OpenRevise

Flashcards · Biology

Exchange and Transport in Animals

89 cards from 5 lessons

  1. What is surface area to volume ratio?

    The surface area of an object divided by its volume.

  2. What happens to the surface area to volume ratio as an object gets bigger?

    It gets smaller.

  3. A cube has sides of 2 cm. What is its surface area?

    6 × (2 × 2) = 24 cm².

  4. A cube has sides of 2 cm. What is its volume?

    2 × 2 × 2 = 8 cm³.

  5. What is the surface area to volume ratio of a 2 cm cube?

    24 ÷ 8 = 3, so 3:1.

  6. Why can a single-celled organism manage without a transport system?

    It has a large surface area to volume ratio, so diffusion across its surface meets all its needs.

  7. Why can't diffusion alone supply the cells of a large animal?

    The surface area to volume ratio is small and the distances are long, so diffusion is far too slow.

  8. Why do multicellular organisms need exchange surfaces?

    Their body surface is too small for their volume, so they need specialised surfaces to swap materials quickly.

  9. Name the four features of an effective exchange surface.

    Large surface area, thin membrane, efficient blood supply (in animals) and ventilation (in animals, for gas exchange).

  10. Why does a thin membrane help exchange?

    It gives a short diffusion path.

  11. Why does a blood supply help exchange?

    It carries substances away, keeping the concentration gradient steep.

  12. What are villi, and what do they do?

    Finger-like folds in the small intestine wall that give a large surface area for absorbing digested food.

  13. What is an alveolus?

    A tiny air sac in the lungs where oxygen and carbon dioxide are exchanged.

  14. How are the lungs ventilated?

    By breathing, which moves fresh air in and stale air out.

  15. How is a fish's gill adapted for gas exchange?

    Many thin gill filaments give a large surface area, with a rich blood supply and water flowing over them.

  16. How does a root hair cell help a plant?

    Its long thin extension gives a large surface area for taking up water and mineral ions.

  17. How are leaves adapted for gas exchange?

    They are flat and thin, with air spaces inside giving a large surface area, and stomata to let gases in and out.

  18. Three cubes with sides 1 cm, 2 cm and 3 cm and an empty table under each. Work out the surface area to volume ratio of each cube. The three cubes with their surface areas, volumes and ratios filled in.

    Surface areas 6, 24 and 54 cm². Volumes 1, 8 and 27 cm³. Ratios 6:1, 3:1 and 2:1. The ratio falls as the cube gets bigger.

  19. An alveolus beside a capillary with a pointer marked X to the capillary. Name the structure marked X in this lung and say how it helps gas exchange.

    A capillary. It carries a rich blood supply that takes oxygen away and brings carbon dioxide, keeping the concentration gradient steep.

  20. An alveolus beside a capillary with unlabelled arrows. Label every part of this gas exchange surface. The same alveolus and capillary with every part labelled.

    Alveolus, thin wall one cell thick, capillary, red blood cells, oxygen in, carbon dioxide out, air in and air out.

  21. What is the heart?

    An organ that pumps blood around the body in a double circulatory system.

  22. Which chamber receives blood from the vena cava?

    The right atrium.

  23. Which chamber pumps blood to the lungs?

    The right ventricle.

  24. Which chamber pumps blood to the body?

    The left ventricle.

  25. Why is the wall of the left ventricle thicker than the right?

    It has to pump blood around the whole body, so it needs more force.

  26. What does the aorta carry?

    Oxygenated blood from the left ventricle to the body.

  27. What does the pulmonary artery carry?

    Deoxygenated blood from the right ventricle to the lungs.

  28. What does the pulmonary vein carry?

    Oxygenated blood from the lungs to the left atrium.

  29. What do the coronary arteries do?

    They supply the heart muscle with oxygenated blood.

  30. Why is it called a double circulatory system?

    Blood goes through the heart twice on each complete trip round the body.

  31. Why is blood returned to the heart after the lungs?

    It loses pressure in the lung capillaries, so the heart gives it a new push to the body.

  32. Where is the natural pacemaker?

    In a group of cells in the right atrium.

  33. What does an artificial pacemaker do?

    It sends electrical pulses to the heart to correct an irregular heartbeat.

  34. How do you work out a heart rate from a count in 15 seconds?

    Multiply the count by 4 to get beats per minute.

  35. Do you need to know the names of the heart valves?

    No. They are not required.

  36. A heart with a pointer marked X to the aorta. Name the vessel marked X and say what it carries.

    The aorta. It carries oxygenated blood from the left ventricle to the body.

  37. A heart with a pointer marked X to the right ventricle. Name the chamber marked X and say where it pumps blood.

    The right ventricle. It pumps deoxygenated blood to the lungs along the pulmonary artery.

  38. A heart with no labels. Label every part of the heart. The same heart with every part labelled.

    Right atrium, right ventricle, left atrium, left ventricle, vena cava, aorta, pulmonary artery, pulmonary vein and coronary artery.

  39. What is an artery?

    A vessel that carries blood away from the heart.

  40. What is a vein?

    A vessel that carries blood back to the heart.

  41. What is a capillary?

    A tiny vessel with a wall one cell thick, where exchange happens.

  42. Why do arteries have thick walls?

    The blood is at high pressure, so the walls must be strong and able to stretch and recoil.

  43. What are in an artery wall to help it stretch?

    Muscle and elastic fibres.

  44. Why do veins have valves?

    To stop the low-pressure blood flowing backwards.

  45. Why is a vein's lumen wide?

    It gives less resistance to the flow of low-pressure blood.

  46. Why is a capillary wall only one cell thick?

    It gives a short diffusion path for exchanging substances.

  47. Why do capillaries form huge networks?

    They give a large surface area for exchange with the cells.

  48. Does an artery always carry oxygenated blood?

    No. The pulmonary artery carries deoxygenated blood to the lungs.

  49. Does a vein always carry deoxygenated blood?

    No. The pulmonary vein carries oxygenated blood from the lungs.

  50. What is the formula for rate of blood flow?

    Rate = volume of blood ÷ time.

  51. 600 cm³ of blood flows through a vessel in 2 minutes. What is the rate?

    600 ÷ 2 = 300 cm³ per minute.

  52. Which vessel type can you feel a pulse in?

    An artery.

  53. Why does blood move slowly through capillaries?

    It gives more time for substances to diffuse.

  54. Three blood vessels with a pointer marked X to the valve of the vein. Name the vessel marked X and say how its structure suits its job.

    A valve in a vein. It closes to stop blood flowing backwards, because the blood is at low pressure.

  55. An artery, a vein and a capillary with no labels. Label the three blood vessels and their features. The same three vessels with every feature labelled.

    Artery: thick muscular wall, elastic fibres, narrow lumen. Vein: thin wall, wide lumen, valve. Capillary: wall one cell thick.

  56. What is the windpipe called?

    The trachea.

  57. What does the trachea split into?

    Two bronchi, one for each lung.

  58. What do the bronchioles end in?

    Alveoli.

  59. What are alveoli?

    Tiny air sacs where gas exchange takes place.

  60. What surrounds each alveolus?

    A network of capillaries.

  61. Which gas moves from the alveoli into the blood?

    Oxygen.

  62. Which gas moves from the blood into the alveoli?

    Carbon dioxide.

  63. How do the gases move across the alveolus wall?

    By diffusion, down their concentration gradients.

  64. Why do the lungs have millions of alveoli?

    To give a very large surface area for gas exchange.

  65. Why are the alveolus walls only one cell thick?

    To give a short diffusion path.

  66. Why does a rich blood supply help gas exchange?

    It carries oxygen away and brings carbon dioxide, so the concentration gradients stay steep.

  67. How does breathing help gas exchange?

    It ventilates the alveoli, which keeps the concentration gradients steep.

  68. What happens to the alveoli in emphysema?

    Their walls break down, so the surface area for gas exchange is reduced.

  69. How do you work out the volume of air breathed per minute?

    Volume per breath × number of breaths per minute.

  70. Is air breathed out the same as air breathed in?

    No. It has less oxygen and more carbon dioxide.

  71. The lungs with a pointer marked X to the alveoli. Name the part marked X and say what happens there.

    The alveoli. Oxygen diffuses into the blood and carbon dioxide diffuses out here.

  72. The lungs and airways with no labels. Label the airways and the structures of the lungs. The same lungs with every part labelled.

    Trachea, bronchus, bronchioles, lung, alveoli and capillary network.

  73. What are the four components of blood?

    Plasma, red blood cells, white blood cells and platelets.

  74. What is plasma?

    The pale yellow liquid part of the blood that carries dissolved substances.

  75. Name three substances transported in plasma.

    Carbon dioxide, soluble food molecules such as glucose, and urea (also hormones and heat).

  76. What do red blood cells do?

    They carry oxygen from the lungs to the body cells.

  77. What is haemoglobin?

    The red pigment in red blood cells that binds to oxygen.

  78. Why are red blood cells biconcave?

    The shape gives a large surface area for oxygen to diffuse in and out quickly.

  79. Why do red blood cells have no nucleus?

    There is more room for haemoglobin, so they can carry more oxygen.

  80. What do white blood cells do?

    They help to defend the body against pathogens.

  81. Do white blood cells have a nucleus?

    Yes.

  82. What are platelets?

    Small fragments of cells that help the blood to clot.

  83. What do platelets do at a wound?

    They cause the blood to clot, forming a scab that stops bleeding and keeps microorganisms out.

  84. How can you tell a white blood cell from a red blood cell in a photograph?

    The white blood cell is larger and has a stained nucleus. The red blood cell has no nucleus.

  85. What carries urea in the blood?

    The plasma.

  86. Give one risk of a blood transfusion.

    Infection from the donor blood, a mismatched blood group or an allergic reaction.

  87. Which part of the blood carries heat energy?

    The plasma.

  88. A drop of blood with a pointer marked X to a platelet. Name the blood component marked X and say what it does.

    A platelet. It is a small fragment of a cell that helps the blood to clot at a wound.

  89. A drop of blood with no labels. Label every component of the blood. The same drop of blood with every component labelled.

    Plasma, red blood cell (biconcave, no nucleus), white blood cell (has a nucleus) and platelets.