Photosynthesis ????

1
Photosynthesis????

• ???????????
• ???

2
Quick Revision Where does photosynthesis occur?
Leaf ??
X-section ??? Palisade mesophyll ????
Chloroplast???
3
Warm-up Questions
The following microphotograph is a transverse
section of a
A. stem.
B. leaf.
C. root.
4
Sorry, youve got the wrong answer!!!
Can you find cortex (??), which is very obvious
in a cross-section of a stem ?
Try again...
5
Sorry, youve got the wrong answer!!!
Are the vascular bundles(???) concentrated in the
centre of the section ?
Try again...
6
Congratulations!!!
Youve got the correct answer!!!
Go to next question...
7
Warm-up Questions
Here is a transverse section of a leaf. It is a
leaf of
A. monocotyledonous xerophyte
B. dicotyledonous hydrophyte
C. dicotyledonous mesophyte
8
Sorry, youve got the wrong answer!!!
Xerophyte is a kind of plants adapted in desert
habitat.
Try again...
9
Sorry, youve got the wrong answer!!!
Hydrophyte is a kind of plants adapted in aquatic
habitat.
Try again...
10
Congratulations!!!
Youve got the correct answer!!!
Bonus .
11
Bonus
Give two reasons to support your answer. Hints
-----
12
Definition of Photosynthesis
Photosynthesis is a process by which green
plants use sunlight trapped by chlorophyll to
produce organic compounds (carbodyrate) from
carbon dioxide and water, oxygen is released as
by-product.
13
Summary of Photosynthesis
Sunlight ??
Carbon dioxide ????
Water ?
Chlorophyll ???
Oxygen ?
Glucose ???
14
Experiments
light
1.To show that starch is produced during
Photosynthesis.
15
Four steps
1.Boil the leaf in water, why ? 2.Boil the leaf
in alcohol, why ? 3.Wash the leaf in warm water,
why ? 4.Add iodine solution to the leaf,
what is the expected result ?
16
Experiments
light
Aim To show that light is necessary for
Photosynthesis. Control Do we need a Control
for this experiment ?
17
Experiments
light
Aim To show that chlorophyll is necessary for
photosynthesis.
Control Do we need a Control for this
experiment ?
Any Assumption ?
18
Experiments
light
Aim To show that carbon dioxide is necessary
for photosynthesis.
Any Criticism on the set-up ? (Think about
Variables.)
19
light
Is it better ?
20
Experiments
light
Aim To show that oxygen is produced
during photosynthesis.
21
Logics
In an experiment, think about Aim and
objective Control experiment Dependent
variables Independent variables Assumptions Limita
tions
22
Limitations of the summary equation
light
6CO2 6H2O C6H12O6 6O2
chlorophyll
1.Photosynthesis is a two phase process,
which cannot be shown in the equation. 2.Source
of oxygen cannot be shown. 3.Glucose is not the
first product of photosynthesis.
23
Photosynthesis involves two stages

• Light reaction
• light is necessary
• light split water into hydrogen and oxygen
• Dark reaction
• light is not necessary
• hydrogen is used to reduce carbon dioxide
  to carbodyrate

24
Light reaction
Light ??
Water ?
Oxygen ?
Hydrogen? (??)
Chlorophyll ???
Released from the plant
Dark reaction
25
Dark reaction
Hydrogen? (??)
Carbohydrate ?????
Carbon dioxide ????
26
This powerpoint was kindly donated to
www.worldofteaching.com http//www.worldofteac
hing.com is home to over a thousand powerpoints
submitted by teachers. This is a completely free
site and requires no registration. Please visit
and I hope it will help in your teaching.