b6 - Flashcards in GCSE Biology

bacteria structure

cell wall - keep shape and stop them bursting // strand of DNA - cytoplasm control cell's activities and replication // plasmids - loops of DNA // flagellum - movement // shapes - rods, curved rods, spirals, spheres

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bacteria variation (eating)

they can consume a range of organic nutrients providing energy, some types produce their own nutrients // survive in any habitat

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bacteria reproduction

asexual (clones of each other) - binary fission // reproduce very quickly, if a disease causing bacteria enters your body they can reproduce and cause disease before you respond faster when warm and good supply of nutrients (fridge slows reproduction

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culture bacteria

culture bacteria on an agar plate, bacteria transfered from plate using wire inoculation loop

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agar plate

petri dish full of agar jelly

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aseptic techniques

stop infection/contaminating agar by microbes -hair tied back stop falling into agar -gloves -sterilizing equiptment (bunsen) -sealing dish -despose safely (pressure starilising in autoclave)

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yoghurt

equiptment sterilised killunwanted microbes -milk pasturised (72 15s) kill microbes -cooled -starter culture added -incubated (40) in vessle called fermenter -bacteria break down lactose sugar into lactic acid -milk clots + solidifies

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continued....

-sample to check consistancy -flavours/colours added - packaged

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starter culture for yoghurt

lactobacillus bacteria

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virus structure

Aren't cells, protien coat around a strand of genetic material - only reproduce in linving cells so infect plant/animal/bacteria cells to multiply a particular virus will only attack specific cells

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virus reproduction

attaches to a specific host cell and injects genetic material into the cell - uses the host cell to make the compounds of new viruses - cell splits open - viruses realeased

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disease transmition - food // water

food poisening - eating bacteria contaminated food prevented by good hygine and cooking food correctly // cholera drinking water contaminated with sewage (developing countries poor sanitation) prevent with good sanitation

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airbourne // contact

influenza - (virus) airbourne droplets when you cough/sneeze prevent tissue, washing hands and disinfecting contaminated surfaces // athelete's foot - (fungus) spread bare feet on damp floors prevent by washing feet regularly

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continued

not walking bare foot, disinfevcting surfaces

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incidence of a disease is

number of new cases that occurs in a population in a certain time

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what effects incidence

good sanitation and public health measures linked to low incidence (clean water, good sewage works, public health education, clean hospitals reduce spread) developing countries can't afford good sanitation and health measures

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stages of infectious disease

1) microorganism enters body 2) reproduces rapidly 3) they produce toxins which damage cells 4) toxins cause symptoms the immune systems reaction to toxins can cause symptoms (fever)

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incubation period

time between exposure to the microorganism and development of symptoms

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antiseptics

outside the body - clean wounds/surfaces - prevent infection [household appliances and hospitals to prevent mrsa]

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antibiotics

inside body - treat infection - only bacteria

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resistance

mutations can lead to becteria becoming less affected by a particular antibiotic - survival of the fittest [natural selection] becomes more common

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prevent resistance

only take antibiotics when you need them [create situation where resistant bacteria are better] -finish the course

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natural disasters and disease

-damage swewage/water systems [contaminated water] -displaced [large numbers +poor saniation] - health services damaged -electricity supplies [fridges - food poisening]

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pasteur

microbes in air cause disease and decomposition // heated broth in 2 flasks left open to the air, one had curved neck so microbes couldn't get in the broth - broth with curved neck stayed fresh

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lister

surgeon - half patients died of sepsis - thought it was decomposition so realised he needed to kill microbes so dressed wounds in carbolic acid [antiseptic] killed bacteria

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fleming

bacteria didn't grow near mould [penicillium notatum] penicilin

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yeast anareobically

respires anareobically called fermentation [glucose~ethanol+carbon dioxide (energy)] [c6h12o6~2 c2h5oh + 2 co2 (energy)]

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yeast areobically

more energy same as animals/plants [glucose+oxygey~carbon dioxide+water] it prefers thsi becasue it releases more energy so fermentation only happens in absence of oxygen

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yeast reproduction variation

the faster it respires the faster it reproduces - controlled by temperature, toxins, food and pH (and faster with oxygen because it respires faster) to measure it measure amount of glucose it breaks down the faster it reproduces the more glucose

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waste water with yeast

sugary water cannot be released into water ways - pollution- bacteria would feed on it -eutrophication- yeast uses sugar in respiration

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brewing 1

beer made from barley - grains allowed to germinate (starch is broken into sugar by enzymes) - grains dried in kiln (malting) - malted grain mashed up (sugary solution) - sived - hops added to make bitter / wine - grapes are mashed - water added

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2

yeast added - incubated - ferments sugar into alcohol [vessles stop microbes and air getting in] the rise in ethanol kills yeast - fermentation slows (different species tolerate different levels)

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3

drawn off through a tap - clarifying agents are added to remove particles and make it clearer

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4

beer pasturised to kill yeast reduce risk of spoiling / wine left to keep fermenting - beer casked wine bottled

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distillation

increase alcohol content (cane sugar = rum) heated to 78 alcohol vapour rises and condenses in the collecting tube

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biofuels -- biomass

biomass is living or recently dead organic material and a store of energy which can be transeferred - fast growing trees can be burt - heat, biomass can be fermented by yeast and bacteria which can be burnt as fuel.

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biogas

70% methane ch4 30% carbon dioxide, traces of hydrogen, nitrogen and hydrogen sulfide. >50% methane burns easily 10% methane explosive. It is made by bacteria in a digester, the bacteria's respiration produces methane

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biogas as a fuel

burned to power a turbine which can generate electricity, useful in remote areas with no mains supply. burnt to heat water to produce steam for central heating systems, burnt for fuel for cars and buses

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how is biogas made

from plant waste or poo, in a fermenter (digester) sludge waste is used on a large scale. Different bacteria some decompose organic matter then others decompose their waste - fermentation. constant warm temperature 30-40

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how biogas is made continued...

optimum temperature for bacteria's respiration, cooler don't produce it as fast, hotter bacteria killed, anareobic

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biogas generator

-an inlet for waste material -an outlet for digested material -an outlet for biogas to be piped where needed.

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large scale biogas

uses continuous flow method - organic waste is continuously fed into the digester and biogas and solid digested material is removed at a steady rate

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slude waste

sewage waste or waste from sugar factories

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fermentation

the breakdown of substances without oxygen

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advantages of biofuels

produced sustainably, the crops can be replaced quickly, plants photosynthesis taking in the carbon dioxide they release when they burn (carbon neutral) if burnt at same rate as groen and teh areas of land cleared were not cleared by burning plants

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advantages continued

cleaner fuel than diesel or petrol, doesnt produce particulates which cause lung disease

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disadvantages of biofuels

doesn't contain as much energy as natural gas [more dilute], large areas of land are cleared increasing greenhouse gases and habitat loss, extinction of species [loss of habitat/change in food]

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ethanol as a fuel

ethanol is cleaner with fewer pollutants, revewable, produced by yeast to ferment glucose - sugar cane,corn and barley can be used as a source of glucose

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gasohol

10%ethanol 90%petrol - less crude oil, the growth of crops means carbon dioxide is absorbed - brazil use it they have little oil and a lot of sugar cane

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sandy soils

-large mineral particles -large pores -high air content -permeable (water pass through)

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clay soils

-tiny particles -packed tightly together leaving small pores -retain water because water molecules cling to the particles. low air content low permeability

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loam soils

mixture of sand and clay -properties depend on proportions

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humus

decomposed dead organic matter - broken down by decomposers releasing minerals and nutrients - compounds used by other organisms / increases air content - more oxygen available

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measure water content

-mass of soil -heat to 105until it reaches constant mass (boil off water) -take second mass (difference is water content) / -heat to 550 for 2h (burn off humus) -third mass (difference between 2nd and 3rd = mass of humus)

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measure air content

-loosly pack soil in test tube -fill pipette with water add to soil -when the water reaches the top -subtract water left to starting water = air content

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life in soil

-plants need it for anchorage, minerals and water -animals need plants for food and oxygen / ecosystem containing complex food webs (herbivores, carnivores and detritivores) other organisms (microscopic protozoans, fungi, nematode worms, bacteria)

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detritivores

feed on dead organisms

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conditions in soil

-water and oxygen [living things need water for reactions in cells, oxygen for respiration eg plants get it from the soil] (see humus)

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earthworms

charles darwin: -bury leaves and organic material in soil so bacteria and fungi decompose them -burrows allow air to enter (aeration) and water to drain through it [areation - oxygen, drainage stops waterlogged soils which reduces oxygen]

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Earthworms continued

-mix up soil layers, distributing nutrients -soil in poo is less acidic [neutralise soil acidity, acidic soils are less fertile]

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advantages of life in water

- a lot of water [no drainage/dehydration] -less temperature variation -support for things with no skeletal system -easy waste disposal [easily dispersed]

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disadvantages of water life

-more resistant to movement (more energy) -water regulation [water has a different concentration of solutes from the cells]

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water regulation

salt water: more solute in water, water molecules move out of cell by osmosis - shrivel and die / freshwater: higher solute concentration in cells, water enters cells by osmosis, cells swell and burst

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Amoebas

water diffuses into contractile vacuole by osmosis, which moves to the membrane and contracts to empty water out the cell

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plankton

microscopic organisms in fresh and salt water. phytoplankton: plants, photosynthesise, main producers of aquatic food web / zooplankton animals which feed on phytoplankton

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phytoplankton populations

photosynthesis affected by light temperature and minerals. winter and deep: light and temperature are low, mineral concentration high, light and temp limit photosynthesis / summer high: minerals limit photosynthesis.

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phytoplankton populations

populations increase now - algal bloom / population of zooplankton increase because there is more food

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food webs

grazing: living producer (phytoplankton) / deep water little light - bacterial producers rely on sulfur from vents / marine snow - dead decomposing material falling from surface

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water pollution

eutrophication (fertilisers/sewage) // industrial chemicals/pesticides [ddt/pcbs] taken up by organisms and are not broken down so passed on, concentration increases

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indicator species

sensitive to oxygen and ph stonefly nymph, freshwater shrimp, bloodworm, rat tailed maggot

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enzymes in biological washing powder

non-biological powders use chemics to get rid of stains, biological powder uses enzymes. carbs-amylases lipids-lipases protien-proteases. products are soluable in water. moderate temps because of denaturing, not work in acidic/alkaline tap water.

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stain removers

specific enzymes break down stain

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medicine with enzymes

diabetes benedict's solution goes from blue to orange if sugar is present [chemical properties] / reagent strips are based on enzyme reactions

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food

sucrose is broken into fructose and glucose by enzymes, they are sweeter so you need less / rennet is used for cheese / pectinase used in fruit juice extraction breaks down pectin

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immobilised enzymes

dont need to be separated after reaction, encapsulate them in aldinate beads [mix with alginate and drop into calcium chloride solution] -dont contaminate produce -continuous flow processing

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lactose free milk

lactose intolerent peoplelack the enzyme so gut enzymes break it down causing abdominal pains, wind and diarrhoea. by immobalised enzymes lactose broken down by lactase making glucose and galactose. is used

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continuous flow processing

-milk run through column of immobilised lactase, the products come out the tube

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reagent strips

blood added to *****, enzymes cause it to change colours depending on glucose concentration

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genetic engineering

alters the genetic code. gene is removed and inserted in another organism [dna code is universal]

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genetically modified organism

transgenic organism

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5 steps

identify gene -remove it -cut open dna of organism you want to put it into to -insert it -the host is transgenic [done by enzymes]

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insulin

-identify gene -remove it using restriction enxymes -restriction enzymes cut plasmid leaving it with sticky ends -ligase joins gene and plasmid -plasmid taken uo by bacteria [plasmid is vector]

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assaying techniques

bacteria checked to see if they have the gene

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dna finger printing

a way of comparing samples, in forensic science evidence is compared with the suspect / paternity test [see if father]

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storing it?

some think should be on national database to make crime solving faster others think invasion of privacy [what else used for?] false positives/misinterpretations

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how it works

-extract dna from cells -restriction enzymes cut into fragments where they recognise a sequence of bases -if the sample contains taht lots it will be cut -separated using electrophoresis -fragments suspended in gel -electriccurrent passed through

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