science note photosynthesis

1. PHOTOSYNTHESISPHOTOSYNTHESISPHOTOSYNTHESISPHOTOSYNTHESIS
state what photosynthesis isstate what photosynthesis is
state the factors required forstate the factors required for
photosynthesisphotosynthesis
state the products ofstate the products of
photosynthesisphotosynthesis

2. Check it!
Plants in Action
What is
the
process
that uses
the sun’s
energy
to make
simple
sugars?

3. Photosynthesis
 is the process in which green plants
use light to produce food
 green plants manufacture glucose from
water and carbon dioxide in the presence
of sunlight trapped in their chlorophyll.
 oxygen is released in the process
 glucose is stored as starch in the plant
+ +Carbon
dioxide
Water Glucose Oxygen
Light energy
from the sun
Trapped by
chlorophyll

4.  CARBON DIOXIDE
from the air
 WATER
absorb by the roots from the soil
 CHLOROPHYLL
a green pigment in the leaf of green plant
absorbs the sun’s energy
convert sun’s energy to glucose
 GLUCOSE
stored as starch in other parts of plant
 OXYGEN
release to the air
+ +

5. PlantsLeaves are green
because they
contain
the pigment:
chlorophyllchlorophyll
Leaves have aLeaves have a
large surface arealarge surface area
to absorb as muchto absorb as much
lightlight as possibleas possible
"Thanks for the Glucose!""Thanks for the Glucose!"

6. Stoma
This opening how plants exchange gases!
Check it! Can you name the two important
gases that go in and out of the leaves?
Why are theWhy are the
stomatastomata
located on thelocated on the
underside ofunderside of
leaves?leaves?

7. REQUIREMENTS OF
PHOTOSYNTHESIS
chlorophylllight
carbon
dioxide
water

8. To know whether photosynthesis
is take place in a plant :
• We can test for the presence of starch in the
leaves
Step Purpose
Boiling the leaf in the
water
To break the cell wall
Heating the leaf in
alcohol
To remove the chlorophyll in
the cells
Dipping the leaf in hot
water
To soften the leaf
Adding iodine solution
onto the leaf
To test the presence of
starch in the leaf

9. Alcohol was heated in a
beaker of hot water
Method of heating is WATER BATH
Why should the alcohol be heated in this
manner?
Alcohol is flammable, so
it will catch fire when
heated directlly

10. If starch is present in a
leaf, the leaf turns
blue black/dark blue
when tested by iodine
solution
Lets see the video

11. Determining the requirements of photosynthesis
• To investigate whether carbon dioxide
is required for photosynthesis
1. A potted plant was kept in the dark for two
days
2. A potted plant was exposed to sunlight for
two hours
3. Leaves X and Y were tested for the
presence of starch
 function potassium hydroxide
pellets to absorb carbon dioxide in
conical flask X

12. Determining the requirements
of photosynthesis
• To investigate whether carbon dioxide
is required for photosynthesis
Leaf Presence of carbon
dioxide in flask
Observation Inference
X Absent The leaf turn
brown
Starch is not
present,
photosynthesis
does not take
place
Y Present The leaf turned
blue black
Starch is
present,
photosynthesis