Plant nutrition

1
Plant nutrition

• Method of nutrition used by plants is
  photosynthesis.
• Raw materials needed
• CO2 and H2O
• Conditions present
• chlorophyll and sunlight

2
Leaf Structure
3
To show presence of stomata
4
Section of leaf
5
Structure of Stomata
6
Stomata open and close
close
open
7
Photosynthesis

• Summary equation
• CO2 H2O C6H12O6 O2
• Products of photosynthesis
• 1 sugar (built up to starch for storage)
• 2 oxygen.

Light, chlorophyll
8
How to show that plant is photosynthesising

• Test for presence of starch .
• Photosynthesis is the only way a plant can
  produce this.
• How to test for starch?
• Use iodine solution.

9
To test a leaf for starch

• Boil leaf in water.
• Boil leaf in alcohol to remove chlorophyll
• Wash in water .
• Why must the leaf be boiled in water?
• To allow I2 solution to penetrate cells.
• Why must the leaf be decolorised?
• To allow blue black colour to show up.
• Why must the leaf be washed in water?
• To soften it.

10
To show that chlorophyll is needed

• 1 Destarch a potted plant with variegated
• leaf by
• 2 placing the plant in the light for 48 hrs.
• 3 Remove a leaf test for starch.
• 4 Only the green parts of the leaf give a
• dark blue (blue- black) colour with I2
• solution.

11
To show that light is needed

• Destarch 2 potted plants.
• Leave 1 in the dark (experimental).
• Put one in the light (control).
• All other conditions must be the same.
• Leave the 2 plants for 48 hrs.
• Take a leaf from each plant to test for
  starch
• In which plant will starch be present?

12
To show that CO2 is needed for photosynthesis

• Destarch 2 potted plants.
• Place 1 plant in a bell jar with a dish of
• soda lime to absorb CO2.
• Place the other in a bell jar without CO2
• (Which plant is the control?)
• All other conditions should be the same for both
  plants.
• Leave the plants for 48 hrs, then test the leaf
  for
• starch (with I2 solution).
• In which plant will starch be present?

13
To show that O2 is given off during photosynthesis

1. Place some water plants eg hydrilla under an
   inverted filter funnel in a beaker of H2O.
2. Dissolve some NaHCO3 in the H2O ( to provide CO2
   to the plant.
3. Place the apparatus in sunlight for 6 hrs.
4. Set up a control in the same way, but left in the
   dark.
5. Gas bubbles will only be released from the plant
   placed in sunlight.
6. This gas rekindles a glowing splint.

14
What happens to sugar formed in photosynthesis

• 1 Broken down in respiration.
• 2 Built up into starch for storage.
• 3 Turned into fats for storage other uses.
• 4 Combined with N2 to form proteins.
• 5 Moved to other parts of the plant.

15
photosynthesis
16
To test for presence of starch using I2 solution
17
To show that CO2 is needed for photosynthesis
18
To show that chlorophyll is needed.Use
variegated leaf.
19
To show that O2 is given off
20
To show that O2 is given off.Glowing splint
rekindles.