movement of substances

Question 1

define diffusion?

Answer 1

net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient

Question 2

define osmosis?

Answer 2

• net movement of water molecules from a region of higher water potential to a region of loer water potential through a partially permeable membrane, down water potential gradient

Question 3

what are the similarities of diffusion and osmosis?

Answer 3

• net movement of small particles down a concentration/w.p gradient
• passive process i.e. does not require energy to occur

Question 4

what are the differences between diffusion and osmosis?

Answer 4

diffusion:
-net movement of any small molecules
- takes place with or without partially permeable membrane
osmosis:
- net movement of water molecles only
- can only take place with partially permeable membrane

Question 5

explain plant cell in higher w.p.?

Answer 5

• ___ has higher wp than cell sap
• net movement of ___
• vacuole size increases, press content against cell wall
• cell swells
• cell becomes firm and turgid

Question 6

explain plant cell in lwoer w.p.?

Answer 6

• cytoplasm and cell membrane pull away from cell wall
• plasmolysed
• soft and flaccid

Question 7

explain animal cell in higher w.p.?

Answer 7

• cytoplasm has lower wp than outside solution, water enters via osmosis
• cell expands and bursts

Question 8

explain animal cells in lower w.p.?

Answer 8

• cytoplasm has higher w.p. than surrounding solution, water leaves by osmosis
• cell shrinks and crenates

Question 9

what is turgor important in plants?

Answer 9

• maintains shape of soft tissues in plants

- loss in turgidity –> wilt

Question 10

define active transport?-

Answer 10

process by which energy is required to move particles across a membrane against concentration gradient, from a region of lower concentration to a region of higher concentration
- occurs only in respiring cells

Question 11

explain active transport in higher w.p.?

Answer 11

• strip swells, lengthens and becomes firm and turgid
• epidermal cels lined with waxy cuticle that is impermeable to water
• expansion of cortical cell > epidermal
• curl out

Question 12

explain active transport in lower wp?

Answer 12

• shrink, shorten, soft and flaccid

- curl inwards as shrinking of cortical cells > epidermal