B3 - diffusion + osmosis + active transport

Question 1

define diffusion

Answer 1

movement of particles from a region of higher concentration to the region of lower concentration down the concentration gradient as a result of their random movement

Question 2

define concentration gradient

Answer 2

difference in region of higher concentration and a region of lower concentration

Question 3

what is the relationship between the concentration gradient and rate of diffusion

Answer 3

steeper the concentration gradient, faster rate of diffusion

Question 4

explain diffusion

Answer 4

particles from a region of higher concentration will have more kinetic energy which allows them to move freely and randomly in all directions and diffuse to a region of lower concentration

Question 5

what are the factors of diffusion

Answer 5

-temperature
-concentration gradient
- distance
- surface area to volume ratio

Question 6

how does temperature affect the rate of diffusion

Answer 6

higher temperature, more kinetic energy, more movement of particles, faster rate of diffusion

Question 7

how does distance affect the rate of diffusion

Answer 7

less thickness of cell membrane, faster rate of diffusion

Question 8

how does surface area to volume ratio affect the rate of diffusion

Answer 8

higher surface area to volume ratio, faster rate of diffusion
note: therefore usually diffusion is faster in small organisms than big ones

Question 9

define osmosis

Answer 9

net movement of water molecules from a region of higher water potential to a region of lower water potential down a concentration gradient through a partially permeable cell membrane

Question 10

what is the relationship between solute concentration and water potential

Answer 10

high solute concentration, low water potential

Question 11

define solute

Answer 11

substance dissolved in a solvent

Question 12

define solvent

Answer 12

substance that a solute dissolves in

Question 13

define solution

Answer 13

solute + solvent

Question 14

define concentrated solution

Answer 14

high solute concentrated

Question 15

define diluted solution

Answer 15

low solute concentration

Question 16

define partially permeable cell membrane

Answer 16

a cell membrane that allows some substances through but not others

Question 17

define net movement

Answer 17

total movement

Question 18

define equilibrium

Answer 18

no net movement

Question 19

define isotonic, hypertonic, hypotonic

Answer 19

-isotonic - equal solute concentration = equal water potential
- hypertonic - higher solute concentration - lower water potential
- hypotonic - lower solute concentration - higher water potential

Question 20

hypertonic solutions in plants: its affects on the plant cell?

Answer 20

-net movement is in
-vacuole increase because internal pressure increases (turgor pressure) so turgid
-cytoplasm and cell membrane are pushed against cell wall because of vacuole size

Question 21

isotonic solutions in plants: its affects on the plant cell?

Answer 21

-no net movement (water moves in and out)
-vacuole is same because internal pressure (turgor pressure) is the same
- cytoplasm and cell membrane are same

Question 22

hypotonic solutions in plants: its affects on the plant cell?

Answer 22

-net movement is out
-vacuole decrease because internal pressure decreases (turgor pressure) so flaccid
-goes through plasmolysis

Question 23

define plasmolysis

Answer 23

cytoplasm and cell membrane rips away from the cell wall

Question 24

2 importance of water potential in plants

Answer 24

• support and keep the plant upright
  -brings water and minerals into root hair cell

Question 25

hypertonic solutions in animal: its affects on the animal cell?

Answer 25

-net movement is in
-goes through haemolysis
-cytoplasm increases and then comes out of cell

Question 26

isotonic solutions in animal: its affects on the animal cell?

Answer 26

-no net movement
-cell membrane and cytoplasm stays the same

Question 27

hypotonic solutions in animal: its affects on the animal cell?

Answer 27

• net movement is out
  -goes through crenation
• cytoplasm decreases in size

Question 28

define hemolysis

Answer 28

cell membrane bursts

Question 29

define crenation

Answer 29

cell membrane shrinks

Question 30

2 importance of water potential in animals

Answer 30

• keeps cell shape
• keeps it fully functioning

Question 31

define passive

Answer 31

does not require cells energy from respiration

Question 32

which 2 process are passive

Answer 32

diffusion, osmosis - they go down the concentration gradient

Question 33

define active transport

Answer 33

movement of particles through a cell membrane from a region of lower concentration to the region of higher concentration up a concentration gradient using energy from respiration

Question 34

4 key points about active transport

Answer 34

-goes up a concentration gradient
- uses energy from respiration
-always need a cell membrane
- requires special protein carriers to transfer molecules from 1 side to another

Question 35

explain how active transport if used in root hair cells

Answer 35

• mineral ions (solutes) are higher inside the cell than out so minerals cannot be absorbed by diffusion or osmosis as they occur down a concentration gradient.
• special protein carriers transfer the mineral ions into the cell using energy from respiration
• so there is an even more lower water potential in the cell so water can water enter by osmosis

Question 36

what does root hair cell need to have to do active transport

Answer 36

lots of mitochondria for reparation to releases energy for active transport

Question 37

give an example of active transport in humans

Answer 37

in the small intestine, glucose enters the body using active transport

Question 38

Explain why the red dye diffuses into the agar jelly

Answer 38

(This is diffusion, not Osmosis) The concentration of red dye if higher outside the cube, the movement of diffusion is from a region of higher concentration to a region of lower concentration down a concentration gradient through the random movement of particles so the red dye diffuses into the agar jelly.

Question 39

define active

Answer 39

require the cells energy