unit 3 biology

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what is osmosis?
osmosis is the movement of water.
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why is osmosis similar to diffusion?
it is random and requires no energy from the cell.
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what type of membrane does osmosis take place across?
a semi or partially permeable membrane.
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in osmosis, where does the water move from to?
it moves from a region of high water concentration (e.g. a diluted substance) to a region of lower water concentration ( e.g. a concentrated substance)
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what is active transport?
the movement of ions or molecules across a cell membrane into a region of higher concentration.
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in which direction of the concentration gradient does active transport take place?
against the concentration gradient.
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why is active transport useful to a cell?
active transport is useful for cells so they are able to absorb ions from dilute solutions.
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what is an example of where active transport is used?
root hair cells absorb mineral ions from the dilute solutions in the soil by active transport.
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what is required in order for active transport to take place?
energy released in respiration.
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what sugar is used during respiration?
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what does your body do to cool its self down when is it hot?
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what may happen if you sweat a lot?
your body will loose lots of water and mineral ions so your cells can become dehydrated.
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what is necessary to do if you exercise and sweat for a long time?
replace the sugar, mineral ions and water which has been lost or used.
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what is a sports drink?
a solution of sugar and mineral ions.
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what does the water in a spots drink help to do?
rehydrate the body cells.
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what are sports drinks designed to do?
help balance the concentration of body fluids and the concentrations inside cells.
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what is a drink called when it matches the concentration of body fluids?
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in which organ in the body is oxygen absorbed and carbon dioxide removed?
the lungs.
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what 3 things make an efficient exchange surface?
1. a large surface area. 2. thin walls/short diffusion path. 3. an efficient transport system (this is a blood supply in animals)
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what surface is inside of the lungs?
the gaseous exchange surface.
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how is the surface area of the lungs increased?
there is lots of alveoli (air sacs).
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what makes the alveoli effective?
they're large surface area, thin walls and good blood supply from the many capillaries surrounding them.
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where are the lungs located inside the body?
inside the thorax, inside the ribcage and above the diaphragm.
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what does the diaphragm separate?
the lungs from the abdomen.
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what happens when we breath in?
the intercostal muscles between the ribs and the diaphragm contract, the ribcage moves up and out, the diaphragm flattens, the volume of the thorax increases and the pressure decreases as air is drawn in.
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what happens when we breath out?
the intercostal muscles relax, the ribcage moves down and in, the diaphragm becomes a dome shape, the volume decreases and pressure increases as air is forced out.
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what is ventilation?
the movement of air in and out of the lungs.
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give 3 examples of why someone cannot get enough oxygen into their bloodstream.
1. if the alveoli are damaged. 2. if the tubes leading to the lungs are narrowed. 3. if a person is paralysed the intercostal muscles may not work properly
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who was the iron lung designed for?
people with polio who were paralysed.
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how did the iron lung work?
the person lay with their chest in a sealed large metal cylinder. when the air was drawn out of the cylinder the persons chest moved out and they breathed in. when air was pumped back in to cylinder it created pressure on the chest & forced air out.
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what type of pressure did the iron lung create?
the vacuum inside the cylinder created a negative pressure.
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which type of breathing aids create positive pressure?
breathing aids that which force measured amounts of air into the lungs.
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whats an example of a positive pressure breathing aid?
bags of air linked to masks that force air down the trachea.
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state 3 advantages of using positive pressure breathing aids over negative pressure breathing aids.
1. they are often smaller. 2. easier to manage in the home. 3. can be linked to computers for control.
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what is for digested into in the gut?
small, soluble molecules that can be absorbed into the blood in the small intestine.
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what line the small intestine and what are they used for?
villi. they are the exchange surface for food molecules.
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what part of the body can villi be compared to as a similar shape?
a finger.
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what do villi do to the surface area of the small intestine?
greatly increase it.
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what are the features of a villi?
one cell thick walls, rich blood supply and a large surface area.
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how can soluble products of digestion be absorbed into the villi.
either diffusion or active transport.
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how are gases diffused in and out of leaves?
through tiny holes called stomata.
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what controls the size of the stomata?
the guard cells which surround them.
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which 2 gases leave and enter through the stomata and what are they used for?
1.oxygen: used for respiration and is a waste product of photosynthesis. 2.carbon dioxide: used for photosynthesis and is a waste product of respiration.
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other than O2 and CO2 what else leaves a leaf through the stomata and why?
water vapour due to evaporation in the leaves.
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in a leaf why do gasses not have to diffuse very far?
because leaves are late and very thin.
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in a plant what are taken up by the roots?
water and mineral ions.
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what do root hair cells do?
increase the surface area of a root for the absorption of water and mineral ions.
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what happens when a plant looses water faster than its being replaced by the roots?
the stomata close to prevent wilting.
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what is the movement of water through a plant called?
the transpiration stream.
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when is evaporation faster in a leaf?
when it is hot, dry, windy or bright conditions.
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why do the guard cells on a leaf close?
so prevent excessive water loss.
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why does wilting reduce water loss in a plant?
because the leaves collapse and hang down which reduces the surface area.
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what does the circulatory system consist of?
blood vessels, the heart and blood.
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what does the right side of the heart do?
forces deoxygenated blood to the lungs where it picks up oxygen and loses CO2.
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what does the left side of the heart do?
pups the oxygenated blood from the lungs to the rest of the body.
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what are the two top chambers and where do they receive blood from?
the right atrium receives blood from the vena cava and the left atrium receives blood from the pulmonary vein.
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what are the two bottom chambers of the heart called and where does the blood leave the heart on both sides?
right ventricle pumps blood out of the pulmonary artery and the left ventricle pumps blood out of the aorta.
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what prevents blood flowing backwards in a heart?
the valves
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how is the heart supplied with blood?
through the coronary arteries.
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what does the actions of the two sides of the heart cause?
double circulation.
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what do arteries do and what are their characteristics?
carry blood away from the heart and they have thick walls containing muscle and elastic tissue.
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what do veins do and what are their characteristics?
transport blood back to the heart and they have thinner walls than arteries and often have valves to prevent back flow of blood.
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what are capillaries and what are their characteristics?
they carry blood through the organs and allow the exchange of substances with all the living cells and they are narrow with one cell thick walls.
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what can be inserted into a blood vessel to keep it open if it becomes blocked?
a stent.
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what is a cure for leaky valves in the heart?
artificial or animal valves can be inserted into the heart to replace the damaged ones.
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true or false; blood is a tissue?
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what does the fluid plasma contain?
red blood cells, white blood cells and platelets.
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give 3 substances plasma transports.
carbon dioxide from the organs to lungs, soluble products of digestion from small intestine to other organs and urea from liver to kidneys where urine is made.
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what are red blood cells and what do they do?
they're biconcave disks with no nucleus. they contain the red pigment haemoglobin which combines with oxygen to form oxyhemoglobin in the lungs and it carries the oxygen to all organs where the oxyhemoglobin splits into haemoglobin and oxygen.
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what do white blood cells and why are they different to red blood cells?
they form part of the body defence system against microorganisms. they have a nucleus.
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what are platelets and what do they do?
small fragments of cell, do not a nucleus and help blood to clot at the site of a wound.
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what can blood from donors be split into?
cells and plasma.
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how must donor blood be stored?
must be refrigerated but some blood products can be frozen.
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when can blood plasma be given to a patient?
in a transfusion to increase blood volume.
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what is per fluorocarbons, PFC's, and why is it different to regular blood?
it is artificial blood. it doesn't need to be refrigerated and doesn't contain cells so doesn't need to be matched.
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state 4 disadvantages on artificial blood.
1. expensive 2.doesnt carry as much oxygen 3. some types are insoluble in water so don't mix well with blood 4. can cause unpleasant side effects.
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state 2 advantages and 3 disadvantages of artificial hearts.
advantages: don't need to match the persons tissue and theres no need for immunosuppressant drugs. disadvantages: cause problems with blood clotting, long stays in hospital and expensive.
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what does xylem tissue do?
it transports water and mineral ions from the roots to the stem, leaves and flowers.
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what does phloem do?
it carries dissolved sugars from the leaves to the rest of the plant, including the growing regions and storage organs.
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what is homeostasis?
keeping the body conditions within a narrow range.
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what must be controlled with the body?
temperature, blood glucose, water and ion content and levels of waste products.
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what waste products must be removed from the body?
carbon dioxide and urea produced in the liver, removed by the kidneys in the urine and temporarily stored in the bladder.
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what happens if theres too much water in the body?
it may damage or destroy cells.
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what do the kidneys do?
they filter the blood, excreting substances we don't need and keeping those we need.
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how is urine produced in the kidneys? stage 1
Filtration - where lots of water, ions, urea and sugar are squeezed from the blood into the tubules.
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how is urine produced in the kidneys? stage 2
Selective reabsorption – the useful substances (ions and sugars) are reabsorbed back into the blood from the tubules. The amount of water in the blood is regulated here to maintain it at a constant rate. This is known as ‘osmoregulation’.
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how is urine produced in the kidneys? stage 3
Excretion of waste - urea and excess water and ions travel to the bladder as urine, to be released from the body.
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if a person suffers from kidney failure how can they be kept alive?
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in a dialysis machine what type of membrane does the blood flow through?
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what is in dialysis fluid and why?
the same concentration of useful substances e.g. glucose and mineral ion. this means that these substances do not diffuse out of the blood so they don't need to be reabsorbed.
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why is there no urea in dialysis fluid?
so the urea in the blood diffuses out and into the fluid.
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state a disadvantage of dialysis.
has to be done at regular intervals, often.
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what happens in a kidney transplant?
the diseased kidney of the patient is replaced by a donor kidney from a victim of a fatal accident or a living donor.
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why must a new kidney be a very good tissue match?
to avoid rejection.
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why are some kidneys rejected?
the proteins called antigens on the surface of the calls of the new kidney may be recognised as foreign so the recipients antibodies may attack the antigens.
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what are immunosuppressant drugs?
drugs that suppress the immunes responses to prevent rejection of a new organ.
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what is the risk of having a kidney transplant?
the immunosuppressant drugs leaves the patient vulnerable to common infections that can be more serious.
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what is the core temperature of the body and why must it be kept stable?
about 37degrees so that enzymes will work efficiently.
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where in the brain is the body temperature controlled?
thermoregulatory centre.
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how do receptors on the skin control body temperature?
they send impulses to the brain to give information about skin temperature.
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why does the skin look red when its hot?
because of the increased blood flow.
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explain 2 things that happen when the core temperature rises.
blood vessels near the skins surface dilate so more blood flows through the skin capillaries. energy is transferred by radiation so the skin cools down. sweat glands produce more sweat and the water evaporates because energy from skins surface.
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explain two things that happen when the core temperature falls.
blood vessels near skins surface constrict and less blood flows through the skin capillaries so less energy is radiated. we shiver because the muscles contract quickly which requires respiration and some of the energy released warms the blood.
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state 5 things a doctor considers when deciding if a patient should go ahead with a kidney transplant.
1. their general health 2. how long they've been on dialysis 3.the total cost of treatment 4.the risks of the operation (e.g. the antistatic and infection) 5.the availability of a donor kidney
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state 3 ethical issues of kidney transplant.
1.should the register be opt in or opt out? 2.should people be paid to be a donor? 3.should people pay to jump the queue?
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what does the pancreas monitor?
the level of glucose in our blood.
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what does the pancreas produce when theres too much sugar and what does it do?
it produces insulin which causes the glucose to move from the blood into the cells.
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what is excess glucose converted into in the liver and why?
glycogen for storage.
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whats type 1 diabetes and how is it controlled?
when little or no insulin is produced and blood glucose levels may become very high. its controlled by injections of insulin before every meal and careful attention to diet and levels of exercise.
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state 5 new methods being developed to treat and possibly cure type 1 diabetes.
1.pancreas transplant 2.transplanting pancreas cells 3.using embryonic stem cells to produce insulin secreting cells 4.using adult stem cells from diabetic patients 5.genetically engineering pancreas cells to make them work properly.
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what is the current population of the world?
7 billion.
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what are non-renewable, raw materials?
materials that cannot be replaced.
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what is industrial waste?
the waste produced by making goods.
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how do humans reduce the amount of land available to plants and animals?
by building, quarrying, farming and dumping waste.
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what is the continuing increase of population doing to the earth?
affecting the ecology of the earth.
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what 3 things do humans pollute?
1.waterways (sewage, fertiliser and toxic chemicals) 2.air (smoke and gasses such as sulphur dioxide, which contributes to acid rain) 3.land (toxic chemicals like pesticides and herbicides which can also be washed into the water)
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what does sewage contain and why does it have to be treated?
human body waste and water from our homes. it must be treated to remove gut parasites and toxic chemicals or these can get into the land.
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where are large quantities of waste placed and why is it not eco-friendly?
household and industrial waste is often placed it landfill sites. toxic chemicals can leak out and industrial waste such as radioactive material can be very hazardous.
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how can farming polite water and land?
farmers sometimes spray herbicides (weedkillers) and pesticides (kills insects). these poisons get into the soil and food chain. eventually many of it ends up being washed into rivers.
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what produces acidic gases that are released into the atmosphere?
cars, power stations and burning fuels.
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why is releasing sulphur dioxide dangerous?
it dissolves in the water in the air forming acidic solutions which then fall as acid rain. this then changes the pH in the soil, damaging roots and may release toxic mineral ions like aluminium ions. these damage organisms in the soil and waterways.
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what is deforestation?
when trees are cut down.
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what are 3 disadvantages of deforestation?
1.increased level of CO2 due to burning of the trees or decay of wood my microorganisms 2.reduces the rate at which CO2 is removed from the atmosphere by photosynthesis 3.reduced biodiversity due to loss of food and habitats.
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why has deforestation occurred?
so that crops can be grown to produce ethanol-based biofuels and so there can be increases in cattle and rice fields for food.
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why has deforestation increased the level of methane in the atmosphere?
because the spaces are used for cattle and rice farming which both produce high levels of methane.
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why does destroying peat bogs increase the level of CO2?
because the peat (dead plant matter) is used in compost for gardens. this compost is decayed by microorganisms which releases CO2.
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how is carbon dioxide sequestered?
CO2 is removed by plants and algae in photosynthesis and is dissolved in oceans, rivers and lakes.
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name 2 greenhouse gasses.
methane and carbon dioxide.
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what do the greenhouse gasses cause and contribute to?
the greenhouse effect and global warming.
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what 5 things may happen if the earths temperature increases by a few celsius?
1.cause high changes to the earths climate 2.cause a rise in sea levels due to melting i.e. caps and glaciers 3.reduce biodiversity 4.cause changes in migration patterns, e.g. of birds 5. result in changes in the distribution of species
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what are biofuels?
fuels made from natural products.
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what are two types of biofuels?
ethanol-based and biogas.
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how can ethanol-based produced?
they can be produced by fermentation. microorganisms respire anaerobically to produce the ethanol, using sugars from crops as the energy source. glucose is produced by carbohydrate. the glucose and sugar can be fermented by yeast to produce ethanol.
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how is the ethanol extracted to be used as fuel in motor vehicles?
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why is ethanol described as carbon neutral?
because only the carbon dioxide used for photosynthesis by the crops is returned to the atmosphere where the ethanol is burned.
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what is the main type of biogas and how is it produced?
methane & during anaerobic fermentation by bacteria.
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how can any waste materials containing carbohydrates be broken down?
they can be broken down in biogas generators. these provide ideal conditions for bacteria to reproduce and ferment that carbohydrates. they must be at a suitable temp and oxygen free.
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where are biogas generators normally placed and why?
underground for insulation or in an insulation jacket to maintain the temperature.
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what products can be used to make biogas in industry, at home or at farms?
in industry: waste sugar from factories or sewage works at home: human and garden waste on a farm: animal manure
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what is biogas used for?
energy for heating, cooking etc.
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if the food chain is shorter is more or less energy wasted?
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explain 2 things done to make the production of meat more efficient so humans get the most energy from the meat.
1. keep the animal in a closed area or tie their feet so no energy is wasted on movement 2. keep animals indoors so less energy is used keeping themselves warm.
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why is producing meat from animals kept in small areas controversial?
because it can be seen as cruelty to the animal.
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what is sustainable food production?
managing resources and finding new types of food (e.g. mycoprotein)
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what regulations are put in place for fishermen so fish stocks in the ocean are monitored?
they can only remove a strict allocation of fish per year (a quota) and they must only use certain sized nets to avoid catching small, young fish.
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what fungus is grown to produce mycoprotein and why is it good for humans?
fusarium & it is protein rich and suitable for vegetarians.
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where can micro-organisms be grown on a large scale?
industrial fermenters.
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what 4 things are in an industrial fermenter?
1.an air supply of oxygen for respiration 2.stirrers or gas bubbles to keep them spread out and to provide an even temperature 3.a water-cooled jacket around the outside as the microorganisms release energy as heat 4.sensors for pH&temperature.
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why is it difficult to be sure that data about environmental issues is said and reliable?
scientists can often come to different conclusions when considering the same data. explanations depend on their opinions & they can be biased. e.g. some think global warming is related to greenhouse gasses but others think its a natural trend/cycle.
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Card 2


why is osmosis similar to diffusion?


it is random and requires no energy from the cell.

Card 3


what type of membrane does osmosis take place across?


Preview of the front of card 3

Card 4


in osmosis, where does the water move from to?


Preview of the front of card 4

Card 5


what is active transport?


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