Plasma Membrane

Question 1

Elements in lipids

Answer 1

CHO

Question 2

Elements in phospholipids

Answer 2

CHOP

Question 3

Characteristics of lipids

Answer 3

non-polar, insoluble in water (hydrophobic), poor conductors of heat, good insulators

Question 4

Components of a triglyceride

Answer 4

1 x glycerol, 3 x fatty acids

Question 5

Bond formed between glycerol and fatty acids

Answer 5

ester

Question 6

Function of lipids

Answer 6

Energy source
Protection of vital organs
To prevent evaporation in plants
To insulate the body
They form the myelin sheath around neurones
As a water source (respiration produces metabolic water)

Question 7

Components of phospholipid

Answer 7

Hydrophilic polar phosphate head
Glycerol
Hydrophobic non-polar fatty acid tail

Question 8

Components of the plasma membrane

Answer 8

Phospholipid bilayer
Protein channels
Protein pumps
Glycoproteins
Glycolipids
Cholesterol

Question 9

Arrangement of phospholipid bilayer

Answer 9

hydrophilic phosphate heads are facing the environments with water (e.g., cytosol) whereas the hydrophobic fatty acid tails are facing each other and away from the environments containing water

Question 10

Function of cholesterol in plasma membrane

Answer 10

provides stability and flexibility to the membrane

Question 11

Function of the plasma membrane

Answer 11

Regulates the inputs and outputs of a cell

Question 12

Function of glycoproteins and glycolipids

Answer 12

cell communication and recognition

Question 13

Diffusion

Answer 13

Diffusion is the net movement of particles from a high concentration to a low concentration, down a concentration gradient.

Question 14

Is diffusion active or passive?

Answer 14

Passive (no ATP required)

Question 15

Substances that use simple diffusion

Answer 15

Small, non-polar molecules like O2 and CO2 (exception: water)
Hydrophobic, non-polar molecules e.g., steroid hormones

Question 16

Facilitated diffusion

Answer 16

Facilitated diffusion is the net movement of particles from a high concentration, to a low concentration, down a concentration gradient, through a protein channel.

Question 17

Is facilitated diffusion active or passive?

Answer 17

Passive (no ATP required)

Question 18

Substances that use faciilitated diffusion

Answer 18

Large, polar and hydrophilic substances that can’t cross directly through the phospholipid bilayer
E.g., glucose, charged ions (chloride ion, sodium ion)

Question 19

Similarities between diffusion and facilitated diffusion

Answer 19

similarities between diffusion and facilitated diffusion?
They are both passive processes
They both move substances down a concentration gradient (high to low)

Question 20

Differences between diffusion and facilitated diffusion

Answer 20

Diffusion is movement through the phospholipid bilayer whereas facilitated diffusion is movement through a protein channel.
Diffusion is the movement of small, non-polar, hydrophobic molecules whereas facilitated diffusion is the movement of large, polar, hydrophilic substances

Question 21

Factors that affect diffusion

Answer 21

Concentration gradient
Distance / thickness of membrane
Surface area to volume ratio
Temperature

Question 22

How concentration gradient affects rate of diffusion

Answer 22

If the difference in concentration on either side of the membrane is greater, diffusion will occur faster.

Question 23

How distance / thickness of plasma membrane affects rate of diffusion

Answer 23

If the semi-permeable membrane is thinner, diffusion will occur faster.

Question 24

How surface area to volume ratio affects rate of diffusion

Answer 24

A larger surface area to volume ratio means more particles can move across the membrane at the same time.

Question 25

How temperature of plasma membrane affects rate of diffusion

Answer 25

Particles with greater kinetic energy will diffuse faster. The membrane permeability increases as the temperature increases. This means that diffusion will take place more quickly when the membrane becomes more permeable

Question 26

Independent variable

Answer 26

The independent variable is a factor that is changed or manipulated in an experiment to determine its effect on the dependent variable.

Question 27

Dependent variable

Answer 27

The dependent variable is measured to determine if the change or manipulation of the independent variable had any effect.

Question 28

Controlled variable

Answer 28

A controlled variable is one that is kept constant throughout the experiment.

Question 29

Osmosis

Answer 29

Net movement of water molecules from a high-water concentration, through a partially permeable membrane, to a low water- concentration, down a concentration gradient.

Question 30

Is osmosis active or passive?

Answer 30

Passive

Question 31

Hypotonic

Answer 31

a solution that is lower in solute and higher in water molecules than the solution being compared to

Question 32

Hypertonic

Answer 32

a solution that is higher in solute and lower in water molecules than the solution being compared to

Question 33

Isotonic

Answer 33

two solutions are of equal solute concentration. There will be no net movement of water

Question 34

Animal cell in hypertonic environment

Answer 34

crenated

Question 35

Animal cell in hypotonic solution

Answer 35

lysed

Question 36

Plant cell in hypertonic environment

Answer 36

plasmolysed

Question 37

Plant cell in hypotonic envrionment

Answer 37

turgid

Question 38

Osmosis scaffold

Answer 38

OSMOSIS has occurred. This means that Water has moved FROM the hypotonic ______ THROUGH the partially permeable membrane of _____ TO the hypertonic _______ ______ has become crenated / lysed / plasmolysed / turgid

Question 39

Active transport

Answer 39

The net movement of particles from a low concentration to a high concentration, against a concentration gradient, through a protein pump which requires ATP.

Question 40

Is bulk transport an active or passive process?

Answer 40

Active (requires ATP)

Question 41

Endocytosis

Answer 41

the bulk movement of large substances into a cell

Question 42

Phagocytosis vs pinocytosis

Answer 42

Both forms of endocytosis. If the substance being engulfed is a solid, it is called phagocytosis. If the substance being engulfed is a liquid, it is called pinocytosis

Question 43

Steps in phagocytosis if a cell is obtaining nutrients

Answer 43

Phagocytosis this means that A cell engulfs a solid forming a food vacuole Food vacuole fuses with lysosome Solids are destroyed by digestive enzymes in lysosome

Question 44

Steps in phagocytosis if a cell is destroying pathogens

Answer 44

Phagocytosis this means that A white blood cell engulfs a pathogen forming a phagosome Phagosome fuses with lysosome forming a phagolysosome Pathogen is destroyed by digestive enzymes in lysosome

Question 45

Exocytosis

Answer 45

bulk movement of large substances out of a cell