B2.1.2 - Osmosis

Question 1

Define osmosis

Answer 1

Movement of water from less - more (concentrated solution) through partially permeable membrane

Question 2

What is a partially permeable membrane?

Answer 2

A membrane in which only certain substances can pass through

Question 3

What kind of process is osmosis?

Answer 3

Passive, no energy required

Question 4

Dilute sugar solution; ____ water concentration and ____ water _________?

Answer 4

High water concentration therefore high water potential

Question 5

Concentrated sugar solution; ___ water concentration and ___ water _________

Answer 5

A low water concentration therefore low water potential

Question 6

A dilute and concentrated solution. In osmosis, where does water go and why?

Answer 6

Water moves from dilute to concentrated
- because moves from area of high to low (water potential)
- down concentration gradient

Question 7

Osmosis in animal cells

Answer 7

1) Hypotonic: External solution more dilute, moves INTO animal cells, causing burst
2) Isotonic: Concentration in solutions on either side is the same
3) Hypertonic: External solution more concentrated, excess water OUT the cell, causing shrivel

Question 8

Osmosis in plant cells

Answer 8

1) External solution more dilute, water INTO cell and vacuole
- causes swelling, resulting in pressure (turgor)
2) External solution less dilute, water OUT cell
- becomes soft
- eventually, cell membrane moves away from cell wall and dies (plasmolysis)

Question 9

What is turgor?

Answer 9

Pressure built by swelling due to external solution more dilute in plant cell osmosis
Essential in keeping leaves/stems of plants rigid