Nutrition in Plants - PowerPoint by liuqingyan

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									           Review Question
• Which mode of nutrition do the green plants
  carry out?

A.    Autotrophic nutrition

B.    Heterotrophic nutrition
         Sorry! You’re wrong!
• Heterotrophic nutrition is the mode of
  nutrition in which organisms have to depend
  on other organisms or dead organic matters as
  their food sources. Green plants, however,
  can make organic food by themselves using
  simple inorganic substances.

                      Back
              Very Good!
• Autotrophic nutrition is the mode of
  nutrition in which organisms can make
  organic food by themselves using simple
  inorganic substances.
• The process by which the green plants
  obtain nutrients is called :-
           Photosynthesis
    Overview of nutrition in green
               plants
carbon dioxide and water
               photosynthesis
carbohydrates (e.g. glucose)           mineral salts
                                    (e.g. NO3-, SO42-)

 fatty acids      glycerol     amino acids      water

 nutrients for plants can be used to produce all
    plant materials (e.g. enzymes, cell wall,
    cytoplasm, cell membrane, chlorophyll)
      Nature of photosynthesis
• Anabolic process
• Takes place in chloroplast
• Necessary factors :
•Carbon dioxide
•Water
•Sunlight
•Chlorophyll
Light
Light Absorption Spectrum

Why leave looked green?
Different pigments in absorption
            spectrum
How light energy used?
              Light reaction
• Light energy is trapped by chlorophyll in
  chloroplast
                   Light reaction
Light energy absorbed by chlorophyll splits water molecules into
hydrogen and oxygen
                   Light reaction
Oxygen is released as a gas through stoma to outside
                   Light reaction
Hydrogen is fed into dark reaction
                 Dark reaction
• No formed required; can combines with CO2 to form
Water islight isas a by-product
Hydrogen produced in light reactiontake place either in
carbohydrates
  light or darkness
Chlorophyll Structure
    Light Reaction

Photophosphorylation
Cyclic photophosphorylation
Dark Reaction

 M. Calvin
Calvin Cycle
CHLOROPLAST
Fate of product of photosynthesis




                          Kreb
                          cycle
Factors affect rate of
  photosynthesis
    Expt. Show effect of factors


Conc. Of                 Distance

NaHCO3



                           Heat
   Fate of carbohydrate products in
               the plant
carbon dioxide and water
               photosynthesis
carbohydrates (e.g. glucose)           mineral salts
                                    (e.g. NO3-, SO42-)

 fatty acids      glycerol     amino acids      water
   Fate of carbohydrate products in
               the plant
 carbon dioxide and water
               photosynthesis
carbohydrates (e.g. glucose)           mineral salts
                                    (e.g. NO3-, SO42-)

 fatty acids      glycerol     amino acids      water

release energy by respiration
   Fate of carbohydrate products in
               the plant
 carbon dioxide and water
               photosynthesis
carbohydrates (e.g. glucose)           mineral salts
                                    (e.g. NO3-, SO42-)

 fatty acids      glycerol     amino acids      water


convert into starch for storage
   Fate of carbohydrate products in
               the plant
 carbon dioxide and water
               photosynthesis
carbohydrates (e.g. glucose)           mineral salts
                                    (e.g. NO3-, SO42-)

 fatty acids      glycerol     amino acids      water


change into sucrose and is transported
to other parts through phloem
   Fate of carbohydrate products in
               the plant
carbon dioxide and water
               photosynthesis
carbohydrates (e.g. glucose)           mineral salts
                                    (e.g. NO3-, SO42-)

 fatty acids      glycerol     amino acids      water



 combine to form fats and oils to form
 cell membranes and as a food store
   Fate of carbohydrate products in
               the plant
carbon dioxide and water
               photosynthesis
carbohydrates (e.g. glucose)           mineral salts
                                    (e.g. NO3-, SO42-)

 fatty acids      glycerol     amino acids      water



                     join together to become
                     protein molecules
  Mineral requirements in plants
• In order to synthesize amino acids, nitrate
  ions must be taken into the plant from the
  soil through the root
• Other minerals are also necessary to
  maintain the life of the plant
    Expt. Show effect of minerals



Different
Nutrient
added
    The importance of nitrogen
• For synthesis of proteins, chlorophyll, etc.
• Taken in the form of nitrate ions
• Deficiency symptoms:
  – Little growth (no protein made)
  – Yellowing of leaves (chlorophyll made)
  The importance of magnesium
• Essential component of chlorophyll
• Deficiency symptoms:
  – Yellowing of leaves (no chlorophyll made)
  – Poor growth (no food manufactured because
    of lack of chlorophyll)
  Use of fertilizers in agriculture
• Continuous harvesting crops removes the
  valuable mineral salts from soil
  Fertilizers are added to replace such loss
• Two kinds of fertilizers:
  – Natural fertilizers
  – Chemical fertilizers
          Natural fertilizers
• From manure
• Organic compounds in it are decomposed
  by bacteria in soil to form mineral salts
         Chemical fertilizers
• Mainly nitrogenous and phosphorous
  compounds manufactured artificially
    Comparison between natural and
         chemical fertilizers
Natural fertilizers     Chemical fertilizers
Very cheap              More expensive
Contain humus which     No humus so cannot
can improve soil        improve soil texture
texture
Less soluble in water   Very soluble in water
so less likely to be    so more likely to be
washed away             washed away
    Comparison between natural and
         chemical fertilizers
Natural fertilizers        Chemical fertilizers
Less soluble in water      Very soluble in water
so more difficult to be    so easier to be
absorbed                   absorbed

Time is needed for the     More readily to be
decomposition to           used by the plants
complete before
nutrient is available to
plants
   Importance of photosynthesis
• It is the only method to convert energy in
  sunlight into chemical energy
  – Animals have to depend on plants for food
    supply
  – Plants: producers; animals : consumers
• To maintain a constant oxygen level in the
  atmosphere
Experiments to test for necessary factors
          of photosynthesis

 • Experimental set-up: To remove the factor
   under study and to see if photosynthesis still
   takes place
 • Control set-up: Identical to experimental
   set-up except that the missing factor is
   present
A set-up to study whether light is
  necessary for photosynthesis


Region B

Region A                  leafy shoot



water
Which is the control, the exposed region
      A or the shaded region B?
  What is the purpose of setting up
             region A?
 • As a control
    Too simple and not explicit!
To show that photosynthesis cannot take place in the absence of
light
                Destarching
• Reason:
  – To avoid any existing starch in the leaves
    interfering with the result, and to show that any
    starch found after the experiment was produced
    during the period of investigation
• Method:
  – By placing the plant in dark for at least 24
    hours
      Parts of plant where
   photosynthesis takes place
• Places where chloroplasts are found
• Mainly in the leaf because
  – it contains a lot of chloroplasts
  – it is well adapted for performing photosynthesis
Cross-section of a dicot leaf
                       upper
                       epidermis
                       protect
                       internal
                       tissues
                       from
                       mechanical
                       damage and
                       bacterial
                       and fungal
                       invasion
Cross-section of a dicot leaf
                       Cuticle
                       • a waxy
                         layer
                       • prevent
                         water loss
                         from the
                         leaf
                         surface
Cross-section of a dicot leaf




                       mesophyll
Cross-section of a dicot leaf


                       palisade
                       mesophyll
                       columnarmany
                       contains cells
                       closely packed
                       chloroplasts
                       together
                       absorb light
                       more
                       efficiently
Cross-section of a dicot leaf
                       irregular cells
                       loosely packed
                       together to leave
                       numerous large
                       air spaces
                       allow rapid
                       diffusion of
                       gases
                       less chloroplasts
                       for
                       throughout the
                       photosynthesis
                       leaf
                        spongy
                        mesophyll
Cross-section of a dicot leaf



                       same as
                       upper
                       epidermis
                       except the
                       cuticle is
                       thinner
                      lower
                      epidermis
Cross-section of a dicot leaf



                      stoma
                      opening which
                      allows gases
                      to pass
                      through it to
                      go into or out
                      of the leaf
Cross-section of a dicot leaf




                       guard cells
                       control the
                       size of stoma
Cross-section of a dicot leaf


                        vascular
                        bundle
                        (vein)
Cross-section of a dicot leaf


                       xylem
                       •to transport
                        water and
                        mineral
                        salts
                        towards the
                        leaf
Cross-section of a dicot leaf



                       phloem
                       •to transport
                        organic
                        substances
                        away from
                        the leaf
Adaptation of leaf to
  photosynthesis
              Upper epidermis
              and cuticle is
              transparent
              Allows most
              light to pass to
              photosynthetic
              mesophyll
              tissues
Adaptation of leaf to
  photosynthesis
              Palisade
              mesophyll cells
              are closely
              packed and
              contain many
              chloroplasts
              To carry out
              photosynthesis
              more efficiently
Adaptation of leaf to
  photosynthesis
              Spongy
              mesophyll cells
              are loosely
              packed with
              numerous large
              air spaces
              To allow rapid
              diffusion of gases
              throughout the
              leaf
Adaptation of leaf to
  photosynthesis


              Numerous
              stomata on
              lower epidermis
              To allow rapid
              gaseous
              exchange with
              the atmosphere
Adaptation of leaf to
  photosynthesis
             Extensive vein
               system
             • Allow sufficient
               water to reach
               the cells in the
               leaf
             • To carry food
               away from them
               to other parts of
               the plant
   CHEMOSYNTHSIS

•Iron bacteria
•Colorless sulphur bacteria
•Nitrifying bacteria
Iron bacteria
Nitrifying bacteria

								
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