNA

Molecules: Two closley related species will have similar or identical biological molecules.

Major components of evolution:

Variation must occur before evolution takes place

Once variety exists, their will be some which have advantages

Individuals with advantages survive a reproduce

Their offspring will in herit the advantageous charcteristics

The next generation will be better adapted

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Pesticide resistance

Pesiticide kill pests, insecticide are a selection pressure for insects, all unsuitable insects will die, leaving only the resitant will survive.

The next generation will be resistant and the insecticide will no longer work. The same thing happens with bacteria and antibiotics.

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Maintaining Biodiversity

Reasons for Conservation:

Evolution has provided the best answer for many technological questions i.e. wing shape

Natural ecosystems provide humans with many resources, regulation of the atmosphere,detoxification and recycling of waste.

Ethically all organisms have the right to survive

Global warming causes:

The loss of biodiversity means that species are less able to adapt to change due to the changes in their habitat. So they could move however they are obstructed by: Large bodies of water, man made structures

Agriculture, using wild varities to breed with other domestic crops we can get a crop which is able to live in the changing climate.

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In situ (Advantages)

Insitu: Species are protected in their natural enviroment


- Species are conserved in their natural habitat

-Permanently protects biodiversity

-Permenantly protects significant elements of nature

-Allows mangement  of the area to ensure that ecologicak intergrity is maintained

-Provides opportunity for ecologically sustainable land use

-Faciliates scientific research

-May be possible to restore the ecological integrity

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In Situ (Disadavantages)

Protected animals could come out of the reserve to raid crops

People continuing to hunt the protected animals for food

Illegal harvesting of timber and other plant productions

Tourist feeding protected animals or leaving litter

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Ex Situ (Animals)


Some species would become extinct otherwise

Some breeding programs are successful


Animals are not in their natural habitat

Space is limited and this limited the number of individual which restricts gentic diversity

A decrease in genetic diversity results in lack of variation

This means the species are less able to adapt to changing conditions

Breeding programs require reintroduction

The difficulties with the acceptance by the existing wild memebers of their species

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Ex Situ (Plants) (Advantages)


Seeds are dormant

Seeds are produced in large amounts, collecting has little impact on the enviroment

Seeds are stored in a protected enviroment

Seeds take up very little space

Breed asexually

Botanic gardens can increase in number of individuals quickly

Ample supply of indiviuals for research

Capitivity bred plants can be put into the wild

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Ex Situ (Plants) (Disadvantages)


Colection of wild seeds can cause some disturbance

Collected sample may not be a representative genetic sample

Plants breeds asexually will have very little genetic variation, reducung biodiversity

Conclusions from research samples are not valid for whole species

Botanic Gardens:

They become a source of genetics for future scientists looking for useful genes

Plants may become extinct otherwise

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Convention in internation trade in endangered spec


Regulate and moniter internation trade in selected species

Ensure that international trade does not does not endanger the survival of a population

Ensure trade of wild plants is prohibited for commercial purposes

Ensure trades in artificially propogated plants is allowed, subject to permit

Ensure that some, slightly less endagngered, wild species may be traded, subject to a permit, as agreed by the exporting and importing countries

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Rio Convention on Biodiversity


Conserve biological diversity

Use components sustainably

Have appropriate shared access to genetic resources

Have appropriate sharing and transfer of scientific knowledge and technologies

Have fair and equitable sharing of the benefits arising out of the use of genetic resources

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Enviromental Impact Assessment

They are a means of accessing the likely signficant enviromental impact of a development. The EIA ensure that the local planningauthority makes its decision in the knowledge of any likely significant effects on the enviroment. This helps to ensure that the importance of the predicted effects is properly understood by the public and the planning authority befre it makes a decision

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