Transport of Water and Solutes in Plants Flashcards
The membrane that encloses and defines all cells as separate from their environment
plasma membrane
consists of a lipid bilayer that is semipermeable
cell membrane or plasma membrane
characterizes the plasma membrane consisting of a double
layer or bilayer, of lipid molecules,
cholesterol and proteins
fluid mosaic model
A number of proteins are
embedded in the lipid bilayer in a
way that resembles a
mosaic pattern
The membrane structure is ___ rather than motionless,
and the lipids move ___ within the membrane.
fluid ; laterally
The phosphate end of the phospholipid molecule is
polar
the fatty acid chains are
nonpolar
polar “head” is
hydrophilic
nonpolar “tail” is
hydrophobic
plasma membrane is choosy about what substances can pass through it, it’s said to be
selectively permeable or semipermeable
ease with which substances can pass through a border
permeability
most substances can easily pass through
permeable
substances can’t pass through
impermeable
pupose of membrane’s regulation of the passage of materials
maintain homeostasis
requires no energy on the part of the cell
passive transport
The molecules are moving from where they’re __ to where they’re
___.
more concentrated ; less concentrated
Movement of molecules from a region of higher concentration to a region of lower concentration
diffusion
it is the only means for gaseous movement within the plant’s body
diffusion
The molecules in a gas, a liquid or a solid are in constant motion due to
their
kinetic energy
random movement of molecules due to kinetic energy
Brownian motion
Unequal distribution of molecules
concentration gradient
Once the molecules become uniformly distributed, ___ ___ exists.
dynamic equilibrium
The greater the difference in concentration, the more rapid the diffusion. The closer the distribution of the material gets to equilibrium, the slower the diffusion rate.
extent of the conentration gradient
Heavier molecules move more slowly; therefore, they diffuse more slowly. The reverse is true for lighter molecules.
mass of the olecules diffusing
As the density of a solvent increases, the diffusion rate decreases. The molecules slow down because they have a more difficult time passing through the denser medium.
solvent density
nonpolar or lipid-soluble materials pass through plasma membranes more easily than polar materials, allowing a faster diffusion rate.
solubility
Increased surface area increases the diffusion rate; whereas, a thicker membrane reduces it.
Surface area and plasma membrane thickness
The greater the distance that a substance must travel, the slower the diffusion rate. This places an upper limitation on cell size.
distance travelled
Diffusion of water across a semi-permeable membrane.
osmosis
Movement of water from region of high concentration to a region of
low concentration down a concentration gradient.
osmosis
The method plants use to draw water from the soil into the xylem cells in their roots
osmosis
The molecules diffuse through the membrane with the help of transport proteins (carrier proteins).
Facilitated diffusion
act like pores that allow water to diffuse across the membrane at a very fast rate
aquaporins
Uses energy usually in the form of ATP to pump molecules against the concentration gradient.
active transport
2 types of transport
passive transport
active transport
Types of passive transport
diffusion
osmosis
facilitated diffusion
In active transport movable carrier proteins are called
pumps
root hairs of plants allows plants to absorb mineral ions, which are necessary for healthy growth.
active transport
describes how an extracellular solution can change a cell’s volume by affecting osmosis.
tonicity
A solution’s tonicity often
directly correlates with the
solution’s osmolarity
describes the solution’s total solute concentration
osmolarity
A solution with ___ ___ has a greater number of water molecules relative to the number of solute particles.
low osmolarity
A solution with ___ ___ has fewer water molecules with respect to solute particles
high osmolarity
types of tonicity
hypertonic
isotonic
hypotonic
hypertonic
animal cell=
plant cell=
shriveled ; plasmolysed
isotonic
animal cell=
plant cell=
normal ; flaccid
hypotonic
animal cell=
plant cell=
lysed ; turgid
extracellular fluid having a higher osmolarity than the cell’s cytoplasm; therefore, the fluid contains less water than the cell does
hypertonic
Because the cell has a relatively higher water concentration, water will leave the cell.
hypertonic
Because the cell has a relatively higher water concentration, water will leave the cell.
Hypertonic
the extracellular fluid has lower osmolarity than the fluid inside the cell, and water enters the cell.
hypotonic
In this situation, water will follow its concentration gradient and enter the cell.
hypotonic
point at which the plant cell membrane pushes against the cell wall, making the cell swollen and
firm, usually because it’s full of liquid
turgidity
The plasma membrane pushing (force) against the cell wall creates a pressure
turgor pressure
When the plasmolysed cell is placed in a hypotonic solution, the water travels into the cell, due to the higher concentration of water outside the cell. Then the cell swells and becomes turgid.
deplasmolysis
