This chapter discusses resource acquisition and transport in vascular plants. It covers plant nutritional requirements, mutualistic relationships with bacteria and fungi, and unusual adaptations in epiphytic, parasitic, and carnivorous plants. The chapter also describes the vascular tissues of xylem and phloem that transport water, minerals and sugars. Water and solutes move through plant tissues via apoplastic and symplastic pathways. Transport processes like osmosis, proton pumps, and aquaporins control water movement. The cohesion-tension model explains how transpiration drives long-distance water transport. Stomata regulate transpiration and gas exchange. Sugar is transported from sources to sinks through the phloem via pressure flow and active transport

1. Chapter 29
Resource Acquisition, Nutrition, and Transport in
Vascular Plants

2. Plant Nutrition

3. Adaptations for Acquiring Resources
 Shoots = capture light efficiently
 Roots = acquire water and minerals

4. Nutritional Requirements
Essential element: required for plant to
complete life cycle and produce another
generation
 Macronutrients (large amounts): CHNOPS +
K, Ca, Mg
◦ Nitrogen = most important!
 Micronutrients (small amounts): Fe, Mn, Zn,
Cu, etc.

6. Mutualistic Relationships:
1. Rhizobium bacteria supply nitrogen at roots
(fix atmospheric N2 to usable N)
• Plant supplies sugar & amino acids
2. Mycorrhizae (plant + fungus)

7. Role of soil bacteria in the nitrogen
nutrition of plants

8. Unusual nutritional adaptations:
epiphytes, parasitic plants, canivorous
plants
Epiphyte: grow on
surface of another
plant, absorb H2O from
rain through leaves

9. Parasitic Plants: not photosynthetic; absorb
sugar and minerals from living hosts

10. Carnivorous Plants: photosynthetic, but obtain
some nitrogen and minerals by digesting small
animals; found in nitrogen-poor soil

11. Transport Processes

12. Vascular Tissues: conduct molecules
Xylem Phloem
Nonliving functional Living functional
Xylem sap = H2O &
minerals
Phloem sap = sucrose,
minerals, amino acids,
hormones
Source to sink
(sugar made) to (sugar
consumed/stored)

13. Transport pathways in plant tissues:
 Apoplast = materials travel between cells
 Symplast = materials cross cell membrane, move
through cytosol & plasmodesmata

14. TRANSPORT OF WATER

15.  Selectively permeable membrane: control
movement of substances in/out of cells
 Osmosis: passive transport of water
 Proton pump: active transport; uses E to
pump H+ out of cell → proton gradient
 Cotransport: couple H+ diffusion with
sucrose transport
 Aquaporin: channel protein which
controls H2O uptake/loss
Review:

16. Solute transport
across plant cell
plasma membranes

17. Osmosis
 **Water potential (ψ): H2O moves from high ψ →
low ψ potential, solute conc. & pressure
◦ Water potential equation: ψ = ψS + ψP
◦ Solute potential (ψS) – osmotic potential
◦ Pressure potential (ψP) – physical pressure on
solution
◦ Pure water: ψS = 0 Mpa
◦ Ψ is always negative!
◦ Turgor pressure = force on cell wall
 Bulk flow: move H2O in plant from regions of high
pressure → low pressure
** Review AP Bio Investigation 4 (Osmosis & Diffusion)

18.  Turgid: firm (healthy plant)
 Flaccid: limp (wilting)
 Plasmolysis: cell membrane shrinks & pulls
away from cell wall due to H2O loss; kills
most plant cells
Turgid Plant Cell Plasmolysis

20. Plant roots absorb essential elements
from soil
 Root hairs: increase surface area of
absorption at root tips
 Mycorrhizae: symbiotic relationship
between fungus + roots
◦ Increase H2O/mineral absorption
The white mycelium of the fungus ensheathes these roots of a pine tree.

21. Transport of H2O and minerals into xylem:
Root epidermis → cortex → [Casparian Strip] →
vascular cylinder → xylem tissue → shoot system

22. Casparian strip controls entry into
vascular cylinder

23. How does material move vertically (against gravity)?
Transpiration: loss of H2O via
evaporation from leaves into air
Cohesion-tension hypothesis:
◦ Transpiration provides pull
◦ Cohesion of H2O transmits
pull from roots → shoots
◦ Adhesion of H2O to xylem
walls (fight gravity)
◦ Negative pressure of xylem
sap (tension)

25. Stomata regulate rate of transpiration
 Stomata – pores in epidermis of leaves/stems, allow gas
exchange (CO2 in, O2 out) and transpiration (H2O out)
 Guard cells – open/close stoma by changing shape
◦ Take up K+ → lowers ψ → take up H2O → pore opens
◦ Lose K+ → lose H2O → cells less bowed → pore closes

26.  Cells stimulated to open by: light, loss of CO2 in
leaf, circadian rhythms
 Stomata closure: drought, high temperature,
wind

27. BIOFLIX:WATERTRANSPORT
IN PLANTS

28. TRANSPORT OF SUGAR

29. Sugar Transport
 Translocation: transport of sugars into phloem
by pressure flow
 Source → Sink
◦ Source = produce sugar (leaf photosynthesis)
◦ Sink = consume/store sugar (fruit, roots)
 Via sieve-tube elements
 Active transport of sucrose

30. Bulk flow by
positive pressure
flow in a sieve
tube
(active transport)

31. Material movement via
symplast is dynamic
 Plasmodesmata allows movement of RNA &
proteins between cells
 Phloem can carry rapid, long-distance electrical
signaling
◦ Nerve-like function
◦ Swift communication
◦ Changes in gene expression, respiration,
photosynthesis