Category: Osmosis

Results

Table 1: showing percentage germination of mung beans in de-ionized water and at different concentrations of KCL.

Graph 2: showing the total growth of mung beans in de-ionized H2O and at different concentrations of KCl as at day 7 (the end of the experiment).

Discussion

Soil salinity is a key abiotic factor that is important in limiting plant yield and is responsible for unproductive land that accounts for approximately ninety-five million hectares the world over (Mine 239). Saline soils are responsible for undesirable effects in plants that include ion toxicity and rivalry. Furthermore, it results in some other detrimental effects due to osmotic potential.

Essentially, there are two key effects in plants that are understood to be the reason behind high salt toxicity in plants (Herr 45). These two include the osmotic and ionic effects. The latter is responsible for the change in enzymatic processes, and also influences the transportation of ions within the plant, eventuating in ion imbalance. Consequently, these effects manifest themselves on the overall rate of germination in seeds. Salt concentration is vital in influencing the rate of water intake in plants in a process called osmosis. Water is a vital component in the germination of seeds, acting as a medium through which the mineral salts are transported.

In this experiment, the main objective was to study the effects of salt concentration on the rate of germination in mung beans (Herr 46). As such, the above results (Table 1) were recorded, with mung beans recording maximum germination (100%) in the control and when in low salt concentration (at 0.1M KCL) as at the end of the experiment. Ideally, the total number of mung beans that germinated due course decreased with an increase in salt concentration from 0.1 to 0.5 Molar KCL.

Importantly, when the results of table 1 were plotted on the graph, the above trend (Graph 1) was observed, portraying the rates of growth under the different environments of salt concentrations. From the above trends, as expected, it is evident that the rate of growth of mung beans in both the control (de-ionized water) and at low salt concentration (0.1M KCL) was higher than when they were grown in the other salt concentrations. As shown by the slopes of the trends in graph 1, the rate of germination of mung beans decreases from DI H₂O to 0.5M KCl.

To this end, it can be deduced that the recommended concentration of KCl to enhance germination of mung beans is 0.1M KCL. Essentially, all the trends assume sigmoid-shaped pattern, bringing the element of intra-specific competition among the mung beans as we approach day 7 (Neumann 98).

Essentially, the reason for the slow growth rate of mung beans in the higher salt concentrations (i.e. in 0.25, 0.4 and 0.5 M KCL), as expected, reflects on the osmotic and ionic effects. As it has been explained before, the rate of seed germination is a function of the salinity of the soil. As such, the rate of germination decreased with salinity. Increased salinity adversely affects osmotic potential, responsible for limiting water intake in the mung bean seeds. As a consequence, imbibition is hampered, resulting in delayed or no germination in extreme cases. The significance of water in seed germination cannot be ignored. Vitally, water is an important compound responsible for initiating seed growth.

It activates important metabolic processes that enhance embryo growth. Of note, it activates hydrolytic enzymes e.g. amylases vital in metabolizing stored food important for embryo development. The embryo shoots through a soft testa courtesy of imbibition. Importantly, the presence of high K⁺ and CL^ ions on the growth of mung bean seeds might have been the reason for the trend witnessed in the above graph (graph 1). The presence of these ions influences the absorption of other important elements, an effect that is greatly influenced by the reactivity series of elements (Neumann 107). As such, ion imbalance occurs, limiting mung bean seed germination.

The summary of the aforementioned observation can be explained by the bar graph above (graph 2), portraying the total growth as at the end of the experiment. Just like it had been predicted, the total germination of mung bean seeds in the control (100%) was greater than when grown in the higher saline environment. Just like it had been predicted, increased salinity is the reason for the above observation, exhibiting negligible population of mung bean seeds that developed in 0.5M KCL.

Even though the above experiment portrayed the expected trends, the results can be improved in future experiments if the following errors can be eliminated. First, all the environmental factors including the humidity and light ought to be kept constant. As such, all the seeds would be subjected to a common environmental condition to yield a near-perfect result. Finally, the unevenness in the health of mung bean seeds greatly affects the outcome of the experiment. As such, future experiments need to emphasize on working with a bigger sample size to decimate this effect in order to yield more credible results.

Conclusion

In this laboratory experiment, the main objective was to investigate the effect of salinity on the germination of seeds (mung beans) (Neumann 107). A series of parallel experiments were performed; one with de-ionized water acting as a control and the others with 0.1, 0.25, 0.4 and 0.5M KCl. As expected, the results concurred with the theoretical explanation which predicts higher growth rate in de-ionized water as opposed to when in saline water.

The results showed mung beans population at 100% in de-ionized water and 0.1M KCl. The percentage germination as at day seven at 0.25, 0.4 and 0.5M KCl was 73.3, 32.5 and 3.3% respectively. The reason for these trends is that salinity influences osmotic potential, the ability for seeds to adsorb water vital for imbibition. Imbibition is an essential process that initiates the growth by activating hydrolytic enzymes and softening the testa to enhance the radicle to shoot.

With the elimination of experimental errors, future experiments can yield more credible results. To this end, performing the experiment under common environmental condition of humidity and light would help minimize the errors. Moreover, working with increased seed count would help reduce the effect of experimenting with unviable seeds.

Works Cited

Herr, Stephen. Effect of soil salinity on seed germination, Cambridge: Cambridge University Press, 2005. Print.

Mine, Ozkil. Effect of different levels of NaCL and KCL on the growth of some biological indexes. Pakistan Journal of Biological Sciences, 10.11 (2007): 1941-1943. Print.

Neumann, Marten. Inhibition of root growth by salinity stress, Amsterdam: Kluwer Academic Publishers, 2005. Print.

Purifying seawater has many benefits. Among those include providing potable water for third world countries, adequate amounts of agricultural water supply, and the ability to use the oceanic water supply as a source of drinking water. The current methods for purifying contaminated or salinated water include reverse osmosis and distillation. Both methods are energy-intensive and costly in terms of materials and equipment. Distillation also leaves behind the toxic contaminants which are usually disposed of in wastelands making the environment unsuitable for agriculture, drinking, and farmed animals. The contaminants are sometimes dumped back into the ocean which alters the chemical composition and balance of the sea and affects oceanic wildlife. As a result, it is important to explore alternative methods.

Some alternative methods to reverse osmosis and distillation include temperature swing solvent extraction (TSSE), battery electrode deionization, and forward osmosis. In a TSSE process, an inexpensive solvent reacts to low temperatures to extract freshwater. It involves decreasing the temperature of the solution which results in a lower solubility of water which drives the separation process. TSSE achieves purification up to 98.4%, and it is a low-cost alternative to distillation. It also eliminates the need for contaminant wastelands and has been found easy to scale up.

Another alternative method is bacteria electrode deionization. This method involves directing salty water into channels where electrodes separate purified water from the original feed by capturing the contaminate salts. The downside of this method may be that using too high voltage results in parasitic reactions and electrode oxidation, both of which are irreversible and undesired. To combat this problem, a voltage below the threshold could be used (0.6 V used in cited works). This method requires very low energy consumption which makes it a great substitute for other desalination methods.

Forward osmosis is another method that can replace reverse osmosis and distillation. Water is extracted from a feed using high osmotic pressure. This process can only be used for a hypertonic solution, not a hypotonic one. The setup for this process has two forward osmosis cells with flow chambers. They push towards countercurrent flow along the membrane. In order to replenish the water supply and prevent diffusion back through the undesired part of the membrane, a pump feeds seawater into the tank to compensate for the water that gets purified through the membrane. A downside of this process was found to be that hydrogen and hydroxide diffused through the membrane to maintain a charge balance.

Overall, a method that could be used to change the world would be purifying seawater. The undying supply of seawater could be used to solve droughts, agricultural issues, the world hunger crisis, and if done enough, could help our rising sea levels. As a result, the methods of purification discussed would be great alternatives to the costly and energy consuming current methods.

Introduction

Osmosis is a process by which water or other fluid travels across a semi-permeable membrane from a low concentration of dissolved particles to a region of high concentration of dissolved particles. Dissolved particles can pass across a semi-permeable membrane from a region of high concentration to an area of low gathering due to differences in the concentration gradient. Pushing the fundamental understanding of osmosis allows one to propose new perspectives for different fields (Marbach & Bocquet, 2019). The aforementioned is crucial in providing significant impact in various fields.

Procedures

For three days, three eggs were placed in vinegar. Then, demineralized egg was taken out of the vinegar and cleaned with tap water. Carefully placing the cleaned egg into the spotless cup, it was weighted. The egg’s actual mass was calculated and noted. After that, distilled water and a hypotonic solution, was added to the cup to the level of three-quarters and left for 40 minutes. The water was carefully drained after 40 minutes, and the egg’s weight in the cup was calculated. The egg was then placed in a clean cup and covered with corn syrup (hypertonic solution), which was then set for 40 minutes. Once more, the solution was cautiously poured out, and the weight of the cup containing the egg was calculated and noted.

Results

The experiment’s findings demonstrate the egg’s increased mass after being soaked in vinegar. This can be explained by the fact that vinegar contains more water than an egg, so water moved through osmosis from the vinegar’s highly concentrated area into the egg’s less concentrated area. The egg’s weight rose from 53.3g to 69.9g, as well as its length and width, which went up from 12cm to 15cm and 16cm, respectively. Meanwhile, we found that corn syrup had a lower concentration of water molecules; therefore, through osmosis, water molecules transferred from the egg into the corn syrup, causing the egg’s weight and size to drop, as shown in the table. Finally, the size and weight of the egg rise as it is submerged in distilled water. This is an evident indicator that water molecules went from a highly concentrated location through osmosis into the egg, which contained fewer water molecules.

Conclusion

Water molecules moved from a region with a high gradient to one with a lower gradient. For instance, water moved out when the egg was submerged in corn syrup, lowering the egg’s weight; with distilled water, the opposite is accurate. As a result of investigating the osmosis process, the experiment’s goal was achieved.

Reference

Marbach, S., & Bocquet, L. (2019). Osmosis, from molecular insights to large-scale applications. Chemical Society Reviews, 48(11), 3102–3144.

This article aims to provide biology teachers with simple yet workable strategies that can be used “…to convert a confirmation-type osmosis laboratory into an inquiry investigation” (Concannon & Brown 23). This is after the realization that the present methods used fail to inculcate a learning culture where students become critical of science, including learning how to analyze scientific concepts and applying the knowledge learned to their daily experiences.

The authors are critical of the fact that although students learn about osmosis – the passage of water molecules that maintains internal cellular stability while the external environment changes – they leave institutions of learning with deeply held delusions about this occurrence.

The authors state that biology teachers should go beyond verification laboratories since these types of laboratories are only limited to science jargon, concepts and facts rather than taking into considerations students’ prior understanding and experiences. As such, all verification activities should be converted to practical inquiry-based explorations. To incorporate inquiry-based investigations to osmosis experiments at the classroom level, teachers must always:

• Involve the learners in driving questions relating to osmosis
• Permit learners to create an approach towards investigating their predictions
• Afford experiment material and time needed to undertake the investigations
• Persuade learners to critically reflect on their experimental results to guide future investigations (Concannon & Brown 24).

On personal reaction, it is indeed true that such a strategy will deeply assist students to lessen their misconceptions about various topics by allowing them the opportunity to practically collect data and generate scientific claims based on active learning experiences.

“Learning Biology by Designing” by Fred Janssen & Arend Jan Waarlo – Sourced from Academic Source Premier Database

The researchers are specifically concerned with developing and testing a biology teaching and learning method known as learning by designing. This approach is basically informed by the fact that students “…develop knowledge about the function and mechanism of biological systems by redesigning them” (Jensen & Waarlo 88). Consequently, the researchers develop three components of learning biology by designing, namely, the design heuristic, the major aspects of the teaching-learning process, and procedures for developing lessons with the preferred features.

In the first component – design heuristic –, the researchers take cognizance of the fact that organisms are optimally designed basically for survival and reproduction. (Jensen & Waarlo 89). In the second component – characteristics of the learning by design teaching/learning process –, “…a description is given of how the teaching/learning process must be organized and executed in order for students to develop adequate knowledge and learn to use the design heuristic independently” (Jensen & Waarlo 89). In the third component – the development of lessons –, the biology teachers may either utilize the design heuristic to expand or adjust their knowledge of biological systems or use the tentative problem structure to make adjustments to the prior knowledge of students in a lesson plan (Jensen & Waarlo 90).

Due to the difficulties involved in teaching biology especially in engaging students in problem-solving, the methodology described by the researchers can effectively be used to trigger students to contribute towards the growth of their own biological knowledge by putting in place strategies that will not only enable the students to acquire a thorough understanding about the function and mechanism of biological systems but also ensuring that students learn to account for such knowledge to a point where they develop the capacity to generate knowledge about biological systems.

Works Cited

Abramowitz, M., Spring, K.R., Parry-Hill, M.Y., & Flynn, B.O. Light and Color. 2005. Web.

Aebi, U., Engel, A., Biozentrum, M.S.B., Durrenberger, M., & Biozentrum, I.E.M. General Introduction. (n.d.). Web.

Audersirk, G., Audersirk, T., & Byers, B.E. Biology: Life on Earth, 9^th ED. Benjamin Cummings. 2010

Ballenger, L., & Myers, P. Family Equidae. Animal Diversity Web. Web.

Bellis, M. (2010). History of the microscope. Web.

CANCERQUEST. The Role of Mutations in Cancer. 2008. Web.

Concannon, J.P., & Brown, P.L. Transforming Osmosis: Labs to Address Standards for Inquiry. Science Activities 43.3 (2008): 23-26. Web.

Emmons, K.M., Kalkbrenner, K.J., Klar, N., Light, T., Schneider, K.A., & Garber, J.E. Behavioral Risk Factors among Women Presenting for Genetic Testing. Cancer Epidemiology, Biomarkers & Prevention 9.89 (2000). Web.

Howard, L. Order Galliformes. Animal Diversity Web. 2004. Web.

Janssen, F., & Waarlo, A, J. Learning Biology by Designing. Journal of Biological Education 44.2 (2009): 88-92.

Myers, P. Order Perissodactyla. Animal Diversity Web. 2010. Web.

Myers, P. Class Insecta. Animal Diversity Webpage. 2001. Web.

State University System of Florida. Taxonomy: What’s in a Name? 2009. Web.

Wund, M., & Myers, P. Class Mammalia. Animal Diversity Web. 2008. Web.

The cell membrane is composed of a phospholipids by-layer that selectively allows substances in and out of the cell. The movement of substances in and out of the cell is a function of various transport mechanisms. The type of transport employed is in turn determined by the type of substance transported (Chiras, 2010).

Osmosis is a form of transport that occurs across a cell membrane. The process involves migration of water molecules from an area of elevated water concentration to an area of decreased water concentration via a semi-permeable membrane (Audesirk, Audesirk & Byers, 2008). The cell membrane acts as the semi-permeable membrane as it allows only the small water molecules to move across it while preventing movement of the solutes that are big in size.

The process of osmosis does not need energy to take place. It is the difference in concentration of water across a semi-permeable membrane drives the process. The process of osmosis is regulated by osmotic pressure that is defined as the force per unit area needed to stop the absolute movement of pure water into aqueous solution through a semi-permeable membrane (Khurana, 2008).

Osmosis is an essential process that is required for the survival of living things. It is involved in processes critical to life in both plants and animals. Such processes include water re-absorption in the proximal convoluted tubule in humans, absorption of water by the cells in the roots of plants and absorption of water across the small intestine in human

Examples of molecules transported across the membrane

Water molecules are main molecules transported across the semi-permeable membrane by the process of osmosis. The process is facilitated by the disparity in potential of water across the semi-permeable. As a result, there is migration of water molecules from an area of elevated water concentration to an area of decreased water concentration via a semi-permeable membrane.

References

Audesirk, T., Audesirk, G., & Byers, E.B. (2008).Biology with physiology: life on earth (5^th ed.). San Francisco, CA: Benjamin Cummings.

Chiras, D.D. (2010). Human biology. Sudbury, MA: Jones & Bartlett Learning.

Khurana, I. (2008). Essentials of medical physiology. New Delhi: Elsevier.

Introduction

Osmosis and diffusion are physical processes that scientists in diverse fields such as physical and biological sciences have used in the elucidation molecules’ movement under various conditions. Fundamentally, osmosis is a mechanism in which solvent molecules move from a section that has a lower concentration of solutes to a section that has a higher concentration of solutes through a semi-permeable membrane (Elmoazzen, Elliot, & McGann, 2009). Comparatively, diffusion is a mechanism in which molecules move from a section that their concentration is high to a section where their concentration is low (Zhou, Nyberg, & Rowat, 2015). The aim of the mechanisms in both osmosis and diffusion is to balance the concentration of molecules in two sections so that they can have the same concentration. Therefore, the research paper aims to describe cell membrane osmosis and diffusion in relation to physics.

Cell Membrane Osmosis

Semi-permeability of the cell membrane and the direction of solvent molecules are two concepts that effectively describe osmosis as a physical process. The cell membrane is semi-permeable because it selectively allows water molecules to pass through it and prevents the entry of biomolecules such as proteins, lipids, carbohydrates, and vitamins (Elmoazzen, Elliot, & McGann, 2009). The difference in the concentration of solutes in two sections that the membrane divides forms osmotic gradient, which determines the direction of the solvent molecules. In pharmacy, osmosis is applicable in modulating pharmacokinetics and pharmacodynamics of drugs. For instance, pharmacists employ osmotic drug delivery systems in ensuring that there are optimum absorption and distribution drugs and minimized metabolism and excretion to increase the bioavailability of drugs in the body.

Mechanism of Osmosis

The mechanism of osmosis relies on the concentration of solutes in various solutions. According to the formula developed by Jacobs and Stewart, osmosis is subject to the concentration of solutes and the thickness of cell membrane, which collectively determines the osmotic pressure or osmotic gradient (Elmoazzen, Elliot, & McGann, 2009). Moreover, the integrity of the membrane determines the occurrence of osmosis. Elmoazzen, Elliot, and McGann (2009) explain that the membrane should be semi-permeable for osmosis to occur, which means that it should only be permeable to solvent molecules but impermeable to solutes. The formula developed by Jacobs and Stewart to determine the concentration across cell membrane indicates that:

Concentration gradient = C_o – C_i/ l

Where C_o represents the concentration inside the cell, C_i represents the concentration outside the cell, and l represents the thickness of cell membrane.

In elucidating the thermodynamics of osmosis, physicists mainly use the osmotic virial equation, which MacMillan and Mayer formulated in 1945. The osmotic virial equation indicates that osmolality of a solution that has a single solute is a function of polynomial molality of solute as indicated by the following equation.

Where π is osmolality, m_i is molality, and B_i and C_i are constants of osmotic virial equation

The osmotic virial equation can also determine osmolality of solutions with solutes. According to Elmoazzen, Elliot, and McGann (2009), solutes in a given solution increases osmolality, as the osmolality of multi-solute solutions constitutes the sum of osmolalities of each solute present. However, the determination of osmolality in multi-solute solutions is not direct as there are solute-solute interactions. When a solution has two solutes, named i and j, the cross-constant, B_ij, explains the interaction effect of solutes on osmolality.

Diffusion

Diffusion is simply a physical mechanism that describes how molecules move from a section where their concentration is high to the section where their concentration is low. Two sections of molecules, which are the section of high concentration and the section of low concentration, create concentration gradient for the molecules to move. In this view, diffusion is essentially the movement of molecules down the concentration gradient. In biological systems, the physiological process of respiration follows the mechanism of diffusion, and thus, allows organisms to exchange carbon dioxide for oxygen. In physics, the movement of gases in a given space effectively demonstrates the mechanism of diffusion.

Mechanism of Diffusion

The mechanism of diffusion is dependent on the concentration of molecules in a given space or environment. The fundamental mechanism of diffusion is that molecules move from a section where their concentration is high to where their concentration is low. The movement of molecules is subject to concentration gradient and electrostatic forces, which ensure there is a net movement of molecules (Zhou, Nyberg, and Rowat, 2015). Concentration gradient initiates and determines the direction of the moving molecules while electrostatic forces sustain the movement of molecules. The movement of gases demonstrates how diffusion of molecules occurs in the air.

In a bid to illustrate the mechanism of diffusion, scientists have come up with different formulas. Boltzmann’s H-function is one of the formulas that scientists use in predicting the process of diffusion. According to Boltzmann’s equation, the distribution of molecules (H) is a function of time moment (t), the position of molecules (x), and velocity of a molecule (dx) (Hubbard, Lund, & Halter, 2013). When two different molecules have the same time moment, position, and velocity, diffusion does not occur. Consequently, the diffusing molecules reach a stationary state or dynamic equilibrium.

Fick’s laws constitute the basis of the elementary theory that demonstrates how diffusion of molecules occurs. The first Fick’s law predicts that the amount of molecules, which is the diffusion flux (J), have a positive relationship with the negative concentration gradient (D), concentration gradient (dC), and negative relationship with the distance (dx) (Zhou, Nyberg, & Rowat, 2015). In essence, according to the Fick’s laws, anti-gradient of concentration determines the occurrence and extent of diffusion in certain molecules. Hubbard, Lund, and Halter (2013) hold that Fick’s laws support Boltzmann’s equation, and thus, they are helpful in predicting the movement of molecules. Therefore, Fick’s laws indicate that diffusion is a physical process that is subject to the concentration gradient and the position of molecules.

Applications

Osmosis has notable applications in diverse fields such as physics, physical chemistry, pharmacology, medicine, and biophysics. In physics and physical chemistry, reverse osmosis is a process involved in desalination of salt water to obtain fresh water. Since dilution of drugs requires clean water, pharmaceutical industry also uses reverse osmosis in producing purified water and water for injection. Osmosis also applies in medicine as medical providers use isotonic solutions in preserving the integrity of tissues and blood cells. Biophysics effectively illustrates the mechanism in which plants absorb water from the soil and distribute in all cells using the process of osmosis.

Diffusion also has extensive application because it elucidates the movement of molecules, particles, and other forms of matter in a given space or environment. In pharmacology, diffusion is applicable in drug design because it effectively elucidates pharmacodynamics and pharmacokinetics, which define efficacy, safety, and mechanisms of action. Physicists and physical chemists apply physics of diffusion in studying thermodynamics, kinetics, entropy, enthalpy, and pressure. Biophysicists also apply diffusion in assessing physics and physiology of respiration and the integrity of the respiratory system.

Conclusion

Analysis of osmosis and diffusion shows that they play a central role in elucidating physical process involved in the movement of molecules, particles, and other forms of matter in physics, biology, and chemistry amongst other fields of knowledge. A critical analysis shows that osmosis and diffusion are similar physical processes that are subject to physical laws. However, osmosis requires cell membrane and involves solvent molecules only. In biological systems, osmosis involves the movement of water across cell membranes. Diffusion also occurs in biological systems when it entails the exchange of gases in the alveoli.

Critique of the Sources

The research paper used three research articles in describing physics of cell membrane osmosis and diffusion. The first article by Elmoazzen, Elliot, and McGann (2009) describes equations of osmotic transport with a view of elucidating a new equation that applies to non-dilute solutes. The article presents the physics of osmosis correctly because it uses numerous equations. Moreover, the physics of osmosis are understandable since the article clearly shows derivations of 38 equations. Therefore, the use of equations and their derivations depicts physics and promotes understanding of osmosis.

The second article by Hubbard, Lund, and Halter (2013) also correctly presents the physics of diffusion using numerous equations, which effectively illustrate the physical process of diffusion. Specifically, the article focuses on Boltzmann’s function and derives 36 equations, which effectively enhances understanding of diffusion. The third article by Zhou, Nyberg, and Rowat (2015) examines diffusion from the perspective of Fick’s laws. The article correctly presents physics of diffusion using Fick’s law, but the presentation is not understandable because it does not illustrate derivation of diverse relevant equations. Essentially, the article concentrates on explaining the application of the Fick’s law in diffusion using limited equations of physics.

References

Elmoazzen, H., Elliot, J., & McGann, L. (2009). Osmotic transport across cell membranes in nondilute solutes: A new nondilute transport equation. Biophysical Journal, 96(1), 2559-2571.

Hubbard, J., Lund, S., & Halter, M. (2013). Boltzmann’s H-Function and Diffusion Processes. Journal of Physical Chemistry, 117(42), 12836-12843.

Zhou, L., Nyberg, K., & Rowat, A. (2015). Understanding diffusion theory and Fick’s law through food and cooking. Advances in Physiology Education, 39(3), 192-197.

The most efficient and famous expertise to desalinate seawater along with brackish water is reverse osmosis. This results in a lower cost of water production since energy consumption is leveled to minimum ranges. Desalination occurs in the fouling membrane systems. The biofouling of seawater reverse osmosis (SWRO) membranes is widely regarded as the most important area for future research (Australia: Department of Sustainability, Environment, Water, Population, and Communities, 2013). Diverse membrane applications are yet to be tested in seawater desalination. The desalination capacity, especially in the U.S.A., for the municipal water supply ranges to two-thirds. All these procedures are carried out by the industries and more is to be done to advance the technologies. One of the processes is fouling. Membrane fouling occurs as a result of the accretion of substances on/in/or near the membrane. This accretion can lead to a decline in water production for steady pressure operations over time.

Another process linked to desalination is scaling, which occurs when dissolved materials increase salt concentration on the feedwater side of the membrane. This continues till when the solubility of the salt is exceeded in the reject water and at long last, precipitation occurs (Ettouney, 2013). Scaling also occurs in high-pressure membranes as well as nanofiltration. The desalination that occurs through scaling can be managed through feedwater monitoring, which is usually alleviated with both chemical and physical pretreatment. Another type of fouling that occurs as a desalination process is referred to as colloidal or particulate fouling. The process is a result of water permeating through membranes that have suspended materials. This finally leads to a membrane flux (Kucera, 2013). Biological fouling is also a desalination component that should be considered. It is the most challenging in RO membrane separation processes. Some of the chemicals that are introduced into the treatment process of biological fouling include impure acids and phosphate-based scale inhibitors. Organic fouling is also another membrane fouling that occurs through the adsorption of organic matter onto the membrane surface. Organic fouling leads to irreversible fouling since the removal of substances is hard once it is absorbed.

The process of desalination involves processes like antiscalants where chemicals are added before membrane separation to reduce the precipitation of sparingly soluble salts. In desalination applications, the potential for microbial growth from the application of phosphonate and carboxylate is still under research (Enayatollahi, 2013). More so, during desalination, the process is carried out in a way similar to the treatment of drinking water. The red tiles are highly destructive when marine algae rapidly increase in concentration. The blooms found in the process can adversely add to the turbidity of seawater. If this does not occur, the release of organic material could be a major problem. The harmful algal blooms are widely known for the harmful results they have on RO desalination facilities.

Desalination is also caused by some organic matters, as well as biodegradable fractions. Membrane fouling can be predicted through several measurements (Committee on Advancing Desalination Technology, 2013). For instance, the traditional fouling ability of a membrane can be estimated using a more advanced modified fouling index (MFI). Generally, seawater UV254 is usually low and it is advisable to measure it with a longer path length. This is why a specific UV absorbance (SUVA) is extensively used in drinking water treatment to measure the level of organic carbon in source waters. Liquid chromatography is also applied in the desalination process (Craig, 2013). It is used as an option for determining NOM has a lower SUVA. The separation procedure is based on size-exclusion chromatography (SEC), which, in turn, is linked to multidetection process of organic carbon. There is a major need for consistent measurement of AOC using the seawater matrix. The AOC test is a microbial assay that uses two strains of bacteria, P17 and Sprillum NOX. It controls their growth in the pasteurized water until maximum growth desalination occurs.

Models have been well known for designing RO desalination processes. They usually occur in dual areas like the mechanistic transport model and lumped parameter model. Biological fouling and modeling bacterial growth is widely known as a way of diverging biofouling on RO membranes. These processes are well known to have effects on seawater matrices such as drinking water treatment as well as distribution systems. The process also occurs in wastewater treatment (Kiefer, 2013). Therefore, high pressure membranes have been devised to know the exact cause in the RO matrices. For instance, the computational fluid dynamics (CFD) uses Navier-Stokes equation to determine the membrane systems. However, biofouling strategies should be prevented through continues or intermittent biocide application. More so, conventional desalination pretreatment involves a number of things like pre-chlorination, coagulation/flocculation, clarification as well as filtration. One of the methods of conventional desalination (filtration) presented above is carried out using granular media like sand or dual media filtration (DMF). This is due to the fact that the membranes used in the filtration process are commercially available.

References

Australia. Department of Sustainability, Environment, Water, Population, and Communities. (2013). Grants for the Construction of the Adelaide Desalination Plant Issue 32 of Audit report (Australian National Audit Office) Performance audit. Australia: Australian National Audit Office.

Committee on Advancing Desalination Technology. (2013). Desalination: A National Perspective. London: National Academies Press.

Craig, B. (2013). An investigation on biological stability of product water generated by lab-scale and pilot-scale distillation systems. London: Sage.

Enayatollahi, R. (2013). Solar Humidification Dehumidification Desalination System. Washington: LAP Lambert Academic Publishing.

Ettouney, H. (2013). Fundamentals of Salt Water Desalination. New York: Elsevier.

Kiefer, J. (2013). The desalination and Biofouling procedures. New York: Peter & Sons.

Kucera, J. (2013). Desalination: Water from Water. New York: Wiley Publishers.

The aim of the potato slice experiment was to demonstrate the different behaviors of a plant cell in different environments and the extent of the effect on a particular environment. The importance of this experiment was to find out these properties and behaviors and put them into consideration when planting, handling or storing plants products. The process of osmosis was also to be demonstrated and observed during the experiment.

Introduction

Osmosis is the movement of water across a semi-permeable membrane caused by a difference in concentration (Haynie, 2001). A semi-permeable membrane only allows the molecules of the solvent to pass through. In this case, the molecules allowed to pass are the water molecules moving from a low concentration solution to that of higher concentration. The process does not require any energy to be input but instead releases energy as witnessed when a root splits a stone or forces its way through small stones as it grows.

Osmosis therefore only occurs when a permeable cell separates two solutions of different concentrations. This can be demonstrated using an animal cell or a plant cell placed in a solution of either higher or lower concentration than of its own cell components. The cell behaves differently depending on the nature of the solution; it can lose, maintain or gain weight. A cell placed in a hypertonic solution (high solute concentration) will lose its water while one placed in a hypotonic (less solute concentration) solution will gain water. However, when a similar cell is placed in an isotonic solution, (solute concentration equal to that of cell) its weight will remain the same.

This process is important to living organisms as most of them have many semi-permeable membranes and most of the activities going on in their bodies are osmotic. Osmosis is used by the plants as they take in water through their roots necessary for photosynthesis and growth. Osmosis can at times be very harmful to the living organisms; it can cause their death as seen when a snail passes through a layer of salt. In a situation where fresh-water fish is placed in saline water or salt-water fish in fresh water, the fish die because of either cell bursting or dehydration due to their different cell components. Osmosis is therefore evidently vital to the survival of all living things whether plants or animals.

The potato slice experiment was meant to demonstrate the different behaviors of a plant cell in different environments and the extent of the effect on a particular environment.The objective of this was to get important inferences that can be taken into consideration when planting plants, handling or storing their products. It was expected that the potatoes placed in low solute concentrated solution gain weight and those in high solute concentrated solutions lose weight. This was attributed to the fact that the cells always try to attain equality in terms of concentration. The difference in weight after placement in the solutions was as a result of the potato slice absorbing or loosing water molecules (Haynie, 2001).

Materials and Methods

We were split into seven groups and each group was given a potato slice and a cylinder containing sucrose solution. Note that the sucrose solutions given to us were of different concentrations to enable us observe the effect of hypertonic, isotonic and hypotonic solutions. This was aimed at enabling us compare the rate of effect of the different solutions when they have different concentrations. Each of the groups weighed the potato slice before placing it in the sucrose solution. The weight of potato slices was different and this required us to calculate the percentage change in weight so as to make comparisons. The change in weight simply signaled the effect, but the percentage change was a good indication of the rate of effect after immersion in the solution for 45 minutes (long enough for the observations to be clear).

Results

As shown on the table below, the potato slices 1, 2, 3 and 4 gained weight indicating that the sucrose solutions of molarity 0-0.3 were less concentrated than the potato slice cells. For example, potato slice 1placed in pure water, with an initial weight of 4.3g, had its final weight increased to 6.0g. Potato slice 5 showed no reasonable change in weight and if there was any, it was too small to be detected by the weighing machine. We made the assumption that this solution had the same concentration with that of the potato slice cells i.e. an isotonic solution. Potato slices 6 and 7 lost weight when placed in the solutions (hypertonic solutions).

Discussion

From the above results, it was clearly seen that a plant cell increased in weight if placed in hypotonic solution and lost weight when placed in a hypertonic solution. Cells placed in isotonic solutions were found maintain a relatively constant weight.The percentage and rate of change was observed to be dependent on the concentration of the solution in which the slice was immersed. It was also observed that the percentage change in weight dropped from potato slice 1 to 4, (from 39.5 to 14.3%) and increased from slice 6 to 7.

This meant that as the difference in concentration increased, the osmotic pressure (the force per unit area of exchange required to prevent passage of water) also increased (Lenart & Flink, 1984). This in turn increased the rate of movement of the water molecules. The process of osmosis was successfully demonstrated and observed in during the experiment.

This meant that if the environment of a fresh water fish must change, then efforts must be made to avoid adverse situations that may cause instant death. The situation may even be worse if the home of a fish is progressively contaminated with a solute as it would take some time before experiencing its effect. During this window period, human beings may still be consuming the fish and they too would be in danger. This inference prompts for constant checks in our environment especially when toxic and dangerous solutions that can pass through our skin find their way to our bodies. Care should be taken at all times to avoid coming into contact with such environments.

References

Haynie, D. (2001). Biological Thermodynamics. Cambridge: Cambridge University Press.

Lenart, A., & Flink, J. M. (1984). Osmotic Concentration of Potato. International Journal of Food Science and Technology, 19(1), 45-63.

Results

Table 1: showing percentage germination of mung beans in de-ionized water and at different concentrations of KCL.

Graph 2: showing the total growth of mung beans in de-ionized H2O and at different concentrations of KCl as at day 7 (the end of the experiment).

Discussion

Soil salinity is a key abiotic factor that is important in limiting plant yield and is responsible for unproductive land that accounts for approximately ninety-five million hectares the world over (Mine 239). Saline soils are responsible for undesirable effects in plants that include ion toxicity and rivalry. Furthermore, it results in some other detrimental effects due to osmotic potential.

Essentially, there are two key effects in plants that are understood to be the reason behind “high salt toxicity in plants” (Herr 45). These two include the osmotic and ionic effects. The latter is responsible for the change in enzymatic processes, and also influences the transportation of ions within the plant, eventuating in ion imbalance. Consequently, these effects manifest themselves on the overall rate of germination in seeds. Salt concentration is vital in influencing the rate of water intake in plants in a process called osmosis. Water is a vital component in the germination of seeds, acting as a medium through which the mineral salts are transported.

In this experiment, “the main objective was to study the effects of salt concentration on the rate of germination in mung beans” (Herr 46). As such, the above results (Table 1) were recorded, with mung beans recording maximum germination (100%) in the control and when in low salt concentration (at 0.1M KCL) as at the end of the experiment. Ideally, the total number of mung beans that germinated due course decreased with an increase in salt concentration from 0.1 to 0.5 Molar KCL.

Importantly, when the results of table 1 were plotted on the graph, the above trend (Graph 1) was observed, portraying the rates of growth under the different environments of salt concentrations. From the above trends, as expected, it is evident that the rate of growth of mung beans in both the control (de-ionized water) and at low salt concentration (0.1M KCL) was higher than when they were grown in the other salt concentrations. As shown by the slopes of the trends in graph 1, the rate of germination of mung beans decreases from DI H₂O to 0.5M KCl.

To this end, it can be deduced that the recommended concentration of KCl to enhance germination of mung beans is 0.1M KCL. Essentially, all the trends assume sigmoid-shaped pattern, bringing the element of intra-specific competition among the mung beans as we approach day 7 (Neumann 98).

Essentially, the reason for the slow growth rate of mung beans in the higher salt concentrations (i.e. in 0.25, 0.4 and 0.5 M KCL), as expected, reflects on the osmotic and ionic effects. As it has been explained before, the rate of seed germination is a function of the salinity of the soil. As such, the rate of germination decreased with salinity. Increased salinity adversely affects osmotic potential, responsible for limiting water intake in the mung bean seeds. As a consequence, imbibition is hampered, resulting in delayed or no germination in extreme cases. The significance of water in seed germination cannot be ignored. Vitally, water is an important compound responsible for initiating seed growth.

It activates important metabolic processes that enhance embryo growth. Of note, it activates hydrolytic enzymes e.g. amylases vital in metabolizing stored food important for embryo development. The embryo shoots through a soft testa courtesy of imbibition. Importantly, the presence of high K⁺ and CL^– ions on the growth of mung bean seeds might have been the reason for the trend witnessed in the above graph (graph 1). The presence “of these ions influences the absorption of other important elements, an effect that is greatly influenced by the reactivity series of elements” (Neumann 107). As such, ion imbalance occurs, limiting mung bean seed germination.

The summary of the aforementioned observation can be explained by the bar graph above (graph 2), portraying the total growth as at the end of the experiment. Just like it had been predicted, the total germination of mung bean seeds in the control (100%) was greater than when grown in the higher saline environment. Just like it had been predicted, increased salinity is the reason for the above observation, exhibiting negligible population of mung bean seeds that developed in 0.5M KCL.

Even though the above experiment portrayed the expected trends, the results can be improved in future experiments if the following errors can be eliminated. First, all the environmental factors including the humidity and light ought to be kept constant. As such, all the seeds would be subjected to a common environmental condition to yield a near-perfect result. Finally, the unevenness in the health of mung bean seeds greatly affects the outcome of the experiment. As such, future experiments need to emphasize on working with a bigger sample size to decimate this effect in order to yield more credible results.

Conclusion

In this “laboratory experiment, the main objective was to investigate the effect of salinity on the germination of seeds (mung beans)” (Neumann 107). A series of parallel experiments were performed; one with de-ionized water acting as a control and the others with 0.1, 0.25, 0.4 and 0.5M KCl. As expected, the results concurred with the theoretical explanation which predicts higher growth rate in de-ionized water as opposed to when in saline water.

The results showed mung beans population at 100% in de-ionized water and 0.1M KCl. The percentage germination as at day seven at 0.25, 0.4 and 0.5M KCl was 73.3, 32.5 and 3.3% respectively. The reason for these trends is that salinity influences osmotic potential, the ability for seeds to adsorb water vital for imbibition. Imbibition is an essential process that initiates the growth by activating hydrolytic enzymes and softening the testa to enhance the radicle to shoot.

With the elimination of experimental errors, future experiments can yield more credible results. To this end, performing the experiment under common environmental condition of humidity and light would help minimize the errors. Moreover, working with increased seed count would help reduce the effect of experimenting with unviable seeds.

Works Cited

Herr, Stephen. Effect of soil salinity on seed germination, Cambridge: Cambridge University Press, 2005. Print.

Mine, Ozkil. “Effect of different levels of NaCL and KCL on the growth of some biological indexes.” Pakistan Journal of Biological Sciences, 10.11 (2007): 1941-1943. Print.

Neumann, Marten. Inhibition of root growth by salinity stress, Amsterdam: Kluwer Academic Publishers, 2005. Print.