Gas Exchange and Transport

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Learning objectives Possible learning and teaching activities Expected learning outcomes

Students should learn Students should be able to

 the effects of asthma on ventilation.  develop an awareness of the effects of asthma on

ventilation.

 the exchange of gases at the respiratory surface.  Explore students’ prior knowledge on gas exchange.

 explain how air sacs are adapted for gas exchange.

 the uptake, transport and release of gases by blood. [Refer to Section 8.2.1.]

 state the roles of blood in gas exchange.

8.1.2 Gas exchange in flowering plants

 the roles of stomata and lenticels in a terrestrial flowering plant.

 Examine the stomata and lenticels using temporary mount, prepared slides or photomicrograph.

 Measure the stomatal density of leaf specimens using temporary mount.

 describe how gas exchange occurs in terrestrial flowering plants.

8.2 Transport

 the need for a transport system in multicellular organisms.

 Ask students to suggest various ways by which multicellular organisms transport oxygen, food and wastes in their bodies. Then ask students why transport system is needed in some multicellular organisms.

 explain the need for a transport system in some multicellular organisms.

8.2.1 Transport in mammals 8.2.1.1 The circulatory system

 the functions of the circulatory system.  Dissect a small mammal to examine the heart and main blood vessels.

 describe the functions of the circulatory system.

8.2.1.2 Heart

 the structure of the heart in relation to its function.  Dissect a mammalian heart to examine its structures.

 relate the structure of the heart to its function.

 a brief treatment of the cardiac pacemaker and cardiac cycle.

 Search for information on artificial hearts, artificial heart valves, artificial pacemaker and heart transplants.

 Use sphygmomanometer to measure blood pressure.

 outline the role of cardiac pacemaker in the cardiac cycle.

 describe the sequence of events in the cardiac cycle in terms of diastole and systole.

 Use a data logger to measure heart rate, and to record and display electrocardiogram (ECG).

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Learning objectives Possible learning and teaching activities Expected learning outcomes

Students should learn Students should be able to

 nervous and hormonal control of the heart rate in relation to changing demands.

 describe the nervous and hormonal control of heart rate.

 the coronary blood supply to heart. Likely causes of coronary heart disease and preventive measures. [Refer to Section 6.4.2.]

 develop an awareness of the causes of coronary heart disease and preventive measures.

8.2.1.3 Blood vessels

 the structure of arteries, capillaries and veins in relation to their functions.

 Examine prepared slides of T.S. arteries, capillaries and veins to study their structures.

 Make L.P. drawings of blood vessels and make annotations to relate their structures with functions.

 relate the structure of arteries, capillaries and veins to their functions.

8.2.1.4 Blood, tissue fluid and lymph

 the composition of blood and functions of the following blood cells: red blood cell, blood platelet, phagocytes and lymphocytes.

 Examine prepared slide of mammalian blood smear to study the blood cells.

 relate the composition of blood to its functions.

 the role of blood in the transport of oxygen and carbon dioxide.

 Search for information on the effects of high altitude training for athletes on oxygen carrying capacity of blood.

 state the role of blood.

 oxygen dissociation curves: significance of the Bohr effect.

 Discuss with students the oxygen dissociation curves of different animals.

 interpret the oxygen dissociation curves.

 explain the importance of Bohr effect.

 the formation of tissue fluid and lymph and their return to the blood circulatory system.

 describe the process of tissue fluid and lymph formation.

 the roles of tissue fluid and lymph.  state the roles of tissue fluid and lymph.

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Learning objectives Possible learning and teaching activities Expected learning outcomes

Students should learn Students should be able to

8.2.2 Transport in flowering plants 8.2.2.1 Vascular tissues

 the basic anatomy of vascular tissues in a young root, a young stem, a woody stem and a leaf of dicotyledonous plants.

 Examine the vascular tissues of a young root, a young stem, a woody stem and a leaf of

dicotyledonous plants using temporary mounts or prepared slides.

 Prepare free-hand sections and temporary mounts of stems, and use simple staining techniques where appropriate.

 Make L.P. and H.P. drawings of vascular tissues and cells and make annotations to relate their structures and functions.

 relate the structure of the vascular tissue to transport.

8.2.2.2 Absorption and transport of water and mineral salts

 the absorption and transport of water:

cohesion-tension theory and root pressure.

 Explore students’ prior knowledge on transpiration.

 Investigate the rate and path of water transport using a dye solution.

 describe the cohesion-tension theory and root pressure, and evaluate their relative importance in the transport of water in plants.

 the pathways of water movement: apoplast, symplast and vacuolar.

 describe the pathways of water movement.

 the absorption of mineral salts by diffusion and active transport; the transport of mineral salts in xylem vessels.

 explain how plants absorb water and mineral salts.

 the structure of guard cells and the distribution of stomata.

 Examine prepared slides of leaf epidermis to study the structure of guard cells and the distribution of stomata.

 relate the structure of guard cells to their functions.

 that transpiration creates water potential gradient within the plant.

 state that transpiration creates water potential gradient within the plant.

 describe the movement of water along water potential gradient within the plant.

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Learning objectives Possible learning and teaching activities Expected learning outcomes

Students should learn Students should be able to

 the factors affecting transpiration.  Design and perform an investigation to study the effects of the following on the rate of transpiration:

(1) air current (2) temperature (3) light (4) humidity

 explain how environmental factors affect transpiration.

8.2.2.3 Transport of organic solutes

 the evidence for transport of organic solutes in phloem using radioactive tracer and aphids.

 Read about the experiments using radioactive tracer and aphids to study the translocation of organic solutes.

 point out the need for translocation of organic solutes.

 evaluate the evidences of phloem transport.

 the translocation of organic solutes in phloem between different regions of the plants (e.g.

photosynthetic tissues, storage organs and growth regions).

 an outline of the mass flow hypothesis of phloem transport.

 Read about the pros and cons of the mass flow hypothesis.

 outline the mass flow hypothesis of phloem transport.

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