2.4 Transport Across Membranes

Question 1

Some materials enter _________ while others need to be ________ ____________ using ______

Answer 1

Some materials enter passively while others need to be transported actively using energy

Question 2

Passive Transport

Answer 2

Movement of a substance across
a membrane WITHOUT using
energy

Question 3

________ drives passive
transpor

Answer 3

Diffusion

Question 4

Molecules/ions move from
areas of HIGH to LOW
concentrations

Answer 4

Diffusion

Question 5

Rate of diffusion depends on…

Answer 5

concentration gradient that exists across a membrane

Question 6

Dynamic Equilibrium

Answer 6

Equal concentration on
both sides of the
membrane, movement
between both sides
continues, but there is no
net change in concentration

Question 7

1. Simple Diffusion

Answer 7

Movement of small/non-
polar substances across the membrane without
using energy

Ex. CO2 and O2 can move
freely across membrane

Question 8

Smaller substances move…

Answer 8

faster than larger substances

Question 9

2. Facilitated Diffusion

Answer 9

Use of proteins to help
move substances
* (e.g., amino acids and
sugars)

Uses integral TRANSPORT
PROTEINS

Question 10

When equilibrium is
reached,

Answer 10

facilitated
diffusion stops

Question 10

Channel Protein

Answer 10

form hydrophilic pathway
through membrane

Question 11

Carrier Protein

Answer 11

physically binds to
molecules to aid in
transportation

Question 12

Channel Protein Used to transport…

Answer 12

certain ions

(Ex. Na+, K+, Cl-)

Question 13

Involved in nerve signals and
muscle contractions

Answer 13

Channel Proteins

Question 14

Carrier Proteins Bind to

Answer 14

specific substances

(Ex. amino acids and glucose)

Question 15

Changes shape to help transport substances

Answer 15

Carrier Proteins

Question 16

3. Osmosis

Answer 16

Passive Diffusion of water across a membrane

Question 17

The Concentration of Solutes around cells determines their shape

3 Types

(Osmosis)

Answer 17

Hypotonic

Hypertonic

Isotonic

Question 18

Hypotonic Solution

Answer 18

low concentration of solutes outside cell = water rushes into cell

Question 19

Isotonic Solution

Answer 19

equal concentration of solutes inside and outside of cell = no net movement of water

Question 20

Hypertonic Solution

Answer 20

high concentration of solutes outside cell = water rushes out of cell

Question 21

Active Transport

Answer 21

The movement of
substances across the
membrane USING energy

Question 22

Movement is AGAINST
the concentration
gradient

Answer 22

Active Transport

Question 23

Uses ATP to “pump”
substances across

Answer 23

Active Transport

Question 24

1. Primary Active Transport

Answer 24

Move POSITIVELY
CHARGED IONS across
membranes

Question 25

Helps establish
Electrochemical
Gradients which are
important in Nerve
Functioning

Answer 25

Primary Active Transport

Question 26

2. Secondary Active Transport

Answer 26

Uses energy from the Concentration Gradient
built up by Primary Active Transport to transport
substances

Question 27

Secondary Active Transport

Symport

Answer 27

Transported
substances move in
the same direction as
ions

Question 28

Secondary Active Transport

Antiport

Answer 28

Transported
substances move in
the opposite direction
as ions

Question 29

Exocytosis

Answer 29

Transport of LARGE
substances from inside the cell to the outside of the cell using vesicles

Requires ATP

Question 30

Endocytosis

Answer 30

Transport of substances from
outside to inside the cell using
vesicles in one of three ways:

1. Pinocytosis (cell drinking)
2. Receptor-Mediated Endocytosis
3. Phagocytosis (cell eating)

Require ATP

Question 31

Pinocytosis (cell drinking)

Answer 31

brings in fluid along with any
molecules inside the fluid

Question 32

Receptor-Mediated
Endocytosis

(endocytosis)

Answer 32

has molecules
bind to receptor proteins on
the outer surface before
coming into the cell

Question 33

Phagocytosis (cell eating)

Answer 33

brings in solid materials like
bacteria, dead cells, or other
foreign material

Question 34

Therefore SOLUTE (dissolved substances) CONCENTRATION determines

Answer 34

water movement

Question 35

Osmosis ALWAYS moves from..

Answer 35

Always moves from an area of LOWER SOLUTE CONCENTRATION (high water
content) to an area of HIGHER SOLUTE CONCENTRATION (low water content)