Think about… 9.1 Nutrition in plants 9.2 Gas exchange in plants Recall ‘Think about…’

2. Think about… 9.1 Nutrition in plants 9.2 Gas exchange in plants Recall ‘Think about…’ Summary concept map

3. Fake aquatic plants Some terrestrial plants are sold as ‘aquatic plants’ …

4. Fake aquatic plants If they are put under water, they will die very soon.

5. 1 What is the importance of plants to the environment and other organisms

6. 2 Why will the terrestrial plants die soon after they are put under water

7. 3 How can we distinguish between aquatic plants and terrestrial plants

8. 9.1 Nutrition in plants Amoeba: phagocytosis humans: eating

9. 9.1 Nutrition in plants Different organisms have different modes of nutrition (營養方式) Amoeba: phagocytosis humans: eating

10. 9.1 Nutrition in plants How about plants? How do they obtain their food?

11. 9.1 Nutrition in plants CO2 O2 light (by-product) chlorophyll carbohydrates water

12. 9.1 Nutrition in plants CO2 O2 light (by-product) photosynthesis (光合作用) chlorophyll carbohydrates water

13. 9.1 Nutrition in plants Process of photosynthesis: carbon dioxide + water light energy chlorophyll carbohydrates + oxygen

14. 9.1 Nutrition in plants carbohydrates

15. 9.1 Nutrition in plants carbohydrates lipids proteins plant materials minerals (礦物質)

16. 9.1 Nutrition in plants carbon dioxide + water inorganic autotroph carries out autotrophic nutrition plant organic carbohydrates

17. 9.1 Nutrition in plants Significance of plants as autotrophs

18. 9.1 Nutrition in plants Significance of plants as autotrophs energy from the sun eaten by cows used by plants to make food eaten by humans

19. 9.1 Nutrition in plants Significance of plants as autotrophs plants • act as producers (生產者) • serve as basic food source

20. 9.1 Nutrition in plants Importance of minerals major elements(大量元素) Mineral ions required by plants minor elements(微量元素)

21. 9.1 Nutrition in plants Importance of minerals • required in relatively large amount • e.g. N, P, K, Mg major elements(大量元素) • required in very small amount • e.g. Cu, Zn, Co minor elements(微量元素)

22. 9.1 Nutrition in plants Importance of minerals insufficient minerals deficiency diseases (營養缺乏病)

23. 9.1 Nutrition in plants Importance of minerals Nitrogen (N) NO3- NH4+ Synthesis of proteins • Poor growth • Yellow leaves

24. 9.1 Nutrition in plants Importance of minerals Phosphorus (P) PO43- • Synthesis of DNA, proteins • For enzymatic reactions • Poor root growth • Purple patches on leaves

25. 9.1 Nutrition in plants Importance of minerals Potassium (K) K+ • Poor growth • Curled-up leaves with dark-coloured edges • Promotes photosynthesis,transport • For enzymatic reactions

26. 9.1 Nutrition in plants Importance of minerals Magnesium (Mg) Mg2+ Synthesis of chlorophyll • Poor growth • Yellow leaves

27. 9.1 Nutrition in plants 9.1 Simulation Investigation of the effects of different minerals on plant growth 1 Prepare 5 conical flasks with different nutrient solutions as shown. Wrap aluminium foil around each flask to prevent any algal growth.

28. 9.1 Nutrition in plants 9.1

29. 9.1 Nutrition in plants 9.1 2 Observe the appearance of the seedlings. Put the flasks in bright light. Refill with fresh nutrient solutions every week. Observe the seedlings again after 2 weeks.

30. 9.1 Nutrition in plants 9.1 Results and discussion Except for those in flask A, all seedlings show poor growth. The result shows that the deficiency of any essential mineral will lead to poor growth in the seedlings.

31. 9.1 Nutrition in plants How are water and minerals absorbed in plants?

32. 9.1 Nutrition in plants mainly by roots

33. 9.1 Nutrition in plants Structure of the root 3D animation root cap (根冠) • protects the tip of the root

34. 9.1 Nutrition in plants Structure of the root epidermis (表皮) • one layer of thin-walled cells • with root hairs • protects the inner tissues

35. 9.1 Nutrition in plants Structure of the root root hair (根毛) • developed from epidermal cells • provides large surface area for absorption

36. 9.1 Nutrition in plants Structure of the root cortex (皮層) • several layers of thin-walled cells • stores food • allows passage of water and minerals

37. 9.1 Nutrition in plants Structure of the root phloem (韌皮部) • transports food xylem (木質部) • transports water and minerals vascular bundle (維管束)

38. 9.1 Nutrition in plants Structure of the root root hair epidermis root cap

39. 9.1 Nutrition in plants Structure of the root

40. 9.1 Nutrition in plants Structure of the root epidermis cortex phloem xylem

41. 9.1 Nutrition in plants Structure of the root Adaptive features 1 Thin epidermis • one layer of thin-walled cells • not covered by cuticle • water and minerals can easily pass through

42. 9.1 Nutrition in plants Structure of the root Adaptive features 2 Numerous root branches and root hairs • provide large surface area for absorption

43. 9.1 Nutrition in plants Structure of the root Adaptive features 3 Long and fine root hairs • easily grow between soil particles to absorb water and minerals

44. 9.1 Nutrition in plants Absorption of water and minerals only occurs in roots. 

45. 9.1 Nutrition in plants Absorption of water and minerals can occur through any part of a plant which is not covered by cuticle.

46. 9.1 Nutrition in plants 9.2 Examination of the structure of roots 1 Examine the external structure of the root of a young seedling with a hand lens. Draw a labelled diagram of the root.

47. 9.1 Nutrition in plants 9.2 2 Examine a prepared slide of the transverse secion of the root with a microscope.

48. 9.1 Nutrition in plants 9.2 3 Identify the internal structure of the root. Draw a labelled low-power diagram.

49. 9.1 Nutrition in plants Absorption of water in roots Animation

50. 9.1 Nutrition in plants Absorption of water in roots root hair epidermis xylem vessel soil particle cortex water in soil