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