Thursday, 25 April 2013

BIOLOGY PAPER 3


Chapter 3 – Movement of Substances across the Plasma Membrane
List of PEKA experiments:
  1. The movement of substances across a semi-permeable membrane
  2. To demonstrate the process of osmosis using simple osmometer
  3. Conducting a role-play to show the movement of substances across the plasma membrane
  4. Studying the effects of hypotonic, hypertonic and isotonic solutions on animal cells
  5. To study the effects of hypotonic, hypertonic and isotonic solutions on plant cells (cell sap of onion cells)
  6. Determining the concentration of an external solution which is isotonic to the cell sap of a plant
NumberActivity 3.1 (Experiment)
Pg.20
TitleThe movement of substances across a semi-permeable membrane
Aim / Objective of the StudyTo study the movement of substances across the Visking tubing
Problem StatementWhat factor influences the diffusion of substances through a semi-permeable membrane?
HypothesisThe diffusion of molecules through a semi-permeable membrane is based on the size of the molecule
Variables
  • Manipulated variable: Size of the solute molecules in the Visking tubing
  • Responding variable: Colour of the solution in Visking tubing
  • Fixed variable: Time, volume of solutions and surrounding temperature
Material
  • Benedict’s solution
  • 1% starch suspension
  • Iodine solution
  • 30% glucose solution
  • Distilled water
Apparatus
  • Visking tubing
  • Cotton thread
  • Test tubes
  • Beakers
  • Water bath (Bunsen burner, tripod stand & wire gauze)
Technique usedTest for the presence of starch and glucose with iodine and Benedict’s solution respectively
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NumberActivity 3.2 (Experiment)
Pg.23
TitleStudying osmosis using an osmometer
Aim / Objective of the StudyTo demonstrate the process of osmosis using simple osmometer
Problem StatementWhat substances can diffuse through a semi-permeable membrane?
HypothesisOsmosis takes place when water moves from a region of low solute concentration to a region of high solute soncentration across a semi-permeable membrane
Variables
  • Manipulated variable: Concentration of solution
  • Responding variable: Increase in the level of sucrose solution / The level of sucrose solution in the capillary tube
  • Fixed variable: Concentration of sucrose solution, surrounding temperature
Material
  • 30% sucrose solution
  • Distilled water
Apparatus
  • 25 cm capillary tube
  • Visking tubing
  • Retort stand and clamp
  • Cotton thread
  • Ruler
  • Marker pen
  • A pair of scissors
  • 250 ml beaker
  • Syringe
  • Stopwatch
Technique usedMeasure and record the increase in the height of sucrose solution with a ruler.
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NumberActivity 3.3 (Simulation)
Pg.26
TitleConducting a role-play to show the movement of substances across the plasma membrane
Aim / Objective of the Study
  • To study the movement of soluble substances across the plasma membrane through the process of passive transport.
  • To study the movement of water molecules across the plasma membrane by osmosis
  • To study the movement of substances across the plasma across the plasma membrane through the process of active transport.
Material
  • Strings
  • Cardboard
  • A pair of scissors
  • Marker pen
Apparatus-
Technique usedConduct an interesting and creative role-play to learn the movement of substances across the plasma membrane (phospholipid bilayer)
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NumberActivity 3.4 (Observation)
Pg.27
TitleStudying the effects of hypotonic, hypertonic and isotonic solutions on animal cells
Aim / Objective of the StudyTo study the effects of hypotonic, hypertonic and isotonic solutions on animal cells (red blood cells)
Material
  • Fresh chicken blood
  • 0.15 M sodium chloride solutions
  • 0.50 M sodium chloride solutions
  • Distilled water
  • Filter paper
Apparatus
  • Glass slides
  • Cover slips
  • Filter papers
  • Light microscope
  • Test tubes
  • Beakers
  • Dropper
Technique usedObserve and study the effects of hypotonic, hypertonic and isotonic solutions on animal cells from the slides by using microscope
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NumberActivity 3.5 (Observation)
Pg.28
TitleStudying the effects of hypotonic, hypertonic and isotonic solutions on plant cells
Aim / Objective of the StudyTo study the effects of hypotonic, hypertonic and isotonic solutions on plant cells (cell sap of onion cells)
Material
  • Onion bulb
  • 0.5 M sucrose solutions
  • 1.0 M sucrose solutions
  • Distilled water
Apparatus
  • Light microscope
  • Glass slides
  • Cover slips
  • Razor blade / scalpel
  • A pair of forceps
  • Mounting needle
  • Filter papers
Technique usedObserve and study the effects of hypotonic, hypertonic and isotonic solutions on plant cells from the slides by using microscope.
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NumberActivity 3.6 (Experiment)
Pg.30
TitleDetermining the concentration of an external solution which is isotonic to the cell sap of a plant
Aim / Objective of the StudyTo determine the concentration of an external solution which is isotonic to the cell sap of a plant
Problem StatementWhat is the concentration of an external (sucrose) solution which is isotonic to the cell sap of plants?
Hypothesis
  • The concentration of the solution which is isotonic to the cell sap of plant cells has no effect on the mass, length and size of plant cells.
  • 0.36 M sucrose solution is isotonic to the cell sap of plants
Variables
  • Manipulated variable: Concentration of sucrose solution
  • Responding variable: Length of potato strips / Mass of potato strips
  • Fixed variable: Volume of sucrose solution used, surrounding temperature and time
Material
  • Fresh potato
  • Distilled water
  • 0.1 M sucrose solution
  • 0.2 M sucrose solution
  • 0.3 M sucrose solution
  • 0.4 M sucrose solution
  • 0.5 M sucrose solution
  • 0.6 M sucrose solution
Apparatus
  • Petri dishes
  • A pair of forceps
  • Razor blade / Sharp scalpel
  • Cork borer
  • Ruler
  • 50 ml beakers
  • Electronic scale / electronic balance
  • Tissue paper
Technique used
  • Measure the length of potato strips with ruler
  • Determine the percentage difference in length
  • Mass of potato strips with an electronic balance
  • Determine the percentage difference in mass

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