B2 PAG

Osmosis practical

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Graph

  • above the x-axis = gaining mass

  • cross x-axis = equilibrium(before plasmolysis occurs)

  • below x-axis = losing mass

exam tip: split graph in half when describing trends

Procedure

equipment: tile, cork borer, potato, scalpel

requirements: no skin/holes on potatoes + equal length for equal surface area, blotting to remove excess water.

  • mass itself isn’t calculated, but percentage change.

  • percentage change = difference / initial value

ALWAYS INCLUDE NUMBERS.

Other variables that the student should have controlled in this experiment:

  • temp

  • potato type

  • potato age

  • drying amount

EXAM QUESTIONS

2 marks

2 marks = 2 details about 1 component. 

2 marks

when in doubt:

list adaptations and their purposes

  • what do the adaptations allow the veins to do?

e.g

large lumen = larger volume

valves= prevent backflow as there isn’t a driving force

2 marks

3 chambers = (de)oxygenated blood mixed together

  • less oxygen reaches tissues

4 marks

2 marks

6 marks

order: body, vena cava, right atrium, tricuspid, right ventricle, semilunar, pulmonary artery, lungs

lungs, pulmonary vein, left atrium, bicuspid, left ventricle, semilunar, aorta