1.4/ 1.5 - Plasma Membrane/ Movement Across Membranes

Question 1

Roles Of Membranes (Are Varied)

Answer 1

• Encloses the cellular contents, forming a barrier between the intracellular and extracellular environment
• Controls the selective entry and exit of substances
• Play a key role in cell recognition and communication
• Enables the formation of distinct compartments, allowing conditions to be tightly controlled and optimised to fulfil specific roles more efficiently
• Acts as a site for biochemical reactions

Question 2

Concentration Gradient

Answer 2

Molecule moves from a place of high to low concentration

Question 3

Phospholipid Bilayer

Answer 3

Phosphate Head - Hydrophilic (Water Love)
Fatty Acid Tails - Hydrophobic (Fear Water)

Question 4

Passive Transport

Answer 4

Moving from a place of high to low concentration (No Energy)
Modes Of Transport-
- Diffusion
- Facilitated Diffusion
- Osmosis

Question 5

Active Transport

Answer 5

Moving from a place of low to high concentration (Energy)
Modes Of Transport-
- Exocytosis (Exit)
- Endocytosis (Enter)

Molecular Characteristics-
Large, charged and/or water soluble substances

Example-
Ions, Amino acids, Glucose

Question 6

Simple Diffusion

Answer 6

Direction Of Movement-
High to low concentration

Molecular Characteristics-
Small and/or uncharged or lipid soluble substances

Example-
O², CO², Alcohol

Question 7

Facilitated Diffusion

Answer 7

Direction Of Movement-
High to low concentration

Molecular Characteristics-
Large, charged and/or water soluble substances

Example-
Ions (e.g - sodium), Amino acids, Glucose

Question 8

Osmosis

Answer 8

Direction Of Movement-
High to low concentration

Molecular Characteristics/Example-
Water

Question 9

Factors That Impact The Rate Of Exchange

Answer 9

• Type of substance
• Concentration
• Temperature
• Cell requirement
• Surface area avaliable

Question 10

Tonicity

Answer 10

Is a term used to describe the relative concentration of one solution compared to another
This can be used to determine the net movement of free water molecules by osmosis

Question 11

Hypertonic Solution

Answer 11

Hyper = fit
Has a high concentration of solute relative to the solution to which it is being compared

Question 12

Isotonic Solution

Answer 12

Has the same concentration of solute relative to the solution to which it is being compared

Question 13

Hypotonic Solution

Answer 13

Hypo = hippo
Has a lower concentration of solute relative to the solution to which it is being compared