Molecules Biodiversity Food and Health[1]

7/30/2019 Molecules Biodiversity Food and Health[1]

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Molecules, Biodiversity, Food and Health

Biological Molecules

ProteinsAmino AcidsStructure

Monomer of proteins Join to form backbone of polypeptide 20 types naturally occurring Differences caused by R-groups

Synthesis

Plants: Convert nitrates into amino group and bond to organic part made from photosynthesis products Animals: Proteins broken down, 8 essential amino acids - cant be made from materials inside body

- Can only store certain amount, amino group toxic if too many- Liver breaks amino acids down deamination urea

Building proteins

Reaction between carboxyl group and amino group Condensation reaction, bond broken by hydrolysis Forms peptide bond to make dipeptide

Zwitterions

Amino acid dissolves in water Carboxyl group disassociates and releases H+ Amino group receives H+ No net charge

Protein StructurePrimary structure

Unique amino acid sequence of a polypeptideSecondary structure

H-bonds form between amino acids Non-specific, polypeptides can take up same shape

Alpha-helix

H-bonds 4 along the chain Small parts of whole polypeptide can take up configuration

Beta-pleated sheet

Anti-parallel zigzagging chain Stronger and less elastic than Alpha-helix

Tertiary structure

3D structure made in Golgi apparatus H-bonds, Ionic bonds, Disulphide bridges

Globular proteins

Irregular, compact shape Soluble hydrophilic outside, hydrophobic inside

Fibrous proteins

Long chains rich with hydrophobic amino acids Insoluble, unfolded, non-specific

Quaternary structure

How polypeptides link together (prosthetic group) Haemoglobin: 4 polypeptide chains and haem group


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CollagenStructure

3 polypeptide chains wound around each other H-bonds between chains = strength Each collagen - strength Collagen fibrilcollagen fibre

Function

Arteries - collagen layer prevents bursting walls at highpressure

Tendons mostly made of collagen Bones formed from collagen Cartilage and connective tissue made of collagen

HaemoglobinStructure

4 polypeptide chains-

2 a-chains, 2 b-chains, 1 haem group

Function

Carries oxygen around the body Bonds to oxygen in lungs, releases in tissues Haem group contains Fe2+ - responsible for colour

Haemoglobin + oxygen --> oxyhaemoglobin

(purple-red) (bright red)

One complete haemoglobin combines to four oxygenmolecules

CarbohydratesMonosaccharidesStructure

General formula: CH2O- 3 carbon atoms = Triose- 4 carbon atoms = Tetrose- 5 carbon atoms = Pentose ribose- 6 carbon atoms = Hexose glucose, fructose

Glucose can exist as two forms alpha and beta glucose

Disaccharides 2 monosaccharides joined together by condensation Monosaccharides broken by hydrolysis One monosaccharide loses H atom from C1 and other

loses OH group from C4, creating a 1,4-glycosidic bond

Sucrose:glucose + fructose

Used in plants to transport food reserves

Lactose:glucose + galactoseSugar in the milk of mammals

Maltose:glucose + glucose

First product of starch digestion


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Polysaccharides

Polysaccharide Structure Function

Starch Made of 2 polymers:

Amylose: polymer of glucoses joined by a-1,4-glycosidic bonds. Forms

helix with 6 molecules per turn & about 300 per helix

Amylopectin: polymer of glucoses jonied by a-1, 4-glycosidic bonds but

with branches of a-1,6-glycosidic bonds. Causes molecule to be branched

Storage in plants

Glycogen Similar to amylopectin but with many more branches which are shorter

Storage in

animals and fungi

Cellulose Adjacent chains of long, unbranched polymers of glucose joined with -1,4-glycosidic bonds. The chains form hydrogen bonds with each other to

form microfibrils which again pack together into macrofibrils

Structuralconstituent of

plant cell walls

LipidsLipids: A diverse group of chemicals that dissolve in organic solvents but not water - includes fatty acids,

triglycerides and cholesterol.

Roles of LipidsEnergy store

Lipids stored in adipocytes Cell designed for continuous synthesis and breakdown of triacyglycerols Provide 9 kcal/gram

Waterproofing

The cuticle of plant leaves are protected against drying out by a lipid layer (waxy cuticle) , as lipids arehydrophobic - limits diffusion of water

Allows release of volatiles (prevents pests, attracted pollinating insects)Insulation

Mechanical support around soft organs Electrical insulation around long nerve cells E.g. Whale blubber is lipid that reduces heat loss & helps keep aquatic mammals buoyant

Shock absorption

Act as soft barrier to protect vital organs Prevent musculoskeletal system from easily breaking when hit


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Cell membranes

All biological membranes are made of a phospholipid bilayer Phospholipids have a hydrophobic head and hydrophilic tail Partial permeability - substances don't move across the barrier

indiscriminately

Scents

Most naturally occurring fats and oils are the fatty acid esters ofglycerol Esters with a low molecular weight are used as fragrances and found

in essential oils

TriglyceridesStructure

3 fatty acids attached to a glycerol molecule- Acids as they contain the carboxyl group -COOH

General formula C3H8O3

Condensation reaction bonds the glycerol and fatty acids

- Carboxyl group reacts with OH of glycerol- Forms ester bond

PhospholipidStructure

Like a triglyceride, but ne fatty acid is replaced by aphosphate group

Phosphate heads are hydrophilic tiny ve charge- In water, phospholipid heads attracted to water and tails

repelled, so they form a bilayer

Cholesterol and Steroids Cholesterol and other substances that are formed from it are called steroids Huge number of different kind in the body testosterone and oestrogen Cholesterol helps regulate the fluidity of the membrane

WaterStructure

2 hydrogen atoms covalently bonded to one oxygen atomPropertiesHigh specific heat capacity

Takes a lot of energy to raise the temperature of water Water temp fairly stable when air pressure changes rapidly

High latent heat of evaporation

A lot of energy needed to change water vapour Sweating, panting and transpiration effective cooling

High density

Maximum density at 4C expands upon freezing ice floats H-bonds form a lattice in ice crystals Water supports organisms with up thrust

Cohesion

Clingy water molecules rise up vascular tissue of plants in continuous column Surface tension pond skaters can walk on water

Good solvent

Water molecule polar other polar molecules attracted Transports substances in solution around body


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TestsCarbohydratesStarch

Add solution of potassium iodide to sample If starch is present, the solution changes from yellow-

brown blue-black

Reducing sugars

Monosaccharide and disaccharide (molecule can reactwith other molecule by giving electrons to them

When reducing sugar is heated to 80 with Benedictssolution, solution changes from blue orange-red

Non-reducing sugars

Sucrosewould have no colour change Make sure there are no reducing sugars in sample

boil with hydrochloric acid

Hydrolyses any sucrose to glucose and fructose Cool solution and neutralise with sodium

hydrogencarbonate

Carry out Benedicts test again Should now give a positive result

ProteinsBuiret Test

Add buiret reagentto a sample Buiret reagent reacts with peptide bonds - pale bluelilac

LipidsEthanol emulsion test

Mix sample with ethanol dissolves any lipid Pour liquid into water Cloudy white emulsion near top of water


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Nucleic Acids

PolynucleotidesDNAStructure

Deoxyribonucleic acid- Phosphate group- Deoxyribose- Organic base

Base can be a purine two rings- Adenine- Guanine

Base can be a pyrimidine one ring- Cytosine- Thymine

These components link together to form longchains calledpolynucleotides

Two chains of nucleotide lie side by side in anti-parallel

- Link by hydrogen bonds- Forms a double-helix

Role of DNA

A gene is a sequence of DNA that codes for a polypeptide A sequence of 3 bases on the DNA molecule codes for one amino acid Thus, the gene determines the primary structure of a protein

Complimentary base pairing

Key to the ability of DNA to hold and pass on the code for making proteins There is just the right amount of space for a purine to link with a pyrimidine A only links with T, C only links with G The code can be copied over perfectly from generations Instructs proteins to construct the exact molecule


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RNAStructure

Ribonucleic acid- Phosphate group- Ribose sugar- Organic base

Single stranded Contains uracil instead of thymine RNA uses information from the DNA to make

proteins

- Determines the primary structure of aprotein

DNA replicationSemi-conservative replication

DNA replication takes place during Interphase Each of the new DNA molecules are made of one old strand and one new strand of DNA1. Hydrogen bonds between bases are broken by DNA helicase2. Free nucleotides (present in the nucleus) pair up with complimentary exposed bases3. New strand is linked together by covalent bonds betweenphosphate and sugars by DNA polymerase4. 2 new DNA molecules, each contains one old strand and one new strand


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Enzymes

Enzyme actionStructureStructure

Globular proteins- Specific tertiary structure

Biological catalystsLocation

Intracellular- Catalyse reaction in the cell- E.g. hydrolases inside lysosomes

Extracellular- Released from cells onto food- Break down organisms into nutrients- E.g. amylase which hydrolyses starch to maltose

How enzymes work Reducingthe required activation energy for a reaction Enzymes contain active sites which have a specific shape

- Fits with the substrate molecules shape Enzymes can bind reactants to each other

- Increases reaction chance Enzymes can break substrates apart Enzymes can expose the substrates bonds or create a water-free zone so non-polar reactants can react

more easily

The enzyme is unchanged by the processEnzyme-substrate complex

The theory that an enzymes active site fits perfectlyto the substrate

- Held by temporary bonds between R-groups The combined structure is called the enzyme-

substrate complex

Each type of enzyme will usually only fit to onetype of substrate

Induced-fit hypothesis

The theory that when the substrate fits into theactive site, the shape of the enzyme changes slightly

Allows hold of the substrate in exactly the rightposition


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Changing conditions

Effect of changing concentrationEnzyme concentration

As enzyme concentration increases, more active sites becomeavailable

- A maximum reaction rate will be reached when all the substrate moleculesoccupy active sites

The substrate concentration becomes the limiting factor

Substrate concentration

As substrate concentration increases, collisions increase- A maximum reaction rate is reached when all the active sites

are occupied

- Called Vmax

Effect of changing temperature Higher tempMore kinetic energymore collisions higher rate of reaction

When they do collide, a higher proportion of them willhave the required activation energy

Usually 10 temperature rise = double collisions However, increased vibrations put a strain on bonds in

enzyme- Enzymes progressively and irreversibly denatured

Each enzyme has an optimum temperature- Close to body temperature in warm-blooded

animals

- Optimum temp depends on length of time its expected to workEffect of changing pH

Acids have a low pH high percentage of H+ ions- H+ interferes with negatively charged amino acids in active

sites

- H+ can also replace H-bonds and ionic bonds in structures likethe alpha-helix

Optimum pH varies between enzymes- pH range is usually very small

Measuring reaction rate Collect gas in a gas syringe, measure how much collected over a

period of time

- E.g. break down of hydrogen peroxide to water and oxygen using catalase To investigate the rate that amylase breaks down starch to maltose, measure how much starch

disappears by taking samples at know intervals and using the iodine test

- Use a colorimeter to measure the intensity of the blue-black colour- Plot a graph

The beginning curve is the initial rate of reaction, it is quite steep as the reaction is fastest at thebeginning as more un-reacted reactants are available


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InhibitorsEnzyme inhibitors

A substance that slows down or stops an enzyme-controlled reaction It is possible for other molecules to bind with the active site is it is similar to the substrate Creates competition for it and the substrate for the site Inhibitors that seriously disrupt controlled reactions act as metabolic poisons

- Death cap mushroom toxin called alpha-amanitin inhibits enzymes that catalyse production of RNA,cells are no longer able to synthesise proteinsCompetitive inhibitors

When the concentration of the inhibitor rises or that of the substrate falls, it becomes more likely thatthe inhibitor will bind with the enzyme, rather that the substrate

Reversible if the concentration of the substrate is increased Irreversible if the inhibitor bonds permanently to the active site

- Penicillin permanently binds to the active site of an enzyme essential for the synthesis of bacterialcell walls

Non-competitive inhibitors When the inhibitor binds to another part of the enzyme Can seriously disrupt the normal arrangement of the bonds holding the enzyme in shape Enzymes function blocked no matter how much substrate is present Reversible if the inhibitor bonds briefly Irreversible if the inhibitor bonds permanently

- Digitalis binds with the enzyme ATPase, resulting in increased contraction of the heart muscle

Cofactors and coenzymes Some enzymes require the presence of another substance Briefly bind with the enzyme, some alter its shape so it can bind more effectively with the substrate

Cofactor

Simple molecule of inorganic ion Many made from vitamins

- Vitamin B3 is required for the synthesis ofcoenzyme A Cl- cofactor in salivary glands change shape so starch molecules can fit into the active site Ca2+ cofactor for enzyme thrombin changes soluble, globular protein fibrinogen to insoluble, fibrousprotein fibrin

Coenzyme

Larger molecules Coenzyme A needed in many metabolic pathways, including aerobic respiration


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Diet and food production

NutritionBalanced dietsA balanced diet contains a range of all of the different nutrients in the right proportions

Food sources

Animals are heterotrophs- Rely on organic substance that have been made by plants

Plants are autotrophs- Use inorganic substances to build organic substances

Nutrient Function Sources Notes

Carbohydrate Provides energy Bread, rice, potatoes Includes sugars and starches

Proteins New cells, and components

e.g. haemoglobin, collagen

Meat, eggs, fish, dairy 20 amino acids, 8 essential

amino acids

Lipids Cell membranes, steroids,

provide energy

Dairy, red meat, oils 2 essential fatty acids

Vitamin A Pigmentrhodopsin in rod

cells in eye

Meat, egg yolks, carrots

Vitamin C Collagen Citrus fruits, blackcurrants,

potatoes

Vitamin D Bones and teeth Dairy, oily fish, egg yolks Also made in skin exposed

to sunlight

Iron Haemoglobin Meat, beans, chocolate,

eggs, shellfish

Shortage = anaemia

Sodium Bones and blood clotting Dairy, fish Shortage = osteoporosis

Malnutrition The result of any diet that is unbalanced Obesity, kwakiorshor, anorexia nervosa, marasmus

Cholesterol Evidence shows that having high cholesterol levels increases CHD risk, diet high in saturated fats

increases cholesterol levels, other evidence doesnt support this view

Cholesterol insoluble- Carried in the blood plasma in the form oflipoproteins- Tiny balls made of lipids, cholesterol and proteins

Come in several varieties- Different proportions of proteins and lipids- The more protein, the greater the density of the lipoprotein

High density lipoproteins HDLs

A lot of protein with small amounts of lipids Usually pick up cholesterol from dying body cells and transport it to the liver

Low density lipoproteins - LDLs

More lipids and less protein than HDLs Usually carry lipids and cholesterol from liver to other parts of the body

Chylomicrons

Contain a lot of lipid and very little protein Formed in the wall of the ileum from digested fats Transport lipids from small intestine to liver


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Obesity When BMI is over 30 (BMI = kg/m2) Constantly eating nutrients that contain more energy than you use

- Spare energy stored as fat in adipose tissue - underneath skin and around body organs Increases risk of developing heart disease and type II diabetes

Coronary Heart Disease CHD

Common disorder of coronary arteries - most common cause of death Cardiac muscles must have a continuous supply of oxygen to contract CHD is caused by atherosclerosis (hardening) in the coronary arteries Become blocked

- Build up of materials inside walls- Makes the lumen narrower- Increases blood pressure- Can happen in arteries brain stroke

Can occur naturally with old age Can become worse with tobacco chemicals and LDLs

- CO damages endothelium of arteries-

Repaired by WBC that encourage smooth muscle growth & deposit lipids- Deposits known as atheromas / atheromatous plaque Angina occurs when the artery cant keep up with oxygen requirements Blood clots can form

- Coronary thrombosis CO sticky platelets, increased chance of blood clots- Platelets in blood come in contact with collagen in artery wall- Platelets secrete chemicals that clot the blood, thrombus- Narrows artery and may block vessel, can lead to stroke- Muscle cells diemyocardial infarction

Arteriosclerosis is the hardening of artery wallsMyocardial Infarction

Myocardial = heart muscle, infarction = loss of blood flow to tissue 90% of myocardial infarctions caused by coronary thrombosis Severe causes heart to stop beating

Cardiac arrestcan be very severe or may not even realise it, described ascrushing burning

Cholesterol and CHD

LDLs deposit cholesterol in the damaged walls or arteries- Makes up a large proportion ofatheromatous plaque

HDLs protect from CHD- Remove cholesterol from tissues

Saturated fats result in more LDLs Not directly linked cholesterol in blood doesnt all come from food Statins (drug) inhibits the enzyme in the liver cells which catalyses one of the

reactions involved in cholesterol synthesis

Hypertension

Persons resting blood pressure is persistently high Increases risk of CHD

- Causes arterial walls to thicken and stiffen- Developed atheromatous plaques- Heart has to pump blood at higher pressures

High salt content in blood can increase risk- High salt concentration in blood draws water in by osmosis- Increases volume of blood and thus increases pressure

People with hypertension may be given diuretics- Cause kidneys to excrete large amounts of fluid, reduces volume in body, reduces blood pressure


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Improving food productionPlants

Done mostly by specialist plant breeders, not farmers Give selectively bred seeds to farmers to grow May be genetically modified

Improving efficiency

Improve growth rate of crops Increase yield Reduce losses from disease and pests Standardising plant size to make harvesting easier Improve responses to fertilisers

Animals Selectively bred by farmers in farms

Improving efficiency

Improve growth rate Increase productivity Increase disease resistance

Selective breeding Breeding animals with desirable traits leads to those traits becoming exaggerated Artificial selection is the intentional breeding of certain traits Three stages:

- Isolation- Artificial selection- Inbreeding/ Line breeding

1. Selecting the pair of animals/plants that display the desired characteristics2. Allowed to reproduce3. Offspring sorted into those with best combination of characteristics4. Offspring reproduce

E.g. Chickens bred for egg production or meat production. Egg-layers can produce over 300 a year, whilemeat-producers have low fat content and a better colour and texture

Modern methods

Marker-assisted selection Section of DNA is used as a marker to recognise characteristic Offsprings DNA is checked for the marker

- Allows selection at a very early stageE.g. Tomatoes a wild tomato variety with good resistance to yellow leaf curl virus was found, the alleleresponsible for the resistance was identified and bred into a domestic variety

Using chemicalsFertilisers

Replace minerals in the soil Contain nitrate, potassium, and phosphate Increase growth rate and overall size of crop

Pesticides

Designed to kill organisms that cause diseases in crops Include fungicides Broad-spectrum insecticides kill all insects, not just pests specific are more expensive

Antibiotics

For infected animals Reduce the spread of disease around animals that are intensively farmed and close to each other


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MicroorganismsFood spoilage

Microorganisms obtain nutrition by digesting organic matter around them They leave behind waste products

How microorganisms spoil our food

Visible growth of microorganisms on food- Mouldy bread (Penicillium mould is blue-green)

Releasing enzymes onto the food and absorbing the nutrients external digestion process- Food smells sweet sugars released from carbohydrate molecules- Food eventually reduced to mush

Producing toxins- Clostridium botulinum produces toxin botulin one of the most toxic substances known

Cause infection- Salmonella bacteria attacks the lining of the digestive system

Preventing food spoilage Using food quickly while still fresh Longer kept food must be treated to prevent spoilage

- Killing microbes already on the food- Preventing them from reproducing

Food must then be packaged to prevent further contaminationTreatment methods

Cooking denatures proteins and kills microorganism Pasteurising heating to 72C for 15 seconds and cooling rapidly to 4C, killing harmful microbes Drying, slating, coating in sugar dehydrate microbes Smoking - develops dry hardened outer surface, smoke contains antibacterial chemicals Pickling uses acid pH to kill microorganisms by denaturing enzymes and other proteins Irradiation ionising radiation kills microorganisms by disrupting DNA structure Cooling and freezing retard enzyme activity so metabolism, growth and reproduction is slow

Packaging methods

Canning heated and sealed in air tight containers Vacuum wrapping air excluded so microbes cannot respire aerobically Plastic or paper packaging

Making foodTypes of food made with microorganisms

Yoghurt - Lactobacillus uses lactose sugar in milk to make lactic acid causes milk proteins to curdle Cheese - Made from curdled milk, acted upon by Lactobacillus, additional flavour by other bacteria Bread - Made to rise by yeast, respires anaerobically to release CO2, bubbles of gas collect in dough Alcohol - Another product of anaerobic respiration of yeast, cereal grains with maltose can be used to

brew beer, as the yeast respires the sugar

- Yeast respires fructose and glucose in grapes Quorn Single-cell protein, mycoprotein made by fungus, vegetarian, healthy, cholesterol-free

Advantages

Fast protein production Production increased and decreased on

demand No animal welfare issues Source of protein for vegetarians No animal fat or cholesterol Combined with removal of waste products

Disadvantages

Many dont want to eat fungal protein Microorganisms need to be grown in huge

fermenters Must be purified Care to prevent infection Not as tasty as traditional protein sources


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Health and Disease

Parasites and pathogens

Getting infectedHealth: A state of complete physical, mental & social well being and not merely the absence of disease of

infirmity.

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

Pathogen

An organism that causes disease Live by taking nutrients from their host but damage it in the process

Parasite

An organism that lives in or on another living things, causing harm to the host Usually cause harm by taking nutrition from the host External parasite: Live on the host

- Head lice Internal parasite: Live in the host

- Tapeworm Most can go unnoticed for a long time before they cause considerable damage

- Can cause damage that allows other organisms to invade the host and cause secondary infectionsTransmission of disease

A pathogen must be able to- Travel between hosts- Get into tissues- Reproduce- Cause damage to tissues

Most common form of transmission- Means of a vector- Physical contact- Droplet infection

MalariaTransmission

Cause by eukaryote Plasmodium Spread by vector

- FemaleAnophelesmosquito Mosquito feeds on blood Plasmodium live in red blood cells and feed on

haemoglobin

1. The mosquito will suck the parasite gametes into itsstomach

2. Zygotes form in the mosquitos stomach3. Infective stages move to the mosquitos salivary glands4. Mosquito injects saliva into another person as an

anticoagulant

5. Infective stages enter liver, multiply and enter blood again6.

Enter red blood cells, where gametes are formed

Global impact

Kills 3 million a year, 300 million infected 90% of sufferers live in sub-Saharan Africa


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HIV/AIDSTransmission

The Human Immunodeficiency Virus enters the body and remains inactive- HIV positive

When the virus becomes active it destroys T-lymphocytes- T helper cells prevent infection- Ability to resist infection is reduced

Subject will catch a range ofopportunistic infections Acquired Immune Deficiency

Syndrome

Transmitted via:- Exchange of bodily fluids (not saliva)- Unsterilized surgical equipment- Unprotected sex- Across the placenta- During childbirth- During breast feeding

Global impact Pandemic Half of sufferers in sub-Saharan Africa 2005 45 million people living with HIV/AIDS

TuberculosisTransmission

Mycobacterium tuberculosis Mycobacterium bovis Usually found in lungs

- Its inactive in many people or controlled by their immune system Droplet infection

- Contained in tiny droplets of liquidreleased when an infected person coughs,

sneezes, talks

- Takes very close contact with an infectedperson to contract the disease

Contraction more likely in- Overcrowding- Poor ventilation- Poor health- Poor diet-

Homelessness- Living or working with infected peopleGlobal impact

WHO declared TB to be a public health emergency in 1993 Most common in South-east Asia and sub-Saharan Africa Increasing threat of new strains ofMycobacterium being resistance to most of the drugs available

WHO Health organisations use epidemiology to study the spread of disease They identify risk factors, incidence, prevalence, mortality, morbidity Endemic regularly found among particular people in a certain area, epidemic spreading rapidlyover a large area, pandemic worldwide epidemic They educate, raise awareness, screen people, provide health centres, provide vaccinations, target

research for cures


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Defence

Immune responseImmune response: A specific response to a pathogen which involves the action of lymphocytes

Primary defences Pathogens need to enter the body of the host The primary defences are those that prevent pathogens entering the body

Skin

Epidermis consists of layers of cells, mostly called keratinocytes Cells reproduce at base of epidermis, then migrate to surface

- Cytoplasm dries out and is replaced by keratinkeratinisation- Keratinised layer of dead cells acts as a barrier to pathogens

Mucous membranes

Potential for infection high where air and food enters airways, lungs, digestive system Protected by epithelial layer containing goblet cells that secrete mucus Mucus lines passages and traps pathogens Ciliated cells waft layer of mucus to top of trachea where it is swallowed

- Most pathogens killed by acidity of the stomach, as the pathogens enzymes are denatured Mucous membranes found in gut, genitalia, anus, ears and nose

Other primary defences

Eyes protected by antibodies in tears Ear canal lined by wax, traps pathogens Vagina is protected by acidic conditions

Secondary defences Many trapped pathogens are not killed by conditions in the body Phagocytes kill the pathogens before they reproduce and cause

symptoms

Neutrophils

Most common Multi-lobed nucleus Made in bone marrow Squeeze out of capillaries in tissue fluid Short lived, released in large numbers as a result of infection

Macrophages

Larger cells manufactured in bone marrow Travel in blood as monocytes Settle in body organs, particularly lymph nodes

- Develop into macrophages Specific response to invading pathogens Long-lived Antigen-presenting cells

- Break particles up into their component molecules andplace some molecules in their plasma membrane


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How phagocytes work

Engulf and destroy pathogens

1. Pathogen recognised by chemical markers on its outer membraneMarkers are antigens

Specific to the organism

2. Proteins in the blood called antibodies attach to foreign antigens3. Phagocytes have membrane-bound proteins that act as receptors

Binds to antibody already attached to pathogenProcess may be assisted by other organisms called opsonins

4. Phagocytes envelop pathogen by folding in its membranePathogen trapped inside vacuole called phagosome

Lysosomes fuse with phagosome and release enzymes called lysins digest bacterium

Ends up as harmless nutrients that can be absorbed by the cytoplasm

5. Neutrophils die after digesting a few pathogens and may collect in an area to form pusRole of macrophages

Initiate the specific response to disease immune response- Activation oflymphocytes

Infected cells release histamines attract neutrophils- Histamine also makes capillaries more leaky- More fluid leaves the capillary in infected areaswelling and redness

More tissue fluid passes into lymphatic system Pathogens towards macrophages waiting in lymph nodes

AntibodiesAntigen

A molecule that stimulates an immune response Any molecule can act as an antigen Detected by immune system, stimulates production

ofantibodiesspecific to the antigen and pathogen

Antibody

A protein that can identify and neutralise antigens(aka immunoglobulin)

Produced by lymphocytes in response to infection Specific to antigen Attach to antigens and render them harmless

Structure

4 polypeptide chains held together by disulphide bridges Constant region enables antibodies to attach to phagocytic cells Variable region has specific shape that ensures antibody attaches to correct antigen Hinge region allows flexibility and branches to move apart for attachment to more than one antigen

How they work

Attaching to antigens on pathogen When the antibody blocks the binding site, the pathogen cant bind to its host cells neutralisation Each variable region can act as a binding site to bind antigen to pathogen

- Can attach to a number of pathogens at the same time agglutination When the pathogens are stuck together they cannot enter host cells

Producing antibodies

When an infecting agent is detected, the immune system produces antibodies May take a few days for numbers to rise enough to combat the infection successfully primary

immune response

If the body is infected a second time, the immune system can act more quickly secondary immuneresponse


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Lymphocytes Small white blood cells B-lymphocytes

- Form in bone marrow T-lymphocytes

- Develop in thymus gland during childhood- Gland in neck, disappears in teen years

Stimulated to act when in contact with antigens Each lymphocyte is specific to one antigen Produce antibodies

Cell signalling

Achieved through cell surface molecules and through release ofcytokines Target cell has receptor B lymphocytes and T lymphocytes have receptors that are complimentary to the antigen

- Detection = lymphocyte activated1. Identification

Pathogen carries antigens on its cell surface Act as markers that say it is foreign Detected by body cells

2. Distress signals Internal cell organelles e.g. Lysosomes will attempt to fight invader Parts of pathogen cell damaged End up attached to plasma membrane

- Act as signals that can be detected by immune system- Act as markers to indicate host cell is infected T killer lymphocytes destroy infected cell

3. Antigens Macrophages in lymph nodes engulf and digest pathogen Separate out antigens and incorporate them into the cell surface membrane

Antigen presenting cell Finds lymphocytes that can neutralise that antigen

4. Instructions

Cytokines released by cells- Act as instructions to target cells by binding to specific receptors on target cell

Cause release of messengers inside cell which alter its behaviour through gene expression Macrophages release monokines that attractneutrophils

-

Movement by chemotaxis (movement of cells towards a chemical) Macrophages release monokines to stimulate B cells to differentiate and release antibodies T and B cells release interleukins that stimulate proliferation and differentiation of T and B cells Many cells release interferon which inhibits virus replication and stimulates activity ofT killer

cells

Memory cells: cells that circulate the blood after a specific immune response. They speed up the response to a

subsequent attack by the same pathogen.


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How lymphocytes respond to antigens

B lymphocytes T lymphocytes


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Immunity

VaccinationsVaccination: A deliberate exposure to antigenic material, which activates the immune system to make an

immune response and provide immunity.

Controlling disease A person that is vaccinated will have artificial active immunity

- Deliberate exposure to antigenic material rendered harmless Immune system treats the antigenic material ad a real disease

Immune system manufactures antibodies and memory cells that provide long-term immunityHerd vaccination

Using a vaccine to provide immunity to almost all of the population at risk Ifenough people are immune, the disease can not spread To eradicate smallpox, 80-85% of the population had to be vaccinated UK, vaccination programme to immunise children of many diseases

- TB, diphtheria, tetanus, whooping cough, polio, meningitis, measles, mumps, rubellaRing vaccination

Used when a new case of disease is reported Involves vaccinating all the people in the immediate vicinity of the new case Such as vaccinating people in the surrounding houses, or a whole town or village Used to control the spread of livestock disease

Type of vaccines

Whole, live organisms- Not as harmful as real disease, but with similar antigens- Smallpox vaccine

Harmless version of pathogenic organism- Measles and TB vaccine

Dead pathogen- Typhoid and cholera vaccines

Preparation of the antigens from the pathogen- Hepatitis B vaccine

Harmless toxin called a toxoid- Tetanus vaccine

Immunity

Active immunity: Immunity achieved through activation of the immune system. Lymphocytes in body

manufacture antibodies and release them from the blood - may last for many years or even lifetime.

Passive immunity: Provided by antibodies that havent been manufactured by stimulating immune system,

provided by mother across placenta or breast feeding or intravenous injection, short-lived.

Natural immunity: Gained through normal living, result of infection that stimulates immune response

Artificial immunity: Gained by deliberate exposure to antibodies of antigens

Possible threats Many pathogens can mutate and form new strains resistant to drugs and vaccines

Influenza Virus that affects the respiratory system People over 65 and with a respiratory tract infection are most at risk Immunisation programme for all those over 65 New strains are used each year, and research determines which strains are most likely to spread


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Finding new drugsNeed for new drugs

New diseases are emerging Some diseases have no treatment Diseases mutate and evolve which makes antibiotics ineffective, as the new drugs gives the

microorganism a selection pressure, so strains of microorganism that are resistant of less susceptible

to the drug will survive and reproduce, so the next generate will be resistant

Discovery

Accidentally, e.g. Alexander Flemings discovery of penicillin Traditional medicines such as plants

- 80% of the world relies on traditional medicine Anaesthetics

- Opium, to chloroform Wildlife observation

- Monkeys and bears rub citrus oils on their coat as antiseptics- Chimpanzees swallow leaves folded in a way to remove parasites from their digestive tract- Elephants use clay to counteract dietary toxins- Birds line their nest with medicinal leaves to protect chicks from blood sucking mites

Modern research- Antibiotics developed over the last 50 years come from Streptomyces- Pharmaceutical companies make us of receptors, as if it can be blocked then the pathogen cannot

gain access to the cell

- Genomic by sequencing the genes of microorganisms, we should find a range of candidates fromwhich vaccines can be made

Smoking

EffectsShort term

Tar settles in the lining of the airways and alveoli- Increases diffusion distance for gas exchange

Chemicals in the tar may cause an allergic reaction- Smooth muscles contract, lumen narrows, flow or air

restricted to alveoli

Tar paralyses and destroys cilia- Unable to move mucus up the trachea- Stimulates more mucus to form- Trapped bacteria is not removed, so they multiply and block

bronchioles

- Lungs more susceptible to infectionLong term

Smokers cough- Attempt to shift bacterial mucus- Delicate lining of airways becomes damaged, and will be replaced by scar tissue thicker and less

flexible

- Smooth muscle thickens reduces lumen, flow of air permanently restricted Frequent infections will inflame lining of airways and attracts white blood cells

- White blood cells release enzymes that digest part of the lining in order to pass through into the airspaces of the lungs

- Enzyme elastase is used, that breaks down the elastic tissue in the lining of the lungs- Reduce elasticity of the alveoli- Exhaling alveolus walls do not recoil enough to push the air out, the bronchioles collapse, trapping

air in the alveoli

- Alveoli may burst as pressure in lungs increases


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DiseasesBronchitis

Inflammation of the lining of the airways Damage to cilia and overproduction of mucus

Mucus collects in the lungs, which causes irritation, continual coughing up mucus filled withbacteria and white blood cells

Increased risk of lung infectionEmphysema

Loss of elasticity in the alveoli, causing them to burst Lungs have reduced surface area for gas exchange

Shortness of breath, harder to exhale, breathing will be shallow and rapid Blood less well oxygenated with causes fatigue

Chronic obstructive pulmonary disease COPD

Combination of diseases that includes chronic bronchitis, emphysema and asthmaLung cancer

Cigarette smoke contains carcinogens in the tar such as benzopyrene Carcinogens enter nucleus of the cells of the lung tissue and cause a mutation, which may cause

uncontrolled cell division

Continual coughing and shortness of breath Pain in chest and blood coughed up in sputum

Nicotine and carbon monoxide Increase the risk of:

- Atherosclerosis- Coronary heart disease- Stroke

Nicotine

Chemical in smoke that causes addiction Body becomes used to the affects over time and smoker no longer feels wells without nicotine Mimics the actions of transmitters in the nerve synapses

- Makes nervous system more sensitive, smoker feels more alert Causes release ofadrenaline

- Increases heart and breathing rate- Causes constriction of arterioles raises blood pressure- Decreases blood flow to extremities

Makes platelets more sticky- Increases risk of blood clot or thrombus

Carbon monoxide

Enters red blood cells, combines with haemoglobin more readily that oxygencarboxyhaemoglobin- Reduces oxygen concentration in the blood

Damages the lining of arteriesRisk factor

Changes in body leads to serious diseases such as the multifactoral coronary heart disease Increases chance of blood clots because of sticky platelets People in less economically developed countries will be less at risk of developing CHD

- Eat less fatty foods, less likely to be obese- Less likely to smoke- Shorter life expectancy, wont live long enough to develop CHD- More likely to die from other diseases such as malaria, HIV/AIDS and tuberculosis

Epidemiology: study of the distribution of a disease in populations, and the factors that influence the spread


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Biodiversity

Habitats and species

DefinitionsSpecies: A group of individual organisms very similar in appearance, anatomy, physiology, biochemistry and

genetics, whose members are able to interbreed freely to produce fertile offspring

Habitat: The place where organisms lives, with a specific set of conditions that those organisms are adapted to

live in

Biodiversity: The variety of life, the range of living organisms to be found. Biodiversity may be considered at

different levels

The range of habitats in which different species live The difference between species; structural and functional Genetic variation between individuals in the same species

SamplingPlantsRandom sampling

To measure the biodiversity of a habitat - observe all species, identify and count Too many to count, select small portion and study carefully, multiply to estimate whole habitat

- Take samples at regular distances- Use random coordinates generated by a computer, use GPS

The number of samples depends on the time you have and the size of the habitat Record results on a table

Measures

Use quadratto define the size of the sample area Hard to count small herbs and grasses, so measure percentage ground cover

- Plants that you see but arentfound in random sample recorded as present with no abundance- Measure percentage using a point frame, frame holding a number of long needles or pointers

ACFOR abundance scale: Abundant, common, frequent, obvious, rare Can use a transect line long rope, take samples along line in habitat

Animals Animals move, so you need to catch the small animals and estimate numbers

Sweep netting

Walking through a habitat with a net, sweeping through vegetation in wide arcs Empty the contents on a white sheet to identify them

Collecting from trees

Spread a white sheet under the branch and knock the branch Dislodged animals drop onto the sheet, count them before they fly away

Pitfall trap

Small container buried in soil to rim is just below surface Animals moving through the plants will fall into the container, with little

water or paper to stop them crawling out

Tullgren funnel

Place leaf litter in a funnel, light above litter drives animals downwards aslitter dries out

Fall through mesh screen to be collected in jar underneathLight trap

To collect flying insects at night Ultraviolet light attracts insects, under light is collecting vessel containing alcohol Moths and insects attracted to light and fall into alcohol


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Measures of biodiversity

Species richness and evenness

Species richness

Number of species present in a habitat Make observations within habitat and record all different species you see Not a measure ofdiversity

Species evenness

A measure of the relative abundance of individuals of a species Habitat with even numbers is more diverse than when one species outnumber all the others Plants: use the sampling technique, then measure percentage cover Animals: mark and recapture technique

- Number captured first x number captured second time / number recaptured

Simpsons Index of Diversity Measure of diversity in a habitat Takes into account species richness and evenness

D = 1 [(n/N)2]

n is the total number of a particular species N is the total number of all individuals of all species High value indicates diverse habitat

- Place for many different species and organisms- Small change to the environment may affect a species- Total number of individuals affected is a small proportion so the effect is small on the whole habitat

Low value = habitat dominated by a few species- Habitat dominated by a few species- Small change to environment affects one of those species could destroy whole habitat


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Classification

Types of classificationDefinitionsBiological classification: is the process of sorting living things into groups. Natural classification does this by

grouping things according to how closely related they are, reflecting evolutionary relationships

Taxonomy

Taxonomy: the study of the principles of classification

The study of differences between species Species usually grouped by physical similarities Modern classification has come to reflect the evolutionary distance between species

- Any two species will have a common ancestor at some point- The more recent to common ancestor, the more closely related the two species

Phylogeny

Phylogeny: The study of the evolutionary relationships between organisms

The study of how closely different species are related Humans and gorillas are monophyletic they belong to the same phylogenetic group as they have a

common ancestor, thus they can be placed in the same taxonomic group

The thrush is more closely related to snakes than mammals as they have a common ancestor, thus thethrush must be placed in a different group from mammals

KingdomsThe Five KingdomsProkaryotes

No nucleus looped and naked DNA - evolved before nucleus became the place for DNA Smaller ribosomes Respiration from mesosomes

Protoctists

Include all organisms that dont fit into the other four kingdoms Many are single-celled, some are Multicellular Eukaryotes Mostly free living Autotrophic or heterotrophic

Fungi

Organisms that are mostly saprophytic (cause decay of organic matter) They consist ofmycelium Walls made from chitin Network of numerous strands called hyphae Has several nuclei

Plants

Multicellular Autotrophic Surrounded by cell wall made of cellulose Multicellular embryos from fertilised eggs

Animals

Multicellular Heterotrophic Fertilised eggs that develop into a blastula


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How organisms are classified

System of ClassificationThe binomial system

Two names are used to identify each species- Genus and species

Typed as Genus species Handwritten as Genus species Latin names, common for every country

Dichotomous key

Way of identifying and naming a specimenyou found

Each question has yes or no, leading toanother question and eventually leads you to

the name of the specimen

Helps to identify what species are presentwhen doing an Environmental ImpactAssessment

- As it is illegal to cause some animals harmor death if they are endangered

Modern classificationEarly classification

Based on observable features- No microscopes

More information from electron microscopes help classify Aristotle classified things as plants or animals Animal kingdom and plant kingdom had single-celled organisms that had features of animals and plants

Recent classification

We now use physiology and biochemistry to help classification systems DNA can be used to classify The more similar the sequence, the more

closely related the two species

Three domains

1990, Carl Woese suggested a newclassification system based on a detailed

study of DNA

Bacteria- Different cell membrane structure- Different enzymes- Flagella with internal structure- No proteins bound to genetic material

Archeae- Similar mechanisms to Eukaryotae:- Similar enzymes- Building RNA

Eukaryotae


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Evolution

VariationTypes of variationIntraspecific variation: differences between individuals within a species

Discontinuous variation Discontinuous variation: variation in which each organism belongs to one of a few clearly defined

groups

e.g A persons blood group

Almost always caused by genes with no environmental inputContinuous variation

Continuous variation: variation in which there is a continuous range of values between two extremese.g. human skin colour, eye colour, leaf length

May be caused by genes or the environment- Eye colour caused by genes with hundreds of possible combinations of alleles- Skin colour caused partly by genes, partly by the environment- Leaf length caused entirely by environment

Causes of variationGenetic variation

Different varieties of a gene for a particular characteristic are called alleles In sexually reproducing organisms, alleles shuffle when a new organism is produced

- Caused by gamete formation, when meiosis mixes up chromosomes- When fertilisation occurs, an infinite number of possible combinations of alleles can be forms when

a sperm fuses with an egg

Also possible for new alleles to be produced occasionally by a mutation- When a mistake is made as DNA is replicated- A nucleotide may be missed out, or an extra one slipped it

Environmental variation

Two people with the same combinations of alleles may end up differently because of their environment- People with naturally fair skin may have different colours because of sunbathing- Alleles that allow people to grow tall may not have the same effect because of different

environments

- Plants with identical genes may differ as one may grow in the shade, or with different nutrients Arise during an individuals lifetime

- Cannot be inheritedAdaptations

Types of adaptationsAdaptation: a variation that helps an organism to survive

Behavioural adaptations

An aspect of an organisms behaviour that helps it to survive in the conditions it lives inE.g. touching an earthworm makes it contract, earthworms have no eyes

Physiological adaptations

One that ensures the correct functioning of cell processesE.g. yeast can respire sugars anaerobically or aerobically, depending on oxygen level

Anatomical adaptations

A structural variation that enhances the survival of the organismE.g. Legionellla bacteria have flagella so they can move independently


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Charles DarwinTheory of natural selection

1856, Charles Darwin (and independently, Alfred Russel Wallace) put forward a new theory- Darwin perhaps more known because he developed the ideas more and wrote On the Origin of

Species

- He developed logical theories about how and why different areas of biology happenedThe four observations

All organisms over-reproduce Populations tend to remain fairly constantover long time periods Organisms within a species vary Some of the variations are inherited

The three deductions

Theres competition for survival Individuals with the best adapted characteristics for their environment are more likely to survive and

reproduce

If the characteristics can be inherited, the organisms will pass the characteristic to their offspring The characteristics of a species would gradually change, as better adapted individuals are more

likely to survive and pass characteristics on. Species would become better and better adapted to

their environment.

Selection pressures Selection pressure: an environmental factor that decreases or increases the chance of survival of

organisms with particular variations

Results in natural selection If an individual has beneficial characteristics, it will be selected to survive and pass on its

characteristics

Examples of selection pressures:- Availability of suitable food selected organisms will be able to eat the available food- Predators selected organisms can avoid being seen and eaten, or can escape- Diseases - selected organisms will survive a disease- Physical and chemical factors selected organisms will be able to grow in extreme conditions

SpeciationNew speciesSpeciation: the production of a new species

A species is a group of organisms that can interbreed to produce fertile offspring

To produce a new species, a group needs to be produced that can no longer breed with the originalspecies

- The population must become reproductively isolated Speciation is difficult to study as it takes a long time to happen, but we can look at patterns that tell us

what may have happened in the past

Allopatric speciation

Two populations of the same species may become separated by a geographical barrier, such as wateror mountains

The environments that they live in are different, so they will have differentselection pressures- Different adaptations will occur- Eventually, the differences may become so great that the populations can no longer interbreed

Sympatric isolation

No geographical isolation Possibly a reproductive barrier within the population, from a biochemical change; behavioural change

e.g. a courtship dance being unrecognisable; physical change, sexual organs incompatible


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Evidence for evolutionFossils

Fossils are the preserved remains of organisms that lived and died long ago- Many form from hard part of organisms e.g. bone and shells, become mineralised- Soft parts can also become fossils, as well as droppings and worm burrows

Tiny proportion of organisms fossilise Enough fossils of some organisms give us an idea of how they evolved

Horse fossils

Many, dating 55 million years ago to almost present Organised according to age shows changes sequence From the type of rocks found, can deduce environment that the

species lived, and trace the changes

- Early species, toes lived in swamps- Modern horses single toes can run fast

Changes - natural selection favoured characteristic over another Environment changed, the selection pressures caused different

selected characteristic - succession of different species

We cant say this evolved into that, only that they are relatedMolecular evidence

Look at molecular structure of genes, not features they produce - fundamental evidence for evolution Some ancient bones are in such good condition that DNA can be extracted

E.g. DNA in mitochondria in bones of woolly mammoths found similar to elephant mitochondrial DNA

Common ancestor about 6 million years ago

Eye gene

DNA analysis can sometimes give unexpected results- Animals eyes have structural differences - assumed separate evolution- Insect eyes evolved in line leading to insects, while vertebrate eyes

evolved in line leading to vertebrates

E.g. the gene eyfrom a fruit fly was found to have similarities to the gene Pax-6 in vertebrates.

- Eyis a gene that controls the development of the fruit flys compound eye- Pax-6 is a gene that turns on other genes that cause an eye to develop- Researchers injected Pax-6 into a cell in a larval fruit fly that would

develop into the wing

- The wing grew a compound eye Seems as there is a common origin of eyes in all animals, despite different

looks

ResistanceAntibiotic resistanceAntibiotic: a substance that kills bacteria without harming animal cells

Example of natural selection- We change the selection pressures by changing the bacteriums environment

Bacteria become resistant to antibiotics by adapting to produce enzymes that inactivate the antibiotic- Tremendous selective advantage, as those not resistant are killed- Bacteria reproduce very quickly producing huge numbers of resistant descendants- Bacteria can also transfer resistant plasmids from different species

E.g. MRSA Methicillin-resistantstaphylococcus aureus, is very harmful to those with weak immune systems

Insecticide resistance Natural selection led to development of insects resistant to insecticides Almost 20% of insecticides used are aimed at getting rid of insects that damage cotton plants

- Species of moth caterpillar that damage plant have become resistant to many insecticides- Led to use of toxic chemicals that also kill harmless or beneficial organisms


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Maintaining Biodiversity

Conservation of speciesHumans affect nature

We use the environment to our advantage

We have grown in numbers We are using more and more of the Earths resources Loss of biodiversity and extinction many occur We hunt for food and over harvest We kill for protection We cause pollution We destroy habitats

Extinction: When the last living member of a species dies and the species ceases to exist

Loss of biodiversity

Extinction reduces biodiversity Humans have cleared huge amounts of vegetation to make food Replace with a crop of low diversity a monoculture

Why we should conserve speciesEconomic reasons

Evolution has provided us with answers to many technological problems Provide medicines and furniture Grown timber, food and fuel

Ecological reasons

Rainforests regulate the atmosphere Purify fresh water Form and fertilise soil Recycle nutrients Pollinate crops

Ethical reasons

All organisms have a right to survive and live in the way that they have adapted to Human groups still live in natural habitats

Aesthetic reasons

We experience joy and wellbeing when we observe the infinite variations of nature Patients recover more rapidly from stress and injury when they are exposed to pleasing naturalenvironments

Importance of genetic diversity It is important to maintain the diversity of wild plants and animals because of the potential that exists in

the wide range of species currently alive

Without genetic diversity, species will be unable to adapt to changes in the environment A higher proportion of species will get a new disease A reduction in variation because of human activity reduced the gene pool and hinders a species ability

to evolve

Wild animals and plants may hold the answers to problems caused by climate change as they haveadapted to these problems

We would be able to breed new varieties that can cope with conditions Genetic engineering can produce transgenic organisms New medicines can be found in wild plants Range of possible vaccines


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Climate change

Movement of species Species with little genetic variation will be less able to evolve when there are changes in temperature Only alternative would be for a species to move Slow migration of populations, communities and whole ecosystems towards the poles Migration obstructed by developments, agricultural land, water and humans

Effect of agriculture

Domesticated plants and animals are at potential risk of extinction if the climate changes as they havebeen selectively bred to provide the best yield

- We have developed crops and animals with little variation- These species will be unable to evolve

Effect of diseases

Crops grown in new areas will not be resistant to new diseases and pests Higher temperatures will provide a longer growing season but pests will have more time to increase in

numbers

More diseases and pests will be able to cause greater infestation the next year after the winter as theyare able to survive

- Less yields for humans Human diseases will migrate to new areas, such as malaria being able to move to hotter areas as the

world heats up

Types of conservation

In situ

Conserving a species in its normal environment

Conservation parks

Possible to stop unacceptable activities by establishing areas specially for conservation of a species In the UK, we have

- 14 National Parks- National Nature Reserves- Sites of Special Scientific Interest- Local Nature Reserves

Advantages Disadvantages

Permanently protects biodiversity andecosystems

Protects natural and cultural heritage Opportunity for ecological sustainable

land uses

Facilitates scientific research Maintains ecological integrity

Protected animals raid local crops People continue to hunt Illegal harvesting of timber and other

plants

Tourists feed protected animals

Repopulation

Possible to rebuild lost biodiversity if crops and animals are reintroduced to their habitats Large areas for grazing are being helped to turn back into traditional meadows


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Ex situConserving an endangered species by activities that take place outside its normal environment

Zoos

Many now prefer to be known as wildlife parks Concentrate on breeding endangered species Enable repopulation into the wild


Sperm freezing, artificial inseminationused to reproduce

Reproductive physiology specific Research on domestic species helps the

whole population

Saves rare individuals from experiments

Many fail to successfully breed Decrease genetic diversity Species less able to adapt Species have to survive reintroduction to

the wild

Difficulties with accepting wild membersSeed banks

Many botanical gardens e.g. Kew Gardens Collection of seed samples Seeds stored in dry and freezing conditions Seeds tested at regular intervals to see if they can germinate

- Seeds planted in petri dishes of nutrient agar in controlled conditions- Germination rate measures- Enabled scientists to monitor the condition of the seeds


Seeds can be collected without harm to theecosystem

Seeds are a natural part of a plants lifecycle

Can be stored in huge numbers withouttaking up too much space

Plants can often breed asexually Provides large sample for research Can be easily replanted Can remain viable for decades

Collection of wild seeds may cause somedisturbance

Collected samples may not berepresentative of genetic diversity

Seeds may not be viable after a very longtime

Plants breed asexually so offspring will begenetically identical

Conclusions reached from research maynot be valid for whole species

International cooperation

International problemCITES Convention on International Trade of Endangered Species 1973 to ensure international trade of wildlife does not threaten their survival Regulates and monitors international trade Trade in wild plants is prohibited for commercial purposes Less endangered species allowed to be traded Hard to enforce

Convention on Biological Diversity

Promotes sustainable development for our need of food, medicines, shelter and a healthy environment Encourages cooperation between countries and states to share genetic resources and technologies

EIA Environmental Impact Assessment

Documents

Molecules Biodiversity Food and Health[1]