DIFFUSION, OSMOSIS, TURGIDITY AND PLASMOLYSIS
The cell has a territorial environment in which it operates. There are activities that involved in making sure that the cell itself functions effectively. These environmental factors that play a vital role in the effective running or functioning of the cell are as follows
Diffusion is defined as the process by which molecules ions of a particular substance either gas or liquid from a region of high concentration to a place of lower concentration until they are evenly distributed. The various substances involved in the process of diffusion can either be liquid, gases or solid.
FACTORS AFFECTING THE RATE DIFFUSION
STATE OF MATTER:
diffusion varies with the various states matter. The diffusion of gases is always faster than that of liquids because the molecules of gas is more free and loosely joined
the nature or the size of the molecules affects the rate of diffusion. In practical terms, the smaller the size of the molecules involved the faster the rate of diffusion. The larger the molecules the slower the rate of diffusion.
DIFFERENCES IN CONCENTRATION:
for diffusion to take place in medium, there must be differences in the concentration in two areas. The greater the rate of differences in concentration between the molecules the faster the rate of diffusion
high temperature increases the speed at which molecules move during diffusion. Thus the higher the temperature , the faster the rate of diffusion
IMPORTANCE OF DIFFUSION TO ANIMALS
Diffusion plays an important role in the life of animals through the following ways
i. Diffusion helps in the intake of oxygen or nutrients from mother to foetus in the womb through the placenta
ii. Gaseous exchange in mammals takes place in the lungs during respiration through diffusion
iii. Gaseous exchange in many cells and organisms like Amoeba which takes in oxygen and gives out carbon dioxide through diffusion
iv. Diffusion helps in the movement of carbon dioxide from the lungs capillaries in the air sac
DON’T FORGET TO READ MY BLOG ON CLASSIFICATION OF FARM ANIMALS HERE
IMPORTANCE OF DIFFUSION TO FLOWERING PLANTS
Diffusion is important to flowering plants in the following ways
i. Diffusion helps in the movement of carbon dioxide through the stomata into the leaves during respiration
ii. Diffusion helps in the movement of carbon dioxide through the stomata to the leaves during photosynthesis
iii. Water vapour leaving the leaves during transpiration is through diffusion
iv. Diffusion helps in the movement of oxygen through the stomata during respiration
DIFFUSION IN NATURE OR NON –LIVING CONDITIONS
Diffusion is also very important in nature or non-living conditions through the following process
i. The spread of smell or odour of perfume from a person or within a room
ii. Diffusion of molecules in iodine, potassium permanganate and copper
iii. Diffusion helps in the spread of insecticide in a room
iv. Diffusion helps in the spread of gases released from the anus
DEFINITION OF OSMOSIS
Osmosis is defined as the flow of water or solvent molecules from a region of dilute or weaker solution to a region of concentrated or stronger solution through a selectively permeable membrane.
IT SHOULD BE NOTED THAT OSMOSIS IS A SPECIAL TYPE OF DIFFUSION
here is a little extras from wikipedia. to read the rest articles follow here
THIS ARTICLE IS ABOUT THE CHEMICAL PROCESS. FOR THE OZZY OSBOURNE ALBUM, SEE OSMOSIS. FOR OTHER USES, SEE OSMOSIS (DISAMBIGUATION).
THE PROCESS OF OSMOSIS OVER A SEMI-PERMEABLE MEMBRANE. THE BLUE DOTS REPRESENT PARTICLES DRIVING THE OSMOTIC GRADIENT.
 IS THE SPONTANEOUS NET MOVEMENT OF SOLVENT MOLECULES THROUGH A SELECTIVELY PERMEABLE MEMBRANE INTO A REGION OF HIGHER SOLUTE CONCENTRATION, IN THE DIRECTION THAT TENDS TO EQUALIZE THE SOLUTE CONCENTRATIONS ON THE TWO SIDES.
IT MAY ALSO BE USED TO DESCRIBE A PHYSICAL PROCESS IN WHICH ANY SOLVENT MOVES ACROSS A SELECTIVELY PERMEABLE MEMBRANE (PERMEABLE TO THE SOLVENT, BUT NOT THE SOLUTE) SEPARATING TWO SOLUTIONS OF DIFFERENT CONCENTRATIONS.
 OSMOSIS CAN BE MADE TO DO WORK.
IS DEFINED AS THE EXTERNAL PRESSURE REQUIRED TO BE APPLIED SO THAT THERE IS NO NET MOVEMENT OF SOLVENT ACROSS THE MEMBRANE. OSMOTIC PRESSURE IS A COLLIGATIVE PROPERTY, MEANING THAT THE OSMOTIC PRESSURE DEPENDS ON THE MOLAR CONCENTRATION OF THE SOLUTE BUT NOT ON ITS IDENTITY.
OSMOSIS IS A VITAL PROCESS IN BIOLOGICAL SYSTEMS, AS BIOLOGICAL MEMBRANES ARE SEMIPERMEABLE.
IN GENERAL, THESE MEMBRANES ARE IMPERMEABLE TO LARGE AND POLAR MOLECULES, SUCH AS IONS, PROTEINS, AND POLYSACCHARIDES, WHILE BEING PERMEABLE TO NON-POLAR OR HYDROPHOBIC MOLECULES LIKE LIPIDS AS WELL AS TO SMALL MOLECULES LIKE OXYGEN, CARBON DIOXIDE, NITROGEN, AND NITRIC OXIDE.
PERMEABILITY DEPENDS ON SOLUBILITY, CHARGE, OR CHEMISTRY, AS WELL AS SOLUTE SIZE. WATER MOLECULES TRAVEL THROUGH THE PLASMA MEMBRANE, TONOPLAST MEMBRANE (VACUOLE) OR PROTOPLAST BY DIFFUSING ACROSS THE PHOSPHOLIPID BILAYER VIA AQUAPORINS (SMALL TRANSMEMBRANE PROTEINS SIMILAR TO THOSE RESPONSIBLE FOR FACILITATED DIFFUSION AND ION CHANNELS).
OSMOSIS PROVIDES THE PRIMARY MEANS BY WHICH WATER IS TRANSPORTED INTO AND OUT OF CELLS.
THE TURGOR PRESSURE OF A CELL IS LARGELY MAINTAINED BY OSMOSIS ACROSS THE CELL MEMBRANE BETWEEN THE CELL INTERIOR AND ITS RELATIVELY HYPOTONIC ENVIRONMENT.
CONDITIONS NECESSARY FOR OSMOSIS TO TAKE PLACE
There are three major conditions necessary for osmosis to take place, they are as follows
i. Presence of a solution e.g. salt or sugar solutions
ii. Presence of a weaker solution like distilled water
iii. Presence of a selectively or differentially permeable membrane
LIVING CELLS AS OSMOMETER
In Osmosis, there are usually two solutions which are separated by a differentially permeable membrane. The weaker solution is said to be hypotonic while the stronger solution is said to be hypertonic. When both solutions the same concentration, they are said to be Isotonic
WHAT IS HYPOTONIC?
A solution is said to be hypotonic when a cell of a living plant or animal is surrounded by pure water or solution whose solute concentration is lower, water passes into the cell by Osmosis
WHAT IS ISOTONIC?
A solution is said to be Isotonic when the solute concentration of the cell and its surrounding medium are the same
iii. WHAT IS HYPERTONIC?
A SOLUTION IS SAID TO BE HYPERTONIC WHEN THE CELL IS SURROUNDED BY A STRONGER SOLUTION, AND THE CELL LOSES WATER TO ITS SURROUNDING. THE SHRINKING OF THE CELL IS AS A RESULT OF THE SURROUNDING SOLUTION SAID TO BE HYPERTONIC
DIFFERENCES BETWEEN OSMOSIS AND DIFFUSION
i. Diffusion occurs in gases and liquids————Osmosis occurs only in liquids mediums
ii. Differentially permeable membrane not required———–permeable membrane is required
iii. Diffusion occurs in living and non-ling organisms————-occurs naturally in living organisms
What is plasmolysis?
Plasmolysis is defined as the outward movement and flow of water from living cell when they are placed in a hypertonic solution. Plasmolysis is often regarded as the opposite of Osmosis.
The process of plasmolysis involves the withdrawal of water from living cells up to the extent that it will result in the pulling away of the cytoplasm from the cell membrane or cell wall. As a result of this, the cytoplasm will shrink and the whole cell collapse.
When this happens, the cell is said to be plasmolysed. This will eventually lead to wilting or death of the plant.
PROCESS OF PLASMOLYSIS IN PLANT CELL
When a living plant cell is placed or surrounded a sugar or salt solution, a more concentrated or hypertonic solution than the cell sap, water will be lost from the cell to the stronger solution resulting in Exosmosis. As a result of this, the vacuoles will shrink, pulling the cytoplasm away from the membrane or the cell wall.
EXPERIMENT TO DEMONSTRATE PLASMOLYSIS USING SPIROGYRA FILAMENT
Place a piece of spirogyra filament on a glass slide containing few drops of water, covered with cover slip. Observe the set up under a microscope. The cell is noticed to normal or turgid
Add a few drops of concentrated salt or sugar solution on the tissue. Leave it for at least five minutes, and observe it under a microscope. It will be observed that the cytoplasm is drawn away from the cell wall showing that Exosmosis has occurred or the cells have been plasmolysed
WHAT IS HAEMOLYSIS?
Haemolysis is defined as the process by which red blood cells corpuscles become split or burst as a result of too much water passing into it.
This situation will occur when red blood cell is placed in a weaker or hypertonic solution where the red blood cell take in water, become swollen and may even burst.
EXPERIMENT TO DEMONSTRATE HAEMOLYSIS USING THE RED BLOOD CELL
When the red blood cell is placed or surrounded by distilled water, or hypertonic solution, water passes into the cell showing that osmosis has taken place. This then result in the increase in size of the cell or the cell becomes turgid or swollen. For the fact that the distilled water is hypertonic or less in concentration than the red blood cell, water is absolved by the cell. This will make the cell and burst.
SIMILARITIES BETWEEN PLASMOLYSIS AND HAEMOLYSIS
I. They both occur in living cells
II. Both processes can lead to the death of the cells involved
III. Cells expand initially as more water comes into the cells in both process
DIFFERENCES BETWEEN PLASMOLYSIS AND HAEMOLYSIS
I. Plasmolysis occurs in plant cell————-Haemolysis occur in red blood cells
II. Plant cell shrink———————————-red blood cell bursts in Haemolysis
III. Plasmolysis occurs in hypotonic solution——-Haemolysis occurs in Hypertonic solution
WHAT IS TURGIDITY?
Turgidity is defined as the condition in which cell absorbs plenty of water up to a point where the cell if fully stretched. At this point the cell is said to be turgid. Turgidity occurs when a cell is placed in a hypotonic solution-distilled water. As a result of the fact that the cytoplasm solution is stronger than the water, the cell absolves water and becomes turgid.
Turgidity is important to plants because it makes them stand erect, gives support to the stem, leaves, flowers and guards the cells
Flaccidity if defined as the condition in which plants lose water to their surroundings faster than they can absorb. When plants loses more water, it is said to be flaccid.
Flaccidity normally occurs when there is no water in the soil or during drought. Such continuous loss of water the surroundings
may cause the plant to wilt or even die if the process continues for a long time
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