Imbibition in Kidney Beans free essay sample

To investigate the effect that emersion in salt solutions has on imbibition in kidney beans. * Safety Considerations: * One must use extreme caution when working with chemicals. Always wear protective goggles and gloves when handling them. KCl is slightly hazardous in case of skin contact, eye contact, ingestion, or inhalation. In case of eye contact, immediately flush eyes with plenty of water for at least 15 minutes. Seek medical attention if irritation develops. In case of skin contact, wash with soap and water. Cover the irritated area with a moisturizer. Seek medical attention if irritation develops. In case of inhalation, move to fresh air. Seek medical attention if breathing is difficult. In case of ingestion, loosen any tight clothing, such as collar, tie, or waistband. Do not induce vomiting unless directed to do so by medical personnel. Seek medical attention if symptoms appear. In case of spillage, use appropriate tools to put the spilled solution into a waste disposal container. Finish cleaning by spreading water on the contaminated surface and dispose of according to local requirements. Introduction * Research Question: * Does a salt solution have an effect compared to distilled water on imbibition in kidney beans? * Background: * Imbibition is defined as the physical adsorption of water onto the internal surfaces of structures. For plants, this means the uptake of water due to the low water potential of the dry seed. 2 * Imbibition is a determining factor of seed germination. It causes the seed to expand and rupture its coat and triggers metabolic changes in the embryo that enable it to resume growth. * The extent to which water imbibition occurs is dependent upon three factors: composition of the seed, seed coat permeability, and water availability. * Composition of the seed: Seeds typically possess extremely low water potential due to their osmotic characteristics. The low water potentials are a consequence of the relationship of water with components of the seed. Imbibition is not dependent on metabolic energy, and is instead related to the properties of the colloids present in seed tissues, such as proteins. Proteins exhibit both negative and positive charges that attract the highly charged polar water molecules. High protein containing seeds will imbibe more water than starch or oil containing seeds, which have little to no affinity for water. * Seed coat permeability: Water permeability is usually greatest at the micropylar area where the seed coat is quite thin, as well as at the hilum. Thick, gooey mucilages extruded from seed coats increase imbibition, as do the cellulose and pectins located in cell walls. Availability of water: The ability to imbibe water is dependent on cell water potential and is a result of three forces: * Cell wall matric forces: Cell walls and intracellular inclusions such as mitochondria and ribosomes are characterized by the presence of membranes. These membranes possess charges that attract water molecules and contribute to the total cell water potential. In a salt solution, there are less water molecules for the membranes to attract, causing less water to be imbibed into the seed. Cell osmotic concentration: The greater the concentration of soluble compounds, the greater the attraction for water. * Cell turgor pressure: As water enters a cell, it exerts a swelling force on the cell wall called turgor pressure. Turgor pressure is a result of the restraining force of the cell wall and tends to slow water absorption. * Water potential measures the tendency of water to leave one place in favor of another. Water always moves to a more negative water potential. The water potential of pure water is zero. The soils in which seeds are planted also exhibit their own water potentials. The physical properties of soils determine the retention and conductivity of water. For example, soils heavy in clays are able to absorb water more vigorously and retain it longer than those possessing high quantities of sand. Therefore, seed and soil water potential must compete with the soil water potential for imbibition to occur. Most soils exhibit a high degree of hydraulic conductivity that replenishes the available water surrounding the seed as it continues the process of imbibition. 3 * KCl and NaCl are salts, which have lower water potentials than distilled water. KCl is often found in fertilizers. NaCl is often a factor in the problem of dry-land salinity, which results when more water enters the groundwater system than is discharged from the system, causing the water table to rise. As it rises, the groundwater dissolves the soluble salts stored in the subsoil and brings salty water into the reach of plants. Dry-land salinity causes a decline in agricultural productivity that is associated with saline soils. High concentrations of salt in the soil restrict plant uptake of water and prevent plants from taking up essential nutrients and are therefore toxic to plants. Distilled water Distilled water After 48 hours Left to right: KCl, salt water, distilled water Left to right: KCl, salt water, distilled water Close-ups after 48 hours of emersion Salt water Salt water KCl KCl Distilled water Distilled water KCl KCl Salt water Salt water Left to right: KCl, salt water, distilled water Left to right: KCl, salt water, distilled water This graph shows the differences between the three solutions in the start weight and the end weight of the beans. It can be seen that the change in mass decreases going from distilled water, to salt water, to KCl. The end weight was measured 48 hours after emersion. This graph shows the differences between the three solutions in the start weight and the end weight of the beans. It can be seen that the change in mass decreases going from distilled water, to salt water, to KCl. The end weight was measured 48 hours after emersion. KCl Change in mass: 3. 23 g KCl Change in mass: 3. 23 g Salt water Change in mass: 3. 35 g Salt water Change in mass: 3. 35 g This graph shows the differences between the three solutions in the percent change in mass of the beans. It can be seen that the percent change in mass decreases going from distilled water, to salt water, to KCl. These values were obtained from end weights taken 48 hours after emersion. This graph shows the differences between the three solutions in the percent change in mass of the beans. It can be seen that the percent change in mass decreases going from distilled water, to salt water, to KCl. These values were obtained from end weights taken 48 hours after emersion. Statistical Analysis Values for T-test| | p| 0. 05| Degrees of freedom| 4| Critical value| 2. 132| t| 71. 2090| Result5| 2. 132 71. 2090| A t-test measures the statistical significance a set of data holds. Null hypothesis = There is no significant difference between the change in mass of the kidney bean after being soaked in distilled water, salt water, and KCl. If t critical value, accept null hypothesis, If t critical value, reject null hypothesis t critical value; the null hypothesis is rejected. Therefore, there is a significant difference in the change in mass of the kidney beans after being soaked in distilled water, salt water, and KCl. Conclusion/ Evaluation According to statistical analysis from this experiment, salt solutions do have an effect on imbibition in kidney beans compared to distilled water. While all beans imbibed, the kidney beans soaking in the distilled water imbibed the most, and the kidney beans soaking in the KCl imbibed the least, the beans soaking in the salt solution falling in the middle. This can be seen from the second graph that compares the percent changes in mass of the three groups. The result achieved makes logical sense. A salt solution contains less water molecules than distilled water. Therefore, the membranes of the beans soaking in the salt solutions had less to attract, so less water was imbibed into the seed. This may explain one reason why dry-land salinity is such a large issue for plants. If the water a plant has to soak up is salty, they will not be able to grow as big or strong as they would otherwise be able to because of the lessened amount of usable water they receive opposed to the moisture in the soil. In some cases, they will not even be able to imbibe enough water for the radicle to sprout or the seed coat to break to begin plant growth. This is shown in this experiment in the first table, which shows that none of the seed coats of the seeds soaking in KCl broke. Results of this experiment were similar to research done by Del Valle, Stanley and Bourne, who found that the addition of salt to a soaking solution generally reduced water absorption and swelling in dry beans. * Errors/ limitations: * Measures were not taken to ensure concentrations of KCl and NaCl were similar. The NaCl had a higher concentration of water than it should have for accurate results, causing more imbibition than their realistically should have been. Instead of being in the middle data-wise, it should have been more similar to the KCl solution, as both are salts. One tablespoon of salt in 40 mL of water was not near the concentration of the . 1 M KCl solution. * For the 48 hours the seeds were soaking, they were not covered. This allowed for evaporation. Especially after the 24 hours mark, the seeds were not emerged in nearly as much water, having potential to severely affect the ending masses of all the beans. This would then effect the change in mass and then the percent change in mass for each. Assuming the evaporation rates for each liquid are similar, the changes in mass were simply lower than they should have been. If the evaporation rates for each were different, another variable was created, and the data could be skewed to favor whichever had more water to soak in. * Lab improvements: * A step should be added into the procedure after emersion of the beans to cover the beakers with Saran wrap so as to not block light or create a potential change in temperature for the beans. This would remove the issue of evaporation, ensuring each set of beans has the same amount of liquid to soak in the whole time, ensuring any differences in results are due only to the nature of the solutions the beans are soaking in and not a confounding variable. Research should be conducted to ensure the concentrations of the two salt solutions are similar, so one does not have a higher concentration of water than the other. This would ensure the differences between the beans for the two different salt solutions were really due to differences in the nature of the solutions, and not only to differences in the water concen tration between the two.