4.2- DIFFUSION

Question 1

What is exchange of substances between cells and environment that require metabolic energy called?

Answer 1

active transport

Question 2

What is exchange of substances between cells and environment that don’t require metabolic energy called?

Answer 2

passive transport

Question 3

What is diffusion an example of?

Answer 3

passive transport

Question 4

Do all movement involve energy?

Answer 4

yes

Question 5

What does ‘passive’ mean in passive transport?

Answer 5

energy comes from natural, inbuilt motion of particles, rather than from some external source i.e. ATP

Question 6

How are all particles constantly in motion?

Answer 6

due to K.E. they possess

Question 7

What is the motion of the particles?

Answer 7

random with no set pattern to the way particles move around

Question 8

Where are particles bouncing off of constantly?

Answer 8

bouncing off one another as well as off other objects i.e. sides of vessel in which they’re contained

Question 9

What is the definition of diffusion?

Answer 9

net movement of molecules/ions from region where they’re more highly concentrated to one where their concentration is lower until evenly distributed

Question 10

Examples of molecules that can diffuse across the cell-surface membrane?

Answer 10

carbon dioxide and oxygen

Question 11

Why do charged ions and polar molecules not diffuse across plasma membranes?

Answer 11

because of phospholipids in membrane

Question 12

How is the movement of charged ions and polar molecules made easier (facilitated)?

Answer 12

by transmembrane channels and carriers that span the membrane

Question 13

What is the process by which movement of charged ions and polar molecules made easier called?

Answer 13

facilitated diffusion

Question 14

Is facilitated diffusion an active or passive process?

Answer 14

passive process

Question 15

What does facilitated diffusion rely on?

Answer 15

inbuilt motion (KE) of diffusing molecules
no external input of ATP from respiration

Question 16

Does facilitated diffusion occur down or against a concentration gradient?

Answer 16

down a concentration gradient

Question 17

How does facilitated diffusion differ from diffusion?

Answer 17

occurs at specific points on plasms membrane where there are special protein molecules

Question 18

What two types of proteins are involved in facilitated diffusion?

Answer 18

protein channels and carrier proteins

Question 19

What do protein channels form?

Answer 19

water-filled hydrophilic channels across the membrane

Question 20

What do protein channels allow?

Answer 20

specific water-soluble ions to pass through

Question 21

Are the channel proteins selective or not?

Answer 21

selective

Question 22

What does it mean for the channel protein to be selective?

Answer 22

each opening in presence of specific ion

if particular ion not present, channel remains closed

Question 23

Why is channel proteins being selective a good thing?

Answer 23

control over entry/exit of ions

Question 24

What do the ions do with the channel protein?

Answer 24

they bind with the channel protein

Question 25

What happens when the ions bind to the channel protein?

Answer 25

causes channel protein to change shape in a way that closes it to one side of membrane + opens it to other side

Question 26

What does an alternative form of facilitated diffusion involve?

Answer 26

carrier proteins that span the plasma membrane

Question 27

What happens when a molecule i.e. glucose that’s specific to the carrier protein is present?

Answer 27

it binds with the protein

Question 28

What happens when the molecule binds with the carrier protein?

Answer 28

causes it to change shape in such way that molecule released to inside of membrane

Question 29

Is external energy needed for facilitated diffusion with carrier proteins?

Answer 29

no