Cell Membranes and Transport

Question 1

Key word to describe cell surface membrane + why it’s called that

Answer 1

‘Fluid mosaic’
Fluid - phospholipid molecules can move relative to one another
Mosaic - embedded proteins vary in size and shape, scattered randomly throughout membrane

Question 2

Fluid mosaic model labels

Answer 2

• hydrophilic phosphate head
• hydrophobic fatty acid tails
• phospholipid
• phospholipid bilayer
• intrinsic protein
• extrinsic protein
• cholesterol
• glycoproteins
• channel protein
• carrier protein

Question 3

Function of cell membrane

Answer 3

Take up nutrients and other requirements, secrets chemicals, cell-cell recognition

Question 4

Factors affecting permeability of plasma membrane

Answer 4

• membrane acts as a barrier = semi-permeable
• non-polar molecules/small uncharged molecules pass through by diffusion
• polar molecules/large charged molecules pass through by facilitated diffusion

Question 5

Diffusion definition

Answer 5

Movement of molecules/ions from high to low concentration (down a concentration gradient)

Question 6

Factors that affect diffusion

Answer 6

• concentration gradient
• thickness of membrane/diffusion distance
• surface area
• temperature
• lipid solubility
• size of molecule

Question 7

Facilitated diffusion definition

Answer 7

Diffusion (high to low concentration) where charged atoms/molecules (ions) and large molecules move through membrane through intrinsic proteins

Question 8

Ions travel through…

Answer 8

Channel proteins

Question 9

Glucose/amino acids travel through…

Answer 9

Carrier proteins

Question 10

Osmosis definition

Answer 10

Diffusion of water molecules from high to low water potential through a semi permeable membrane

Question 11

Water potential definition

Answer 11

‘Tendency of water molecules to leave a system’

Question 12

Water potential measured in

Answer 12

kPa

Question 13

Pure water has highest water potential which is

Answer 13

0kPa

Question 14

Water potential equation

Answer 14

Water potential (0 or -) = solute potential (-) + pressure potential (+)

Question 15

Isotonic

Answer 15

No net movement

Question 16

Hypertonic

Answer 16

High water potential in cell

Question 17

Hypotonic

Answer 17

Low water potential in cell

Question 18

Turgid

Answer 18

No more water can enter cell

Question 19

Plasmolysed

Answer 19

Cell loses water, cell membrane pulls away from cell wall

Question 20

Incipient plasmolysis

Answer 20

50% turgid

50% plasmolysed

Question 21

Cytosis for

Answer 21

Bulk transport

Question 22

2 types of endocytosis

Answer 22

Pinocytosis

Phagocytosis

Question 23

Pinocytosis definition and what happens?

Answer 23

Bulk transport of fluids

Fluid reaches cell membrane, invagination, vesicles pinches off and brings contents into cell

Question 24

Phagocytosis definition and what happens?

Answer 24

Bulk transport of solid particles

Solid particle reaches cell membrane, engulfed, vesicles pinches off and brings contents into cell

Question 25

Exocytosis definition and what happens?

Answer 25

Bulk transport our of cell (secretion)
Vesicle from Golgi body migrates to cell membrane
Vesicle fuses with cell membrane, contents released

Question 26

Active transport definition

Answer 26

Movement of ions/molecules from low to high concentration (against concentration gradient) which requires energy from ATP (made by mitochondria from aerobic respiration)

Question 27

Cyanide effect on active transport

Answer 27

Inhibits aerobic respiration, no ATP produced, no active transport as no energy from ATP

Question 28

Graph for diffusion

Answer 28

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Question 29

Graph for facilitated diffusion

Answer 29

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Question 30

Graph for active transport

Answer 30

(Addition of cyanide causes drop)

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