Module 5.2 Membrane Transport

Question 1

True or False: Membranes are selectively permeable

Answer 1

True

Question 2

What does selectively permeable mean?

Answer 2

Only some substances can cross the phospholipid bilayer of the membrane

Question 3

What are some of the selective substances that can cross the phospholipid bilayer?

Answer 3

Selective substances include small neutral molecules such as O2 or CO2 and completely hydrophobic lipids like triglycerides or cholesterol.

Question 4

Because water is polar, its diffusion through a membrane’s hydrophobic interior is

Answer 4

relatively slow

Question 5

Water can diffuse quickly through a channel called

Answer 5

aquaporin

Question 6

The protein channel aquaporin makes what possible

Answer 6

The very rapid diffusion of water into and out of certain cells, such as plant cells, kidney cells, and red blood cells

Question 7

A single aquaporin allows the entry or exit of up to

Answer 7

3 billion water molecules per second

Question 8

What is the role of aquaporin in cell membranes?

Answer 8

Facilitates rapid diffusion of water, allowing up to 3 billion water molecules per second

Question 9

Aquaporins enable a tremendous increase in

Answer 9

water transport over simple diffusion.

Question 10

Define concentration gradient.

Answer 10

The concentration of solute from one area to another. Just like a gradient in color​.

Question 11

How do molecules move in a concentration gradient?

Answer 11

From an area of higher concentration to lower concentration. They are taking the path of least resistance

Question 12

Molecules go from an area of higher concentration to lower concentration because they want to take the path of

Answer 12

least resistance

Question 13

Equilibrium occurs when there is

Answer 13

no longer a gradient and there is an even distribution of molecules

Question 14

Molecules are said to be in equilibrium when

Answer 14

there is an even distribution of molecules and there is no longer a gradient

Question 15

How do molecules move during equilibrium?

Answer 15

They are still moving because molecules always more, but there is no net movement in one direction

Question 16

What is diffusion?

Answer 16

The process of molecules moving from higher to lower concentration until equilibrium is reached.

Question 17

Diffusion does not require

Answer 17

energy

Question 18

Diffusion is the result of

Answer 18

the random movement of molecules

Question 19

Diffusion is one type of

Answer 19

passive transport

Question 20

What is passive transport?

Answer 20

Diffusion across a membrane with no energy investment.

Question 21

Concentration gradients often exist on

Answer 21

opposite sides of a membrane

Question 22

What happens when oxygen is used quickly by a cell?

Answer 22

Creates an oxygen gradient that allows oxygen to diffuse very passively/easily across the membrane.

Question 23

Osmosis is a type of

Answer 23

passive transport

Question 24

What is osmosis?

Answer 24

The movement of free water not bound to a solute across a membrane by passive transport.

Question 25

In osmosis the more solute in a solution the less

Answer 25

free water there is.

Question 26

How are free water and solute related

Answer 26

inversely related

Question 27

Because water and solute are inversely related water will move across the membrane in the

Answer 27

opposite direction as solute

Question 28

In biological membranes, only water goes across membranes by

Answer 28

passive transport

Question 29

Since water is polar, it cannot pass directly through the

Answer 29

phospholipid bilayer

Question 30

Nearly all cells have a

Answer 30

channel protein

Question 31

Nearly all cells have a channel protein in their membranes called

Answer 31

aquaporin

Question 32

Which protein helps with the passive transport of water?

Answer 32

Aquaporin.

Question 33

Aquaporin does what passively?

Answer 33

It passively transports water across the membrane using no energy

Question 34

Aquaporin facilitates moving

Answer 34

3 billion water molecules per second across the membrane​

Question 35

Aquaporin still doesn't cost any

Answer 35

energy

Question 36

What does tonicity refer to?

Answer 36

The ability of a surrounding solution to cause a cell to gain or lose water.

Question 37

Tonicity directly relates to the

Answer 37

solute concentration

Question 38

Hypo- prefix means

Answer 38

less

Question 39

A hypotonic solution has

Answer 39

less solute than the cell ​

Question 40

Hyper- prefix means

Answer 40

more

Question 41

Hypertonic solution has

Answer 41

more solute than the cell

Question 42

Iso- prefix means

Answer 42

same

Question 43

An isotonic solution has

Answer 43

the same solute as the cell​

Question 44

Blood cells are often used as a model for

Answer 44

what occurs in all cells

Question 45

Cells in an isotonic solution

Answer 45

the solute and water concentration are the same in the solution and in the cells

Question 46

Isotonic results in no

Answer 46

concentration gradient of water so there is no net movement of water across the membrane

Question 47

What does is mean when we say there is no net movement of water across the membrane

Answer 47

The same amount of water flowing into the red blood cell is the same amount coming out

Question 48

A hypertonic solution

Answer 48

has more solute in the solution

Question 49

In a hypertonic solution, there is more

Answer 49

free water inside the cell than in the solution.

Question 50

When there is more water inside the cell than in a solution,

Answer 50

water goes down the concentration gradient, travelling out of the cell into the solution

Question 51

What happens to cells in a hypertonic solution?

Answer 51

They shrink and become shriveled due to water moving out of the cell.

Question 52

What occurs in isotonic solutions?

Answer 52

The solute and water concentrations are the same, resulting in no net movement of water.

Question 53

A hypotonic solution has

Answer 53

has less solute in the solution

Question 54

In a hypotonic solution, there is more

Answer 54

free water inside the cell than in the solution.

Question 55

When there is less water inside the cell than in a solution,

Answer 55

water goes down the concentration gradient, travelling into the cell from the solution.

Question 56

What happens to cells in a hypotonic solution?

Answer 56

The become full of water and burst

Question 57

The last type of diffusion/passive transport is called

Answer 57

facilitated diffusion

Question 58

What is facilitated diffusion?

Answer 58

Diffusion of a solute across a membrane using a transport protein.

Question 59

When is facilitated diffusion used

Answer 59

When a polar or charged molecule cannot pass through the phospholipid bilayer

Question 60

All passive transport is

Answer 60

high to low concentration with 0 energy/ATP

Question 61

What types of proteins are involved in facilitated diffusion?

Answer 61

* Channel proteins * Carrier proteins.

Question 62

Channel proteins are like

Answer 62

tunnels through the membrane

Question 63

Carrier proteins are shape-

Answer 63

changers to bring molecules across the membrane

Question 64

What is active transport?

Answer 64

The transportation of molecules against the concentration gradient from low to high

Question 65

What is required for active transport?

Answer 65

* A carrier protein in the membrane * Energy, usually as ATP.

Question 66

A sodium potassium pump is a type of

Answer 66

active transport

Question 67

An endocytosis is another type of

Answer 67

active transport

Question 68

What is endocytosis?

Answer 68

Moving large molecules into the cell using vesicles.

Question 69

In Endocytosis, cells can bring in

Answer 69

large amounts of water and solutes

Question 70

An exocytosis is another type of

Answer 70

active transport

Question 71

What is exocytosis?

Answer 71

Moving large molecules out of the cell using vesicles.

Question 72

Exocytosis can be used to get rid of waste like

Answer 72

protein, polysaccharides or CO2