chapter 2 - movement of substances

Question 1

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

factors affecting rate of diffusion

Answer 2

faster rate of diffusion
- steeper concentration gradient
- shorter diffusion distance
- greater surface area to volume ratio

Question 3

characteristics of diffusion

Answer 3

• passive process
• can occur with or without membrane
• involves any molecules
• down a concentration gradient

Question 4

osmosis

Answer 4

net movement of water molecules from a region of higher water potential to a region with lower water potential across a partially permeable membrane, down a water potential gradient

Question 5

characteristics of osmosis

Answer 5

• passive process
• only in prescence of partially permeable membrane
• involves only water molecules
• down a water potential gradient

Question 6

animal cell placed in the solution of higher water potential

Answer 6

solution has a higher water potential than animal cell’s cytoplasm. net movement of water molecules from solution of higher water potential to animal cell’s cytoplasm, down a water potential gradient, across the animal cell’s partially permeable cell membrane, via osmosis. the cell expands and bursts

Question 7

animal cell placed in solution with lower water potential

Answer 7

the animal cell’s cytoplasm has a higher water potential than the solution with lower potential. net movement of water molecules from the animal cell’s cytoplasm to the solution, down a water potential gradient, across the animal cells’s partially permeable cell membrane via osmosis. animal cell becomes crenated, cell shrinks in size and tiny spikes appear on cell membrane

Question 8

plant cell placed in solution of higher water potential

Answer 8

solution has a higher water potential than plant cell’s cell sap. net movement of water molecules from solution of higher water potential to plant cell’s cell sap, down a water potential gradient, across the plant cell’s partially permeable cell membrane, via osmosis. the cell becomes turgid and vacuole increases in size

Question 9

plant cell placed in solution with lower water potential

Answer 9

the plant cell’s cell sap has a higher water potential than the solution with lower potential. net movement of water molecules from the plant cell’s cell sap to the solution, down a water potential gradient, across the plant cell’s partially permeable cell membrane via osmosis. plant cell becomes flaccid and plasmolysed, cell membrane and cytoplasm shrink away from the cell wall

Question 10

active transport

Answer 10

energy is used to move particles of a substance across a living membrane agaisnt its concentration gradient, from a region of lower concentration to a region of higher concentration.

Question 11

active transport in plants

Answer 11

since acctive transport requires energy, active transport will only occur in repiring living cells, where there is an abundance of mitochondria to release large amount of energy through the oxidation of glucose. when there is a higher concentration of dissolved mineral salts in the root hair cells’ cell sap as compared to the soil, the minerals will be absorbed by root hair cells via active transport

Question 12

characteristics of active transport

Answer 12

• active transport
• occurs in prescence of living membrane
• involves any molecules
• against concentration gradient