10. Transport System in Organisms E-learning - Diffusion & Osmosis

10. Transport System in Organisms E-learning - Diffusion & Osmosis

1. Transport System in Organisms 1

2. Diffusion and Osmosis 2

3. Learning Outcomes for Section 1 At the end of this lesson, you should be able to: observe and infer that diffusion is the movement of molecules from a region of higher concentration observe and infer that osmosis involves the movement of water molecules when two solutions of unequal concentration are separated by a partially permeable membrane explain how diffusion and osmosis are involved in the transport system explain the need for a transport system in multicellular organisms 3

4. Eww... What’s that smell??? 4

5. How can we smell rubbish? Smell come from vapour from the rubbish. Particles in the vapour move about randomly. They bump into each other and spread out quickly. Some of the particles enter our nostrils. The spreading out of particles is brought about by diffusion . 5

6. Diffusion Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. 6

7. What is happening? 7

8. 10.1 Diffusion and Osmosis Factors Affecting the Rate of Diffusion Factor Effect Temperature ↑ Temperature, ↑ rate of diffusion Molecular Mass ↓ Molecular mass, ↑ rate of diffusion Thickness of barrier ↑ (Thicker) cell wall, ↓ rate of diffusion Concentration gradient ↑ Concentration gradient, ↑ rate of diffusion Surface-area-to- volume ratio ↑ Surface area-to-volume ratio, ↑ rate of diffusion

9. 10.1 Diffusion and Osmosis Surface area-to- volume ratio Cube Sides 1 cm Sides 2 cm Sides 3 cm Surface area/ cm 2 6 x 1 x 1 = 6 6 x 2 x 2 = 24 6 x 3 x 3 = 54 Volume/ cm 3 1 8 27 Surface area-to- volume ratio 6 : 1 24 :8 = 3 :1 54 : 27 = 2:1 Time/ s 1 3 10 The greater the ratio, the faster the rate of diffusion.

10. Diffusion through a M embrane Diffusion can also occur through a membrane. There are two types of membranes: Fully permeable membrane Example: Cell wall of plant cells Partially permeable membrane Example: Cell membrane of cells 10

11. Diffusion through a Permeable Membrane A fully permeable membrane allows all molecules to pass through it. A partially permeable membrane allows only small molecules but not large molecules to pass through it. 11

12. Diffusion through a Partially Permeable Membrane A partially permeable membrane allows only small molecules to pass through its pores but not the large ones. The small glucose molecules diffuse through the membrane ( Visking tubing) from inside the tube ( higher glucose concentration) into the water ( lower glucose concentration). The starch molecules are too large to pass through the membrane. 12

13. Diffusion in Living Organisms Photosynthesis Carbon dioxide diffuses from the air (higher carbon dioxide concentration) into the cells in the leaves (lower carbon dioxide concentration) Oxygen produced diffuses from the cells in the leaves (higher oxygen concentration) into the air (lower oxygen concentration). Gases exchange take place via the stomata.

14. Diffusion in Living Organisms The Human Body In the human digestive system, digested food diffuses through the wall of the small intestine into the bloodstream. Also, food and oxygen diffuse from the blood through the cell membranes into the body cells.

15. Osmosis When a piece of raisin is soaked in water, it swells up and becomes less wrinkled. Water has diffused into the cells of the raisin through the partially permeable membrane. After soaking in water for 1 h Turgid (larger and firm) Flaccid (smaller and soft) 15

16. Osmosis Osmosis is the net movement of water molecules through a partially permeable membrane from a region with a higher concentration of water molecules to a region with a lower concentration of water molecules. 16

17. An Example of Osmosis A piece of potato is placed in distilled water. After 20 minutes After 20 minutes original Distilled water

18. An Example of Osmosis After 20 minutes of soaking in distilled water, the potato pieces become larger, longer and firmer . The water concentration of distilled water is higher than the water concentration of in the potato cells. Therefore water molecules move via osmosis from the distilled water into the potato cells causing them to swell and become turgid.

19. Another Example of Osmosis We can show osmosis using Visking tubing. The pores in the Visking tubing allow the smaller water molecules but not the larger sugar molecules to pass through.

20. Another Example of Osmosis The water concentration is _________ in the beaker than in the Visking tubing. Therefore, water molecules move via _________ from the water in the beaker into the Visking tubing. higher osmosis

21. Another Example of Osmosis This causes the water level in the glass tube to _______ and the water level in the beaker to _______. rise drop

22. Osmosis in Living Organisms Roots Water from the soil enters the root hair cells of a plant by osmosis. This is because the water concentration in the soil is higher than in the cell solution of the root hair cells.

23. Osmosis in Living Organisms Stems and Leaves Water moves into the cells of stems and leaves of a plant by osmosis. This makes them firm and strong. Stems of non-woody plants need turgid cells to support the plants. If this support is lost, the plant wilts.

24. 24 Why is a transport system important to multicellular organisms?

25. Diffusion and Osmosis in Unicellular Organisms In unicellular organisms, materials move into and out of the cell directly by diffusion and osmosis. Hence, these organisms do not need a transport system. 25 O 2 CO 2

26. Is diffusion and osmosis efficient for multicellular organisms? In multicellular organisms, there are many cells. Most of these cells are far away from the outside of the organism. Diffusion and osmosis alone are not fast or efficient enough for the cells to get materials directly from the environment. Hence, transport systems are needed to take substances to all the cells and to carry waste substances away. 26

27. Something Interesting 27

28. Checkpoint Time Diffusion and osmosis are two common modes of movement for substances in living organisms. Give one example of diffusion taking place in living organisms. Give one example of osmosis taking place in living organisms.   28

29. Checkpoint Time State whether each of the following statements about osmosis is true or false. 29   Statement True or False (a) Osmosis takes place when two solutions of different concentrations are separated by a partially permeable membrane.   (b) Osmosis can only take place in living tissues.   (c) Osmosis is the net movement of water molecules from a solution of lower concentration to a solution of higher water concentration through a partially permeable membrane.  

30. Transport System in Plants 30

31. Learning Outcomes for Section 2 At the end of this lesson, you should be able to: describe briefly the process of absorption of water and mineral salts by the root of a plant describe briefly the transport of water and manufactured food substances in the plant explain the function of phloem and xylem use terms such as translocation, transpiration pull, active transport, diffusion and osmosis in the description of plants transport system 31

32. The Tallest Tree in the World The giant redwood trees in the USA. The trees are more than a 100m tall. Everyday, the giant redwood tree moves 1000kg of water from the soil to their leaves, 100m above the ground. Is Osmosis sufficient?

33. Transport System in Plants Plants need a transport system to carry water , food and dissolved minerals to all cells in the plant. The transport system is made up of vessels in the root , stem and leaves .

34. Vessels of the Plant Transport System There are two types of vessels: Xylem Vessels Made up of dead cells and have thick walls Carry water and dissolved minerals from the roots to all parts of the plant. Xylem vessels in the roots

35. Vessels of the Plant Transport System Phloem Vessels Made up of living cells and have thin walls Carry sugar produced in the leaves to other parts of the plant. Phloem vessels in the roots

36. Vascular Bundles The two vessels often run side by side forming vascular bundles. Xylem vessels in stem Phloem vessels in stem Vascular bundle

37. Observing vascular bundles in a celery stem

38. Xylem and Phloem in Different Parts of the Plants 38

39. 1. Place a balsam plant in a container of dilute red ink for one day. 10.3 Transport System in Plants Experiment 1: The path of water through a plant 2. After one day, wash the roots under running tap water. How is water transported in a plant? Transport tissue in plants

40. 3. Observe the stem and leaves of the balsam plant. You will find that the red ink has risen in certain strands of the stem and veins of the leaf. 10.2 Transport System in Plants Experiment 1: The path of water through a plant The strands are vascular bundle s which are part of the plant transport system . In the balsam plant, the vascular bundles are arranged in a ring within the stem. Each vascular bundle consists of xylem tissue and phloem tissue . Which part of the vascular bundle was actually stained red?

41. 10.2 Transport System in Plants The xylem tissue In Experiment 1, the xylem tissue was stained red. The xylem tissue consists of long tubes or vessels that pass from the roots to the leaves. Hence, the xylem tissue is able to transport water and mineral salts from the roots to the leaves. xylem tissue phloem tissue The phloem tissue The phloem tissue transports food (e.g. sugars ) produced in the leaves to other parts of the plant.

42. 10.3 Transport System in Plants Experiment 2: How is food transported in a plant? 1. Take the stem of a woody plant (e.g. hibiscus). Remove a ring of bark around the main stem. This should remove the phloem tissue, leaving the xylem tissue intact. 2. Water and mineral salts can still be transported in the plant.

43. 10.3 Transport System in Plants 3. After a few weeks, the part of the stem just above the cut region will swell. Food cannot reach the roots because the phloem tissue is removed. It collects in the stem just above the cut, causing that area to swell. Without food (sucrose, amino acids) , the roots will starve and die. The plant will eventually die as its roots cannot take in water from the soil. What causes the swelling at this part?

44. vacuole root hair cell cytoplasm cellulose cell wall cell membrane Absorption of Water and Mineral Salts by Roots How are water and mineral salts taken into a plant? soil particle film of water

45. vacuole root hair cell cytoplasm cellulose cell wall cell membrane soil particle film of water Soil contains water and mineral salts. The root hair cells take in water by osmosis . The root hair cells also take in mineral salts by active transport , a process which requires energy. Key: Movement of mineral salts Movement of water molecules lower concentration of water molecules higher concentration of water molecules Absorption of Water and Mineral Salts by Roots

46. Absorption of Water and Mineral Salts by Roots Key: Movement of mineral salts Movement of water molecules vacuole root hair cell cytoplasm cellulose cell wall cell membrane soil particle film of water lower concentration of water molecules higher concentration of water molecules After the water and mineral salts are taken in, the water molecules move from one cell to the next by osmosis. The mineral salts move from one cell to the next by diffusion. The water and mineral salts will continue to move from one cell to the next until they reach the stem. How does this process allow plants in hydroponic systems to survive?

47. Transport of Water and Mineral Salts (Xylem) Water and mineral salts move up the plant mainly by transpiration pull and in some plants, by root pressure. Transpiration pull This pulling force is produced when water evaporates from the leaves through the stomata. This force is similar to someone sucking up liquid through a straw.

48. A pretty blue rose from a plain white one.

49. Transport of Food (Phloem) During photosynthesis, food is produced in the leaves in the form of sugar (glucose) which is then transported to other parts of the plant via the phloem . There is a higher sugar concentration in the leaf than in the phloem vessels which are constantly transporting sugar to other parts of the plant.

50. Therefore diffusion occurs to transport sugar from the leaves to phloem vessels. The movement of glucose in the phloem occurs in both directions. Transport of Food (Phloem)

51. Exchanges of Gases during Photosynthesis Carbon dioxide is needed for photosynthesis. There is a higher concentration of carbon dioxide in the surroundings than in the leaf. Therefore, carbon dioxide diffuses from the surroundings to the leaf. Oxygen is produced during photosynthesis. There is a higher concentration of oxygen in the leaf than in the surroundings. Therefore, oxygen diffuses from the leaf to the surroundings. 51

52. Transport System in a Flowering Plant 1. Water enters a plant through its roots by osmosis. Dissolved minerals are absorbed through diffusion and active transport. 2. Water and minerals move up the stem through xylem vessels. 3. Xylem vessels carry water and dissolved minerals from the roots to the leaves. 4. Most of the water evaporates and diffuses from the leaves through transpiration. 7. Oxygen diffuses from the leaves to the surroundings. 8. Sugar moves from the leaves through phloem vessels to the rest of the plants. 52 Movement of water Movement of sugar Movement of carbon dioxide Movement of oxygen 5. Carbon dioxide diffuses from the surrounding to the leaves. 6. Carbon dioxide and some water are used during photosynthesis by the leaves to produce sugar and oxygen.

53. Checkpoint Time Complete the following sentences. Water molecules that are taken into a plant move from one cell to another by ________________. Plants can obtain ______________ and ________________________ from soil. Mineral salts that are taken into a plant move from one cell to another by __________________. 53

54. Checkpoint Time The figure below shows a cross section of the stem of a green plant. Identify the parts labelled 1 and 2. 1: _____________________ 2: _____________________ 54

55. Checkpoint Time Name the substances transported by the parts labelled 1 and 2. 1: ______________________________________ 2: ______________________________________ 55

56. Transport System in Humans 56

57. Learning Outcomes for Section 3 At the end of this lesson, you should be able to: describe and explain the functions of the 3 main transport system in humans i.e. the heart, the blood vessels and the blood understand parts of the heart and the double circulation system involved understand the function of arteries, veins and capillaries and briefly describe areas where they are found briefly describe different parts of the blood and how blood acts as a transport medium 57

58. Transport System in Human Circulatory system is the main transport system in the human body. It consists of three parts: Heart – an organ which pumps blood around the body Blood – a liquid which transport materials Blood vessels – network of tubes which carry blood round the body 58

59. Transport System in Human Heart Its purpose is to pump blood round the body. The heart has 4 chambers. Two upper chambers called the right atrium and left atrium (plural: atria) Two lower chambers called the right ventricle and left ventricle (plural: ventricles) The wall down the middle of the heart that separates the left side from the right side is called the septum . 59

60. Transport System in Human Heart The valves in the heart open and close to ensure that blood flows only in one direction. 60

61. Section of a Mammalian Heart 61 Artery Septum Vein Right atrium Valve . Valve Right ventricle Artery Vein Left atrium Valve . Valve Septum Left ventricle

62. Transport System in Human Blood The human body has about 5 litres of blood. Blood has 2 functions: To transport materials (e.g. nutrients, oxygen, carbon dioxide and other waste substances) round the body To protect us against diseases Blood contains: red blood cells white blood cells platelets plasma 62

63. Transport System in Human Blood Red blood cells Red blood cells are biconcave in shape to increase its surface-area-to-volume ratio for oxygen absorption. Red blood cells have no nuclei so as to pack in more oxygen. Red blood cells contain haemoglobin , which combines with oxygen and carries it round the body The haemoglobin then releases oxygen as it passes the cells. This oxygen is used by the cells for respiration. The red blood cells then collect carbon dioxide (a waste product of respiration) by diffusion. The red blood cells are bright red when they carry oxygen. 63

64. Transport System in Human Blood Red blood cells When oxygen is bound to haemoglobin, blood appears to be bright red . At the cells where oxygen is needed for respiration, haemoglobin will release the oxygen molecules it is carrying. When oxygen is released from haemoglobin, blood appears to be dark red . The red blood cells then collect carbon dioxide (a waste product of respiration) by diffusion. 64

65. Transport System in Human Blood White blood cells There are fewer white blood cells than red blood cells. They are colourless and are larger than red blood cells and have nuclei. Some white blood cells are used to fight infections. They produce antibodies to kill bacteria Alternatively, they engulf and digest bacteria . 65

66. Transport System in Human Blood White blood cells 66

67. Transport System in Human Blood Platelets These are tiny pieces of blood cells. They help blood to clot when we bleed. Platelet 67

68. Transport System in Human Blood Plasma Plasma is a pale yellow liquid made up of 95% water with dissolved substances including nutrients (glucose, amino acids, fatty acids, mineral salts) and waste substances. It transports digested food, waste materials (e.g. carbon dioxide and urea) and other materials (e.g. hormones and mineral salts). 68

69. Transport System in Human Blood Vessels Blood vessel is a network of tubes carrying blood around our body, from the heart to the rest of our body, and then back to the heart. There are three types of blood vessels: arteries , veins and capillaries . 69

70. Blood Vessels Transport System in Human Artery Vein Capillary Function Carry oxygenated blood away from the heart to all other parts of the body Except pulmonary artery Carry deoxygenated blood from the rest of the body back to the heart Except pulmonary vein Connect arteries to veins Carry blood to all cells Allow exchange of nutrients, gases and wastes Pressure Under high pressure Under low pressure - Thickness of walls Have thick, elastic muscular walls Have very thin walls Have walls which are one-cell thick (to ensure fast diffusion of substances) Presence of valves No Yes (To prevent the backflow of blood) No Diagram 70

71. Transport System in Humans right lung Key: Deoxygenated blood Oxygenated blood brain other parts of the body left lung Veins Veins carry blood towards the heart. heart

72. right lung Key: Deoxygenated blood Oxygenated blood brain other parts of the body left lung The arteries The arteries carry blood away from the heart. The heart The heart is a muscular pump . Its pumping action keeps the blood circulating around the body quickly and continuously. heart Transport System in Humans

73. n Humans right lung Key: Deoxygenated blood Oxygenated blood brain other parts of the body left lung The capillaries These are very tiny blood vessels that connect the arteries to the veins . The capillary walls are one-cell thick . This allows quick diffusio n of nutrients and oxygen from the blood to the tissue cells . The capillaries Waste substances such as carbon dioxide can also move from the tissue cells into the blood in the capillaries. Blood Blood is continuously circulated around the body, transporting many substances. Blood also protects the body from disease-causing germs. Blood In places with low oxygen, our body produces more red blood cells to transport more oxygen. heart Transport System in Humans

74. Transport System in Human 74

75. Transport System in Human Explain why the left ventricle has a thicker muscular wall than the right ventricle. 75 The left ventricle must pump blood at high pressure so that blood can travel to the rest of the body.

76. Double Circulation in Human The double circulatory system of blood flow occurs when the blood enters the heart twice . All animals with lungs have a double circulatory system. The cycle is heart  body  heart  lungs  heart In contrast, fish have a single circulation system because they do not have lungs. The cycle is heart  gills  body  heart 76

77. Double Circulation in Human Double circulation is much more efficient than single circulation. In a fish blood pressure goes down as is passes through capillaries in gills so it is slower and takes longer for oxygen and nutrients to get around the body. In humans the blood pressure can be increased after it has left the lungs. It is faster. Humans are more active than fish and need to produce more energy and heat. 77

78. Respiratory System: Lungs In the lungs, blood picks up oxygen and loses carbon dioxide . The air we breathe contains high concentration of oxygen and low concentration of carbon dioxide. Lung

79. The blood flowing towards the lungs contains low concentration of oxygen and high concentration of carbon dioxide. Therefore, oxygen from the lungs will diffuse into the blood and carbon dioxide from the blood will diffuse into the lungs . Respiratory System: Lungs Lung

80. Our Respiratory System

81. Digestive System In the small intestine , blood picks up small, digested food molecules such as glucose, amino acids and fatty acids. As the blood flows around the body, it will distribute these food molecules to the cells that need them. Oesophagus

82. Checkpoint Time Identify the components of the human circulatory system. 82

83. Checkpoint Time The diagram below shows a vertical section of the heart in humans. Label A , B , C and D . A : __________________ B : ___________________ C : __________________ D : ___________________ 83

84. Checkpoint Time The diagram below shows a vertical section of the heart in humans. In which labelled structure does blood reach the maximum pressure?   84