Download Power Point for Lesson 1-3

Enhancement of Analytical Thinking
through Scientific Investigations
Lesson 1, 2, 3
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Scientific Investigations
So many things to consider !
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Scientific Investigations
 What do you want to investigate?
(e.g. The mechanism(s) of cell movement…)
 What is your target study model?
(e.g. To study animal? Plant? Bacteria?)
 What do you want to get from the
investigations?
(e.g. Any part(s) of the cell that assist(s) cell movement?
Mechanisms underlying the observations?)
 ......
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Scientific Investigations
“ WHAT ” does matter!!!
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Scientific Investigations
After you have defined a study target (e.g. studying the
movement of animal cells), the next question is:
 Why do you want to investigate such thing?
(Significance of your study to the whole
picture?)
 Why do you think your approach will work?
 Why using such model?
 ......
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Scientific Investigations
And then…… executing your plan……
 How can you perform the investigation?
In this regard, you may need to correlate this with “What”
is the expected outcome……
 How can you set up the experiment?
 How long should the investigation be
performed? How many samples should I
include in the investigation?
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Scientific Investigations
WHAT
=
WHY
RESULT
HOW
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Scientific Investigations
The problem is: “ How ” ?
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Scientific Investigations
Qualitative Analysis
Vs
Quantitative Analysis
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Scientific Investigations
Qualitative Analysis
Example:
Color of the candy being investigated……
Detect the presence of vitamins inside a kiwi……
The kind of gas being released in a biochemical
reaction……
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Scientific Investigations
Quantitative Analysis
Example:
The amount of individual color detected in a
candy……
The number of vitamin types detected in a kiwi……
The amount of gas released in a biochemical
reaction……
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Scientific Investigations
Problem for lesson 1, 2 and 3:
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2
3
Movement of water in plant cells
What
Why
How
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Scientific Investigations
Design of Methods/Procedures
What to study? Plant cell
Study models: potatoes and/or beet root
What to study? Movement of water
How to study? (Any thing that can “push” water into
cells or “pull” water from cells?)
Why study movement of water in potatoes and beet root?
(e.g. easy to handle? Representative of unspecialized
plant cells, etc.)
Qualitative Analysis or Quantitative Analysis?
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Scientific Investigations
Think ……
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Scientific Investigations
Hint ……
Cells soaked in different
concentrations of salt solutions……?
Advantages of using potato
and beet root……?
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Scientific Investigations
Experimental result ?
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Scientific Investigations
Potato strips soaked in water ?
Potato strips soaked in diluted salt solution?
Potato strips soaked in concentrated salt solution?
Reference link:
http://en.wikipedia.org/wiki/Image:Osmotic_pressure_on_blood_cells_diagram.svg
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Osmosis
 Movement of water molecules
 Across the cell membrane which is selectively
permeable to different molecules
 From an area of high water potential (low solute
concentration) to an area of low water potential
(high solute concentration)
A RELATIVE concept of solute concentration
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Reference links on semi-permeable membrane:
http://en.wikipedia.org/wiki/Image:Semipermeable_membrane.png
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Isotonic solution
Hypotonic solution
Hypertonic solution
(a solution contains same concentration
of solute as in another solution)
(a solution contains a relatively lower
concentration of solute than another
solution)
solution
(a solution contains a relatively
higher concentration of solute
than another solution)
cell
Move into the cell
Solute (e.g. salt)
Tendency of water molecule
Move out of the cell
Water molecule
Osmosis – Biological Importance
 Cell contains a selectively permeable membrane which
allows some solutes to pass through (e.g. water
molecule) but not other large molecules (e.g.
polysaccharide, large proteins)
 Osmosis is one of the means that facilitates transport of
water in and out of the cell
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Osmosis – Biological Importance
Question:
Do you know how guard cell works?
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