Movement Across Membranes

Question 1

What is diffusion?

Answer 1

Diffusion is the movement of molecules from higher concentration to a lower concentration

Question 2

Does diffusion require energy?

Answer 2

No

Question 3

What can affect the rate of diffusion?

Answer 3

Concentration gradient, distance moved, surface area, barriers, temperature

Question 4

What is simple diffusion?

Answer 4

Molecules can move directly through the membrane without assistance

Question 5

What are examples of molecules that use simple diffusion?

Answer 5

Oxygen diffuses into the blood and carbon dioxide diffuses out of the blood

Question 6

What is facilitated diffusion?

Answer 6

Carrier proteins allow large lipid-insoluble molecules that cannot cross the membrane by simple be transported into the cell

Question 7

What is an example of a molecule that requires facilitated diffusion?

Answer 7

The transport of glucose into red blood cells

Question 8

Does facilitated diffusion require energy?

Answer 8

No

Question 9

What is channel-mediated facilitated diffusion?

Answer 9

Channels (hydrophilic pores) in the membrane allow inorganic ions to pass through the membrane

Question 10

What is an example of a molecule requiring channel-mediated facilitated diffusion?

Answer 10

Potassium ions exiting nerve cells to restore resting potential

Question 11

What do simple diffusion, facilitated diffusion and channel-mediated facilitated diffusion have in common?

Answer 11

None require energy

Question 12

What is active transport?

Answer 12

Active transport uses energy to transport molecules against their concentration gradient across a partially permeable membrane

Question 13

Where does the energy required for active transport come from?

Answer 13

ATP

Question 14

What does ATP stand for?

Answer 14

Adenosine Tri Phosphate

Question 15

Why does active transport require energy?

Answer 15

Because molecules are being moved against their concentration gradient

Question 16

What is the difference between primary and secondary active transport?

Answer 16

For primary active transport ATP is used directly whereas for secondary energy is stored in the concentration gradient

Question 17

Is ATP directly used in secondary active transport?

Answer 17

No

Question 18

What is the function of a cell wall?

Answer 18

Provides strength and a fixed shape

Question 19

What structures make up the plasma membrane?

Answer 19

Phospholipids, proteins, cholesterol, glycoproteins, glycolipids

Question 20

What are the functions of glycoproteins?

Answer 20

Play an important role in cellular recognition and immune responses. Helps stabilise the membrane structure

Question 21

What is the function of glycolipids?

Answer 21

They act as surface receptors and stabilise the membrane. Also have the role in helping cells aggregate in the formation of tissues

Question 22

Where are peripheral proteins located on the membrane?

Answer 22

Are stuck to the surface of the membrane

Question 23

What is the function of cholesterol in the membrane?

Answer 23

Cholesterol disturbs the close packing of phospholipids and keeps the membrane more fluid

Question 24

What is the plasma membrane made up of?

Answer 24

Phospholipid bilayer

Question 25

Is the head of a phospholipid hydrophilic or hydrophobic?

Answer 25

hydrophilic

Question 26

What is hydrophilic?

Answer 26

Water attracting

Question 27

What is hydrophobic?

Answer 27

Water repelling

Question 28

What is the tail of a phospholipid made up of?

Answer 28

Fatty acids

Question 29

What is the head of a phospholipid made up of?

Answer 29

An alcohol and phosphate group

Question 30

Are the two tails of a phospholipid hydrophilic or hydrophobic?

Answer 30

Hydrophobic

Question 31

What are 4 functions of the plasma membrane?

Answer 31

- allows substances in and out of the cell - cellular communication - transports materials - surround cell organelles

Question 32

What if the function of integral proteins?

Answer 32

Helps to transport certain materials across the membrane

Question 33

What are the two types of transport across membranes?

Answer 33

Passive or active

Question 34

What is the difference between passive and active transport?

Answer 34

Passive transport does not require energy whereas active requires ATP to occur

Question 35

What is passive transport?

Answer 35

The movement of particles from a high concentration to a low concentration. Movement is down the concentration gradient.

Question 36

What are examples of passive transport?

Answer 36

Diffusion, facilitated diffusion, osmosis

Question 37

What is active transport?

Answer 37

The movement of particles against the concentration gradient. This means from low to high concentration

Question 38

What is an example of active transport?

Answer 38

Sodium pumps

Question 39

When is equilibrium reached?

Answer 39

When the concentration of molecules on each side of the membrane are equal at this point net movement stops

Question 40

What is osmosis?

Answer 40

Osmosis is the diffusion of water molecules across a partially permeable membrane from a region of higher to lower concentration of water molecules

Question 41

What is osmotic potential?

Answer 41

The tendency for water to move across a membrane based on te solute concentration

Question 42

Does osmosis require energy?

Answer 42

No

Question 43

What is a solvent?

Answer 43

The substance that does the dissolving

Question 44

What is the universal solvent?

Answer 44

Water

Question 45

What is a solute?

Answer 45

The particles being dissolved eg. sugar, salt

Question 46

What is solute concentrations?

Answer 46

The amount of solute in a given solution

Question 47

What is an isotonic solution?

Answer 47

Two solutions containing the same concentrations of solutes

Question 48

What is a hypotonic solution?

Answer 48

A solution with less concentration of solutes than the solution in the cell

Question 49

What is a hypertonic solution?

Answer 49

A solution with more concentration of solutes than the solution in the cell

Question 50

What happens to a hypotonic cell?

Answer 50

Swells

Question 51

What happens to a hypertonic cell?

Answer 51

Shrinks

Question 52

Why does active transport require energy?

Answer 52

Because the materials are moving against their concentration gradient

Question 53

What is the function of transport proteins?

Answer 53

Harness the energy of ATP to pump molecules from a low to high concentration

Question 54

What is exocytosis?

Answer 54

The movement of large amounts of materials to the outside of the cell

Question 55

What is endocytosis?

Answer 55

The intake of large molecules by the cell

Question 56

What are the two types of endocytosis?

Answer 56

Pinocytosis and phagocytosis

Question 57

What is pinocytosis?

Answer 57

The intake of fluids

Question 58

What is phagocytosis?

Answer 58

The intake of solids

Question 59

Does endocytosis and exocytosis require energy?

Answer 59

Yes

Question 60

What does a glycoprotein enable?

Answer 60

Cell to cell communication