4.1

Question 1

which component of the fluid mosaic model is the main transport system in the membrane

Answer 1

integral proteins

Question 2

what are the 3 passive transport mechanisms

Answer 2

diffusion
facilitated diffusion
osmosis

Question 3

what are the 3 active transport mechanisms

Answer 3

endocytosis
exocytosis
active transport

Question 4

define diffusion

Answer 4

movement of particles down the concentration gradient from an area of high concentration to an area of low concentration

Question 5

define facilitated diffusion

Answer 5

diffusion that takes place through carrier proteins or channel proteins

Question 6

define osmosis

Answer 6

movement of solvent molecules from an area of high water potential to an area of low water potential down the concentration gradient through a partially permeable membrane

Question 7

define endocytosis

Answer 7

movement of large molecules into calls through vesicle formation

Question 8

define exocytosis

Answer 8

movement of large molecules out of the cell through vesicle formation containing molecules within the surface cell membrane

Question 9

define active transport

Answer 9

movement of substances directly across the membrane requiring energy

Question 10

what factors effect how a substance is transported

Answer 10

size of molecule
solubility in lipids & water
polarity of the molecule

Question 11

what are gated channels

Answer 11

protein channels that only open when a specific molecule or electrical charge is present

Question 12

how do carrier proteins work

Answer 12

picks up a specific molecule
carrier then changes shape so it can move through the membrane
releases molecule on the other side

Question 13

what is osmotic concentration

Answer 13

measure of the concentration of the solutes in a solution that have an osmotic effect

Question 14

what is an isotonic solution

Answer 14

when osmotic concentration of the solutes in the solution is the same as that in the cell

Question 15

what is a hypotonic solution

Answer 15

when osmotic concentration of solutes in solution is lower than that in the cell therefor water moves into the cell

Question 16

what is a hypertonic solution

Answer 16

when osmotic concentration of solutes in the solution is higher than that in the cell therefore water moves out of the cell

Question 17

what happens to animal cells when too much water moves out of the cell

Answer 17

cell becomes shriveled and the cytoplasm loses its internal structure
chemical reactions in the cell stop working

Question 18

what is generated as water enters a plant cell and the cytoplasm swells and presses in the cell walls

Answer 18

hydrostatic pressure

Question 19

what is pressure potential

Answer 19

the inward pressure exerted by the plant cell wall on the protoplasm of a cell stopping the entry of water by osmosis

Question 20

what is turgor

Answer 20

when the osmotic force moving water into the plant call is balanced by the pressure potential

Question 21

what is incipient plasmolysis

Answer 21

when water moves out of the cell so turgor is lost and the cell membrane pulls away from the cell wall as the protoplasm shrinks

Question 22

How is incipient plasmolysis measured

Answer 22

using serial dilutions looking for the point at which 50% cells plasmolysed 50% not

Question 23

What is plasmolysis

Answer 23

so much water leaves the cell that the vacuole is reduced and the protoplasm shrinks away from the cell wall

Question 24

why is most work (experiments) on osmosis osmosis done on plant cells

Answer 24

bigger & easier to see and measure

Question 25

what is water potential

Answer 25

the potential for water to move out of a solution by osmosis

Question 26

why is the water potential of pure water zero

Answer 26

the highest water potential water molecules always move from pure water into any solution

Question 27

what is turgor pressure (P)

Answer 27

the inward pressure exerted by the plant cell wall, force which opposes the entry of water by osmosis

Question 28

what is osmotic potential

Answer 28

the potential of a solution to cause water to move into the cell across a partially permeable membrane as a result of dissolved solutes

Question 29

what is the equation for water potential

Answer 29

water potential = turgor pressure + osmotic potential

Question 30

why is the water potential of an animal cell the same as its osmotic potential

Answer 30

there is no cell wall to exert a hydrostatic pressure

Question 31

what does active transport allow a cell to do

Answer 31

move substances across membranes against a concertation or electrochemical gradient using ATP

Question 32

what’s a carrier protein

Answer 32

proteins that move a substance through the membrane in active transport

Question 33

what does the sodium pump do

Answer 33

moves potassium ions into the cell and sodium ions out

Question 34

what does the cell surface membrane do

Answer 34

provides control over what moves in or out of the cell

Question 35

evidence for active transport

Answer 35

-only takes place in living cells
-depends on temperature & O2 concentration
-large number of mitochondria
-poisons that stop respiration or prevent ATPase also stop active transport

Question 36

define cyanide

Answer 36

metabolic poison that stops mitochondria working

Question 37

what is phagocytosis

Answer 37

the active process when a cell engulfs something relatively large such as bacterium and encloses it in a vesicle

Question 38

what is pinocytosis

Answer 38

the active process by which cells take tiny amounts of extracellular fluid into vesicles

Question 39

why do cells take in extracellular fluid

Answer 39

sources of minerals and nutrients