Campbell Biology 10th edition- Chapter 36
Terms in this set (38)
The movement of substances across a cell membrane without the use of energy by the cell - diffusion
transport of a substance (as a protein or drug) across a cell membrane against the concentration gradient
A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane. Those involved in passive transport do not require energy.
The charge difference between a cell's cytoplasm and the extracellular fluid, due to the differential distribution of ions. It affects the activity of excitable cells and the transmembrane movement of all charged substances.
Use energy from ATP to pump protons out of the cell. This results in a proton gradient with a higher proton concentration outside the cell than inside. The inside of the cell also becomes negative in this process.
Involved in active transport, and co transport
The coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient.
net absorption or loss of water by a cell; diffusion of water
the physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure.
cell that lack water; is soft; causes plants to droop; closed stoma. If placed in higher solute concentration will undergo plasmolysis.
when a cell is in a hypertonic environment, the cell will lose water to its surroundings, shrink, and its plasma membrane will pull away from the wall
Swollen or distended plant cells. (if it has a greater solute concentration than its surroundings, resulting in entry of water.)
The drooping of leaves and stems as a result of plant cells becoming flaccid.
a transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane
apoplastic, symplastic and transmembrane.
3 major pathways of transport
The continuum formed by cell walls, extracellular spaces, and the dead interiors of tracheids and vessels
the continuum of cytoplasm connected by plasmodesmata between cells.
water and solutes move out of one cell, across the cell wall and into the neighboring cell, requires repeated crossings on plasma membranes as substances exit one cell and enter the next
transport of water and solutes through cell walls and extracellular spaces
path of least resistance: travel through cytosol by way of plasmodesmata. Requires only one crossing of a plasma membrane.
when minerals reach the endodermis they continue through the plasmodesmata of endodermal cells and pass into the stele.
The movement of a fluid due to a difference in pressure between two locations. Used for long distance transport through xylem and phloem.
Casparian strip (roots)
A water-impermeable ring of wax in the endodermal cells of plants that blocks the passive flow of water and solutes into the stele by way of cell walls. It forces water and minerals moving through apoplast to cross the plasma membrane of an endodermal cell and enter the stele via the symplast.
The innermost layer of the cortex in plant roots; a cylinder one cell thick that forms the boundary between the cortex and the vascular cylinder. Functions as a last checkpoint for the selective passage of minerals from the cortex into the vascular tissue.
Also prevents solutes that have accumulated in the xylem from leaking back into the soil solution.
The dilute solution of water and dissolved minerals carried through vessels and tracheids.
the emission of water vapor from the leaves of plants
due to root pressure, droplets of water appear in the morning on the leaf tips of some herbaceous leaves
mechanism for long-distance transport up xylem vessels
occurs with in hollow, deadfalls.
moves the entire solution—not just water or solutes—at much greater speed
no solute pressure
no energy used - passive process
accumulation of minerals in the vascular cylinder lowers the water potential there, generating a positive pressure, pushes xylem up
formation of water vapor pocket, that can break the chain of water molecules during transpirational pull.
the main phenomenon driving the flow of water in the xylem tissues of large plants.
It results ultimately from the evaporation of water from the surfaces of cells in the interior of the leaves (negative potential). It depends on water adhesion, cohersion and surface tension.
Light, Co2 depletion, internal clock in guard cells
3 cues that contribute to stomatal opening at dawn
Correlates with active transport of H+ out of the guard cell.
The resulting membrane potential drives K+ into the cell through specific membrane channels.
The absorption of K+ causes the water potential to become more negative within the guard cells, and the cells become more turgid as water enters by osmosis.
a mixture of sugar, nutrients, and water that flows through phloem vessels in a plant
The process by which organic substances (sugars) move through the phloem of a plant - from mature leaves to lower parts of the plant and roots.
positive pressure, always move from source to sink
A plant organ in which sugar is being produced by either photosynthesis or the breakdown of starch. Mature leaves are the primary sugar sources of plants.
loaded by active transport
A plant organ that is a net consumer or storer of sugar. Growing roots, shoot tips, stems, and fruits are examples
requires active transport because sucrose is more concentrated in sieve-tube elements and companion cells than in mesophyll.
for loading only; moved by positive transport
A positive pressure that drives the bulk flow of phloem sap through a sieve tube. When nutrients are pumped into or removed from the phloem system, the change in concentration causes a movement of fluid in that same direction.
In this way, phloem is able to move nutrients in either direction to meet the nutritional needs of the plant.
xylem is usually unidirectional while phleom is not
xylem vs phloem
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