36 Chapter Flashcards
Phyllotaxy
The arrangement of leaves on a stem.
-Determined by the shoot apical meristem
Alternate phyllotaxy/ spiral phyllotaxy
One leaf per node
Opposite phyllotaxy
Two leaves per node
Whorled phyllotaxy
More than two leaves per node
Self-pruning
Programmed cell death and eventual shedding
In low light conditions, horizontal leaves capture sunlight much more effectively than vertical leaves. In sunny regions, horizontal leaves may be damaged from overly intense light, while vertical leaves are not and light penetrates more deeply to lower leaves.
True
Leaf area index
The ratio of the total area of the tip surfaces of the leaves to the area of ground covered by the plant.
Mycorrhizae
Mutualistic associations between roots and fungi.
Two major pathways of transport:
Apoplast
Symplast
Apoplast
Consists of everything external to the plasma membrane of living cells and includes cell walls, extracellular spaces, and the interior of dead cells such as vessel elements and tracheids.
Symplast
Consists of the entire mass of cytosol of all the living cells in a plant, as well as the plasmodesmata, the cytoplasmic channels that interconnect them.
Three routes for transport within a plant tissue or organ:
The apoplastic route
Symplastic route
Transmembrane routes
Apoplastic route
Water and solutes move along the continuum of cell walls and extracellular spaces.
Symplastic route
Water and solutes move along the continuum of cytosol.
Transmembrane route
Water and solutes move out of one cell, across the cell wall, and into the neighboring cell, which may pass them to the next cell in the same way.
Water potential
The physical property that predicts the direction in which water will flow.
-A quantity that includes the effects of solute concentration and physical pressure.
If a plant or seed is immersed in a solution that has a higher water potential, water will…
Move into the cell or seed
ψ
Water potential.
Greek letter pronounced “sigh” (psi)
Plant biologists measure water potential in a unit of pressure called a __________
Megapascal
The ψ of pure water in a container open to the atmosphere under standard conditions is 0 MPa.
True
One MPa is equal to about 10 times atmospheric pressure at sea level.
True
Water potential equation
ψ = ψsubS + ψsubP
Solute potential (osmotic potential)
ψsubS
Pressure potential
ψsubP
The solute potential of a solution is directly proportional to its molarity.
True