Biology As F212

Revisions cards from specification for unit F212 of Biology AS

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Biological Molecules

How does Hydrogen bonding occur between water molecules and how does this relate to its anomalous qualities?

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Biological Molecules

Oxygen is more electronegative than hydrogen so the water molecule is polar, the delta + hydrogen is attracted to the lone pair on oxygen on neighbouring water molecules. This forms a hydrogen bond

High Surface tension

High Specific heat capacity

High latent heat of vaporisation

Liquid at rmt

Ice is less dense than water

High tensile strength

Adhesion and cohesion

Denser than air

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Biological Molecules

Describe the structure of an amino acid

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Biological Molecules

There is an amine group ( NH2)

There is an R group and Hydrogen on the central C atom

There is a carboxyl group (COOH)

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Biological Molecules

What is the function of the R group?

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Biological Molecules

The R group is unique to each amino acid and determines the tertiary shape of the molecule

H - hydrogen bonds

S - disulphate bonds

Hydrophobic - will cause the amino acids to put it on the inside of the 3D structure

Hydrophilic - will cause the amino acids to put it on the outside of the 3D structure

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Biological Molecules

How is a peptide bond formed?

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Biological Molecules

2 amino acids link to form a polypeptide. One amino acid loses an OH group from the COOH. The other amino acid loses a H from the NH2 group

1 water molecule is formed.

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Biological Molecules

What are the conditions for hydrolysis of a dipeptide?

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Biological Molecules

Protease at 37 degrees C and boil it with dilute HCl

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Biological Molecules

Explain the primary structure of an amino acid

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Biological Molecules

This is the specific sequence of amino acid molecules making up a polypeptide chain. It determines the secondary, tertiary and quaternary structure and therefore the function of the protein

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Biological Molecules

Describe the secondary structure of an amino acid

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Biological Molecules

This is the 3D shape into which the polypeptide chain with its primary structure is folded or pleated. The polypeptide chain is twisted or pleated to produce a stable 3D structure such as alpha helix or a beta pleated sheet, stabilised by hydrogen bonds

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Biological Molecules

Describe the alpha helix

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Biological Molecules

Hydrogen bonds form between adjacent CO and NH groups. It is found in fibrous proteins

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Biological Molecules

Describe the tertiary structure of an amino acid

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Biological Molecules

This is the way that the polypeptide chain with its secondary structure folds into a compact precise shape. It is held together by 4 bonds

Hydrogen bonds - broken by a high temperature and pH change

Disulfide bonds

Ionic Bonds - broken by a pH change

Hydrophobic interactions - Proteins fold, creating water free pockets in the middle of the molecule

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Biological Molecules

Describe the quaternary structure of an amino acid

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Biological Molecules

This is the way that polypeptide chains are packed together to give a protein with a precise 3D shape

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Biological Molecules

What is haemoglobin comprised of?

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Biological Molecules

It has more than 2 polypeptide chains, 2 alpha helixes and 2 beta pleated sheets. Its quaternary structure allows it to hold Iron. As oxygen binds with the iron, the shape of the molecule is changed gradually to make it easier to accept oxygen.

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Biological Molecules

Describe a collagen molecule

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Biological Molecules

It is a fibrous protein with 3 polypeptide chains

It has a triple helix

Its chains are linked by covalent bonds

It is an unbranched polypeptide

It is insoluble, strong and flexible

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Biological Molecules

Compare the structure and function of collagen and haemoglobin

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Biological Molecules

Collagen Haemoglobin

Long and thin Primary structure is very precise

Often helical Compact

No tertiary structure Tightly folded

Insolube Soluble

Strong Strong disulfide and H bonds

Structure and support Enzymes and metabolic functions

Fibrous Globular

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Biological Molecules

Describe the structure of alpha glucose

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Biological Molecules

The OH group on C 1 is below the plane of the ring

It is a monosaccharide

It is a ring structure

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Biological Molecules

What is the difference between alpha and beta glucose molecules?

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Biological Molecules

on the alpha glucose, the OH group on C 1 is below the plane of the ring

On the beta glucose, the OH group on C 2 is above the plane of the ring

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Biological Molecules

How is a glycosidic bond formed?

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Biological Molecules

In a condensation reaction, a molecule of water is lost to form a 1,4 glycosidic bond ( between C1 and C4)

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Biological Molecules

how do you make maltose, sucrose and cellulose?

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Biological Molecules

alpha glucose + alpha glucose ---> maltose

Alpha glucose + fructose ----> sucrose

Beta glucose + B glucose ----> Cellulose

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Biological Molecules

Compare the structure and functions of Cellulose and Starch

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Biological Molecules

Starch Cellulose

Energy storage in plants Structural

1,4 glycosidic bond and 1,6 1,4 glycosidic bond and H bond between chains

Alpha glucose B glucose

Straight chain and coiled in a helix Bundles called microfibrils and straight chain

Branched - amylopectin, Unbranched - amylose

In chloroplasts In cell walls

Insoluble Insoluble, supports other cells

Spring makes it compact High tensile strength

No affect on water potential Allows water to move along cell walls

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Biological Molecules

describe the structure and function of Glycogen

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Biological Molecules

It is the main carbohydrate storage in animals. It is made of alpha glucose molecules.

It is more branched than starch so it can be hydrolysed faster so glycogen can release glucose very quickly

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Biological Molecules

What is the difference between triglycerides and phospholipids?

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Biological Molecules

A triglyceride is 3 fatty acids + 1 glycerol and is non polar

A phospholipid is 2 fatty acids and 1 glycerol and 1 phosphate group

It is polar

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Biological Molecules

What are the uses of lipids and cholesterol?

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Biological Molecules

Thermal insulation, buoyancy, protections from mechanical damage, energy storage, electrical insulation. Fats release twice as much energy as carbohydrates but are more compact in droplets so easy to carry. They are insoluble in water so don't affect the water potential of a cell.

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Biological Molecules

What are the tests for protein, reducing sugars and non reducing sugars?

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Biological Molecules

Protein - Biuret test, NaOH + CuSO4 blue---> lilac

Reducing sugar - Benedicts test, Heat to 80 degrees C and add benedicts Blue---> orange

Non reducing sugar - Modified benedicts, Boil with HCL acid. Neutralise with NaHCO3. Add benedicts blue ---> orange

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Biological Molecules

What are the tests for starch and lipids?

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Biological Molecules

Starch - Iodine, potassium iodide yellow----> blue/black

Lipids - Emulsion, Shake with absolute alcohol. Add cold water, forms a cloudy white emulsion

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Biological Molecules

How can the concentration of glucose in a solution be determined using colorimetry?

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Biological Molecules

The bluer the colour, the less transmission of light, the lower the concentration of glucose

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Nucleic Acids

Describe DNA

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Nucleic Acids

DNA is deoxyribonucleic acid

It is a polynucleotide

It is double stranded

It is made of nucleotides containing the bases adenine, thymine, cytosine and guanine

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Nucleic Acids

Describe RNA

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Nucleic Acids

RNA is ribonucleic acid

It is single stranded and usually made up of the bases adenine, uracil, cytosine, and guanine

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Nucleic Acids

What are the 3 things that make up a nucleic acid?

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Nucleic Acids

Phosphate group, pentose sugar and a nitrogenous base

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Nucleic Acids

What nitrogenous bases are purines and pyrimidines?

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Nucleic Acids

Purines - A and G

Pyrimidines - C and T

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Nucleic Acids

Describe the structure of DNA

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Nucleic Acids

Hydrogen bonds form between complementary base pairs ( A to T, G to C) on two antiparallel DNA polynucleotides. This twisting forms a double helix

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Nucleic Acids

Outline of DNA replicates

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Nucleic Acids

DNA replicates during interphase of the cell cycle before the nucleus divides. DNA replication is semi conservative - Each new DNA molecules contains one old polynucleotide strand and one new one. DNA helicase and unwinds and unzips the DNA by breaking weak hydrogen bonds between complementary base pairs.

Free nucleotides in the nucleus pair up with the exposed bases on the unzipped strands

The nucleotides of the new DNA strands are linked together

The enzymes DNA polymerase catalyses formation of strong covalent bonds between phosphates and deoxyribose sugars to form backbones for new DNA.

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Nucleic Acids

What is a gene?

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Nucleic Acids

It is a specific sequence of DNA nucleotides that codes for a polypeptide

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Nucleic Acids

Explain Protein Synthesis

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Nucleic Acids

RNA transfers DNA base sequences to ribosomes and converts it into amino acid sequences. 1 gene unwinds and base pairs separate when weak H bonds are broken.

Free RNA form a mRNA molecules to carry a copy of the base sequence. This is called transcriptions and happens in the nucleus

Single stranded mRNA leaves the nucleus through a nuclear pore and attaches to a ribosome

Specific tRNA molecules bring specific amino acid molecules to the ribosome. This is translation

Amino acids join together by peptide bonds

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What are enzymes?

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Enzymes are globular proteins with a specific tertiary structure, which catalyse metabolic reactions in living organisms

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Where do enzymes work?

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Enzymes can work intracellular or extracellular

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What is meant by Specific Enzymes?

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The substrate molecule must have the correct complementary 3D shape to fit into the enzyme's active site to allow catalysis

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what is the lock and key hypothesis?

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It assumes the enzyme already has a complementary shape to the substrate and the specific enzyme will bind with he specific substrate if their shapes are complementary.

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What is the induced fit hypothesis?

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When an enzyme encounters a substrate the active site is not exactly the complementary shape to the substrate. As the enzyme approaches the substrate the active site changes to produce and enzyme substrate complex. The enzyme moulds itself around the substrate so their shapes are complementary and can react producing an enzyme products complex. The products are then released.

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What affect do enzymes have activation energy?

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Enzymes decrease the activation energy in a reaction by holding the substrate in such a way that they can react more easily.

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What is the affect of pH on enzymes?

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A high concentration of hydrogen or hydroxide ions interfere with hydrogen and ionic bonds, disrupting the tertiary structure which is irreversible

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What is the effect of a change in temperature upon an enzyme?

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The rate of reaction increases due to increasing numbers of more energetic collisions. Eventually increasing vibration breaks hydrogen and ionic bonds, disrupting the tertiary structure. The active site is lost and the reaction ceases. The enzyme is progressively denatured, Fewer enzyme substrate complexes are made.

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What is the affect of enzyme and substrate concentration on enzyme activity?

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Enzyme - provided nothing else is limiting, more enzymes means more active sites and more collisions so the reaction occurs faster as more enzymesubstrate complexes are made. With a fixed substrate concentration, the substrate is limiting some of the active sites are free some of them time.

Substrate - When all active sites are occupied, further increase in substrate concentration has no effect as no more enzyme substrate complexes can be made.

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What are the investigations for the affect of pH, Temperature and enzyme concentration?

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pH - H2O2 with yeast suspension as a source of catalase, measure the rate of O2 production. Use different buffers to change the pH

Temp - H2O2 with yeast suspension, measure the rate of O2 production. Use different temps in a water bath to change temp

Enzyme concentration - Trypsin with milk powder solution as a source of caesin. Use colorimeter to measure absorption or black cross test. Solution should clear on addition of trypsin

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What is an inhibitor?

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a substance which binds to an enzyme and reduces catalytic activity

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Explain how competitive inhibitors work

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The inhibitor resembles the substrate chemically and binds to the active site of the enzyme (blocking it). The inhibitor thus competes with the substrate for the active site. So less product is formed ---> reversible

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Describe non competitive inhibition

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The inhibitor binds to another part of the enzyme (inhibitor site). This disrupts the hydrogen bonds and hydrophobic interactions in the tertiary structure. It changes the whole shape of the enzyme including the active site so it no longer has a specific 3D nature so the substrate no longer fits and the reaction slows down ---> reversible but mostly irreversible

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What is a cofactor?

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Some enzymes only work in the presence of a non protein cofactor. A cofactor is tightly bound to its enzyme and is called a prosthetic group. They may attach to the active site to make its shape more efficient

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What is a coenzyme?

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A coenzyme is an organic cofactor e.g. vitamins

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Describe the action of a named poison

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Cyanide - blocks the active site of cytochrome oxidase. This enzyme catalyses the oxidation of hydrogen to form water, the final product in aerobic respiration

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Diet and Food Production

Define the term balanced diet

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Diet and Food Production

A balanced diet is when you ensure the concentration and proportion that you eat enables efficient functioning of the body

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Diet and Food Production

How can consumption of an unbalanced diet lead to malnutrition?

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Diet and Food Production

If your energy intake exceeds your energy usage, you will store the energy as fat in adipose tissues. Obesity is the condition in which excessive fat deposition impairs health. The location of the fat has an affect : middle - more at risk

Hips and thighs - less at risk

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Diet and Food Production

What are the possible links between diet and coronary heart disease?

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Diet and Food Production

If you have a diet high in saturated fat you will have high levels of LDL's. LDL's will deposit cholesterol in artery walls and there is a risk of an atheroma building up in the artery wall

If you have a diet high in salt, it lowers the water potential of the blood so water enters the blood by osmosis so increases the volume of the blood, so increases the blood pressure leading to CHD.

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Diet and Food Production

Why are plants important to human diet?

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Diet and Food Production

Human depend on plants for food as they are the basis of all food chains

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Diet and Food Production

How is selective breeding perfomed?

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Diet and Food Production

A farmer grows the plants or animals in isolation so he can ensure which organisms are crossed with which. From the offspring, ones with enhanced desirable characteristics are chosen for crossing. They breed to produce more offspring with the enhanced desirable characteristic.

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Diet and Food Production

What is selective breeding used for?

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Diet and Food Production

It produces organisms which are disease resistant, fast growing, pest resistant or produce high yields ( perhaps domestic animal yield of more eggs or bigger udders for more milk)

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Diet and Food Production

What are the advantages and disadvantages of using fertilisers and pesticides with plants and the use of antibiotics with animals?

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Diet and Food Production

Fertilisers increase the crop yield and therefore income but it costs money and can damage the environment

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Diet and Food Production

What are the advantages and disadvantages of using micro-organisms to make food for human consumption?

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Diet and Food Production

Advantages - protein production is fast

production can be controlled

no animal welfare issues

good source of protein for vegetarians

no animal fat or cholesterol

Disadvantages - Protein must be purified

Contamination issues

Doesn't taste great


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Diet and Food Production

How can we prevent spoilage of food by micro-organisms?

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Diet and Food Production

Low temps - inactivating enzymes

Boil - Denatures enzymes

Vacuum packing/freeze dried - No air, no damage from ice crystals

Smoking meat - kills micro-organisms

Salting/sugaring - Lowers water potential so water moves out of food and organisms to enzymes aren't in solution

Pickling - acidic denaturing of enzymes

Oil immersion - no oxygen

Irradiation - gamma rays kills mico-organisms

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Health and Disease

What is meant by the terms health and disease?

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Health and Disease

Health is a state of complete physical, mental and social well being.

Disease is anything that impairs normal function of the body or mind. It can be physical, mental, social, infectious, non-infectious, degenerative, inherited, self-inflicted and deficiency.

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Health and Disease

Define the terms parasite and pathogen

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Health and Disease

A parasite is an organism that lives in or on another organisms. Parasites which cause disease are called pathogens.

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Health and Disease

What are the causes and the means of transmission of malaria?

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Health and Disease

Malaria is the disease caused by the virus Plasmodium

It is carried by a vector - female anopheles mosquito

It affects the liver cells, red blood cells and brain cells

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Health and Disease

What are the causes and means of transmission of AIDS/HIV?

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Health and Disease

AIDS is caused by HIV (Human immunodeficiency virus). It is transmitted via contaminated hypodermic syringes, from mother to child across the placenta or breast milk, through sex, via blood transfusions and by infected body fluids. It uses reverse transcriptase to attack t helper lymphocytes, macrophages and brain cell.s

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Health and Disease

How is TB caused and how is it transmitted?

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Health and Disease

TB is caused by the bacteria mycobacterium tuberculosis. It is transmitted via airborne droplets and unpasteurised milk. It causes a primary infection in the lungs

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Health and Disease

What is the global impact of TB, malaria and HIV/AIDS?

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Health and Disease

TB is in many places where there is overcrowded living conditions. So many antibiotics are used to treat it, and it reproduces so quickly, multidrug resistant strains are an increasing problem.

Malaria is found in warmer countries where the anopheles mosquito can survive e.g sub tropics and tropics. Plasmodium is showing increasing resistance to drugs. Climatic changes are causing the spread of mosquitoes. Mosquitoes are becoming resistant to DDT and other insecticides.

HIV is worldwide but especially in sub Saharan Africa and SE Asia. There is no vaccine and symptomless carriers.

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Health and Disease

What do immune response, antigen and antibody mean?

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Health and Disease

Immune Response - The action of lymphocytes in response to entry of an antigen into body. Activated B lymphocytes differentiate to produce plasma cells which produce antibodies.

Antigen - A molecule which the body recognises as foreign = "non self". Distinctly large molecules on surface of pathogens. Usually proteins or glycoproteins. They stimulate an immune response by triggering antibody production

Antibody - Usually glycoproteins (globular) and are immunoglobulins. They are produced by plasma cells. Each type of antibody acts on a specific antigen.

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Health and Disease

What are the primary defences against pathogens and parasites?

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Health and Disease

Skin - hard for pathogens to cross the other layer of intact skin because the cells are dead and keratinised

Mucus membrane - in lungs and gut. layers of cells which contain goblet cells. The mucus is produced by goblet cells then the cilia in trachea beat in synchrony to sweep the mucus up to the pharynx where it is swallowed.

Acid in stomach and ****** - acid denatures enzymes of pathogens. Harmless bacteria secrete lactic acid.

Lysosymes - enzymes in tears and saliva, breaks bonds in cell walls of murein in bacteria

Blood Clotting - Seals wounds, prevents pathogens entering. Globular soluble fibrinogen protein is converted to insoluble fibrous fibrin - forms a network of strands where platelets and red blood cells get trapped.

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Health and Disease

Describe the structure and mode of action of phagocytes

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Health and Disease

Attraction - Neutrophils are attracted to the site of infection by histamine and by chemicals produced by pathogens. Neutrophils move towards pathogen along a concentration gradient.

Recognition and attachment - Neutrophils have receptor proteins that recognise antigens on the pathogens. The bacteria attaches to the neutrophil

Endocytosis - plasma membrane of neutrophil invaginates. This traps the pathogen within a vesicle. The pathogen is trapped once the cell surface membrane has fused to form a vescicle.

Lysosomes fuse with vescicle. toxins and H2O2 are secreted into the vesicle to kill bacteria.

Neutrophils are able to squeeze through the walls of blood capillaries and move about in the tissues spaces.They have a lobed nucleus and granular cytoplasm. Monocytes are larger cells and become macrophages which spend their lives patrolling tissues. They have non granular cytoplasm and a large bean shaped nucleus.

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Health and Disease

Describe the structure of antibodies

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Health and Disease

An antibody is a molecule that is synthesised by an animal in response to the presence of foreign substances known as antigens. Each antibody is a protein molecule called an immunoglobulin. It has two heavy chains and 2 light chains. The antibody has a constant and variable part, the variable part acting something like a key which specifically fits into a lock. There is the antigen binding site and disulphide bonds.

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Health and Disease

Outline how antibodies work

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Health and Disease

Neutralisation - Antibodies covering the pathogen binding sites prevent the pathogen from binding to a host cell and entering the cell

Agglutination - A large antibody can bind many pathogens together. The group of pathogens is too large to enter a host cell.

Precipitation - Soluble antigens are precipitated out by antibodies

Lysis - Antibodies attract enzymes which rupture the cell surface membrane

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Health and Disease

Describe the structure and mode of action of T lymphocytes and B lymphocytes

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Health and Disease

lymphocytes have a large nucleus and a thin halo of clear cytoplasm

The pathogen is engulfed by cells from the immune system. The antigens are removed from the pathogen.

Antigens are presented on the surface of engulfing cells ( antigen presentation)

The correct T killer cells and T helper cells are selected (clonal selection)

Some reproduce to form T helper cells, others, T killer cells (clonal expansion)

T helper cells release interleukins, these activate the B cells. B cells are then reproduced. Some B cells differentiate to form plasma cells to make antibodies. Others differentiate to make B memory cells.

T killer cells search for infected cells. They attach to infected cells and secrete toxins into infected cells to kill the cell and the pathogens it contains

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Health and Disease

What are the differences between primary and secondary responses?

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Health and Disease

The primary response is slow, and effective against specific pathogens

The secondary response is speeded up during subsequent encounters with the same pathogen. There are many more antibodies produced very quickly in the secondary response

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Health and Disease

compare and contrast active, passive, natural and artificial immunity.

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Health and Disease

Active immunity is when the antigen is encountered and an immune response occurs. It takes several weeks before antibodies appear in the blood and memory cells are produced to provide long lasting protection.

Passive immunity is when the antigen is no encountered and there is no immune response but antibodies appear in the blood immediatly. No memory cells are made and it only provides a temporary protection. e.g. from breast milk

Natural immunity is acquired as a result of normal life processes (from mother early in life or from having had disease and recovered.

Artificial immunity is acquired when the body is deliberately exposed to antibodies or antigens in a non-natural circumstance e.g. vaccine

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Health and Disease

How does a vaccine work?

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Health and Disease

a person is injected ( or fed) a dead or living form of the micro-organism. The strain may be a weak one or it may just have bacteria toxins that are harmless or it may just be a mixture of antigenic material from the bacterial cell wall.

Your body will produce a primary immune response to the foreign material and produce antibodies and memory cells so your body can produce a secondary immune response if it ever encounters the organism again, thus being must faster at eradicating the disease

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Health and Disease

What are possible new sources of medicines?

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Health and Disease

New disease emmerge e.g. swine flu

Some drugs become less effective and some diseases are impossible to treat as bacteria have evolved to a state of antibiotic resistance e.g.MDRTB

Therefore new drugs must be found

Some drugs are discovered by accident like penicillin. Other drugs are herbal compounds found in ethnobotany. Modern techniques such as finding the shape of the particular receptor and finding ad rug that can block it using molecular modelling can help isolate compounds that would be useful. Sometimes observing wildlife can help find new drugs.

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Health and Disease

How does smoking cause chronic bronchitis?

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Health and Disease

Chronic Bronchitis: Tar -->increases mucus production, cilia don't beat, increase in mucus narrows the airways, bacteria trapped in the sticky mucus reproduce in a warm moist environment leading to secondary infections.

In addition, particles trapped in the mucus in the lungs could cause irritation and allergic responses. Mucus in the lungs and particles cause the person to cough and coughing causes scarring of alveoli surface which in turn thickens the surfaces creating a longer diffusion distance. Smooth muscle in bronchioles thickens therefore narrowing airways.

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Health and Disease

How does smoking cause emphysema?

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Health and Disease

After an infection in the lungs---> phagocytes leave capillaries and go into the airways. Enzyme elastase is released to break down elastin in alveoli walls to get to infection. Elastin is important in enabling the alveolli walls to recoil during exhalation to pus air out of the alveoli. Smaller bronchioles and alveoli collapse without elastin trapping air. Trapped air bursts alveoli so there are fewer alveoli and they have thicker walls.

Symptoms are breathlessness, weaziness, tiredness, paleness, rapid shallow breathing

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Health and Disease

How does smoking cause lung cancer?

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Health and Disease

Polycyclic hydrocarbons in the tar settle at the base of the trachea. These are carcinogens and release free radicals which steal electrons from enzymes and DNA which leads to Cancer as mutations occur. You can have a slow growing tumour which remains undetected until it has grown and possibly spread.

symptom is coughing up blood

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Health and Disease

What are the effects of nicotine, carbon monoxide and tar?

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Health and Disease

Nicotine is addictive and a stimulant. It causes the release of adrenaline so increases the heart rate. It narrows some arterioles increasing the blood pressure and causes bad circulation. It makes the platelets sticky

Carbon Monoxide binds irreversably with haemoglobin forming carboxyhaemoglobin. The body may respond to reduce O2 by causing the heart to beat faster. Less O2 reaches respiring cells. Less O2 goes to foetus so the body mass of the baby is less and can cause brain damage. It can damage the lining of the arteries to cause atherosclerosis

Tar lines the airways and alveoli, it decrease the diameter of bronchioles and thickens the alveoli walls. It paralyses cilia and enlarges goblet cells so they overproduce mucus. It is a carcinogen.

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Health and Disease

What are the responses of governments and other organisations to the threat of new strains of influenza each year?

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Health and Disease

In an attempt to avoid another pandemic, people at risk may be immunised. In the Uk there is a vaccination program to immunise all those aged over 65 and those who are at risk for any other reason. The strains of flu used in this immunisation programme change each year. Research is undertaken to determine which of the strains of flu are most likely to spread that year.

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Health and Disease

How is atherosclerosis, CHD and stroke caused?

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Health and Disease

Atherosclerosis is the prgressive build up of fatty material in the walls of the artery. This narrows the artery making the blood pressure higher. It decreases the flow of blood to tissues beyond the fatty material. It increases the chance of a blood clot. The fatty material forms a plaque and consists of cholesterol, fibrous tissue, dead blood, muscle cells and platelets. This is an atheroma. This tissue goes hard and calcified to cause arteriosclerosis.

CHD is when an atheroma builds up narrwoing the coronary artery causing a decrease in the supply of blood to the heart. Therefore less O2 and glucose gets to the heart especially during exercise. Angina is the narrowing of the coronary arteries and so there is less O2 going to the cardiac muscle, there is acute gripping pain but no death of cardiac muscle. MI is a severe lack of O2 to the heart and so cardiac cells die. Heart failure is a progressive weakeneing of th ehheart as the coronary arteries get blocked gradually.

Stroke is damage to the brain due to cardio problems and can result in death. Symptoms are fainting, slurred speech, time delays and confusion. Not enough O2 gets to the brain.

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Health and Disease

How is an atheroma formed?

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Health and Disease

When there is damage to the lining of the arteries ( possibly caused by CO of fatty streaks which appear even in children) White blood cells go to repair the damage and stimulate the growth of smooth muscle cells. LDL's deposit cholesterol and the plaque size increases. Eventually the plaque gets so big it bursts through the lining of the artery and is rough. Matter is now deposited on the now rough surface and a blood clot forms. Nicotine makes your platelets more sticky so increases the risk of a blood clot forming

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Health and Disease

What is epidemiology?

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Health and Disease

It is the study of the distribution of a disease in populations, and the factors that influence its spread

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Health and Disease

What is the Epidemiological evidence that smoking kills people?

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Health and Disease

A regular smoker is 3 times more likely to die prematurely than a non-smoker

50% of regular smokers are likely to die of a smoking-related disease

The more cigarettes a person smokes per day, the more likely she is to die prematurely and the younger she is likely to die

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Health and Disease

What is the epidemiological evidence that links smoking to lung cancer?

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Health and Disease

A smoker is 18 times more likely than a non-smoker to develop lung cancer

25% of smokers die of lung cancer

A heavy smoker is 25 times more likely than a non-smoker to die of lung cancer

The change of developing lung cancer reduces as soon as a person stops smoking

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Health and Disease

What is the epidemiological evidence that links smoking to lung disease?

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Health and Disease

COPD is rare in non-smokers

98% of people with emphysema are smokers

20% of people who smoke have emphysema

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Health and Disease

What is the epidemiological evidence that links cardiovascular diseases with smoking?

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Health and Disease

There are too many risk factors of CVD to link smoking with it directly but there is evidence to suggest the substance released from cigarettes causes artherosclerosis and other circulatory diseases

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Health and Disease

What is the experimental evidence that links smoking to cancer?

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Health and Disease

in the 1960s dogs were made to inhale cigarette smoke. Some dogs had unfiltered smoke. Those with unfiltered smoke developed changes in the lungs similar to COPD. There were early signs of lung cancer. Those with filtered smoke remained healthier, lung tissue cells had changes that lead to lung cancer. The filter removed some of the harmful substances. The tar collected in the filter was shown to have carcinogens in it.

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Define the terms species, habitat and biodiversity

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Species - a group of animals that can breed together to create fertile offspring

Habitat - describes the typical environment of a particular organism, population, community or ecosystem.

Biodiversity - The range of habitats, communities and species in an area and the genetic diversity within a population.

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Explain how biodiversity may be considered at different levels

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The number of species present is determined by the diversity of the habitat

The species can determine what other species are present

The species also determines the level of competition as they compete for the same limiting source

Genetic diversity, if there had been a lot of inbreeding a genetic disorder could arise and the species could be damaged.

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Explain the importance of sampling in measuring the biodiversity of a habitat

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It is impractical to attempt to find and count all the members of a given species to determine the biodiversity of an area so sampling is needed. There are time constraints, damage caused to the environment and microscopic organisms which are hard to identify therefore sampling is more practical

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Describe how random samples can be taken when measuring biodiversity

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Divide the site into 10m x 10m grids. With a random button on a calculator select the co-ordinates on the grid. Count the number of organisms present in those co-ordinates of the gird

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Describe how to measure species richness and species evenness in a habitat

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Species Richness can be calculated by using quadrats . The number of organisms within a number of quadrats represents a known fraction of the total area so can estimate the total number in the whole area. You can count the number of species present in the quadrat and record the number of each individual species. You can use the ACFOR scale to estimate the species evenness

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How do you use the Simpson's Index of Diversity to calculate the biodiversity of a habitat?

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D= 1-( sigma(n/N)^2)

n= number of individuals of a particular species

N = total number of all individuals of all species

The bigger D is, the more diverse the community.

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What is the significance of both high and low values of Simpson's Index of Diversity?

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A high value means there is alot of biodiversity and a low value means there is not alot of biodiversity. The more diverse a habitat is, the more likely it is to be stable. They don't have a single dominant species which if wiped out, could have huge consequences.

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Describe how you would investigate whether leaving strips of land around fields encourages plant biodiversity?

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You could use point quadrats or belt transects to record biodiversity in the field one year, translate this into the Simpsons Index of Biodiversity to obtain a numberical value. You would have to use the same size quadrats each time to make it a fair test on more than one site to gain a practical overview of the area. You could calculate % cover using point quadrats

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Explain why crop yield near hedgerows can be low

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There is competition with the hedge for minerals, water and sunlight so less crops are produced as some may die, or not grow as fast

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Why is a loss of biodiversity a concern to wildlife people?

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It can disrupt food chains

Loss of pollinators so plants don't reproduce

Natural predators could decrease and this would disrupt food chains and entire ecosystems

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What are the advantages and disadvantages of the ACFOR scale?

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Advantages - there is no need to count so it is fast

Disadvantages - There are no numbers so it is hard to calculate Simpson's Index of Biodiversity. It is subjective

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Describe how a transect is carried out along an area of progressive change

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Select your area of progressive change from the bottom of a slope to the top of a slope. Lay a tape measure along the area. Record every organsims that touches the tape measure or if using a belt transect with quadrats, you count the organsims in the quadrat to calculate Simpson's index of biodiversity or decide on the relative abundance of the species according to the ACFOR scale

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Define the terms classification, phylogeny and taxonomy

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classification is the grouping of things together on the basis of features they have in common. Taxonomy is the science of putting things into these categories. It aims to show evolutionary relationships between groups. Phylogeny is the dividing of prokaryotes into 3 domains - Eubacteria, Archaebacteria and Eukaryotes

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really good :D


These are really very good, thank you very much for sharing :). X

Kazveen Aamer

wow.. this is really helpful. thanks =)

Bhavik Mavadia


sarah hughes

thankyou this is very helpful and it must taken a very long time to do 198 revision cards so we are very grateful



really helpfull, thanks

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