1.4 membrane transport

Question 1

types of transport

Answer 1

passive and active

Question 2

passive transport

Answer 2

No energy required
Particles move across the selectively permeable membrane
Along a concentration gradient (high → low)

Question 3

3 types of passive transport

Answer 3

simple diffusion
osmosis
facilitated diffusion

Question 4

active transport

Answer 4

Energy, in the form of ATP, is required.
Helps move molecules that cannot permeate the membrane or that need to move against a gradient.
Requires integral transport proteins

Question 5

3 types of active transport

Answer 5

Primary active transport
Secondary active transport
Endocytosis/Exocytosis

Question 6

concentration

Answer 6

measurement of unit per volume

Question 7

concentration gradient

Answer 7

When concentration differs across a space. As particles move, the concentration tends to reach equilibrium.

Question 8

diffusion

Answer 8

a net movement of particles along a concentration gradient (from high concentration to low concentration) until evenly dispersed

Question 9

Factors affecting the rate of diffusion

Answer 9

How imbalanced the concentration gradient is.
Temperature
Membrane permeability
Surface area
Distance of diffusion

Question 10

facilitated diffusion

Answer 10

when particles diffuse thru the plasma membrane courtesy of integral membrane proteins, such as channel and carrier proteins

Question 11

channel proteins

Answer 11

form pores and can transport charged ions + water

Question 12

carrier proteins

Answer 12

• change shape when molecules bind to them
• are specific to one type of molecule/group of molecules

Question 13

osmosis

Answer 13

• Is a type of diffusion that involves the passive transport of water.
• It is influenced by solute concentration. Water will move across a membrane to equalize the solute concentration on both sides.

Question 14

active transport

Answer 14

Integral protein pumps move molecules against a concentration gradient. This requires energy.
This energy comes from the molecules ATP (adenosine triphosphate).

Question 15

primary active transport

Answer 15

Uses ATP directly to move molecules against a concentration gradient

Question 16

secondary active transport

Answer 16

Makes use of concentration gradients set up by active transport to move another type of molecule against its concentration gradient

Question 17

types of proteins involved in active transport

Answer 17

uniport, symport, antiport

Question 18

sodium-potassium pump

Answer 18

a transport protein that is especially important in nerve cells.
It transports both Na+ and K+ against their concentration gradients.

Question 19

Describe active transport using the sodium potassium pump as an example (6 marks)

Answer 19

1. ATP is hydrolyzed
2. Molecules moved against a concentration gradient
3. Via a protein pump
4. Na+/K+ pump pumps 3Na+ outside the cell
5. ATP → ADP + Pi
6. 2K+ are pumped into the cell.
7. Resulting in an imbalance of charges across the membrane.

Question 20

endocytosis

Answer 20

The taking in of a substance by an inward pouching of the cell membrane. pinocytosis (liquid) & phagocytosis (solid)

Question 21

exocytosis

Answer 21

Exocytosis is a form of active transport and bulk transport in which a cell transports molecules out of the cell.

The release of a substance (secretion) when a vesicle joins with the plasma membrane

Question 22

draw a hypotonic solution

Answer 22

see notebook (drawings, p.2)

Question 23

draw a hypertonic solution

Answer 23

see notebook (drawings, p.2)

Question 24

draw a isotonic solution

Answer 24

see notebook (drawings, p.2)

Question 25

does exocytosis only remove waste products?

Answer 25

Exocytosis can remove both waste products as well as useful substances

Question 26

describe the action of the sodium-potassium pump

Answer 26

1. three sodium ions attach to their binding sites on the pump which is open to the inside of the axon
2. ATP transfers a phosphate group from itself to the pump causing the pump to change shape and the interior is then closed
3. the interior of the pump opens to the outside of the axon, the three sodium ions are released
4. two potassium ions from the outside can then attach to their binding sites
5. the binding of potassium causes the release of the phosphate group; this causes the pump to change shape again so that it is only open to the inside of the axon
6. the interior of the pump opens to the inside of the axon thus releasing the two potassium ions

Question 27

describe a voltage-gated potassium channel

Answer 27

• transports potassium ions
• is a transmembrane protein
• no energy needed
• voltage-gated
• transports potassium ions from the inside to the outside of an axon