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What are the differences between diffusion and active transport?Active transport requires energy carried by ATP, diffusion does notActive transport requires special carrier proteins on the cell membrane, and diffusion doesn’tActive transport moves substances from low to high concentration, diffusion is from high to low concentrationExplain how active transport works to move substances across cell membranes (4 points)Chemical joins to carrier proteinEnergy from ATP changes carrier protein shapeThis pushes chemical throughCarrier protein returns to normal shapeExplain why active transport is needed in our gutsBy diffusion alone, sugar will reach equilibrium / equal concentrations between gut and cellsActive transport needed to force molecules against their concentration gradientState two examples of active transportMineral uptake in root hair cellsAbsorption of glucose in the gutDefine osmosisThe movement of water…Through a partially-permeable membrane…From a low to high concentration of SOLUTESState the two main functions of sports drinksReplace water and ions lost through sweatingReplace sugars that are used in respirationExplain the five steps involved in breathing in Intercostal muscles CONTRACTRibs move UP and OUTDiaphragm contracts and flattensVolume in the thorax increases and the pressure decreasesThis causes air to flow inExplain why larger organisms require specialised exchange surfaces, but very small organisms do notLarge organisms have a small surface area to volume ratioSimple diffusion wouldn’t be enough to allow substances to get to all cellsDescribe and explain the structure of a villi that enables it to act as a specialised exchange surfaceA good blood supply to maintain a steep concentration gradientA lacteal to dissolve and transport fats Thin walls (one cell thick) to decrease the diffusion distanceHow does inhaled and exhaled air differ?Inhaled air has 21% oxygen, exhaled air has 17% oxygenInhaled air has 0.04% CO2, exhaled air has 4% CO2State three examples of specialised exchange surfaces in animalsAlveoli (lungs), Gills of fish, Villi (lungs)State two examples of specialised exchange surfaces in plants and describe what they exchangeRoots – active transport of ions, osmosis for waterLeaves – gas exchange (CO2 and O2)State four reasons for why plants need waterIt’s a reactant in photosynthesisCooling to maintain enzyme optimum temperatureMaintains turgour pressure of cellsTransports substances (e.g. minerals and sugars)Describe the two forces involved in ensuring water is pulled up through the xylem during transpirationCohesion: water molecules attract each otherAdhesion: water is attracted to the walls of xylemWhat part of the leaf allows water to leave, and how do they work?Stomata If there is lots of water, guard cells fill to become turgid – this opens the stoma and water can leaveIf there isn’t much water, guard cells lose water and become flaccidDescribe and explain how humidity affects transpirationAs humidity increases, transpiration decreasesMore humidity means there is more water in the air, decreasing the concentration gradientDescribe and explain how wind speed affects transpirationAs wind speed increases, transpiration increases, but then plateaus Higher wind speed means more water in the air is moved away, increasing the concentration gradient. Once all the water is moved away, no more increase in transpiration can occur.Describe and explain how temperature affects transpirationAs temperature increases, transpiration increasesHigher temperatures mean water gains energy and evaporates at a faster rateDescribe and explain how light intensity affects transpirationAs light intensity increases, transpiration increases, but then plateausMore light means more stomata open, increasing transpiration. However once all stomata are open, no further increase in transpiration can occur. What are the upper chambers in the heart called?Atria (singular: atrium)What is the lower chamber of the heart that pumps blood to: the body?the lungs?Left ventricleRight ventricleWhat is the wall that separates the left and right sides of the heart called?SeptumWhich blood vessel takes blood:From the heart to lungs?From lungs to heart?From heart to body?From body to heart?Pulmonary arteryPulmonary veinAortaVena cavaWhat are the valves that separate atria and ventricles called, and what is their function?Atrioventricular (AV) valvesThey prevent backflow of bloodWhat are FIVE differences between arteries and veins?Veins have valves, arteries don’tVeins have LARGE lumens, arteries have SMALL lumensArteries have thick muscular walls, arteries have thin wallsArteries have a higher pressure than veinsArteries are have many elastic fibres, veins do notWhen are stents used, and how do they work?They are used to widen blocked arteriesBalloon inside the stent is inflated, then burst and removed – this creates space in the arteryWhat are artificial hearts made of and why is this important?Polymers and titaniumVery smooth to avoid friction and clotsNo antigens so body can’t reject themWhat two ways can damaged heart valves be treated?Use animal valvesSynthetic valves can be usedBoth have no risk of rejection How is blood classified?It’s a tissue (the only liquid tissue in the body)State four components of blood and describe their functionsPlasma – carries proteins, CO2 and hormonesRed blood cells – carries oxygenWhite blood cells – destroys pathogens Platelets – cell fragments that form clotsDescribe where the blood transports the following components from and to:Carbon dioxideAssimilates (e.g. sugars) from digestionUreaFrom respiring tissues / muscles to the lungsFrom the gut to respiring tissues/musclesFrom the liver to the kidneysExplain how red blood cells are adapted to carry out their functionBiconcave shape and no nucleus – large surface areaHaemoglobin to carry oxygenWhat compound is created when oxygen binds to the oxygen-carrying compound of red blood cells?OxyhaemoglobinWhat does xylem transport, and where?Water and mineral ions UP the plantWhat does phloem transport, and where?Dissolves sugars from SOURCE (e.g. leaves) to SINK (e.g. roots)What is transpiration?The movement of water from the roots, through the xylem and then out of the leaves by evaporationHow is carbon dioxide produced?Why does it need to be removed?How is it removed?It’s a waste product of respiration It dissolves to lower pH of blood, and causes asphyxiationIt diffuses from blood through the alveoli and leaves with air that is breathed outHow is urea produced?Why does it need to be removed? How is it removed?Ammonia formed by breakdown of amino acids – it reacts with CO2 in liver to form ureaAmmona/urea are alkaline and increase pHUrea travels in blood to kidneys, and is filtered and dissolved in water before being excretedExplain the negative effects of water or ion imbalance on the bodyIf solute concentration in blood is too high, water moves OUT of cells causing metabolism to ceaseIf solute concentration in blood is too low, water moves INTO cells causing them to swell and possibly burst Explain how the kidneys regulate water and ion concentrationWater and ions pass into the NEPHRONSome water and ions are selectively reabsorbed as needed.What happens to sugar in the blood as it passes through the kidneys?It first enters the nephron by filtration…But ALL sugar is reabsorbed back into the blood streamDescribe two treatments for people with kidney failureFrequent dialysis – patient blood passes through a partially permeable membrane to extract urea, and salts are removed or added to blood as neededKidney transplantsDescribe the risks of kidney transplants Donor kidney could be rejected – the immune system may recognise antigens as a threat and produce antibodies to destroy itExplain two methods that are used to reduce the impact or risk of kidney rejectionTissue typing – kidneys from donors are matched with a patient’s tissue typeImmunosuppressant drugs to avoid damage by immune systemDescribe two ways our body monitors temperatureThe hypothalamus monitors blood temperatureThe skin monitors external temperatureExplain two ways that the body changes to cool down if temperature is too highVasodilation – arterioles near the skin widen…… causing blood to pass nearer to skin…… leading to heat loss by radiationSweating – skin heat transfers energy to water. As it evaporates, mean energy of remaining water decreasesExplain two ways that the body changes to prevent heat loss if the temperature is too lowVasoconstriction – arterioles narrow…… causing blood to flow deeper in the body…… leading to less radiationShivering – muscles contract involuntarily leading to heat produced by respirationWhich organ monitors and controls blood glucose concentration?The pancreasWhich hormone increases the amount of glucose in the blood?GlucagonWhich hormone decreases the amount of glucose in the blood?InsulinExplain the steps involved in decreasing glucose concentration in the blood after eatingPancreas detects glucose is too highInsulin is released into bloodstreamInsulin reaches target cells in liver/muscles, causing glucose to be stored as glycogenInsulin causes all cells to increase respirationExplain the steps involved in increasing glucose concentration in the blood after fasting Pancreas detects glucose is too lowGlucagon is released into bloodstreamGlucagon reaches target cells in liver/musclesGlucagon causes glycogen to be broken into glucose which enters the bloodstreamDescribe what causes Type 1 diabetesImmune system recognises antigens on pancreas cells as a threat and attacks themPancreas can’t produce enough insulinWhat four things should Type 1 diabetes sufferers do as part of their treatment?Increase complex (starchy) carbohydrates and reduce simple carbohydratesExercise regularlyMonitor blood glucose and inject insulin at mealtimesAvoid alcoholState four medical risks for people with uncontrolled Type 1 diabetesRetinal damage blindnessUlcers in feet gangrene / loss of toesIncreased risk of strokeIncreased risk of heart attackState four reasons for the human population explosionImproved diets food contains more nutrients and mineralsImproved sanitation / hygiene lower spread of disease Medical advances (give a specific example)Lower infant mortality rateState four problems caused by unsustainable growth in the human populationWorld food shortagesIncrease in pollutionUnsustainable use of resources (e.g. fossil fuels)Land used for farming and building1. Describe why fertilisers are used2. Explain the environmental harm they cause through eutrophication1. They provide nitrates that help plants grow quickly2. Nitrates leach into water sources causing water plants / algae to grow. This reduces oxygen so animals die and rot, producing CO2.Explain how burning fossil fuels leads to acid rainSulfur dioxide dissolves in rainwater to make sulphuric acidNitrogen dioxide dissolve to make nitric acidCarobn dioxide dissolves to make carbonic acidExplain how acid rain causes environmental harmDamages plant leavesAcidifies lakesChanges mineral availability in soilCauses bronchitisExplain two problems associated with allowing untreated sewage into waterwaysBacteria (e.g. cholera and typhoid) may be present causing illnessSewage contains nitrates causing eutrophicationExplain how toxic chemicals lead to bioaccumulationToxins leach into waterwaysThese build up in higher quantities in the food chain, as animals at higher trophic levels consume many organisms Explain the causes and effects of global dimmingIncomplete combustion releases smoke / particulates into the atmosphereThese can block the Sun’s rays, causing dimmingLower light intensity means less photosynthesis occurs. Describe how methane is produced agriculturally and how it causes environmental problemsMethane produced by rearing cattle and growing rice crops.Methane is a powerful greenhouse gas that traps and re-emits infra-red light. This leads to global warming, causing climate change.Explain how CFCs affect the environmentCFCs break down the ozone layer.This layer normally absorbs ultraviolet light.If the ozone layer is depleted, this means the rates of skin cancer increase Explain how detergents affect waterwaysDetergents kill microbes. This means microbes cannot rot dead plants and animals, affecting the food chain.Describe three ways that deforestation leads to an increase in CO2Slashing and burning trees produces CO2 by combustionLeft-over tree stumps rot, decomposers produce CO2Fewer trees mean less photosynthesis so less CO2 absorbedExplain what peat is, and how it leads to CO2 productionPeat is made of preserved sphagnum moss.If used as compost, it decomposes to produce CO2Explain four biological effects of global warming Reduced biodiversity – therefore more extinctions as habitats destroyedIce caps melting – leads to sea levels risingClimate change – leads to storms, droughts that affect organismsMigration patterns affected – animals winter in different countriesExplain how carbon dioxide can be sequestered in oceansCarbon dioxide dissolves in water to form carbonic acidPhytoplankton absorb CO2 through photosynthesisExplain three ways that humans have ensured our farming food chains are efficientThe number of stages (trophic levels) are reduced, meaning less energy is lostAnimals are kept warm, reducing homeostasis energy lossBattery farmed animals can’t move much, reducing energy loss from respirationDescribe and explain two methods of preventing overfishingLarge net sizes – prevents small fish being caught, so they can breed and restock oceansFishing quotas – limiting how many, or which types, of fish allows them to restockWhich fungus is used to make protein-rich food, and by which process?Fusarium, used in fermentationState three common examples of biofuelsWood, biogas, bioethanol (alcohol)State three advantages of using biofuelsReduced fossil fuel consumptionNo net increase in CO2No particulates are producedState and describe the disadvantage of using biofuelsHabitat loss due to large areas of land used for cropsThis leads to extinction of speciesHow is biogas made?Fermentation of carbohydrates from plant material and sewage…by bacteria…at a temperature between 32-35OCto produce methane and other gasesState three uses of biogasVehicle fuelGenerating electricityCentral heating systemsState the difference in production between biogas and bioethanolBiogas requires bacteria for fermentation, bioethanol requires yeastWhat is bioethanol called when it is mixed with petrol?GasoholExplain why Brazil uses gasohol (bioethanol and fuel) in their carsThey don’t have natural oil reservesThey have plenty of sugar caneThey have plenty of landTherefore they can grow and ferment sugar cane to produce bioethanol ................
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