Ch. 5 Membrane Transport

Question 1

What is the function of the cell membrane?

Answer 1

To regulate the exchange of materials between the cytoplasm of the cell and its surroundings
selectively permeable

Question 2

How do molecules naturally move?

Answer 2

move “down their concentration gradients”

• • move until dynamic equilibrium is met
• • movement continued because of “Brownian Motion*

Question 3

2 types of transport

Answer 3

• passive

- active

Question 4

Passive Transport

Answer 4

movement “down the concentration gradient”

• requires no ATP
• called facilitated diffusion when a transport protein is involved

Question 5

Active Transport

Answer 5

movement “ against the concentration gradient:

• does require ATP*
• may involve proteins or pumps that pump in both directions at the same time (counter-transport)

Question 6

processes that result in movement or types of passive transport

Answer 6

• filtration
• diffusion
• osmosis

Question 7

filtration

Answer 7

movement due to hydrostatic pressure/osmotic pressure (force exerted on membrane by water)
no ATP required

Question 8

capillary movement

Answer 8

blood pressure forces water, salts, nutrients, and solutes into tissue fluid , while large particles like blood cells and proteins are held back

Question 9

diffusion

Answer 9

movement of solutes down concentration gradient
requires no ATP
examples:
-movement of O2 from a leaf out into atmosphere
-movement of CO2 out of body

Question 10

factors that affect diffusion

Answer 10

• temperature
• concentration gradient
• amount of membrane surface area
• membrane permeability
• electrical charge
• pressure gradient

Question 11

osmosis

Answer 11

diffusion of water across a selectively permeable membrane

• movement of H2O from area of high conc. to low conc.
• movement may be due to pressure gradients
• requires no ATP

Question 12

Tonicity

in a semi-permeable membrane

Answer 12

defines the concentration of solution across a semi-permeable membrane

• affects ability of the concentration of a solution to affect fluid volume and pressure within a cell
• determines direction water will flow across membrane

Question 13

3 conditions that refer to concentration of a solute

Answer 13

• hypertonic
• hypotonic
• isotonic

Question 14

hypertonic

Answer 14

more solute

-may result in a cell shrinking (crenation)

Question 15

hypotonic

Answer 15

less solute

-may result in a cell splitting (cytolysis)

Question 16

isotonic

Answer 16

same solute

-still has movement due to Brownian Motion

Question 17

Sodium potassium pump

Answer 17

regulates the cell volume by “counter-transport”

• produces heat because of energy exchange during phosphorylation
• maintains the proper ‘resting membrane potential’ for nerve and muscle contraction

Question 18

Vesicular transport

Answer 18

movement of large droplets of fluid/substances into/out of a vesicle

Question 19

2 types of substances in vesicular transport

Answer 19

• pinocytosis

- phagocytosis

Question 20

pinocytosis

Answer 20

flow of liquids and materials in bulk

Question 21

phagocytosis

Answer 21

movement of non-liquid substances

Question 22

endocytosis

Answer 22

moving into the cell

Question 23

exocytosis

Answer 23

moving out of the cell

Question 24

transport of plant cells

Answer 24

-have a contractive vacuole that collects H2O and pumps it out of the cell as necessary