Biology Chapter 5 Test
the gates may open or close in response to three kinds of stimuli. What are they?
- stretching of the cell membrane - electrical signals - chemicals in the cytosol or external environment
in a ______ environment, the cell gains water and swells
hypotonic
most of the time, the environment that plant cells live in is
hypotonic
relatively low solute concentration
hypotonic
when the concentration of the solute molecules outside the cell is lower than thee concentration in the cytosol, the solution outside is ________ to the cytosol
hypotonic
plasmolysis of a human red blood cell would occur if the cell were
in a hypertonic solution
diffusion is driven entirely by the _______ energy
kinetic
During endocytosis, the cell membrane folds in and forms a small pouch. The pouch then pinches off from the cell membrane to become a ________
vesicle
membrane-bound organelle
vesicle
during diffusion, molecules tend to move a) up their concentration gradient b) down their concentration gradient c) in a direction that doesn't depend on thee concentration gradient d)from an area of lower concentration to an area of higher concentration
B) down their concentration gradient
_____________ can help substances move either into or out of a cell, depending on the concentration gradient. The carrier proteins involved in facilitated diffusion are each specific for one type of molecule
Facilitated diffusion
the process of diffusion requires
a difference in the concentration of molecules throughout a space
A cell must expend energy to transport substances using a) cell membrane pumps b) facilitated diffusion c) ion channels d) osmosis
a) cell membrane
Cells must move materials up their concentration gradient, from an area of lower concentration to an area of higher concentration this is known as
active transport
when a cell uses energy to transport a particle through the cell membrane to an area of higher concentration, the cell is using
active transport
the sodium-potassium pump transports a) Na into the cell and K out of the cell b) Na out of the cell and K into the cell c) both Na and K into the cell d) both Na and K out of the cell
b) Na out of the cell and K into the cell
some animal cells engulf, digest, and destroy invading bacteria through the process of a) exocytosis b) phagocytosis c) pinocytosis d) all of the above
b) phagocytosis
when the cells in a plant have low turgor pressure, the plant a) is rigid b) dies c) wilts d) explodes
c) wilts
in facilitated diffusion, the movement of these kinds of molecules across the cell membrane is assisted by specific proteins in the membrane. they are called ______
carrier proteins
This difference in the concentration of molecules across a space is called
concentration gradient
concentration difference across space
concentration gradient
a structure that can move excess water out of unicellular organisms is a
contractile vacuole
organelles that remove water - Collect the excess water and then contract, pumping the water out of the cell
contractile vacuoles
the part of a cell that functions to maintain homeostasis relative to the cell's environment is the a)cytosol b) Golgi apparatus c) nucleus d) cell membrane
d) cell membrane
molecules that can dissolve in lipids may pass through the membrane by _______
diffusion
the movement of molecules from an area of higher concentration to an area of lower concentration
diffusion
this process is used for molecules that cannot diffuse rapidly through cell membranes, even when there is a concentration gradient across the membrane
facilitated diffusion
net movement of water across a cell membrane occurs
from a hypotonic solution to hypertonic solution
if a molecule can pass through a cell membrane, it will diffuse from an area of ______ concentration on one side of the membrane to an area of _____ concentration on the other side
higher lower
in a ______ environment, the cell loses water and becomes shriveled
hypertonic
relatively high solute concentration
hypertonic
when the concentration of solute molecules outside the cell is higher than the concentration in the cytosol, the solution outside is _____ to the cytosol.
hypertonic
without sodium-potassium pumps, cells
might lose sodium and might not be able to transmit electrical impulses
Hypertonic - water diffuses _____ the cell until equilibrium is established
out of
facilitated diffusion is _______ transport
passive
osmosis is a type of ______ transport
passive
some substances can cross the cell membrane without any input of energy by the cell. The movement of such substances across the membrane is known as ____________
passive transport
the ability of a molecule to diffuse across a cell membrane depends on the ____ and ____ of the molecule and on the chemical nature of the membrane
size and type
a carrier protein that actively transports K ions into and Na ions out of cells
sodium-potassium pump
to function normally, many types of animal cells must have a higher concentration of Na ions outside the cell and a higher concentration of K ions insider the cell. the ________________ works to maintain these concentration differences
sodium-potassium pump
the diffusion of ions across the membrane is influenced by
the concentration gradient of the ion
all forms of passive transport depend on
the kinetic energy of molecules (molecular movement)
the pressure that water molecules exert against the cell wall is called
turgor pressure
a membrane protein that provides a passageway across the cell membrane through which an ion can diffuse
ion channel
if the molecular concentration of a substance is the same throughout a space, the substance
is in equilibrium
in an environment that is _______ to the cytosol, the cell will keep its normal shape
isotonic
when the concentrations of solutes outside and inside the cell re equal, the outside solution is said to be ______ to the cytosol.
isotonic
sodium-potassium pumps do what
move Na ions out of cells and K ions into cells
Each type of ion channel is usually specific for ___ type of ion
one
a type of transport in which water moves across a membrane and down its concentration gradient is
osmosis
the process by which water molecules diffuse across a cell membrane from an area of higher concentration to an area of lower concentration is called
osmosis
________ allow lysosomes to fuse with the vesicles that contain the ingested bacteria and viruses
phagocytes
certain cells in animals usee phagocytosis to ingest bacteria and viruses that invade the body. these cells, known as
phagocytes
the movement of large particles or whole cells (type of endocytosis)
phagocytosis
uptake of large particles
phagocytosis
biologist distinguish 2 types of endocytosis, based on the kind of material that is taken into the cell: __________ and __________
phagocytosis and pinocytosis
involves the transport of solutes or fluids (type of endocytosis)
pinocytosis
uptake of solutes or fluids
pinocytosis
ion channels may open or close in response to (3 things)
-stretching of the membrane - a change in electrical charge - the binding of a molecule to the ion channel
what are the 6 steps of the sodium-potassium pump
1. 3 Na ions located in the cytosol bind to the carrier protein 2. a phosphate group is removed from ATP and bound to the carrier protein 3. The binding of the phosphate group changes the shape of the carrier protein, allowing the three Na ions to be released into the cell's environment 4. 3 K ions located outside the cell bind to the carrier protein 5. phosphate group is released, changing the shape of the carrier protein again 6. 2 K ions are released into the cytosol, and the cycle is ready to repeat
the random movements of many molecules in many directions ______ one another, and equilibrium is maintained
balance
Ion channels aid the movement of a) molecules up a concentration gradient b) carrier proteins within the lipid bilayer c) ions across a cell membrane d) water across a cell membrane
c) ions across a cell membrane
bursting of cells
cytolysis
the bursting of cells is called ______
cytolysis
carrier proteins are important in a) osmosis b) endocytosis c) diffusion d) facilitated diffusion
d) facilitated diffusion
glucose enters a cell most rapidly by a) facilitated b)diffusion c) osmosis d) phagocytosis
d) phagocytosis
the simplest type of passive transport is _______
diffusion
molecules tend to move _____ their concentration gradient, from areas where they are more concentrated to areas where they are less concentrated
down
Hypotonic - water diffuses ____ the cell until equilibrium is established
into
the process by which cells ingest external fluid, macromolecules, and large particles, including other cells
endocytosis
___________ and__________ are used to transport large quantities of small molecules into or out of cells at a single time
endocytosis and exocytosis
unlike passive transport, active transport requires a cell to expend _______
energy
when the concentration of the molecules of a substance is the same throughout a space, a state of _______ exists
equilibrium
the process in which a vesicle inside a cell fuses with the cell membrane and releases its contents to the external environment
exocytosis
shrinking of cells
plasmolysis
the cells shrink away from the ell walls, and turgor pressure is lost is called
plasmolysis
the reason that plants wilt if they don't receive enough water
plasmolysis
the exchange of 3 Na ions for 2 K ions creates an electrical gradient across the cell membrane. The outside of the membrane becomes _______ charged and the inside of the membrane becomes ______ charged
positively negatively