Imbibition in Kidney Beans

Topics: Water, Seed, Sodium chloride Pages: 10 (2562 words) Published: March 12, 2012
Imbibition in Kidney Beans
* Aim of Experiment:
* 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.1

* 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.2 * 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...
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