Biology 3 Flashcards

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  • Created by: Emily
  • Created on: 01-05-13 17:48
Osmosis
Osmosis is the movement of water molecules across a partially permeable membrane fro an area of high concentration to an area of low concentration.
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4 ways that exchange surfaces are adapted to maximise effectiveness.
1) they are thin, so substances only have short distances to diffuse. 2) they have a large surface area so lots of a substance can diffuse at once. 3) animals - have lots of blood vessels to diffuse in/out blood quicker. 4) gas exchange - ventilated.
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Stomata
Found on the underneath of the leaf - an exchange surface. Carbon dioxide diffuses through. Opened by guard cells. Flattened shae of the leaf increases the area of this exchange surface so it's more effective.
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In order - what parts of the body aid breathing.
Trachea, bronchi (singular: bronchus), bronchioles, alveoli.
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Explain what happens when you breathe in.
Intercostal muscles pull ribcage and sternum up and out by contracting. Diaphragm [flattens out] contracts. Thorax volume increases. This decreases the pressure, drawing air in.
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Explain what happens when you breathe out.
Intercostal muscles case ribcage and sternum to drop in and down by relaxing. Diaphragm [moves up] relaxes. Thorax volume decreases. This increases the pressure, so air is forces out.
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Explain the 'job' of the lungs and how it does this.
To transfer oxygen to the blood and to remove waste carbon dioxide from it. To do this the lungs contain millions of 'air sacs' - alveoli. This is where gas exchange happens.
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What do the alveoli do?
Maximise the diffusion of oxygen and CO[2] in and out of the blood.
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Name four features of the alveoli.
1) extremely large surface area (about 75m^2 in humans...but you don't need to know that). 2) moist lining for dissolving gases. 3) thin walls. 4)good blood supply.
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Explain what the villi are.
Increase the surface area in the small intestine so that digested food is absorbed much more quickly into the blood.
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Name two features of a villus.
1) have a single layer of surface cells. 2) have a very good blood supply to assist quick absorption.
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Active transport.
The movement of substances against the concentration gradient - from an area of low concentration to an area of high concentration.
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Explain how root hair cells are specialised for absorbing water and minerals.
The cells on the surface of plant roots grow into long 'hairs' which stick out into the soil. This gives the plant a bigger surface area for absorbing water and mineral ions from the soil.
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An example of active transport in humans.
Taking glucose from the gut (and the kidney tubules).
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Explain how phloem tubes transport food in plants.
Made of columns of living cells with small holes in the ends to allow 'stuff' to flow through. They transport food substances (mainly dissolved sugars) made in the leaves to growing regions and storage organs. The transport goes in both directions.
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Explain how xylem tubes take water up.
Made of dead cells joined end to end with no end walls between them and a hole down the middle. They carry water and minerals from the roots to the stem and leaves in the transpiration stream.
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Transpiration.
Is the loss of water from the plant.
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Transpiration is caused by...
the evaporation and diffusion of water from inside the leaves.
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What does transpiration create and what does the plant to do in response?
Creates a slight shortage of water in the leaf, so more water is drawn up from the rest of the plant through the xylem vessels to replace it.
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Why does a leaf transpire?
Because there is more water inside the plant than in the air outside, the water escapes from the leaves through the stomata.
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What is the circulatory systems main function?
To get food and oxygen to every cell in the body and carry waste (e.g. carbon dioxide and urea) to where they can be removed from the body.
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What does the first circuit of the circulatory system do?
Pumps deoxygenated blood to the lungs to take in oxygen. The blood then returns to the heart. Involves the pulmonary vein & artery.
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What does the second circuit of the circulatory system do?
Pumps oxygenated blood around all the other organs of the body. The blood gives up its oxygen at the body cells and the deoxygenated blood returns to the heart to be pumped out to the lungs again. Involves the vena cava and the aorta.
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What is the heart mainly made of?
Muscle tissue.
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Why does the heart have valves?
To make sure the blood goes in the right direction - prevents it from flowing backwards.
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Explain how the heart uses it four chambers to pump blood out.
Blood flows into the two atria from the vena cava and the pulmonary vein. The atria contract, forcing the blood into the ventricles. These then contract, forcing the blood into the pulmonary artery and the aorta and out the heart.
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Arteries.
Carry blood away from the heart. Thick, strong, elastic walls. Fairly small lumen.
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Capillaries.
Arteries branch into capillaries. Once cell thick walls and a very small lumen. Carry blood really close to every cell to exchange oxygen and glucose in, and CO[2] and urea through their permeable walls by diffusion.
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Veins.
Capillaries join up to form veins.Take blood back to the heart. Large lumen and thinner walls than arteries because the blood is at a lower pressure. They have valves to keep the blood flowing in the right direction and prevent it flowing backwards.
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What is the 'job' of the red blood cells?
To carry oxygen from the lungs to all the cells in the body.
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Three features of a red blood cells.
1) Donut shape to give a large surface area for absorbing oxygen. 2) Don't have a nucleus providing more room for absorbing oxygen. 3) Contain a red pigment called haemoglobin.
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Explain why haemoglobin is important.
In the lungs, haemoglobin combines with oxygen to produce oxyhaemoglobin. In body tissue, the reverse happens - oxyhaemoglobin splits up into haemoglobin and oxygen to release oxygen to the cells.
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How do white blood cells defend the body against disease?
They can change shape to gobble up unwelcome microorganisms. They produce antibodies to fight microorganisms, as well as antitoxins to neutralise any toxins produced by the microorganisms.
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Explain what platelets are and how they work.
Small fragments of cells without a nucleus. They help blood to clot at a wound - to stop too much blood loss and prevent microorganisms getting in.
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Name six things plasma contains.
1) Red and white blood cells. 2) Nutrients like glucose and amino acids. 3) Carbon dioxide from the organs to the lungs. 4) Urea from the liver to the kidneys. 5) Hormones. 6) Antibodies and antitoxins produced by white blood cells.
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What is artificial blood and why is it used?
A blood substitute (e.g. salt solution "saline") used to replace a lost volume of blood. It's safe (no air bubbles get into the blood) & tries to give the patient enough time to produce enough new blood cells before the need for a blood transfusion.
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Why and when are artificial hearts used?
Usually temporary fix until a donor heart can be found for patients who's hearts have failed.
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Advantages of fitting an artificial heart.
Not rejected by the body's immune system because they're made from metals/plastics so the body doesn't recognise them as 'foreign' and doesn't attack in the same way as it would with living tissue.
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Disadvantages of fitting an artificial heart.
The surgery can lead to infection & bleeding. Parts can wear out. The electrical motor could fail. Patient has to take drugs to thin blood to prevent clots [that can lead to strokes]. These can cause problems with bleeding if they're in an accident.
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What is coronary heart disease and what does it cause?
When the arteries that supply the blood to the muscle of the heart get blocked by fatty deposits. This causes the arteries to become narrow and blood flow is restricted - can result in a heart attack.
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What are stents and how are they effective?
Stents are small tubes that are inserted into the affected artery. They keep them open so blood can pass through. Lower the risk of a heart attack in people with coronary heart disease.
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Disadvantages of a stent.
The stents can irritate the artery, causing scar tissue to grow - narrowing the artery again. The patient also has to take drugs to stop blood clotting on the stent.
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Define homeostasis.
Homeostasis is the maintenance of a constant internal environment.
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Six things that need to be controlled by homeostasis.
1) body temperature. 2) water content. 3) ion content. 4) blood sugar level. 5) carbon dioxide. 6) Urea.
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Why does the body need to regulate temperature?
The enzymes within the body work best at [around] 37 degrees-C. If the body gets too hot/cold, the enzymes won't work properly and important reactions in the body can be disrupted.
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Explain what happens when you get too hot.
Hairs lie flat against the skin. Sweat produced by sweat glands & evaporates from skin which removes heat. Blood vessels supplying skin dilate - more blood flows close to the surface of the skin so heat is transferred from blood to environment.
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Explain what happens when you get too cold.
Hairs stand up to trap an insulating layer of air. No sweat is produced. Blood vessels supplying skin constrict. Shiver - muscles contract naturally - releases energy to keep warm (because it needs respiration).
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Three main functions of the kidneys.
1) removal of urea from the blood. 2) Adjustment of ions in the blood. 3) Adjustment of water content in the blood.
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Explain ultrafiltration.
High pressure is built up - squeezes water, urea and sugar out of blood and into the Bowman's capsule. Membranes between blood vessels & Bowman's capsule act like filters - big molecules (proteins/blood cells) aren't squeezed out - stay in the blood.
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Explain reabsorption.
As the liquid flows along the nephron all the sugar is reabsorbed into the blood by active transport. Sufficient ions are absorbed into the blood by active transport. Sufficient water is reabsorbed into the blood.
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What happens after reabsorption in the kidneys?
The remaining substances (excess ions, water, urea) continue out of the nephron, into the ureter and down to the bladder as urine.
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Explain what happens during kidney dialysis.
The persons blood flows alongside a selectively permeable barrier surrounded by dialysis fluid (which has the same concentration of dissolved ions and glucose as healthy blood). Waste products diffuse out of blood into dialysis fluid.
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Disadvantages of dialysis.
Each session takes 3-4 hours and most patients have to have dialysis 3 times a week. Also, dialysis can cause blood clots and infections.
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Disadvantages of kidney transplant.
Can be rejected by the patients immune system - the 'foreign' antigens are attacked by the patient's antibodies. The patient has to take drugs to suppress the immune system to prevent rejection. The surgery can also lead to infection and bleeding.
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What happens when blood glucose is too high?
Insulin is secreted by the pancreas. Glucose is removed by the liver. The insulin makes the liver turn glucose into glycogen.
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What happens when blood glucose is too low?
Glucagon is secreted by the pancreas. Glucagon makes the liver turn glycogen into glucose.
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What two ways can control type 1 diabetes?
1) Avoiding food rich in simple carbohydrates (i.e. sugars) and exercise after eating. 2) Injecting insulin into the blood at mealtimes.
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Reasons why world population is rising (not including people getting frisky more often..)
Mostly due to modern medicine and farming methods which have reduced the number of people dying from disease and hunger.
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Four reasons how the world's is demand for a higher standard of living is impacting the environment.
1) demand for luxuries like computers and cars - which require energy. 2) more raw materials are being used (e.g. oil to make plastics). 3) use more energy for the manufacturing process. 4) using more resources than the environment has.
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Four main human activities that reduce the amount of land and resources.
1) Building. 2) Farming. 3) Dumping waste. 4) Quarrying for metal ores.
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Three places where carbon dioxide can be sequestered.
1) Oceans, lakes and ponds. 2) Green plants. 3) Peat bogs.
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Explain how carbon dioxide and methane trap heat from the sun.
Gases in the atmosphere naturally act like an insulating layer. They absorb most of the heat that would be radiated into space and radiate it back to the earth. High levels of methane and carbon dioxide is causing this to happen more.
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Three reasons for deforestation.
1) provide timber to use as a building material. 2) clear land for farming. 3) produce paper.
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Four main problems caused by deforestation.
1) More methane in the atmosphere. 2) More carbon dioxide in the atmosphere. 3) Less carbon dioxide taken in. 4) Less biodiversity.
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Biodiversity.
The variety of different species in a habitat. The more species - the bigger the biodiversity. (Bio - biological, Diversity - variety).
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Why does destroying peat bogs add more carbon dioxide to the atmosphere?
Plants in bogs don't fully decay (because there's not enough oxygen) so the carbon in the plants is stored in the peat. But when the peat bogs are drained, the peat starts to decompose - releasing carbon dioxide.
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How can the demand for peat be reduced?
Buy peat-free compost (e.g. manure, leaf mold or bark chippings).
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Six consequences of global warming.
1) sea expands as it warms causing sea levels to rise. 2) ice caps melt causing sea levels to rise. 3) changed weather patterns. 4) distribution of plants and animals might change. 5) biodiversity could be reduced. 6) changes in migration patterns.
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Fermentation.
When bacteria or yeast break sugars down by anaerobic respiration.
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Explain how ethanol is made by fermentation of sugar.
Yest makes ethanol when they break down glucose. The ethanol is distilled to separate it from the remaining glucose and yeast.
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Explain what a biogas generator is and it's requirements.
Digester or generator. Needs to be kept at a constant temperature to keep the microorganisms respiring. Biogas can't be stored as a liquid (needs high pressure) - so has to be used straight away.
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Batch generator.
Manually loaded up with waste which is left to digest and the by-products are cleared away at the end of every session. Less convenient than continuous generators.
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Continuous generator.
Makes biogas all the time. Waste is constantly fed in and biogas is produced at a steady rate. More suited to large-scale biogas projects. More expensive than batch generators.
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Advantages of biogas generators.
Greener alternative to fossil fuels. Carbon neutral. Doesn't produce large amounts of sulfur dioxide/nitrate oxide. Less methane in atmosphere. Raw material is cheap and readily available. Act as a waste disposal system.
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Three ways that can improve the efficiency of food production.
1) reducing the number of stages in the food chain. 2) restricting the energy lost by farm animals. 3) developing new food sources.
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What is mycoprotein?
Protein from fungi. A fungus called 'Fusarium' is the main source of mycoprotein. It is used to make meat substitutes.
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Disadvantages of modern ways of producing food.
Some people aren't happy with animals being kept in 'unnatural conditions'. Crowded conditions in farms causes a faster spread of disease. Antibotics become less effective because of antibotics animals are given to prevent disease.
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Problems with modern distribution of food.
Some foods produce a lot of 'food miles', burning fossil fuels and releasing carbon dioxide into the atmosphere.
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Two ways that fish stocks can be maintained.
1)Fishing quotas - limits on the number and size of fish that can be caught in certain areas. 2) Net size - limits on the mesh size of the fish net depending on what is being fished.
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Other cards in this set

Card 2

Front

4 ways that exchange surfaces are adapted to maximise effectiveness.

Back

1) they are thin, so substances only have short distances to diffuse. 2) they have a large surface area so lots of a substance can diffuse at once. 3) animals - have lots of blood vessels to diffuse in/out blood quicker. 4) gas exchange - ventilated.

Card 3

Front

Stomata

Back

Preview of the front of card 3

Card 4

Front

In order - what parts of the body aid breathing.

Back

Preview of the front of card 4

Card 5

Front

Explain what happens when you breathe in.

Back

Preview of the front of card 5
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