Transport

Question 1

diffusion

Answer 1

the passive movement of a molecule or ion down a concentration gradient from high to low concentration

Question 2

main factors affecting rate of diffusion

Answer 2

concentration gradient
thickness of membrane
surface area

Question 3

equation linking main factors of diffusion

Answer 3

SA x concentration gradient/ thickness of the membrane

Question 4

other factors affecting diffusion

Answer 4

temperature
availability of ion channels and pores
size of diffusing molecule
lipid solubility

Question 5

aquaporins

Answer 5

channel proteins that move water across the cell membrane, they have hydrophilic pores which allows water to pass by osmosis

Question 6

osmosis

Answer 6

the net passive diffusion of water molecules across a selectively permeable membrane from a region of higher water potential to low

Question 7

water potential

Answer 7

the tendency of water molecules to move out of a solution via osmosis

Question 8

water potential is measured in

Answer 8

kPa/ kilopascals

Question 9

pure water

Answer 9

0 tendency, has the highest concentration

Question 10

adding a solute to water

Answer 10

gives water potential a negative value

Question 11

higher concentration of solute=

Answer 11

stronger pull of water= lower water potential

Question 12

solute potential

Answer 12

measures how easily water molecules move out of solution
more solute=higher conc=more tightly held molecules= lower tendency

Question 13

pressure potential

Answer 13

water entering by osmosis expands the vacuole so pressure is put against the cell wall
makes the cell turgid

Question 14

water potential equation

Answer 14

pressure potential+solute potential= water potential of cell

Question 15

plasmolysis

Answer 15

the vacuole shrinks, and the cytoplasm draws away before becoming flaccid

Question 16

flaccid

Answer 16

plant cells that have lost water and become limp and floppy

Question 17

incipient plasmolysis

Answer 17

the external concentration is high and the cell loses enough water so that the membrane pulls away

Question 18

hypotonic

Answer 18

wp of external>inside so water moves inside

Question 19

hypertonic`

Answer 19

wp of internal>external so water flows outside

Question 20

isotonic

Answer 20

external=inside, no net movement

Question 21

hypotonic solution for animal and plants

Answer 21

animal= no cell wall so will experience cell lysis/ haemolysis in RBCS
plant= cell wall so will take in until pressure prevents it=turgid

Question 22

facilitated diffusion

Answer 22

passive transfer of molecules or ions down concentration gradient across a membrane
completed by intrinsic protein

Question 23

co transport

Answer 23

type of facilitated diffusion that brings molecules and ions across the membrane together by the same transport protein

Question 24

stages of cotransport:sodium glucose

Answer 24

1. glucose and 2 sodium ions bond to carrier protein which changes shape and deposits them inside the cell
2. glucose and sodium separately diffuse through
3. glucose passes into blood by FD
4. sodium is carried out by active transport and potassium moves in
5. more sodium moves from lumen bringing more glucose in also

Question 25

phagocytosis

Answer 25

active process of the cell membrane engulfing large particles bringing them into the cell in a vesicle
eg granulocytes engulf bacteria, lysosome fuses with vesicle and enzymes digest

Question 26

exocytosis

Answer 26

substances leave the cell having been transported through the cytoplasm in a vesicle

Question 27

the cell membrane is constantly having portions…

Answer 27

removed or added through phagocytosis and exocytosis

Question 28

pinocytosois

Answer 28

the same mechanism as phagocytosis but with the uptake of liquid and smaller vesicles

Question 29

active transport

Answer 29

the movement of substances across a membrane against a concentration gradient using ATP from respiration

Question 30

why is AT against a concentration gradient so important

Answer 30

it allows solutes to be accumulated in a cell giving it an appropriate balance

Question 31

active transport happens through

Answer 31

carrier proteins

Question 32

the rate of active transport is limited by

Answer 32

number and availability of carrier proteins

Question 33

active transport processes

Answer 33

muscle contraction
nerve transmission
glucose reabsorption into kidney
mineral uptake into plants

Question 34

active uptake of single molecule/ion

Answer 34

1. ion combines with carrier protein
2. atp transfers a phosphate group to carrier protein inside which changes shape and carries it across the membrane
3. phosphate ion is released from carrier back to cytoplasm and recombines with adp
   4.carrier protein returns to original shape

Question 35

rate of uptake is reduced with the addition of

Answer 35

respiratory inhibitor, eg. cyanide

Question 36

cyanide function in respiratory inhibition

Answer 36

prevents aerobic respiration and the production of ATP by inhibiting cytochrome oxidase so oxygen cannot bind

Question 37

if more oxygen is available to cells

Answer 37

more active transport