What is short-distance movement?
Movement of water at the cellular level plays a major role in bulk water transport. Water can diffuse through cell membranes. However, ions and organic compounds rely on membrane-bound transporters. These are active or passive mechanisms.
What are long-distance movement?
Some "pushing" from pressure of water entering roots is involved. However, most of the force is "pulling." This is caused by transpiration.
What will happen if a plant is placed in a solution with high water potential (low osmotic concentration)?
Cell will become swollen or turgid
What will happen if a plant is placed in a solution with low water potential (high osmotic concentration)?
Cell will exhibit shrinkage or plasmolysis
When a cell is placed in pure water, water will do what?
Move into the cell because water potential of cell is relatively negative
When a cell is placed in a solution with a different solute potential, what will happen to the water?
It will move in the direction that eventually result in equilibrium.
What are the signs for ...
See slides 8 and 10
What are aquaporins and what do they do?
Water channels in vacuole and cell membranes that speed up osmosis without changing direction of water movement
Water will move from _____ into ______ if soil's water potential is greater. It will then move along gradients of successively more negative water potentials in _______, _______, and _____.
stems; leaves; air
What are the purposes of root hairs?
They collectively provide enormous surface area and almost always turgid because water potential is greater than that of soil.
What are the three transport routes that exist through cells?
This route is membrane transport between cells and accross membranes of vacuoles within cells
Eventually on their journey inward, ______ reach the endodermis. Any further passage through the cell walls is blocked by the ________. Molecules must pass through ________ and ________ cells to reach xylem.
cell membranes and protoplasts of endodermal cells
Root pressure is caused by what?
Continous accumulation of ions in roots. This causes water to move into plan and up the xylem, even without transpiration.
Root pressure alone, however, is insufficient to explain xylem transport. ______ provides main force.
______ of a water column varies inversely with diameter. This is because tracheids and vessels have strong cohesive water forces due to small diameter.
Air bubbles can expand and block the tracheid or vessel, causing an _______ or ________. Damage can be minimized by anatomical adaptations.
embolism or cavitation
________ are relocated through xylem from roots to active parts of the plant. What are some examples?
Minerals; phosphorus, potassium, nitrogen, iron, and calcium
Closing ______ can control water loss on a short-term basis. However, ________ open to allow CO2 entry.
_______ cells have thicker inner cell walls and thinner outer cell walls. This causes them to bulge and bow outward when turgid, which opens the stomata.
Turgor in guard cells results from active uptake of _______, _________, and _________.
potassium, chloride, and malate
Transpiration rates and evaporation rates increase with ________ and ________ velocity.
temperature and wind
_______ initiates signaling pathway to close stomata in drought stress. This opens the potassium, chloride, and malate channels and water lose follows.
Abscisic acid (ABA)
Examples of morphological adaptations
dormancy; loss of leaves; covering leaves with cuticle and wooly trichomes; reducing number of stomata; stomata recessed in pits on leaf surface
Plants in fresh water....
form aerenchyma, loose parenchymal tissue with large air spaces. collect oxygen and transport 02 to submerged parts
What are pneumatophores?
Spongy, air-filled roots, that emerge above mud. Have large lenticels for oxygen entrance. They also secret large quantities of salt
Plants called ______ live in saline soils. They produce high concentrations of organic molecules in roots. This decreases water potential enhancing water uptake from soil.
______, _______, and _____ are transported up and down phloem (bi directional transport).
Sucrose, Hormones, and mRNA