Plant Transportation

What is transport?

how an organism distributes vital substances (water, nutrients gases, hormones) to their various cells and also removes waste

What are plant transport mechanisms?

transpiration, aquaporins, and water potential

What is transpiration?

water moves from roots upwards through the xylem

How does water move up the roots?

water evaporating

How does transportation happen between cells?

plasmodesmata - microscopic channels between cell walls of plant cells, allows for transport and communication

What do aquaporins do?

speed up water movement, but do not change its direction

What does water potential do through the plant?

determines which way water will move

Water potential moves water from areas with higher potential to areas with lower potential. T/F

True

What is water potential?

prediction in which direction water will move

What is turgor?

cell placed in hypotonic solution (low concentration) water enters making the cell expand (swollen)

What is plasmolysis?

cell placed into hyper tonic solution (high concentration) water leaves and the cell shrinks

Flaccid (isotonic solution)

water starting to leave the cell

What does root transport do?

moves water and minerals from the roots into endodermis

What is apoplast (water route)?

movement through the cell walls and space between cells

What is transmembrane (water route)?

membrane transport between cells and across vacuole membranes within cells (allows greatest control of which substances move)

What is symplast (water route)?

movement follows the continuum of cytoplasm between the cells connected by the plasmodesmata

What is the endodermis?

innermost layer of the cortex in land plants

What blocks entry into the endoermis?

casparian strips, the endodermis have connecting walls that are waterproofed with suberin

What are xylem and phloem?

complex conducting tissue found in tracheophytes (typically occur together in vascular bundles)

What does the xylem do?

transports water and minerals from roots upwards, outer walls reinforced with lignin (not living)

What are tracheids in xylems?

dead cells that taper at the ends and overlap one another, with pits that allow water movement

what are vessels in xylems?

continuous tubes formed from dead, hollow, cylindrical cells arranged end to end, tend to be shorter and wider

What is root pressure?

Water movement into xylem is facilitated by root pressure

how does root pressure happen?

continuous accumulation of ions in the roots creating negative water potential (pump in minerals creates potential to bring in water)

What is extreme root pressure?

root pressure strong enough to push water out of cut stem for hours or days, can force water up to leaves

What is cavitation?

the blockage of vessels by an air bubble

What does anatomical adaptation do to help against cavitation?

creates alternative pathways

What is mineral transport?

bulk transport of minerals in tracheid and vessels

Where do minerals move to?

from roots to active parts of plant

what is translocation (phloem)?

distribution of carbohydrates made in the green parts to the rest of the plant

What does the phloem also transport?

hormones, mRNA, and other molecules

What does the phloem do?

moves organic molecules up and down plant

what are the two major cell types apart of the phloem?

sieve tube elements and companion cells

What are the sieve tube elements?

sap movement mediated by xylem pressure, separated by sieve cross-walls

what does the companion cell do?

support, help with loading and unloading, carries out metabolic funcations

What is the pressure-flow hypothesis?

dissolved carbohydrates move from source to sink via sieve tubes, phloem loading and unloading is active and requires energy

What are stomata (guard cells)?

2 sausage-shaped guard cells that control the stomata opening,

What happens to stomata cell when turgid?

they bow out and create an opening

What causes transpiration rate to increase?

increased temperature and wind velocity

what causes stomata to close?

insufficient water, high CO2 concentrations, temperatures above 34C

What is the responses to droughts?

stomata - pits, seasonal dormancy - lost of leaves, leaf morphology - thick, hard with few stomata

What is the responses to flooding?

lowers oxygen availability - decreases cellular respiration, limits ATP production, interferes with transport, forming larger lenticels and adventitious roots

What are lenticels?

spongy lens-shaped pore for gas exchange

What are adventitious roots?

non root tissue produced in response to stress

Where are stomata on freshwater flowering plants?

on surface of leaves

What are aerenchyma?

loose parenchymal tissue with large air spaces in it (common in water lilies and other aquatic plants)

What does aerenchyma do?

transport oxygen from parts of plant above the water to those below

What do saltwater flowering plants do to get oxygen?

by controlling salt balance by secreting excess salts and blocking uptake

How much of the worlds cultivated land has high saline levels?

23%

What type of plants can handle soil with high salt concentrations?

halophytes

What are pneumatophores?

plants that grow in swamps and other wet places, that extends above water to facilitate oxygen uptake to the roots below