transport in plants

How is water/small substances transported

• Xylem

  • moves water, hormones, and nutrients

  • Tracheids

  • Vessel elements

  • Holes

• Coming through root hairs → then to vascular tissue (xylem) → up the plant and out of pores (stomata) into the atmosphere

• Bottom → up

• Mycelium absorbed even more water for plant

• Xylem cells are dead, so water can freely move up

• Root hairs

  • surface area expanded

  • Diffusion

How is water taken up by root hairs

Casparian strip: waterproof, corky tissue that is found on the sides and walls of the endodermis

• It directs water through the cytoplasm of endodermal cells

• Produces root pressure

• Helps get water to the xylem

• Symplastic = directly though

  • cell to cell

  • plasmodesmata: allow movement from one cytoplasm to another (protein channels)

• Apoplectic = bound around

  • gets interrupted

Aquaporins: large proteins embedded in the cell membrane

• Osmosis is enhanced by membrane water channels

• Speed up osmosis, but do not change the direction of water movement

• moves water quickly through diffusion or osmosis through the plant

Cavitation

• Blocked vessel

• air bubbles from forces acting upon the liquid

  • rapid change of pressure

  • water can take a detour to fix this

what effects the xylem flow rate

manipulation of solute (not water) concentrations in pits or micropores of vessel elements

Water moves through xylem vessels more quickly. When pits have a higher solute concentration of sap with salts

TACT theory

Force pulling upwards:

T = transpiration

A = Adhesion

C = cohesion

T = tension

Stomata pore

• Guard cells

• Water in vacuole → pore open

• Water not in the vacuole → pore closed

  • Hormone ABA helps close stamata

• Short term water loss

Drop leaves limbs/ sudden drop syndrome

Plant doesnt have enough water to support leaves or branches

• tissues shrink

• adaptation to long term water loss

Water that leaves plant

• Most water that enters the plant leaves the plant

  • local climate

  • tempurature regulation

  • 90% goes to atmosphere

How do larger molecules get transferred in plants

• Phloem

• Starch, sucrose, glucose

• Moves in any direction

• Translocation

  • allows sink areas to grow

  • source to sink

    • Water comes in from the xylem and pushes molecules

    • active transport: uses ATP to move against a concentration gradient

  • tranports nRNA

  • sugars, amino acids

• Phloem is alive

Stomach

• churns

  • mechanical

• Makes chyme

• Pepsin: an enzyme that carries out protein digestion in the stomach

Bile

• Made from liver

• Stored in the gallbladder

• Helps break down lipids/fats

Pancrease

• neutralizes chyme

• Digestive enzymes

• bicarbonate = neutralizes