1. Transport Transport in multicellular plants 5.3.3

2. 5.3.3.1 Explain the need for a transport system in plants Explain what is transported in plants List the components of this system and their Jobs

3. Poster Make an informative A4 poster aimed at GCSE pupils showing – What plants transport and where – The components of the transport system and their specific jobs – Why plants need a dedicated transport system

4. 5.3.3.2 Explain why plants need a transport system Give an overview of the transport of water in plants

5. Why transport? Plant cells need – Carbon dioxide – Oxygen – Organic nutrients – Inorganic ions – water For each requirement state what part of the plant the nutrient will come from and where it transported too.

6. Surface area and the need for transport Very small organisms can absorb all their required nutrients and gasses through their surface The larger the animal the smaller the surface area:volume Therefore the surface is not large enough to provide all the nutrients the organism need They therefore have specific exchange organs with large surface areas and a transport system 1.What are the exhange organs in plants? 2.What is the transport system?

7. Transport of water There are 6 main stages in the transport of water by a plant 1. Water uptake near root tips 2. Water enters xylem 3. Water moves up xylem 4. Water moves from xylem into leaf cells 5. Evaporation of water into leaf air spaces 6. Transpiration of water vapour through open stomata

8. Water potential gradient Water is at its greatest concentration at the roots Therefore the water potential is at its greatest As it travels through the plant it is travelling down its concentration gradient This is passive transport

9. Water enters through the roots The outer layer (epidermis) of root tip cells are drawn out into root hairs This increases the surface area for osmosis to occur over The uptake of water by osmosis produces root pressure which drives the transport

10. Transport through the roots There are two possible pathways 1. Symplast pathway (10%) in which the water travels through the cytoplasm of the cells. The cytoplasms of all cells in the root are connected by plasmodesmata so no further osmosis occurs until the xylem is reached 2. Apoplast pathway (90%) in which water enter the space between the cell wall and cell membrane. Water can diffuse through the open cell walls without entering any cells. However this stops at the endodermis of the cells where there is a water proof strip (casparian strip) and the water has to enter the cells by osmosis and thus the symplast pathway.

12. Looking at slides Look at the slides of the root hairs Save any pictures of good slides Also make labelled diagrams using the guidance given

13. 5.3.3.3 Look at slides of xylem Explain how water is transported from the root to the tips of a plant

14. From the root cells to the xylem Once the water meets the endodermis of the plant the waxy band of suberin in the casparian strip stops the apoplast pathway All the water enters the symplast pathway and passes through passage cells and across the endodermis This allows the plant to control what enters the xylem

15. Xylem tissue These are tubes of dead cells which run from the root to the leaves Water can move at 8m per hour The differential in water potential drives this movement Key processes = osmosis and transpiration

16. Cell types in the xylem (angiosperms) Vessel elements Tracheids Fibres Parenchyma cells

17. Xylem vessels Xylem start off as normal cells They lay down lignin on the outside of the cell This makes the cells water impermeable The cells die leaving only the lignin This is a long hollow tube

18. Tracheids These are also dead cells with lignified walls They do not have open ends so they don’t make vessels They do have pits in their walls so water can pass between them These are the main transport system in primitive plants like ferns and conifers Flowering plants also have them but use mainly vessels

19. Fibres and Parenchyma cells Fibres are elongated cells with lignified walls. They help to support the plant Parenchyma cells are standard plant cells associated with the xylem tissue They may store organic molecules or be involved in gaseous exhange

20. Microscopes View xs of xylem- draw and save

21. 5.3.3.4 Describe the pathway of water from the xylem to the leaf cells Link the structure and function of stomata

22. Movement through leaves At the leaves the xylem branches into leaf veins There is one main vein and side veins branch off this. They deliver water around the leaf

23. Movement through leaves (cont) Water can move from xylem into cells by diffusion It can pass through cells by symplast or apoplast pathways

24. Stomata Water can evaporate from cells into air spaces around stomata (sub- stomatal air space) It can then leave open stomata by diffusion

25. Guard cells open and close stomata Stomata are the openings Guard cells are crescent shaped cells around the opening When turgid the cells make the stomata open When water leaves them the guard cells become flaccid and the opening closes

26. Transpiration drives water transport

27. Looking at cells 1. Look at pre-prepared slides and make detailed drawings 2. Tear a leaf from distilled water solution and carefully pull off the lower epidermis 3. Wet mount and look for the stomata 4. Repeat with a leaf from a strong sugar solution

28. Homework Discuss the importance of stomata to plants with reference to their structure and function.

29. 5.3.3.5 Give examples of the adaptations a plant can have to reduce water loss List and explain the factors affecting the rate of transpiration

30. Adaptations to water availability Plants have to cope with different water availability and develop different adaptations for this Mesophytes- adequate water Halophytes- salty water Hydrophytes- Freshwater Xerophytes- dry environments These plants must limit their water loss

31. Xerophyte adaptations Look at the plants and develop a table showing the adaptation and how it might help the plant AdaptationHow it worksExample thick cuticlestops uncontrolled evaporation through leaf cellsmost dicots small leaf surface arealess area for evaporationconifer needles, cactus spines low stomata densityfewer gaps in leaves stomata on lower surface of leaf onlymore humid air on lower surface, so less evaporation most dicots shedding leaves in dry/cold seasonreduce water loss at certain times of yeardeciduous plants sunken stomatamaintains humid air around stomatamarram grass, pine stomatal hairsmaintains humid air around stomatamarram grass, couch grass folded leavesmaintains humid air around stomatamarram grass, succulent leaves and stemstores watercacti extensive rootsmaximise water uptakecacti

32. Factors affecting transpiration Transpiration is affected by Humidity- High humidity reduces the water potential gradient Light- Light stimulates the stomata to open, allowing gas exchange for photosynthesis. A by product of this is transpiration Temperature- a high temp reduces humidity and increases evaporation rate Air movement- moves evaporated water from the stomata, increasing water potential gradient

33. Potometer Use the potometer to find the effect of light/ wind movement on the rate of transpiration Record all results neatly and write a full conclusion Evaluate in full Use the simulation of the potometer- complete activity 1 and 2. Explain the effect of these factors on transpiration Complete for HWK

34. 5.3.3.5 Draw they structure of phloem and annotate Explain how this is used to transport organic molecules

35. Uses of phloem Sugar is transported in phloem Sugar solution can be up to 30% concentrated Phloem transport is bidirectional- from a source to a sink.

36. Structure of phloem

37. Phloem cells Sieve-cells are cells with narrow pores all around them. Found in primitive plants Sieve tube members have sieve plates on the end walls. Found in angiosperms Companion cells are always found and they control the flow of food though the adjacent sieve cells Phloem must be living to function They are elongated cells

38. Homework Teaching one aspect of phloem in 5 minutes – Loading of sugars – Transport – Unloading – Differences in transport over the seasons – Puncture experiments – Ringing Experiments – Radioactive tracer experiments – Aphid Stylet experiments

39. 5.3.3.8 Compare and contrast the action of phloem and xylem Draw the structure of vascular bundles in different parts of the plant

40. Microscopes Sketch the shape of the vascular bundle in – Roots – Stems – Leaves Clearly label the xylem vessels and sieve elements in each vascular bundle

41. Compare and contrast Using your text book, notes and the laptops produce a large table showing – Similarities – Differences Between xylem vessels and sieve elements Clearly explain the mechanisms and importance within this

42. Homework Essay- ‘Describe the function of xylem and phloem within the vascular bundle of angiosperms. Your answer should make reference to the structure of these elements’ Use this to help you revise for a test next lesson