Biology 3 revision.txt

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  1. Diffusion: from... to... concentration
    High to low
  2. Osmosis: movement of...
    Water molecules from high to low concentration
  3. When the solution is less concentrated, it is said to be...
  4. Active transporrt is from ...... to ....... concentration
    Low to high concentration
  5. Active transport requires ......
    Energy from respiration
  6. In plants, what cell uses active transport to absorb nitrate ions
    Root hair cell
  7. Give two examples of where om the human body, active transport is used
    Small intestines and kidney tubules
  8. Two parts of the organ system that are specialised to the exchange of materials are...
    Villi in the small intestines and alveoli on the lungs
  9. What three things does the villi do/have to make exchange more efficient
    • Large surface area (micro-villi on each villus)
    • Good blood supply (extensive network of capillaries)
    • Thin cell walls (one cell thick)
  10. Heart and lungs are in the ....
  11. The breathing system involves....
    The heart and lungs.
  12. In the breathing system:
    Trachea > b....... > b........ > a........ s..... > a........
    Trachea > bronchi > bronchioles > alveolar sacs > alveoli
  13. alveoli exchange what two gases?
    Carbon dioxide and oxygen
  14. What four things do the alveoli have to make gas exchange more efficient
    • Large surface area
    • Film of moisture
    • Excellent blood supply (close to capillaries)
    • Thin cell walls (one cell thick)
  15. What diffuses from BLOOD TO ALVEOLI
    Carbon dioxide
  16. What diffused from ALVEOLI INTO BLOOD
  17. Alveoli in the lungs: blood becomes .........
  18. Leaves are......, ....... and ...... with lots of ....... .... ........ This provides a large ..... .......... which makes them efficient in ................
    Leaves are broad, thin and with lots of internal air space. This provides a large surface area which makes them efficient in photosynthesis.
  19. What do leaves have on their undersurface
  20. What do stomata do
    Let carbon dioxide in and let oxygen out
  21. Transpiration is....
    The loss of water vapour from a plant
  22. The loss of water vapour from a plant is called
  23. Transpiration is quicker in what 3 conditions
    Hot, dry and windy
  24. The size of the stomata is controlled by a pair of .....
    Guard cells
  25. What do guard cells do
    The size of the stomata is controlled by a pair of guard cells
  26. How is a plant adapted to prevent water loss in a desert
    The stomata gradually closes towards the afternoon when it gets hotter so that no water is lost. It is open during the night so that transpiration and photosynthesis can happen without losing too much water.
  27. If there is not enough water in a plant what happens and why
    The plant wilts because the plant is short of water and can't fill each cell
  28. What are the 3 types of blood vessels
    Veins arteries and capillaries
  29. Describe the circuit of blood flow
    Blood flows in a 'figure of eight' and passes through the heart twice on each circuit
  30. Arteries take blood to or away from the heart?
    Arteries take blood away from the heart
  31. Veins take blood to or away from the heart?
    Veins take blood to the heart
  32. In organs blood flows through.....
  33. How do substances pass from cells to the blood and vice versa
    They pass through capillary walls which are close to the cells by diffusion and active transport.
  34. What types of blood vessel has valves and why
    Veins to stop the backflow of blood
  35. What type of blood vessel has a thick and elastic wall and why?
    Arteries because they are under high pressure so that the blood can get round the whole body. They are able to dilate to adjust to pressure and increase how quickly blood reaches the cells.
  36. Which side of the heart is under more pressure and why?
    Left because it pumps blood to all parts of the body (except lungs)
  37. Which side of the heart takes deoxygenated blood to the lungs
    The right side.
  38. Blood has four main components, what are they?
    • Plasma
    • Red blood cells
    • White blood cells
    • Platelets
  39. The rate of transpiration can be measured using a .........
  40. What does the circulatory system do?
    It transports useful substances around the body and takes waste substances away.
  41. How is oxygen transported round the body
    Red blood cells are biconcave in shape and have a large surface area and no nucleus. This means they can carry more oxygen. The red pigment haemoglobin carries oxygen and combines to make oxyhaemoglobin. This can then be split again when it reaches the working cells which need oxygen.
  42. What do white blood cells do
    Defend against disease
  43. What are the two main types of white blood cell and what do they do
    • Limphocytes make antibodies
    • Phagocytes engulf, digest and destroy
  44. What is plasma
    The liquid part of blood which is a straw colour substance which contains mainly water and dissolved substances
  45. List the useful substances in plasma
    • Some water
    • Ions
    • glucose
    • amino acids
    • Fatty acids + glycerol
    • Hormones
  46. Waste in plasma....
    • Urea
    • Co2
    • Some water
  47. What is respiration?
    Production of energy from glucose, either with or without oxygen. It is done in the mitochondria of a cell.
  48. Respiration energy is used for.... (4)
    • Movement
    • Making large molecules (from small ones)
    • Maintaining body temperature
    • Active transport
  49. What is the aerobic respiration equation?
    • Glucose + oxygen ---> carbon dioxide + water + (ENERGY)
    • The glucose and oxygen are from the blood stream. CO2 is taken back in blood to the lungs and breathed out. Water is lost as sweat, moist breath and urine. And energy is used for many things...
  50. Benifits of aerobic respiration... (2)
    • Get more energy than anaerobic
    • Efficient - lots of energy made
  51. Benifits of anaerobic respiration....
    Quicker than aerobic
  52. Anaerobic respiration happens when..
    When there isn't enough oxygen to get energy quickly
  53. Disadvantages of anaerobic respiration...
    • Not efficient
    • Oxygen debt
  54. What is oxygen debt -include the equation
    • In anaerobic respiration, lactic acid is produced and builds up in the muscles. To neutralise this you need oxygen.
    • Lactic acid + O2 ---> H2O + CO2
    • This is why breathing is heavy after vigourous exercise
  55. During exercise what changes take place (4)
    • Heart rate increases
    • Breathing rate/ depth of breathing increases
    • Blood vessels dilate
    • Glycogen, stored in muscles is broken down to glucose for respiration
  56. What is the equation for anaerobic respiration?
    Glucose ---> Lactic acid (+ energy)
  57. What is the job of the kidneys?
    To 'clean' our blood and maintain concentration of dissolved substances in blood.
  58. A healthy kidney produces urine by...(4/5)
    • Filtering the blood
    • Reabsorbing all sugar
    • Reabsorbing salts and ions
    • Reabsorbing as much water as needed in the body
    • Releasing urea, excess salt water as urine
  59. What three substances do not leave the blood when blood is filtered in the kidney and why?
    • Red blood cells
    • White blood cells
    • Protein
    • Because the molecules are too big
  60. Which substances leave the blood when blood is filtered in the kidney? (4)
    • Glucose
    • Urea
    • Water
    • Sodium
  61. Which substances are reabsorbed when blood is filtered in the kidney?
    • Glucose (all)
    • Water, sodium (partly)
  62. Kidneys:what is ultrafiltration
    In the bowmens capsule lots of water and all small molecules are squeezed out of the blood under pressure, into the tubules.
  63. Kidneys: what happens in selective reabsorbsion
    • Useful substances reabsorbed.
    • Sugar and ions are reabsorbed using active transport .
  64. Kidneys: when is excretion of waste
    After useful substances have been reabsorbed
  65. Kidney transplants: explain the main 3 steps
    A donor kidney with as close a tissue type as possible to the recipient is used. The bone marrow is irradiated and they are treated with drugs to suppress the immune system. The donor kidney is placed near the bladder and after some rest they can lead a normal life.
  66. What are the pros and cons of kidney transplants (4)
    • Pros: lead a normal life, cheaper in the long run
    • Cons: donor kidney could be rejected, more expensive short term
  67. Kidney dialysis: describe and explain what happens
    • Blood flows through the dialysis machine and is separated from the dialysis fluid by a semi permeable membrane. This allows waste substances to pass into the fluid.
    • Dialysis fluid contains the same amount of essential mineral ions and glucose to ensure none is lost from the blood. This must be carried out a regular intervals.
  68. Pros and cons of kidney dialysis (4)
    • Pros: The waiting list is shorter than transplants, its more accessible
    • Cons: life if worked around constant appointments, 3/4 times a week at 4 hours per time.
  69. Characteristics of bacteria (4)
    • Vary in shape
    • Have a cell wall
    • Don't have a distinct nucleus
    • Reproduce rapidly
  70. Yeast has... (4)
    • A nucleus
    • Cytoplasm
    • A membrane
    • A cell wall
  71. Bacterial is used to make (2)
    Yoghurt and cheese
  72. Yeast is used to make (2/3)
    Beer and wine and bread
  73. Fermentation equation (using yeast)
    • Glucose ---> ethanol + carbon dioxide + energy
    • This is ANAEROBIC
  74. Why is aerobic respiration useful for yeast
    Aerobic respiration is useful for yeast as it produces more energy so the yeast can grow and reproduce.
  75. Yeast in baking: what are the 4 main steps
    • 1. Yeast and sugar are added to the flour
    • 2. It is left in a warm place
    • 3. CO2 makes the dough rise
    • 4. When the bread is baked gas bubbles expand and any ethanol evaporates off.
  76. What is malting
    Starch in barley is broken down by the enzyme carbohydrase to make a sugar.
  77. Yeast in brewing: the 4 main step (including both beer and wine)
    • 1. Malting
    • 2. Yeast is added and fermentation takes place.
    • beer, hops are added for flavour. In wine, the yeast uses natural sugars on the grapes as an energy source and flavour.
    • 4. Carbon dioxide is bubbled of to leave the alcohol.
  78. Bacteria in yoghurt: 6 main steps
    • 1.Milk is heated with milk protein and sugars.
    • 2. Heat kills bacteria
    • 3. Useful bacteria are added
    • 4. Bacteria ingest lactose (sugar) and ferment it into lactic acid. (ph 4-5)
    • 5.Acid makes the milk thick and sour (it curdles)
    • 6. Flavour is added
  79. Bacteria in cheese: 5 main steps
    • 1. Milk is heated
    • 2. Bacteria is added and ingests lactose and ferments it to lactic acid.
    • 3. Acid splits milk into curds and whey
    • 4. Rennet is added to help the curds solidify
    • 5. Curds separated from whey.
  80. Similarities (2) and differences (3) on cheese and yoghurt
    • Differences: rennet used to solidify cheese, milk is split as curds and whey.
    • Similarities: milk is heated, solidified using lactic acid to clot milk, both fermented using bacteria
  81. Growing microorganisms: on a large scale they are grown in......
    Can be grown on a large scale in fermenters. E.g. penicillin and mycoprotein.
  82. Name two things grown in a fermenter
    Penicillin and mycoprotein
  83. Penicillin, the 3 main steps....
    • Mould called penicillium is added to the fermenter
    • Grows using nutrients e.g. sugars
    • Mould makes penicillin which is extracted and purified.
  84. Mycoprotein (quorn), four main steps....
    • Fungus called Fusarium is added to the fermenter
    • Nutrient base is starch
    • Fusarium respires anaerobically
    • Biomass harvested and purified
  85. List three components of a fermenter and what they do
    • Stirring motor - keeps the bacteria/fungus in suspense and evenly distributes heat and substance.
    • Cooling water jacket - removes heat made during respiration
    • Probes - monitor pH oxygen CO2 temperature
  86. Spontaneous generation is...
    The idea that life just appears.
  87. Biogenesis is....
    Life from life
  88. Development of Biogenesis: list the 3 main discoveries and the names of the scientists. Include any tests that were done.
    • Redi disproves spontaneous generation. Test done to prove that maggots don't appear, they come from flies
    • Spallanzani suggests that microbes come from the air itself.
    • Pasteur realises that microbes are in dust particles not the air itself. Test: s shaped flask to trap dirt, no microbes grow but air can still come in.
  89. What does biogas use and what does it produce
    • It is made by anaerobic digestion using organic waste material. E.g. manure, food waste etc..
    • Made up of mainly methane and carbon dioxide. It is an alternative fuel source.
  90. How to make biogas... (4)
    • Organic waste is collected
    • A large dome converts it to biogas (bacteria digest to produce CO2 and CH4)
    • Methane is piped off and burned.
    • This produces energy which is carbon neutral.
  91. Gasohol is..
    A fuel source using ethanol.
  92. How to make gasohol -give the ratio and two main methods
    • 10% ethanol 90% petrol
    • Ethanol made by fermentation, two methods...
    • Sugar cane + yeast ---> ethanol
    • OR
    • Corn (starch) is broken down with carbohydrase to produce sugar to whih yeast is added ---> ethanol
  93. Preparing a culture medium (what it contains, the most popular one and extra details of growth and restrictions)
    • A culture medium contains nutrients that the particular microorganism might need. It could include carbohydrates as an energy source, mineral ions, vitamins, protein etc...
    • Agar is the most common growth medium made from seaweed. It melts easily and solidifies at around 50 degrees. Nutrients are added to get the best conditions.
  94. Aseptically conditions for microbes (3 ways to do it aseptically)
    • It means that there is no contamination. The way to do this is follow this procedure:
    • 1. Sterilization of petri dishes and culture medium
    • 2. Sterilization of inoculating loop.
    • 3. Sealing the petri dish.
    • These conditions mean that cultures are grown aspectically
  95. What temperature are cultures incubated at school and why?
    25 degrees to prevent the growth of harmful pathogens.
  96. What do platelets do?
    Clot the blood
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Biology 3 revision.txt
2012-09-20 20:16:56
biology aqa revision gcse

AQA GCSE Biology 3 revision.
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