This document provides an overview of plant physiology and colloidal solutions. It discusses several key topics: - Colloidal solutions exist as a colloidal state between true solutions and coarse dispersions due to particle sizes between 0.001 and 0.2 micrometers. - Preparation methods for colloids include condensation and partitioning. Properties include Brownian movement, the Tyndall effect, osmosis pressure, filtration, adsorption, and electrical charges. - Colloids can be used in agricultural applications such as the formation of deltas at river mouths and improving soil drainage and aeration through adding limestone or gypsum.

1. Physiology lecture 1
2019
Made by : Mariam Magdy Mohamad Rehan

2. CONTENTS
• Introduction
• Colloidal states
• Types of solution
• Colloidal solution
• Preparation of colloids
• Brownian movement
• Tyndall effect
• Osmosis pressure
• Filtration
• Adsorption
• Electrical charges
• Precipitation
• Formation of Delta
• Limestone

3. Introduct
ion
plant physiology: is the science that studies plant functions.
In another word, what is going on in plants that accounts
for their being ative. So many things are happening inside
plants. For example, water and dissolved materials are
moving through special transport pathways: water from soil
through roots, stems and leaves to the atmosphere, and
inorganic and organic molecules in many directions within
the plant. Thousands of kinds of chemical reactions are
under way in every living cell, transforming water, mineral
salts and gases form the environment into organized plant
tissues and organs. Collectively, plant physiology studies
all processes inside the plant starting form seed
germination till the end of the plant life cycle which give rise
to fruits and seeds production. Any advancenent occurred
in plant physiology, is usually followed by an advancement
in the related applied sciences such as agronomy and
horticulture

4. Colloidal State
It is well known that cell is the basic structure
unit of organisms. Protoplasm as the major living
component of the cell has a high viseosity is a bit
like gelatin pudding or sometimes like glue. The
viscosity of the protoplasm is due to its existence
as colloids The physical nature of protoplasm is
determined by vast areas of interfaces between
some of those special molecules especially
proteins and the protoplasmic solution in which
they are suspended. The reactions of life are
catalyzed at these enzyme interfaces.
Crucial to the physical nature of protoplasm are
membranes and particles too small to settle out
by gravity but larger than the atoms, small
molecules, and ions that form true solutes
particles which give rise to true solutions when
dissolved in water or any other suitable solvent.
.. The protoplasm of the cell is not a true
solution but exists as a colloidal in nature

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Solutes
particles are in
the form of
molecules or
atoms (ions)
usually less
than 0.001
micron one-
thousandth of
millimeter in
size.
True
solution particles consisted of
aggregates of
molecules (dispersed
or discontinuous
phase) which are
usually in the range of
between 0.001-0.2 μg
in size. These
colloidal particles are
dispersed in the
solvent (dispersion
medium or
continuous phase) in
a stable
Colloidal solution
particles consisted of aggregates of molecules (dispersed or discontinuous phase) which
are usually in the range of between 0.001-0.2 μg in size. These colloidal particles are
dispersed in the solvent (dispersion medium or continuous phase) in a stable form. 3
Fmulsions and suspensions: they are unstable (settle down) in ture. Examples of emulsions
may be prepared by vigorously shaking two immiscible liquids together such as oil and
water. An emulsion can be madestable by the addition of an emulsifying agent. These
substances generally function in either of two ways: a -They may decrease the surface
tension of the liquids, which reduces the tendency of the small droplets to combine, or b-
they may form a protective film around the droplets making it impossible for them to
combine with each other. Suspensions such as clay soil in water. Temporary suspension of
clay soil can be prepared by adding spoonful of ordinary clay soil is placed in a glass of
water and agitated thoroughly, a murky liquid, which appears uniformly brown in color,
results. If this mixture is The particles of both allowed to stand, it starts to clear rapidly. The
particles of both emulsion and suspension are usually larger than 0.2 μ in size
Emulsion and suspension

6. Types of colloidal solutions
Hydrophilic
colloids
Hydrophobic
colloids
Colloidal particles such as the gelatin have a affinity twater and
can surround itself by a huge amount Colloidal solutions are
divided to: hydration orimbibition). Imbibition makes the collides to
be in the semisolid state (gel). Thus, hot aqueous gelatin or agar
sols will set when cooied to a jilly like mass called a gel. The
conversion of a sol to a gel is called gelation. If a gel of agar or
gelatin is heated, it converts back to the sol state; a process called
solation Gelatin particles can imbibe a huge amount of water, which
sometimes is called bound The bound water contributes to the
stability of the hydrophilic colloidal solution.
the colloidal particles do not have a
strong affinity to bind water molecules
and always remain in the fluid form (Sol)

7. partitioning of larger partieles such as a small colloidal
tempora suspensions or emulsions into small colloidal
particles
Condensation methods are frequently employed in the
formation of hydrophobic colloids. These methods involve
the formation of colloidal particles by inducing a smaller
particles such as true solutes to aggregate and they erally
employ chemical reactions. For example, if a concentrated
solution of ferric chloride is mixed with hot water, a dark red
colloidal suspension of ferric hydroxide results. The FeCl
ionizes and hydrolysis of the ferric ion takes place to form
ferric hydroxide Fe(OH) Aggregation of Fe(OH)s molecules
form the colloidal particles of the dispersed phase.
FeCl +31H O→ Fe(OH) +3(H +CI)
2- Partitioning method:
Preparation of colloids
1- Condensation method:

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Properties of colloids

9. When colloidal particles are
observed in a light inicroscope
by a strong illumination from
one side, they appear as Point
of light They seem to dance
around with many random hops
per second. Thris phenomenon
is called Brownian movement.
Brownian
movement
Properties of colloids

10. Properties of colloids
When a powerful narrow beam
of light is passed through a
colloidal solution in a glass jar,
we can easily see the light path
due the scattering of light on
the colloidal particles. This
phenomenon cannot be
observed in true solutions
however.
Tyndall effect

11. Properties of colloids
Colloidal solutions have far
less osmotic pressure than true
solutes. This is mainly due to
their far less number of
Osmotic pressure is particles
as compared to true solutes.
proportional the number of
particles (ions, molecules or
colloidal aggregates) in the
solution or suspension.
Osmosis
pressure

12. Properties of colloids Most colloidal particles pass through filter paper but cannot
pass through cellophane (differential or smipermeable
membrane), while true solutes can. Colloidal particles are
too large to pass through cellophane. cellophane the
differential permeability of cellophane membrane can be
used to separate colloids particles from true solutes Such
process is called dialysis or membrane dialysis. Different
structural proteins as macromolecules can be separated
from each other by using different molecular size cut off
dialysis membranes Dialysis membranes are commercially
available in different molecular size cut off such as
3000,6000 and 12000 (Dalton) Commercially available
enzymes as macromolecule proteins can be shipped long
distances when preserved in 0.5M sucrose solution Upon
use in the laboratory these enzymes
Filtratio
n
can be separated from sucrose solution through membrane dialysis Colloidal particles can be separated
from their dispersion medium through the use of commercially available ultrafilters. Ultrailters composed of
biologically inert cellulose esters (Millipore filters have been constructed with pore sizes ranging from 10
mμ to 5 Since colloidal particles range in size from 1 to 200 mμ, it is easy to see that separation of the two
phases of colloidal suspension could be accomplished in most cases by these filters..

13. Properties of colloids
The tendency of molecules or ions to adhere to the surface of
certain solids or liquids is known as adsorptiona Although
colloidal particles are small, each is large enough to present a
surface (layer of atoms) to surrounding water molecules and
solute particles. Because of the small size of colloidal
particles, their total surface in a given volume is relatively
huge. It is not surprising therefore, that the adsorptive
capacity of a colloidal suspension is extremely high for a
given weight of colloidal particles. The reactions of life occur
on surfaces, and it is easy to see relatively large surfaces can
exist in a single cell. It is aiso easy to see how hydration
(matric forces) can influence the water status of cells and
soils (exists in colloidal form).
Adsorption

14. The colloidal particles in the colloidal solutions are aniformly surrounded
by one kind of an electric charge. For example, the particles of a ferric
hydroxide colloidal suspension al earry a positive charge. The charges
found on colloidal particles result from the adsorption of free ions in the
dispersion medium, The preferential adsorption of positive ions by a
colloidal particle will give a positive charge, whereas the preferential
adsorption of negative ions results in producing a negatively charged
particles. In the ferric hydroxide colloidal suspension all of the particles
have a positive charge because the ferric ion (Fe), released in the
ionization of FeCl, is preferentially adsorbed. The free chlorine ions (CI)
are attracted to the positive charge on the particles, and also they
accumulate secondarily around the particles forming what is known as a
electrical double layer. Colloid particles can migrate in an electrical field
according to their kind of electric charge. This phenomenon is called
electrophoresis. The fact that all colloidal particles earry the same
electric charges is mainly responsible for the stabitity of colloidal
suspension. Units of like charges repel each other. If it were not for this,
the colloidal particles would collide and aggregate and eventually
precipitate out of suspension.
Properties of
colloids
Electrical
charges

15. Properties of colloids
Distruction or removal of the electric charge will cause the
dispersed particles of a colloidal suspension to collide
aggregate, and finally to precipitate out of suspension. This
may be accomplished by the addition of an electrolyte.
Besides the removal of electric charge, in hydrophilic
colloids, the removal of the bound water is accomplished by
the addition of a dehydrating agent such as ethyl icohol.
When solid salt of an electrolyte such as ammonium sulfate is
added to hydophilic solution, it works as a dehydrating agent
and accompanied by the removal the electric charge at the
same time (double action)
Precipitation

16. Agricultural applications

17. Formation of delta agricultural soil at the mouth of the rivers
through precipitation of silt particles carried by the river
water as they meet with ions from the sea or ocean water.
Formation of Delta

18. Application of limestone or gypsum (calcium sulfate) precipitate silt particles and resulted in a
larger particles. This may improve both water drainage i.e. deeper water table and aeration of
the plant roots
Limesto
ne

19. 2019
THANK YOU
Made by :Mariam Magdy Mohamad Rehan