1. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Chapter 32 Plant Nutrition and Transport

2. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Plants That Clean Up Poisons Dr. Lena Ma studies certain species of ferns –That are able to absorb and thrive on the poison arsenic

3. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The ferns and other plants are being used in phytoremediation –The use of plants to help clean up polluted soil and groundwater Sunflower plants absorbing radioactive metals from a contaminated pond.

4. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings THE UPTAKE AND TRANSPORT OF PLANT NUTRIENTS 32.1 Plants acquire their nutrients from soil and air As a plant grows –Its roots absorb water, minerals, and some O 2 from the soil –Its leaves absorb CO 2 from the air Figure 32.1A Minerals CO 2 O 2 H O 2

5. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Plants use the sugars made by photosynthesis –To construct all the organic materials they need, including the cellulose in the trunks of trees Figure 32.1B

6. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 32.2 The plasma membranes of root cells control solute uptake Root hairs –Greatly increase a root’s absorptive surface Figure 32.2A

7. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Water and solutes can move through the root’s epidermis and cortex –By going either through the cells or between them Figure 32.2B Key Dermal tissue system Ground tissue system Vascular tissue system Root hair Epidermis CortexPhloem Xylem Endodermis Root hair Xylem Epidermis Endodermis Casparian strip Casparian strip Extracellular route, via cell walls; stopped by Casparian strip Intracellular route, via cell interiors, through plasmodesmata Plasmodesmata Cortex

8. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings However, all water and solutes –Must pass through the selectively permeable plasma membranes of cells of the endodermis to enter the xylem for transport upward

9. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 32.3 Transpiration pulls water up xylem vessels Transpiration can move xylem sap –Which consists of water and dissolved organic nutrients, to the top of the tallest tree Figure 32.3 Root hair Flow of water Soil particle Water Water uptake from soil Adhesion Cell wall Cohesion, by hydrogen bonding Xylem cells Cohesion and adhesion in the xylem Xylem sap Mesophyll cells Air space within leaf Stoma Outside air Transpiration Water molecule

10. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 32.4 Guard cells control transpiration The leaf stomata of plants, which can open and close –Are adaptations that help plants regulate their water content and adjust to changing environmental conditions

11. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings A pair of guard cells –Flank each stoma Figure 32.4 H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O K+K+ Stoma Guard cells Stoma opening Stoma closing Vacuole

12. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 32.5 Phloem transports sugars Phloem contains food-conducting cells –That aid in the transport of phloem sap Figure 32.5A Sieve- tube member Sieve plate TEM 2,700 

13. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Low water pressure High sugar concentration High water pressure SUGAR SOURCE PHLOEMXYLEM Sugar Water Source cell Sieve plate Sugar Water Sink cell SUGAR SINK Low sugar concentration Low water pressure Phloem transports food molecules made by photosynthesis –By a pressure flow mechanism Figure 32.5B 1 2 3 4

14. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings At a sugar source –Sugar is loaded into a phloem tube The sugar raises the solute concentration in the tube –And water follows, raising the pressure in the tube

15. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The increase in pressure at the sugar source and the decrease at the sugar sink –Cause phloem sap to flow from source to sink

16. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Aphids, which feed on phloem sap –Have allowed plant biologists to study the contents of the sap and its flow Figure 32.5C Honeydew droplet Stylet of aphid Aphid feeding on a small branchAphid’s stylet inserted into a phloem cellSevered stylet dripping phloem sap LM 760 

17. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PLANT NUTRIENTS AND THE SOIL 32.6 Plant health depends on a complete diet of essential inorganic nutrients Plants must obtain usable sources –Of the chemical elements it requires, “nutrients,” from its surroundings

18. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings If any nutrient is not available –Normal growth may not occur Figure 32.6 Complete solution containing all minerals (control) Solution lacking potassium (experimental)

19. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Macronutrients, such as carbon and nitrogen –Are needed in large amounts, mostly to build organic molecules Micronutrients, including iron and zinc –Act mainly as cofactors of enzymes

20. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 32.7 You can diagnose some nutrient deficiencies in your own plants Stunting, wilting, and color changes –Indicate nutrient deficiencies Figure 32.7A Figure 32.7B Figure 32.7C Figure 32.7E Figure 32.7D

21. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 32.8 Fertile soil supports plant growth Fertile soil contains a mixture of small rock and clay particles –That hold water and ions and also allow O 2 to diffuse into plant roots

22. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Soil can consist of different layers –Or horizons The topsoil usually contains humus, decaying organic material –Which provides nutrients and supports the growth of organisms that enhance soil fertility Figure 32.8A

23. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings A plant’s root hairs –Are closely associated with the soil Soil particle surrounded by film of water Root hair Water Air space Figure 32.8B

24. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Cations, positively charged ions –Adhere to soil particles In cation exchange, root hairs release H + ions –Which displace cations from the soil particles, allowing the root hairs to absorb them Figure 32.8C Clay particle Root hair H+H+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+

25. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Anions, negatively charged ions –Are readily available to plants because they are not bound to soil particles –Tend to drain out of the soil rapidly

26. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 32.9 Soil conservation is essential to human life Aspects of good soil management include –Water-conserving irrigation, erosion control, and the prudent use of herbicides and fertilizers Figure 32.9A Figure 32.9B

27. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 32.10 Organic farmers must follow ecological principles Organic farmers –Are certified to follow ecologically sound practices Figure 32.10

28. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 32.11 Agricultural research is improving the yields and nutritional values of crops Through traditional plant breeding and DNA technologies –Researchers are developing new varieties of plants with improved yields and nutritional value Figure 32.11

29. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PLANT NUTRITION AND SYMBIOSIS 32.12 Fungi help most plants absorb nutrients from the soil Relationships with other organisms –Help plants obtain nutrients

30. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Many plants form mycorrhizae –Mutually beneficial associations with fungi SEM 158  Figure 32.12

31. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings A network of fungal threads –Increases a plant’s absorption of nutrients and water, and the fungus receives some nutrients from the plant

32. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 32.13 Most plants depend on bacteria to supply nitrogen Bacteria in the soil carry out nitrogen fixation –Converting atmospheric N 2 to forms that can be used by plants N2N2 N2N2 Soil H+H+ Organic material Nitrogen-fixing bacteria Ammonifying bacteria NH 3 NH 4 + (ammonium) Nitrifying bacteria NO 3 – (nitrate) Root NH 4 + Amino acids, etc. ATMOSPHERE Figure 32.13

33. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 32.14 Legumes and certain other plants house nitrogen-fixing bacteria Legumes and certain other plants –Have nodules in their roots that house nitrogen-fixing bacteria Shoot Nodules Roots Bacteria within vesicle TEM 5,850  Figure 32.14AFigure 32.14B

34. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 32.15 The plant kingdom includes parasites and carnivores Parasitic and carnivorous plants –Obtain nutrients such as nitrogen from hosts or by eating insects Figure 32.15AFigure 32.15B Figure 32.15CFigure 32.15D