transport in cells

Question 1

define diffusion

Answer 1

the net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient across a semi-permeable membrane

Question 2

name the process whereby substances move in and out of a cell across the cell membrane

Answer 2

diffusion

Question 3

name 3 substances which move by diffusions within animal cells

Answer 3

1. oxygen, 2. carbon dioxide in gas exchange, 3. urea out of cells to be excreted from the body

Question 4

name 3 factors that affect the rate of diffusion

Answer 4

1. the difference in concentrations, 2. temperature, 3. surface area of the membrane

Question 5

how does the S.A: volume ratio of a single-celled organism affect transport across its cell membrane

Answer 5

it has a high S.A: volume ratio so diffusion across its membrane is usually sufficient for it to survive

Question 6

why do multicellular organisms tend to need exchange surfaces and transport systems

Answer 6

low S.A: volume, therefore cannot rely on diffusion across cell membranes

Question 7

name two common features that aid the exchange of substances in animal small intestine + lungs; fish gills; plant roots and leaves

Answer 7

1. large surface area, 2.thin membrane to provide a short diffusion path

Question 8

name two further features that aid the exchange of substances in animals but NOT plants

Answer 8

1. an efficient blood supply, 2. the ability to ventilate

Question 9

define osmosis

Answer 9

the diffusion of water from a dilute solution to a concentrated solution to a concentrated solution through a partially permeable membrane

Question 10

if an animal cell loses a lot of water, what happens

Answer 10

it shrivels and cellular reactions are slowed or stopped

Question 11

if an animal cell gains a lot of water, what happens

Answer 11

it can burst and die

Question 12

if a plant cell loses a lot of water, what happens

Answer 12

it becomes plasmolysed

Question 13

if a plant cell gains a lot of water, what happens

Answer 13

it becomes turgid

Question 14

define active transport

Answer 14

the movement of substances from a low concentration to a high concentration

Question 15

what 2 things does active transport require that diffusion doesn’t

Answer 15

1. a transport protein, 2. energy

Question 16

from what reaction does the energy required for active transport come from

Answer 16

respiration

Question 17

where does active transport happen within a cell

Answer 17

the mitochondria

Question 18

give 2 examples of where active transport is used in biology (1 plant, animal)

Answer 18

1. plant root hair cells absorbing mineral ions from the soil, 2. glucose absorption from the small intestine into the blood