Osmosis Is Very Essential for the Biological Systems - Lab Report Example

?Osmosis Lab Report Osmosis and diffusion are the very essential at both the organ and cellular levels. Osmosis is the movement of the solvent molecules from the region of higher concentration to the region of lower concentration through a semi permeable membrane. In this experiment varying glucose concentrations of 0%, 10%, 20% and 30% were placed in the cellophane bags against the distilled water. After twenty minutes, increase in the weight of the bags by 2.2%, 14.5%, 20.5% and 23.9% was observed for the glucose concentrations respectively. This indicates that if the solute concentration is higher then the movement of the solvent molecules will be higher. This is due to the effect of the thermodynamic property of the solutions to reach equal concentration. Introduction: Cells require the movement of the chemicals inside and outside the cell for their survival. Cells require the movement of mainly the solute and solvent molecules inside and out of the cells for their proper functioning. The movement of the molecules occurs by active and passive processes. If the cell uses ATP for the transport of the molecules then it is termed as active process and if the molecules crosses the membrane with the help of concentration gradient, then it is called as passive process. Simple diffusion, facilitated diffusion and osmosis are the types of passive process. Osmosis is the movement of water molecules from a lower solute concentration to the higher solute concentration through a permeable membrane. Water molecule is much smaller than most of the solute molecules. Thus they are able to move through the membranes in which the solute molecules cannot pass through. This property of the water molecule is called as osmosis. The cell membranes are more permeable to the water molecules than most other solvents. As a result the cell membrane allows most of the water molecules to penetrate inside the cell. This results in the hypotonic condition of the cell. As a result the cell swells. Sometimes the solute concentration will be higher outside the cell membrane and as a result, the cell looses its water molecules out. This results in cell shrinkage termed as hypertonic solution. Is there is no change in the solute concentration inside and outside the membrane, then the solution is said to be isotonic. Osmosis is very essential for the biological systems. The biological membranes are semi permeable in nature. Water molecules travel through the plasma membrane by diffusing across the phospholipid bilayer using the transmembrane proteins. Cellophane membrane is a type of partially permeable membrane that can allow the water molecules to pass through. Cellophane membrane is made by regenerating the cellulose by the addition of some chemicals like alkali, carbon disulfide and sulfuric acid. Cellulose is derived from the wood, hemp and cotton. The Glucose molecules are larger than the water molecules and they don’t diffuse through the cellophane membrane. When the different glucose concentrations are kept separated by the cellophane membrane, the movement of the solvent molecule, (i.e.) the water molecules, from the region of higher concentration to the region of lower concentration occurs. The thermodynamic property of the solution to reach the equal concentration in both sides of the membrane takes place. Materials required: 4 finger bowls 4 pieces dialysis membrane 8 pieces string Metric ruler Hot plate Glass stirring rod Test tubes 50% glucose solution Squeeze bottle of distilled water Paper towels Electronic scale Boiling beads Plastic pan Dropper bottle of Benedict’s solution. Beakers of varying size ( 200 ml, 500 ml, 1000 ml) Pipettes Graduated cylinder ( 10 ml, 25 ml) Distilled water. Method: The 4 cellophane membranes are made active by dipping it in the distilled water. The membranes become wet and flexible. From the stock 50% glucose solution, the appropriate concentration of glucose solutions is prepared by diluting them appropriately with the distilled water. The one end of the bag is tied with a piece of string and the varying glucose concentration of 0%, 10% , 20% and 30% are poured into the bags for a height of 1.5cm approximately. The airs inside the bags are removed by squeezing it at one end and the other end is tied with another string. The four bags are now ready. The bags are then weighed. 4 finger bowls are filled with distilled water and marked as 1,2,3 and 4. The bags are kept in the finger bowls according to the increasing concentration and the time is noted. After ten minutes time interval, the bags are weighed and the procedure is repeated for the twentieth minute. The results are recorded in the tabular column. Results and Discussion : Table 1 S.No Glucose concentration ( %) Initial Weight of the bag (g) Weight after 10 min (g) Weight after 20 min (g) Change in Weight (g) % increase in weight 1 0 11.31 11.91 11.56 0.25 2.2 2 10 11.34 12.63 12.99 1.64 14.5 3 20 11.98 13.58 14.44 2.46 20.5 4 30 12.27 14.17 15.20 2.93 23.9 In the above experiment, for the 0% glucose concentration in the bag, the increase in the weight was 0.25gram which is very less. We can also observe that the weight was higher after 1o minutes and became less by twenty minute. The 10% glucose solution bag had an increase in weight by 14.5%. Similarly the 20% glucose solution bag and 30% glucose solution bag had an in increase in weight by 20.5% and 23.9 % respectively. In the above experiment, as the glucose concentration increases, the weight also increases with respect to the time. The increase in the weight for the increasing glucose concentration is due to passive transport process – osmosis. The movement of the water molecules from the region of lower solute concentration to the higher solute concentration has occurred. The thermodynamic property of the solution to maintain the same concentration on both sides of the membrane is the reason. The solvent molecules moved from the region of higher concentration to the region of lower concentration in order to achieve the same concentration on both sides of the membrane. Cellophane membrane is made of regenerated cellulose only. Cellulose is the major component of the cell membrane of the plant cells. This experiment reflects the cellular osmosis. Conclusion: When the cellophane sack containing varying concentrations of glucose solution is placed inside the distilled water, because of the varying solute concentration on both sides of the membrane, the movement of the solvent molecule occurs. This can be identified by the increase in the weight of the cellophane bag containing the glucose solution. If the solute concentration is higher then the movement of the water molecules is also higher. The osmotic pressure of the free solution pumps the water molecules into the higher solute concentration region across the semi permeable membrane. References: Campbell, NA & Reece, JB 2005, Biology, 7th edition, New York: Pearson Education Inc Read More