Level 2 Biology: Osmosis Internal

Question 1

What does ‘hydrophobic’ mean?

Answer 1

water “hating”

Question 2

What does ‘hydrophilic’ mean?

Answer 2

water “loving”

Question 3

What is a phospholipid composed of?

Answer 3

Phosphate group and lipid

Question 4

What is a ‘Bi-layer’

Answer 4

2 layers

Question 5

What is a ‘Semi permeable membrane’?

Answer 5

It will only allow certain substances into and out of the cell

Question 6

What can a phospholipid bilayer act as a barrier between?

Answer 6

A phospholipid bilayer can act as a barrier between two aqueous environments.

Question 7

passive transport

Answer 7

Does not require energy. Movement of molecules across the cell membrane

Question 8

Active transport

Answer 8

Requires energy (ATP)

Question 9

Dependent on the permeability of the cell membrane there are 3 main kinds of passive transport. What are they?

Answer 9

1) Diffusion
2) Osmosis
3) Facilitated diffusion

Question 10

Definition of Diffusion

Answer 10

Diffusion is the movement of molecules from an area of high concentration to one of low concentration. It uses no energy.

Question 11

What are the 3 key points on ‘Concentration gradient’

Answer 11

1) For things to diffuse there must be a difference in concentration between two areas.
2) If not, the particles won’t be able to move to a lower concentration.
3) The bigger the difference in concentration the faster it will diffuse.

Question 12

What does the ‘rate of diffusion’ depend on? (4 things)

Answer 12

1) The concentration gradient (bigger difference, the faster the diffusion).
2) Temperature (warmer=faster diffusion)
3) Particle size (Smaller=faster)
4) State of matter (gas=Faster diffusion)

Question 13

What is ‘Facilitated diffusion’

Answer 13

Substances are helped across the membrane by carrier proteins. It still uses no energy but the proteins are specific to certain molecules.

Question 14

How do cells absorb glucose?

Answer 14

Cells absorb glucose by facilitated diffusion. Insulin activates the transport proteins, if insulin is not there- can’t absorb glucose

Question 15

What is the cell membrane impermeable to?

Answer 15

Most electrically charged molecules and large water soluble substances such as glucose and amino acids.

Question 16

What do proteins embedded in the membrane contain?

Answer 16

Proteins embedded in the membrane contain channels that the large molecules diffuse through.

Question 17

What are the similarities and differences between diffusion and facilitated diffusion?

Answer 17

Facilitated diffusion is the movement of larger molecules with the aid of protein channels. Diffusion is the movement of molecules form an areas of high concertation to one of low concentration. Both don’t require energy (passive)

Question 18

What is Osmosis

Answer 18

Osmosis is the movement of water from an area of high concentration to one of low concentration (down the concentration gradient) across a semi permeable membrane.

Question 19

What is the requirement for the concentration of water to be lower?

Answer 19

For the concentration of water to be lower means that it must have something else in it (sugar, salt, ions)

Question 20

What is osmoregulation

Answer 20

The balancing of water inside an organism. Cells have to keep their water content balanced or else they either get too full or too empty of water.

Question 21

In animals too much water makes the cell ______?

Answer 21

Pop

Question 22

In animals too little water makes the cell ______?

Answer 22

Shrivel

Question 23

What are the 3 states a cell can be in?

Answer 23

1) Hypertonic
2) Isotonic
3) Hypotonic

Question 24

What is ‘Isotonic’

Answer 24

Isotonic means balanced. Outside cell and inside cell have same amount of water and solute as each other.

Question 25

What is ‘Hypertonic’

Answer 25

The fluid outside cell has HIGH solute (less water). The fluid inside cell has LOWER solute (MORE water). Water comes out and tries to balance the water outside the cell=shrivelled cell (not enough water)

Question 26

What is ‘Hypotonic’

Answer 26

The fluid outside cell has LOW solute (Higher water). The fluid inside cell has HIGHER solute (LESS water). Water goes in and tries to balance the water in the cell=Cell either pops or gets over full of water.

Question 27

What are the 3 key points on ‘Tonicity’

Answer 27

In Isotonic solutions cells have no net loss or gain of water. Net loss of water due to osmosis in hypertonic solutions. Net gain of water due to osmosis in hypotonic solutions.

Question 28

What will an animal cell do in hypertonic and hypotonic solutions

Answer 28

Shrivel or shrink in hypertonic solutions and expand or burst in hypotonic solutions.

Question 29

What will plant cells do in hypertonic and hypotonic solutions

Answer 29

Plant cells become plasmolysed in hypertonic solutions-the cell membrane pulls away from the cell wall. Plant cells become firm in hypotonic solutions- hold their shape and are rigid or turgid.

Question 30

What is Tonicity?

Answer 30

Tonicity is the measure of the water potential gradient of two solutions (solutions on either side of semi-permeable membrane)

Question 31

What is water potential?

Answer 31

Water potential is a measure of the tendency of water molecules to move from one place to another. Water always moves from a region of higher water potential to one of lower water potential down the concentration gradient.

Question 32

What is Active transport?

Answer 32

Active transport is the movement of molecules and ions through a cell membrane from a region of lower concentration to a region of higher concentration USING ENERGY from respiration.

Question 33

What does Active transport require

Answer 33

Carrier proteins (each carrier protein being specific for a particular type of molecule or ion)

Question 34

What also uses carrier proteins?

Answer 34

Facilitated diffusion

Question 35

What is the difference between Facilitated diffusion and active transport despite them both using carrier proteins?

Answer 35

Active transport requires ENERGY

Question 36

Why does active transport require ENERGY?

Answer 36

The energy is required to make carrier proteins change shape, allowing it to transfer the molecules or ions across the cell membrane. The energy required is provided by ATP produced during respiration.

Question 37

What is an iron pump

Answer 37

This is where certain ions or molecules are pumped from one side of the cell membrane to the other. Usually different ions need to be present to make the other ion change sides.

Question 38

What is the difference in two areas called in relation to diffusion?

Answer 38

The concentration gradient

Question 39

What are the factors that affect the rate of diffusion?

Answer 39

Size, temperature and state