B3

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Osmosis is the movement of water. What is osmosis?
The diffusion of water from dilute to a more concentrated solution through a partially permeable membrane that allows the passage of water molecules –random, requires no energy from the cell like diffusion.
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What is active transport?
When substances are absorbed against the concentration gradient. This requires the use of energy from respiration. It enables cells to absorb ions from very dilute solutions.
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When is active transport used?
When cells need to absorb substances which are in short supply. i.e. root cells absorb mineral ions from dilute solutions in the soil.
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What are sport drinks?
Solutions of sugar and mineral ions (water to rehydrate body cells) designed to help balance concentration of body fluids + concentrations inside cells. A drink is isotonic when its concentration matches body fluids
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Why may we need sports drinks?
If water ions are not replaced, the ion/water balance of the body is disturbed and the cells don’t work as efficiently. Glucose is used in respiration, we lose water + mineral ions in sweat. Sports drinks are needed to replace these.
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Large complex organisms have exchange surfaces to obtain food and oxygen. How are exchange surfaces adapted for effectiveness?
They have a large surface area, are thin to provide a short diffusion path, an efficient blood supply (in animals) and are ventilated in animals for gaseous exchange.
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Describe how gaseous exchange surfaces in the lungs are adapted?
SA of the lungs increased by the alveoli, the lungs are ventilated to maintain a steep diffusion gradient, alveoli have thin walls for short diffusion path.
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Where are the lungs situated?
In the thorax (upper part of the body), protected by the ribcage + separated from the abdomen (lower part of the body) by the diaphragm.
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The movement of air into and out of the lungs is known as ventilation. Describe what happens when we breathe in?
The intercostal muscles between the ribs and diaphragm contract, the ribcage moves up + out & the diaphragm flattens, volume of the thorax increases, the pressure in the thorax decreases + air is drawn in.
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The movement of air into and out of the lungs is known as ventilation. Describe what happens when we breathe out?
The intercostal muscles between the ribs and diaphragm relax, the ribcage moves down + in & the diaphragm becomes domes, volume of the thorax decreases, the pressure in the thorax increases + air is forced out.
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Why may someone be unable to get enough oxygen into their bloodstream?
If the alveoli are damaged, the S.A. for gas exchange is reduced. If the tubes leading to the lungs are narrowed, less air can be moved through them. If the person is paralysed, their muscles won’t work to pull the ribcage up + out.
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The “iron lung” was used for people with polio whom were paralysed where the patient would lie with their chest sealed in a large metal cylinder. Describe the process.
When air’s drawn out of the cylinder the person’s chest moved out + they breathed in. The vacuum formed in the cylinder creates negative pressure. When air’s pumped back into the cylinder it creates pressure on the chest + forces air out of the perso
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What do breathing aids do?
They force measured amounts of air into the lungs using positive pressure, bags of air linked to masks can force air down the trachea. Positive pressure aids are often smaller, easier to manage in the home + can be linked to computer for control.
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Describe how gaseous exchange surfaces in the gut are adapted?
The villi have a large S.A and increase the S.A. of the gut. Rich blood supply to one side of the villi produces a steep concentration gradient for efficient diffusion. Thin wall (one cell thick) = short diffusion distance across which diffusion take
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How does exchange of materials occur in the gut?
Villi line the inner surface of the small intestine + provide an exchange surface for food molecules. Soluble products of digestion are absorbed into the villi by diffusion or active transport.
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How are leaves adapted for the diffusion of O2 + CO2 (exchange)?
Internal air spaces. Flat + thin for short diffusion distance Plants lose water vapour through stomata due to evaporation.
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What is transpiration?
The evaporation of water from plant leaves. The movement of water from the roots + through the plant is called the transpiration stream. Water vapour diffuses out through the stomata.
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If water loss is greater than the water replaced by the roots, the plant can dehydrate. Describe what plants may do in hot, dry, windy or bright conditions.
The guard cells (of stomata) can close to prevent excessive water loss. Wilting of the whole plant reduces surface area (leaves collapse + hang down), reducing water loss.
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Large organisms need a transport system to move materials around the body. Describe the human transport system.
The circulatory system consisting of blood vessels (arteries away, veins, capillaries), the heart + blood.
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What is the heart?
A muscular organ that pumps blood around the body. The right pump forces deoxygenated blood to the lungs where it picks up O2 and loses CO2. After returning to the heart, the deoxygenated blood is then pumped to the rest of the body by the left pump.
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Describe the four chambers in the heart. Describe the upper and lower chambers of the heart.
The atria receive blood from the vena cava on the right + pulmonary vein on the left. Atria contract to move blood into the lower chambers-ventricles. Ventricles contract to force blood into the pulmonary artery from the right side + into the aorta o
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Points to remember about the heart (valves, coronary heart etc.) -
Veins-->atria-->ventricles-->arteries. Valves in the heart prevent the blood from flowing in the wrong direction (backflow). Heart muscle is supplied with oxygenated blood via the coronary arteries. Action of the 2 sides of the heart results in doubl
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Describe arteries and veins.
Arteries: Carry blood away from the heart + have thick walls containing muscle + elastic tissue. Veins have thinner walls then arteries + often have valves to prevent backflow of blood.
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Describe capillaries.
Capillaries are narrow, thin walled vessels + carry the blood through the organs + allow the exchange of substances with all the living cells in the body.
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Why is it important that blood vessels are not blocked or too narrow?
As blood will not flow efficiently + the organs will be deprived of nutrients + oxygen. Stents can be inserted to keep blood vessels open (esp. useful when coronary arteries are narrowed due to fatty deposits, cutting off the blood supply to the hear
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What are the repercussions of having leaky valves and how can this be helped?
Leaky valves could result in backflow/blood flowing in the wrong direction. Artificial/animal valves can be inserted in the heart to replace damaged valves.
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What is blood?
Tissue. Plasma (fluid) contains red blood cells, white blood cells + platelets. Blood plasma transports: CO2 from the organs to the lungs, soluble products of digestion from small intestine to other organs + urea from liver to kidneys where urine's m
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Describe red blood cells.
Biconcave disks with no nucleus. Contain red pigment haemoglobin. Use their haemoglobin which combines to form oxyhaemoglobin in the lungs. Carry the O2 to all organs where oxyhaeoglobin splits in haemoglobin + oxygen.
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Describe white blood cells (a) and platelets (b).
(a) have a nucleus + are part of the immune system (defence system against micro-organisms). (b) are small fragments of cells, do not have a nucleus + help blood to clot at the site of the wound.
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What is done with blood from blood donors?
Can be separated into cells + plasma. The plasma can be given to patients in a transfusion to increase blood volume. Donated blood must be refrigerated. Some blood products can be frozen.
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What are the advantages of artificial blood?
Doesn’t contain cells so blood matching isn’t necessary. Blood such as PFCs (perfluorocarbons) don’t need to be refrigerated.
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What are the advantages of artificial blood?
Expensive + doesn’t carry as much O2 as whole blood. Some types are insoluble in water + so don’t mix well with blood. Some artificial bloods cause unpleasant side-effects.
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Patients who suffer heart failure may need a new heart. What is being developed as a result of a lack heart donors?
Artificial hearts to keep the patients alive. Pros: They don’t need to match the person’s tissue + there is no need for immunosuppressant drugs. Cons: problems with blood clotting, long stays in hospitals + expense.
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What are names of the two transport tissues in flowering plants?
Xylem tissue transports water + mineral ions from roots to stem, leaves + flowers. Phloem tissue caries dissolved sugars from the leaves to the rest of the plants, including the growing regions + storage organs.
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What is the transpiration stream in plants?
The movement of water from roots through the xylem and out of the leaves.
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What is homeostasis?
The process of keeping internal conditions - temperature, blood glucose, water + ion content & levels of waste products – within a narrow range.
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What are the waste products that have to be removed from the body?
CO2 produced by respiration (removed via lungs when we exhale) + urea produced in the liver from the breakdown of amino acids (removed by kidneys in urine + temporarily stored in bladder).
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Describe the significance of the water and ion content in our body (enters when we eat or drink).
If the water/ion content in the body is wrong then too much water may move in/out of the cells --> could damage/destroy cells.
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What is the purpose of the kidneys?
They filter blood, excreting substances we don’t need and keeping those that we do.
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How does a healthy kidney produce urine?
By filtering the blood, reabsorbing all sugar, reabsorbing the dissolved ions needed by the body, reabsorbing as much water as the body needs, releasing urea, excess ions and water.
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What is the purpose of a dialysis machine?
To carry out the same job as the kidneys + the blood flows between partially permeable membranes. Restores the concentration of substances in the blood back to normal but has to be carried out at regular intervals.
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Why does the dialysis fluid contain the same concentration of useful substances that the patient’s blood does?
So that substances such as glucose don’t diffuse out of the blood so that they don’t need to be reabsorbed. Urea diffuses out from the blood into the dialysis fluid.
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Why does the transplanted kidney need to be a good ‘tissue match’ to prevent rejection?
There are proteins called antigens on the surface of cells. The recipient’s antibodies may attack the antigens on the donor organs because they recognise them as being ‘foreign’.
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What are immunosuppressant drugs?
Drugs that suppress immune response after transplant. However this leaves them vulnerable to common infections.
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Core body temp must be maintained at 37oC. Where is this monitored and controlled?
Body temp monitored + controlled by the thermoregulatory centre in the brain. The centre has receptors which detect the temperature of the blood flowing through the brain. Temp receptors in the kin also send impulses to brain about skin temp.
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What happens if the core temperature rises?
Blood vessels near skin surface dilate allowing more blood to flow through the skin capillaries. Energy transferred by radiation + skin cools. Sweat glands produce sweat + the enrgy required for its water to evaporate comes from the skin surface.
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What happens if the core temperature falls?
Blood vessels near skin surface constrict + less blood flows through skin capillaries (less energy radiated). Shiver: our muscles contract quickly (requires respiration + some of the energy released warms the blood).
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How is the level of glucose in our blood monitored and controlled?
By the pancreas. If there is too much, the pancreas produces insulin (hormone) which causes the glucose to move from the blood into the cells.
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Describe type 1 diabetes.
If no/too little insulin is produced by the pancreas, the blood glucose level may become very high. Type 1 diabetes is controlled by insulin injections + diet & exercise.
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Insulin causes the blood glucose level to fall. What happens if the level gets too low?
The receptors in the pancreas detect the low level + the pancreas releases glucagon (hormone) which causes the glucagon in the liver to change into glucose, which is released back into the bl
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Describe the new methods being developed to treat (or even cure) Type 1 diabetes.
Pancreas transplants, transplanting pancreas cells, using embryonic stem cells to produce insulin secreting cells, using adult stem cells from diabetic patients + genetically engineering pancreas cells to make them work properly.
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What are the effects of population explosion?
More people want better standard of living, industrial waste (when goods are produced), we reduce amount of land available for animals/plants by building, quarrying, farming + through landfills. Also affects ecology of earth.
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Another effect of population explosion is pollution. Give examples of pollution.
Waterways: with sewage, fertiliser + toxic chemicals. Air: with smoke/gases i.e. sulphur dioxide (acid rain). Land: with toxic chemicals i.e. pesticides + herbicides which can then be washed into water.
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Give two specific examples of how we pollute land (other than farming methods).
Sewage containing human waste + water waste from homes –must be treated properly to remove gut parasites + toxic chemicals or these can get onto land. Household + industrial wate placed in landfill + toxic chemicals leak out.
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How has large-scale deforestation in tropical area for timber and to provide land for agriculture impacted the environment?
It has increased the release of CO2 into the atmosphere due to burning + decay by micro-organisms + has decreased the rate at which CO2 is removed from the atmosphere + reduced biodiversity.
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Why has deforestation occurred?
So that crops can be grown to produce ethanol based biofuels + so that there can be increases in cattle + rice fields for food –both produce methane (greenhouse gas).
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How has the destruction of peat bogs had a negative impact on the environment?
As it results in the release of CO2 into the atmosphere which occurs because the peat is removed from the bogs and used in compost for gardens. The compost is decayed by micro-organisms.
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How can a slight increase in the earth’s temperature (CO2 + methane) impact the environment?
May: cause big changes in earth’s climate, cause rise in seas level, reduce biodiversity, cause changes in migration patterns + result in changed in the distribution of species.
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Where can carbon dioxide be sequestered?
By plants and water - CO2 can be sequestered in oceans, lakes + ponds
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What is the effect of the increase in the Earth’s temp by just a few degrees?
It can: affect migration patterns and the distribution of species, reduce biodiversity, cause a rise in sea level due to melting of ice caps + glaciers & cause big changes in the Earth’s climate.
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How can ethanol based fuels be produced?
By fermentation of glucose (from maize starch using a carbohydrase) by yeast to produce ethanol which is extracted by distillation (carbon neutral as the CO2 used for photosynthesis by crops returned to atmosphere when ethanol burned).
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How is biogas (mainly methane) produced?
During anaerobic fermentation by bacteria. Plants + waste material containing carbohydrate are broken down in biogas generators
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How can biogas generators provide the ideal conditions for bacteria to reproduce and ferment the carbs?
Must be maintained at a suitable temp in oxygen free conditions. Generators are either buried in the ground for insulation or have insulating jackets. Some generators designed to mix the contents.
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How could we produce food more efficiently?
The shorter the food chain, the less energy will be wasted. It is therefore more efficient for us to eat plants than it is to eat animals.
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How can we produce meat more efficiently?
Preventing the animal from moving so it doesn’t waste energy on movement (cruel). Keeping the animal in warm sheds so that it doesn’t use as much energy from food to maintain its body temp.
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What does sustainable food production involve?
Managing resources + finding new types of food i.e. mycoprotein. Ensures there’s enough food for the current population + the future
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How are fish stocks in the oceans controlled?
Fishermen can only remove a strict allocation of fish per year (quota) _ must use certain sized nets to avoid catching small, young fish.
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What is mycoprotein?
Protein-rich food produced by the fungus Fusarium which is grown aerobically on cheap sugar syrup made from waste starch and the mycoprotein harvested.
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Micro-organisms can be grown on a large scale in industrial fermenters. How are the conditions controlled in fermenters?
Air supply (O2) for respiration, stirrers/gas bubbles used to keep micro-organisms spread out + provide even temp, sensors to monitor temp+pH levels + a water-cooled jacket as the respiring micro-orgs release energy which heat contents.
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What is active transport?

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When substances are absorbed against the concentration gradient. This requires the use of energy from respiration. It enables cells to absorb ions from very dilute solutions.

Card 3

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When is active transport used?

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Preview of the front of card 3

Card 4

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What are sport drinks?

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Card 5

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Why may we need sports drinks?

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Comments

lucyb2000

Thanks - These are brilliant! ^_^

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