PowerLecture: Chapter 30

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1 PowerLecture: Chapter 30
Plant Nutrition And Transport

2 Carnivorous Plants Fig a, p.523

3 Carnivorous Plants Fig b, p.523

4 base of epidermal hairlike trigger
epidermal gland Fig c, p.523

5 Carnivorous Plants Fig d, p.523

6

7 Soil - Minerals and Humus Optimal Soil - Loam
equal proportions of sand, silt, and clay 10 to 20 percent humus

8 Humus - charged organic acids help humus attract + charged minerals
organic material - charged organic acids help humus attract + charged minerals Absorbs water - swells; releases water - shrinks Helps to aerate soil

9

10 Soil Horizons See next slide

11 O HORIZON Fallen leaves and other organic material littering the surface of mineral soil A HORIZON Topsoil, with decomposed organic material; variably deep (only a few centimeters in deserts, elsewhere extending as far as thirty centimeters below the soil surface) B HORIZON Compared with A horizon, larger soil particles, not much organic material, more minerals; extends thirty to sixty centimeters below soil surface C HORIZON No organic material, but partially weathered fragments and grains of rock from which soil forms; extends to underlying bedrock BEDROCK Fig. 30-2, p.513

12 Soil Horizons O Horizon - top organic layer leaf litter and humus
A Horizon - Topsoil; humus mixed with mineral particles. E Horizon - eluviation (leaching) layer light in color mostly sand and silt lost most minerals and clay to eluviation.

13 Soil Horizons B Horizon - subsoil -
clay and mineral deposits received from layers above C Horizon - regolith: broken bedrock Plant roots do not penetrate very little organic material R Horizon - bedrock layer

14 Macronutrients Mineral elements required above 0.5 percent of plant’s dry weight Carbon Nitrogen Magnesium Hydrogen Potassium Phosphorus Oxygen Calcium Sulfur

15 Micronutrients Plant requires trace amounts Chlorine Zinc Iron Copper
Boron Molybdenum Manganese

16 Leaching Removal of nutrients from soil by water
Most pronounced in sandy soils Clays hold nutrients better

17 Leaching Fig. 30-3a, p.513

18 Fig. 30-3b, p.513

19 Casparian Strip Forces water and solutes to flow through cells
exodermis root hair Forces water and solutes to flow through cells Transport proteins control flow epidermis forming vascular cylinder cortex Casparian strip Figure 30.6.a   Page 515

20 endodermal cells with Casparian strip
vascular cylinder endodermal cells with Casparian strip In root cortex, water molecules move around cell walls and through them (arrows) Casparian strip Fig. 30-6c, p.515

21 wall of one endodermal cell facing root cortex
the only way that water (arrow) moves into vascular cylinder Waxy, water-impervious Casparian strip (gold) in abutting walls of endodermal cells that control water and nutrient uptake Fig. 30-6d, p.515

22 Root Nodules Swelling on some plant roots containing nitrogen-fixing bacteria Example - legumes infection thread root hair

23 ROOT NODULES infected plant cells w bacteria is becoming a root nodule.
b Fully formed root nodule of a soybean plant Fig. 30-4a, b, p.514

24 Fig. 30-4c, p.514

25 Root Hairs Fig. 30-5a, p.514

26 root hair root epidermal cells Fig. 30-5b, p.514

27 Water Use Evaporation from plant is transpiration (aka Evapotranspiration)

28 Cohesion-Tension Theory of Water Transport
Transpiration creates negative tensions in xylem (leaves to roots) Hydrogen-bonded water column pulled upward

29 Transpiration Drives Water Transport
Water evaporates from leaves through stomata This creates a tension in water column in xylem Figure 30.8.a,b Page 517

30 Replacement Water Drawn in through Roots
Figure 30.8.c Page 517 

31 Fig. 30-8a1, p.517

32 mesophyll (photosynthetic cells)
vein upper epidermis Transpiration is the evaporation of water molecules from aboveground plant parts, especially at stomata. The process puts the water in xylem in a state of tension that extends from roots to leaves. stoma The driving force of evaporation in air Fig. 30-8a2, p.517

33 Cohesion in root, stem, leaf xylem Plus water uptake in growth regions
vascular cambium xylem phloem The collective strength of hydrogen bonds among water molecules, which are confined within the narrow water- conducting tubes in xylem, imparts cohesion to water. Hence the narrow columns of water in xylem can resist rupturing under the continuous tension. Cohesion in root, stem, leaf xylem Plus water uptake in growth regions Fig. 30-8b, p.517

34 water molecule root hair cell
vascular cylinder root hair cell endodermis cortex For as long as water molecules continue to escape by transpiration, that tension will drive the uptake of replacements from soil water. Ongoing water uptake at roots Fig. 30-8c, p.517

35 Cuticle Wax, pectin, cellulose embedded in cutin
Secreted by epidermal cells

36 cuticle (gold) on upper epidermis stoma
cuticle on lower epidermis stoma Fig , p.518

37 Stomata Openings across cuticle and epidermis
Turgor pressure in guard cells opens and closes stomata

38 guard cell guard cell stoma Fig a, p.519

39 chloroplast (guard cells are the only epidermal cells that have these
organelles) 20 µm Fig b, p.519

40 Closing Stomata ABA binds to receptors on guard cell membranes
Calcium ions flow into cells Chloride, malate, and Potassium ions flow out Water moves out

41 ABA signal K+ K+ Ca++ Ca++ malate malate a Stoma is open;
water has moved in. b Stoma is closed; water has moved out. Fig , p.519

42 Transportable Organic Compounds
Cells break starches, proteins, and fats down to smaller molecules for transport Sucrose is main carbohydrate transported

43 Transport through Phloem
sieve plate companion cell sieve-tube member Driven by pressure gradients Companion cells supply energy to start process

44 Translocation Fluid pressure - greatest at a source
Solute-rich fluid flows from high-pressure region toward lower pressure regions section from a stem