transport in cells

Question 1

what is diffusion

Answer 1

the net movement of cells from an area of high concentration to low concentration

Question 2

solute definition

Answer 2

substance that is being dissolved in the solvent

Question 3

solvent definition

Answer 3

the substance that the solute dissolves in

Question 4

solution definition

Answer 4

mixture of solute and solvent

Question 5

factors which affect rate of diffusion

Answer 5

temperature
difference in concentration
surface area

Question 6

another way of saying difference in concentration

Answer 6

concentration gradient

Question 7

what will happen to the rate of diffusion of the concentration gradient is steep

Answer 7

it will occur quicker

Question 8

how to calculate SA : V ratio

Answer 8

1) calculate surface area: length x length x 6
2) calculate volume: length x width x height
3) divide surface area by volume

Question 9

relationship between increasing cube size and SA:V ratio

Answer 9

the smaller the cube, the larger the surface area to volume ratio

Question 10

name the process which oxygen enters the skin cells

Answer 10

diffusion

Question 11

advantage of large SA:V ratio

Answer 11

particles can diffuse quicker / more particles absorbed because more surface is exposed so particles can diffuse more efficiently.

Question 12

why can bacteria rely on diffusion for gas exchange but animals need a transport system

Answer 12

bacteria have larger surface area to volume ratio tha animals. therefore easier for gas exchange. animals have smaller ratio which slows down diffusion alot and wouldn’t be able to reach all cells

Question 13

how and why will a higher temperature affect diffusion

Answer 13

the higher temperature, the faster the rate of diffusion because particles gain more kinetic energy therefore they move around faster

Question 14

advantages of a wall being one cell thick?

Answer 14

shorter diffusion pathway

Question 15

describe how the lungs in mammals are adapted for diffusion

Answer 15

• good blood supply: maintain concentration gradeint
• millions of alveoli in each lung: large surface area
  -alveolus wall only one cell thick: shorter diffusion pathway

Question 16

describe how the small intestine is adapted for diffusion

Answer 16

-surface is folded to form villi: larger surface area
-good blood supply: maintain steep conc. gradient
-walls are one cell thick: short diffusion pathway

Question 17

describe how the gills in fish are adapted for diffusion

Answer 17

-many gill filaments: provides larger surface area
-filaments are very thin: shorter diffusion pathway
-water is pumped over gills: maintains steep conc. gradient

Question 18

describe how the roots and leaves in plants are adpated for diffusion

Answer 18

many roots - larger surface area for oxygen to be absorbed
root haircells are long: larger SA:V ratio
root hair cells are thin: shorter diffusion pathway

Question 19

what is osmosis

Answer 19

the movement of water paarticles from an area of high water potential to an area of low water potential through a partially permeable membrane

Question 20

what happens if the concentration is the same on both sides

Answer 20

no net movement of any particles as the concentration/water potential is equal

Question 21

how to calculate percentage change

Answer 21

final - initial / inital x 100

Question 22

why do we use percentage change

Answer 22

makes our answers easy to compare / comparitive

Question 23

controls or improving the potato cylinder practical

Answer 23

-making sure the potato cylinder is the same size so SA:V ratio wont be affected
-not contaminating any solutions
-making sure cylinders are left in for the same amount of time
-making sure temperature of solution is the same
-you can repeaet experiment several times

Question 24

why is it important to dry the potato

Answer 24

to make sure there isn’t any excess water affecting the mass of the potato

Question 25

what does a larger SA:V ratio mean in the potato experiment

Answer 25

more water absorbed

Question 26

what is active transport

Answer 26

when particles move against the concentration gradient through a membrane and it requires energy
(low to high)

Question 27

difference between active transport and diffusion

Answer 27

active transport requires energy whereas diffusion is a passive process
in A.T particles move against the concentration gradient where as particles in diffusion move from an area of high to low concentration