Biology

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Dissolved Substances

  • dissolved substances move by active transport and diffusion
  • water moves by osmosis which is a special type of diffusion
  • osmosis: from area of high water concentration to low water concentration through a partially permeable membrane until even concentration
  • important for both plant and animal cells
  • water lost from the bosy through sweat - helps cool us down
  • also lose ions in sweat - need both to function properly
  • ions used to lubricate joints, carry substances and protect organs
  • during exercise: sweat a lot - lose ions and water - and use energy from glucose
  • sports drinks replace these
  • active transport - low concentration to a high concentration, against a gradient
  • need a protein carrier and energy is also required for this process
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Exchange Surfaces

  • as organisms get bigger. surface area to volume ratio gets smaller
  • reduces surface area that molecules can be exchanged - diffusion inefficient
  • plants and animals have well adapted exchange systems - digestive system nutrient uptake, roots water uptake
  • features: large surface area, thin surface, efficient blood supply to maintain a concentration gradient
  • villus: epithelial membrane 1 cell thick, dense capillary network, microvilli for large surface area
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Gas Exchange in the Lungs

  • lungs located in thorax (chest) surrounded by rib cage separated form abdomen by diaphragm
  • air in: through nose/mouth, down trachea, into bronchus (2) into bronchioles, end in air sacs (alveoli)
  • alveoli: where gas exchange happens
  • oxygen diffuses from the air into the blood; carbon dioxide diffuses from the blood into the air
  • alveolus increases SA:Vol, wall thin - 1 cell thick, dense blood supply
  • breathing in:intercostal muscles contract, rib cage up and out, expanding chest, diaphragm contracts & flattens, volume in lungs increases, pressure decreases, air in
  • breathing out: intercostal muscles relax, rib cage down and in, reducing volume of chest,diaphragm relaxes & arches up, volume decreases, pressure increases, air out
  • asthmatics: restriction of bronchioles. artificial ventilators to help breathing 
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Exchange in Plants

  • two major exchange surfaces: leaf (water, CO2, O2 diffuse) and roots (water and minerals absorbed)
  • leaf efficiently designed: flat, large SA, internal air spaces, lower surface lots of stomata
  • water out through stomata, CO2 in through stomata from atmosphere, used in photosynthesis, O2 out through stomata, product of photosynthesis
  • roots have root hairs - increase surface area for absorption
  • stomata: lower surface, less heat - reduce water loss, guard cells change shape, open and close stomata, open in day (gases) close at night (stop water)
  • light intensity: increases transpiration, stomata open in light
  • increased temp: increases, faster water moves in the air
  • increased air movement: quicker water moved away, increase conc. grad.
  • increased humidity: decreases, more water in air, conc. grad. reduced
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Circulation and the Heart

  • as animals get larger they need a circulatory system as diffusion (O2, waste CO2, foods) becomes too ineffienct to move those molecules
  • parts: blood, heart, vessels
  • humans: double circulatory system, blood through heart twice, pumps 60-80 times a min
  • circulation: deox. from body through vena cava to r. atrium, contracts into r. ventricle, contracts out pulmonary artery (valve between the 2, prevent backflow), blood to lungs pick up O2, back to heart, in l. atrium through pulmonary vein, contracts into l. ventricle, contracts out aorta to body
  • happen at same time, continuous flow
  • heart failure and valve damage common - artificial hearts (short term solution, not rejected, wires ofter through skin) artificial valves (plastic and metal, long lasting and highly successful)
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The Blood and the Vessels

  • arteries:blood away from heart, capillaries:blood to the organs, veins:blood to the heart
  • arteries: thick walls, high pressure, muscular withstand pressure, elastic fibres stretch for blood, narrow cavity or lumen
  • capillaries: thin walls quick diffusion, lots of them large SA, need by cells out, made by cells in, pressure lost, narrow one cell through
  • veins: thinner walls, low blood pressure, little elastic/muscle, valves to prevent backflow
  • narrowed arteries: build up of fat, stent inserted to open up artery
  • blood tissue - made up of similar cells working together: transport carries around body, protection from infection/blood loss, regulation pH and temp
  • plasma:transports, CO2, soluble products of digestion, urea
  • wbc: nucleus, immune system, fight infection, engulf/digest/antibodies
  • rbc: haemoglobin, transport O2, no nucleus, made bone marrow, liver kills
  • platelets: small fragments of cells, no nucleus. blood clots, prevent infection
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Transport in Plants

  • separate systems involve two types of tissues: xylem and phloem located in vascular bundle
  • xylem: transports water and minerals, from roots to leaves, dead cells stacked to form tubes, transpiration stream (<-- process name)
  • phloem: transports dissolved sugars from leaves (source) to rest of plant (storage organs), living cells stack to from tubes, translocation (<-- process name)
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Homeostasis and the Kidney

  • maintaining a constant internal environment - homeostasis
  • pH, water content, ion content, temp, blodd sugar levels need to kept within narrow limits
  • pH: CO2 lowers pH, damages proteins, lungs control levels (breathing rate)
  • water and ions: taken in food and drink, content wrong affects osmosis, damages cells, kidneys vary levels in urine
  • temp: human 37`C, rise/fall affect cell fuction, in the skin heat is lost or conserved
  • blood sugar levels: in through diet, used in respiration, excess stored, levels high/low become ill, pancreas sugar stored or released
  • toxic wastes removed e.g. CO2 (respiration, lower pH, breathed out) and urea (in liver, breakdown of excess amino acids, makes cells alkaline, urination)
  • kidneys: remove waste products - urea, excess water and ions - in urine, stored in bladder, released in urination
  • filtered, re-absoped, blood contains wastes
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Kidney Treatments

  • acute kidney failure: stop working due to disease or drugs, will recover, dialysis treatment
  • chronic kidney failure: gradually fail, dont recover, overuse drug, diabetes, genetic cause, dialysis or transplant
  • dialysis: remove waste products from blood, restore concetrations in blood to normal, 5-6 hours 3-4 times a week, blood from veinthrough machine to be filtered, limits quality of life
  • transplants: diseased kidney removed, replaced with healthy kidney from donor. prevent rejection by immune system (attack new kidney)
  • dialysis: effective waste removal, allows for recovery, reduced quality of life, expensive
  • transplant: long term solution, better quality of life, cheaper in long term, tissue matching, lack of donors, rejection
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Controlling Body Temperature

  • normal core temp 37`C - body controls it - thermoregulation
  • overheating: caused by environment, exercise, dehydration(prevents sweating), above 40`C dangerous, increased sweating, more water needed in, looking flushed, blood to skin, denatures enzymes and harms cells
  • overcooling: caused by environment, babies and elderly hard to maintain heat, below 35`C dangerous (hypothermia), shivering, no sweat, look pale reduced blood to skin, slows enzyme reactions, making us ill
  • thermoregulatory centre in brain monitors temp of blood flowing through brain, nerves in skin detect temp, to brain. too high/low: trigger response
  • overheat: hairs flat,reduces insulation, sweat galnds release more sweat, uses heat from body to evaporate water, vasodilation: blood vessels expand, more blood flow to skin surface, more heat lost by radiation
  • overcool: hairs up, trap more air, insulate, less sweat, muscles contract, shivering, releases heat, vasonconstriction: blood vessels constrict, less flow near surface, less lost by radiation
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Controlling Blood Sugar

  • needed for cells to release energy during respiration: falls/rises body regulates
  • glucose in through diet, level up, glucose level down used in respiration, excess glucose detected by pancreas, releases insulin, cells in liver take up glucose from blood, lowering levels, glucose stored as glucogen in liver cells, level falls: glucose release from liver cells, pancreas detects low produces glucagon hormone acts on liver cells, released into blood, level normal
  • type 1 diabetes: 1 in 800 people, genetic, some drugs, trauma, thrist, frequent urinating, control diet, taking exercise, monitoring blood glucose levels, injecting insulin, health checks (eyesight)
  • blood glucose levels monitored by blood sample, regular intervals
  • blood insulin levels monitored in hospitals
  • improvements in modern treatments: modern sensors for montoring blood glucose simple and more effective, circulation checked more thoroughly reduces complications due to diabetes (gangrene), research into developing stem cells to replace damaged pancreatic cells
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Human Populations and Pollution

  • increase in human population: improved diet, hygiene, healthcare, reduction in infant mortality rate, standard of living
  • greater demand for manufactured products, heavier demand on raw materials: more waste created, more land for building and farming, less fertile land for food production
  • sustainable lifestyle: replacing resources where possible (replanting trees), avoid overuse of resources (fishing quotas), handling waste correctly to avoid pollution (recycling)
  • loss of habitat: land for building, quarying, farming, landfill waste dumps
  • destroy natural environment, reduction in biodiversity
  • pollutants are released into the air, land and water (land effects from pollutants washed into waterways)
  • air: gases (CO2 and sulfur dioxide) acid rain, global warming, smoke, reduce photosynthesis in plants
  • land: fertilisers washed into water: sewage, disease, chemicals, food chains
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Deforestation

  • cutting down lots of trees - happening worldwide (Brazil in rainforests)
  • wood needed for timber: fuel and building, land: farms, towns, growing crops for biofuels, food for people
  • slash and burn: increases CO2 into atmosphere
  • effect on global gases: burning trees, decompostion of felled trees, reduction of photosynthesis, less CO2 uptake
  • reduction in biodiversity: removed and replaced with a single crop, few habitats, removes large amounts of same mineral from soil
  • build up of methane: cattle farms amd rice fields release methane, global warming
  • destruction of peat bogs:produced over 1000s of years, acidic boggy areas, used in gardening for rich composts, extracted peat dries, decays and releases CO2, use peat free compost
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Global Warming and Biofuels

  • overall increase in average global temperatures: caused by heat trapped in the Earth's atmosphere by a layer of greenhouse gases
  • human activity increasing amount of gases in atmosphere: CO2 released from burning fossil fuels or deforestation, methane from cattle, rice fields, and decaying waste
  • a few degrees can have a massive impact on the Earth
  • large bodies of water absorb large amounts of CO2, reducing levels in the air, phytoplankton absorb CO2 durin photosynthesis, CO2 dissolves in water
  • burning fossil fuels releases lots of CO2 which has been locked up in fuels for millions of years
  • biofuels are a range of fuels from biological materials that are considered better for the environment, include: wood, alcohol, biogas
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Biogas Production

  • biogas is made by the anaerobic fermentation of the carbohydrates in plant material and sewage by bacteria. its a mixture of gases: methane, CO2, hydrogen, nitrogen, and hydrogen sulfide
  • small-scale production: remote regions in third world countries, supply small amounts of fuel for cooking
  • large-scale production: large commercial tanks used, waste is constantly added, widespread use, sewage works in the UK, rate of gas production is affected by climatic conditions (maily temp) working best at 32-35`C, large volumes of gas produced which are used to power vehicles, generate electricity, heat homes
  • advantages: alternative to fossil fuels reduced consumption, no overall increase in greenhouse gases (plants CO2 when growing and released when burnt), burning biogas&alcohol produces no smoke
  • disadvantages: causes habitat loss, large areas of land needed to grow plants, can lead to extinction of species
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Food Production

  • human population increased, new methods to produce enough food, food needs to be produced as locally as possible, reduce transport costs and pollution
  • fungus (fusarium venenatum) used to make a protein-based product called mycoprotein which is produced in large fermenters
  • glucose is added (food for fungus) vitamins and minerals also needed to keep to fungus healthy, paddles stir mixture so fungus doesn't settle, O2 added to allow fungus to respire, protein extracted and processed, pH and temp controlled to maintain the optimum growth rate, protein purified and made into meat substitute products
  • farming produces food, at every link in food chains, energy and biomass is lost, longer the chain, the more energy and biomass lost (more links), food at the end less energy efficient that food from earlier in chain
  • reducing: eating vegetable products, intensive factory-farming methods (battery farming:reduce movement, keep warm: less energy lost)
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Fishing

  • common food - more has been caught from oceans, modern fleets are efficient meaning that fish stocks in the oceans are in decline
  • governments were getting concerned, some species so low soon would be unavailable to be caught as food
  • fish populations needed to be maintained at a sufficient so that breeding continued successfully
  • two main conservation methods: net size - increasing the hole allowing younger fish through to survive and breed, fishing quotas - limited numbers of fish that could be caught, maintained a breeding population
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