Gcse Biology Revision

This revision resource is a combination of topics in gcse bioology.

Classificaton of organisims

  • Animalia:Multi-Cellular,Hetrotrophic-Feeders,No cell walls.
  • Plantae:Multi-Cellular,Cell walls made: Cellulose,Autrophic feeders: Chlorophyll
  • Fungi:Muli-Cellular,No Chorophyll,Cell walls; Cellulose.
  • Protoctista:Mostly unicellular:(Few:Mulitcellular,Complex Cell structure with nucleaus.
  • Prokokayrates:Unicelluar:Simple Cell Sturucture; no nucleaus
  • Virus particles-doesnt show any life process:Growing/Feeding.
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Vertaebrtes and Invertaebrates

  • Phylum Chordata:Animals:Backbone:Length; body.
  • Scientists: Place vertaebrates; groups:Oxygen-abortion methods-lungs,gills,skin.
  • Reproduction-Internal; external fertilisation.
  • Oviparous-Lay eggs
  • Vivaporous-Give Birth
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Species

Limitation species produce fertile offsprings:Some organisims do not  reproduce sexually; some hybrids: fertile.

  • Bionominal system useful:Organisims ; same names:Diffrent.
  • Hybridisation in ducks produces ducks:Contionous range; characteristics. 
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Variation

  • Contionous Variation-Numerical Value
  • Discontinous Variation: fixed set of values.

Reasons of Variety

Organisism ;previously adapted characteristics.Enables them to survive ;extreme enviroments:Deep-sea hydrothermal vents;Polar regions.

Causes of Variation:

  • Genetic Variation-Different characteristics result: Mutation/ Reproduction.
  • Enviromental Variation-Characteristics caused by:  Organisims Enviroment.
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Evolution

Darwin's theory of evolution  by natural evolution:

  • Variation
  • Over-Production
  • Gradual Change
  • Survival

Speciaion occurs because of geographical isolation

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Genes

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Explaining inheritance

Structure of nucleaus: chromosones:Where genes: Located.

Genes exist in different forms called alleles.

Dominant allele: Allele that will always have an effect.

Recessive gene:Will have an effect if other gene: Recessive.

Homozygous:Same alleles.

Heterozygous:Different alleles

Phenotype:Physical characteristics.Set ;alleles cause.

Genotype:Alleles: Certain charateristics.

1/4 chance of inheriting diseases in families.

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Genetic disorders

Sickle cell disease:Tired,Short of breath

Cystic Fibrosis:Weight loss.Difficult to breath.

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Homostasis

  • Maintainance of stable internal enviroment.
  • Control of body temprature:Theremogulotion.
  • Body temprature:37:Chemical reactions work best, in body.
  • Osmoregulotion:Controls water. Controls concentration of some materials. E.G Glucose in Blood.
  • Role of Dermis: Sweat Glands,Blood Vessels,Nerve Endings,Hair-Erector Muscles,Sabecous Glands,
  • Role of Hypathalamus: Regulates Body Temprature.
  • Hypathalamus: Blood flow reduced to skin: Narrowing blood vessels, close to surface: Body is cold.
  • Vasolidation:blood vessels supply blood to  skin can swell;dilate. Allows warm blood to flow near surface of  skin, where heat is be lost to  air.
  • Vasoconstriction:blood vessels supply warm blood to skin becomes: narrow; constrict. Reduces flow of warm blood near surface of  skin;reduces heat loss.
  • Negative Feedback:Changes in body happens in one direction; mechanisims in body work to change in opposite way.
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Explaining inheritance

Structure of nucleaus contains chromosones:Where genes are located.

Genes exist in different forms called alleles.

Dominant allele: Allele that will always have an effect

Recessive gene:Will have an effect if other gene is recessive.

Homozygous:Same alleles.

Heterozygous:Different alleles

Phenotype:Physical characteristics.Set of alleles cause.

Genotype:Alleles for certain charateristics.

1/4 chance of inheriting diseases in families

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Sensitivity

  • Central Nervous System:Brain;Spinal Cord.
  • Central Nervous System:Linked to sense organs by nerves.
  • Dendrites:Recieve impulses;when sent to recep for cells; other neurons;moves along dendron past cell body to axon.
  • Impulse:Passed along axon,to ending;passed across to other neurones
  • Brain:Process electrical signals;sends:impulses to other organs.
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Responding to Stimuli

  • Role of mylin Sheath:heath helps insulate neuronefrom surrounding tissue;allows impulses:Carried faster,
  • Fatty layer around axon
  • Neurotransmitters:Impulses transmitted across gaps in synapses.
  • Reflex arc:Sensory neurones directly control motor neurones.
  • Reflexes:Protects body.
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Hormones

  • Hormones:Located endorine glands.
  • Transported; blood  target organs.
  • Blood glucse organs:Regulated ; insulin;excess blood coverted ; glycogen : air.
  • When glucose gets above certain concentration:Pancreas releases hormone:Insulin
  • Liver takes glucose out  blood;converts glycogen.
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Diabetes

  • Diabetes:Caused: Lack insulin
  • Insulin:Needs to injected; fat layer beneath skin.
  • Insulin spreads into blood vessels;carried around body blood.
  • Type 2 diabetes:Caused:Person resistant insulin
  • Type 2 diabetes:Controlled:Changing person's diet;increasing amount excerise.
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Plant hormones

  • In roots auxins cause cell:stop elogating;causes: phototropism.
  • Phototropism:Growth towards direction; gravity.
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Uses of plant hormones

  • Selective weed-killers:Artificial auxins used: selective weed killer.
  • Selective weed killer:Makes Plants; broad leaves;grows out; control;dies.
  • Farmers kill plants;without affecting crops.
  • Rooting powder:Synthetic auxins;used: Rooting powder.
  • Plant cutting;dipped: Root powder plants develop roots quickly.
  • Seedless Fruit:Flowers sprayed: Plant hormones;cause fruits to develop; not seeds.
  • Fruits sprayed: Gibberllins;increase size.
  • Fruit Ripening:Plant hormones naturally control ripeneing: Fruits.
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Effects of drugs

  • Drug:Chemical Substance:Narcotics,hallocinagen:Controls nervous system.
  • Morphine:Painkiller.
  • Pain-Killers:Block nervous impulses.
  • Lsd:Hallocinages:Distort sense perception:Sight,Hearing,Feeling.
  • Caffeine:Stimulants.
  • Stimulants:Increase speed  reactions;neurotransmission:Synapses.
  • Alcholol:Slow down brain activity.
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Damage caused by smoking

  • Nicotine:Addictive part tobacco; difficult give up.
  • Tar:Contains Carcinogens;causes cancer:developes:lung of mouth.
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The affects of alcohol

Harmful affects of alcohol abuse:

Short Term-Blurred Visions,blowering inhabitants,slowing  reactions.

Long term-Liver Cirrhosis;Brain Damage.

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Ethics and Diabetes

  • Hospitals,not give all patients,liver transplants,until proven; alcohol:Six months.
  • Heart Transplant:Clinically Obese.
  • Hospitals not perform heart transplants until ,stick;diet.
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Pathogens and Infections

  • Pathgens spread:Cholcera bacterium  water,Salmonella,bacterium,food,influenza virus(sneezin,airborne)athelete's foot,Hiv,bodily fluids.
  • Animal Vectors:House-fly,dysentry bactrium,malerian protzoan:Anopheles Mosquito.
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Antiseptics& Anti-Biotics

  • How human body;effective against attacks pathogens.
  • Phyical Barries-Skin,Cilla,Mucus.
  • Hydrochloric acid-Stomach,Lynsomes-Tears.
  • Plants produce chemicals:ani-bactrial effects;defend theselves;used: Humans.
  • Anti-Biotics-Prevent pathogen getting into wound
  • Anti-Biotics affect bacteria-Penicillin-AniBacterials.
  • Anti-Fungals-Treat Fugal Infections
  • Anti-Biotics-Affect Bacteria Nystatin:Anti-Fungals.
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Interdependence&FoodWebs

  • Interdependence:Dynamic; living things.
  • Some energy transferred;less useful,limits energy.
  • Shape:Pyramid;Biomass:Determined;energy transferred;each level.
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Parasites&Mutualists

  • Parasites:Feeding relationship;two organisms live together,feeding off host.
  • Examples:Fleas,Headlies,Tapeworms,Mistletoe.
  • Mutualists:Organisisms benefit off each other.
  • Example:Cleaner-Fish,Nitrogen-Fixing Bacteria,
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Pollution

  • Method to Eutrophocation:
  • Fertiliser:Added,Heavy Rain:Washes: Fertliser off
  • Nitrates,Phospahates:Dissolve:Soil-Water
  • Nitrates;Phosphates;taken up by plants;washed:Steam/River.
  • High Nitrate phosphates concentrations:Water:Enlarge plants;Algae;Grows rapidly.
  • Surafce plants:Block Sunlight ;plants in water die,stops producing oxgen:Photosynthesis
  • Bacteria:Breaks down dead macterials increase:Numbers;use up:More oxyen;water
  • Oxgen Water Concentration:Water Decreases.
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Pollution Indicators

  • Pollution Indicators:Scienticts : Assess pollution level
  • Examples:Polluted Water Indicator:Blood-Worm,Sludge-Worm,
  • Clean Water-Indicator:Stone-Fly,Fresh-Water Shrimps.
  • Air Quality Indicator:Lichen Species,Black Foot Fungus,Roses.
  • Recycling:Reduces demand:Recources;Problem:Waste disposal:Plastics,Paper,Metals.
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Carbon Cycle

  • Photosynthesis:Plants:Remove carbon-dioxide,from atmosphere,
  • Carbon Compounds pass along:Food chain.
  • Respiration:Organisisms release carbon-dioxide into atmosphere.
  • Combustion Fossil Fuels:Release Carbon-Dioxide into atmosphere.
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The NItrogen Cycle.

  • Nitrogen gas: Air;cannot be used: Animals;Plants.
  • Nitrogen-FIxing Bacteria-Lives-Root Noudles/Soil:Fixes Nitrogen Gas.
  • Action of Lightening:Converts Nitrogen gas:Nitrates.
  • Decomposers:Breaks down:Animals;Plants.
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