The effects of osmosis Essay Example for Free

The effects of osmosis Essay Introduction: Osmosis is a movement of water across a semi-permeable membrane. This may only happen when there is a difference in concentration between the two sides of the membrane. The water moves from low concentrations to high concentrations. That is because the low concentrated area tries to dilute the opposite via osmosis. The effects osmosis has on a cell are either that it becomes turgid and hard as water enters the cell or it becomes dehydrated (this is called plasmolysing in plant cells) as water leaves the cell and the solution enters. There is a change of mass, volume, texture and length. Aim: The aim is to investigate the effects of varying concentrations of a salt solution on the amount of osmotic activity between the solution and a potato of a given size. Osmosis: Process of Osmosis Osmosis is the process of the flow of one constituent of a solution (in this case salt) through a membrane while the other constituents are blocked and unable to pass through the membrane. Experimentation is necessary to determine which membranes permit selective flow, or osmosis, because not all membranes act in this way. Many membranes allow all or none of the constituents of a solution to pass through; only a few allow a selective flow. That is why I have chosen potatoes as my semi-permeable membrane. In osmosis, a solvent (often water) moves from a region of low concentration to a region of high concentration through a semi-permeable membrane. Here,  water molecules diffuse into the concentrated salt solution because the water molecules are small enough to move through the semi permeable membrane. The larger salt molecules are unable to move through the membrane into the water solution because the membrane acts as a net. Osmosis will stop when the two solutions reach equal concentrations on either side of the membrane. Hypothesis: The hypothesis is that as the solvent, the water enters the potato cell to dilute the concentrated salt solution in side the cells. As the salt solution gets weaker more water will enter the cell. This is because more water is needed to dilute the stronger salt solution concentration in the potato cells. The water will try to flow in and out of the potato continuously until it will reach an isotonic equilibrium. The potato cells become turgid and hydrated. However the potato is a plant therefore it has a cell wall that means that at some point the cell wall will stop letting in water or slow it?s flow down. If the plant cells did not have a rigid cell wall they would burst, like in animal cells which have soft cell walls. In this particular investigation I intend to prove that the lower the concentration of the salt solution in the petri dish, the greater the mass of the potato will be. This is because the water molecules pass from a high concentration, i.e. in the water itself, to a low concentration, i.e. in the potato chip. Therefore, the 4 cm core bored potato ?chips? in higher water concentrations will have a larger mass than in higher salt concentrations. If the concentrated salt solution is stronger than the isotonic solution then the cell will lose water. Water will leave the cell and dilute the strong salt solution outside the cell. It will make the concentration gradient equalize. As the strength of the concentrated solution increases the more water will leave the cell. The potatoes cell wall will only shrink because it is only the cell wall that will dehydrate or plasmolyse, but only up to a certain extent because it is only the vacuole that will seriously shrink. The plasmolysed plant cell can be seen under a microscope. My prediction for this particular investigation is at about 0.4 / 0.6 [molar] concentration the salt solution there will be an increase in both mass and length of the potato. The weaker the salt solution the further the solution the quicker will cause decrease in mass and length in the potato. To examine and create an appropriate range of results. For this experiment six petri dishes were used each with five 4 cm core-bored pieces of potato. As evidence of osmosis occurring I used the difference of weight before (after being blotted for six minutes) and after being in the salt solution. The control is five core-bored potatoes in a distilled water solution. Here nothing anomalous should occur. To make the results valuable the experiment is replicated five times in each petri dish. Any anomalous results in the potatoes it will be noticed and recorded To ensure reliability of results, the whole experiment will be replicated to increase the accuracy of the results. Further information on potato plant cells: Plant cells always have a strong cell wall surrounding them. When they take up water by osmosis they start to swell, but the cell wall prevents them from bursting, unlike animal cells ie. cheek cells, which explode if they take up to much water. Plant cells become turgid when they are put in dilute solutions. Turgid means swollen, stiff and hard. The pressure inside the cell rises and eventually the internal pressure of the cell is so high that no more water can enter the cell. This liquid or hydrostatic pressure works against osmosis. Turgidity is very important to plants because this is what makes the green parts of the plant stand up into the sunlight. When plant cells are placed in concentrated salt solutions they lose water by osmosis and they become flaccid. This is the exact opposite of turgid. The content of the potato cells shrinks and pulls away from the cell wall. These cells are said to be plasmolysed. When plant cells are placed in a solution, which has exactly the same osmotic strength as the cells they are in a state between turgidity and flaccidity. We call this incipient plasmolysis. Incipient means, about to be.

Personal Teaching Philosophy :: Education Teachers Reflective Writing Essays

Personal Teaching Philosophy As important as a teacher’s philosophy is to the students, I believe that it is more significant to know where it comes from and how it was developed. When I walk into a classroom, not only do I want my students to know what my feelings about education are, but I also want them to know why I have them. I will first give my class an overview of how I came to be a math teacher and the road that I traveled to get there. The fact that I chose math as my concentration because it was the most challenging subject and not the easiest might inspire other students to give math a chance or work harder if they are having trouble. In turn, I will ask each of the students to tell me about their life in general as well as their individual experiences with math. Regardless of their feelings about math, this process will allow me to gain insight into their learning styles so I can work my hardest to plan lessons that make sense and are comfortable. As a teacher, I am there to impart knowledge to my students while simultaneously making them aware of the fact that I am willing and hoping to learn from them in return. I will never assume to know everything about a given topic, and I will emphasize that I view the act of teaching itself as the most effective means of learning. Since I have noticed distaste for math amongst children who don’t learn to appreciate it, I will strive for a change in this thinking through the use of creativity, dedication, and passion for my subject matter. Teachers are lucky enough to wake up every day and go to a place where they have the opportunity to present material that could affect a student’s life forever. The idea that my enjoyment of math might cause a student to look at something in a new light or try harder is awe-inspiring and is reason enough to get up and go to work every day. I feel that math is more versatile than people recognize, and I will work hard to make connections so that students can see the relevance of the material to their lives.

My bondage and my freedom summary Essay

His grandmother was his life, but when he was seven years old she took him to live on a plantation of Colonel Edward Lloyd. Which separated him from his family, brothers and sisters? â€Å"Being a slave made them strangers.† Pg(48) he wrote that he was told that his master was his â€Å"father†. When he describes his younger years on the plantation his mother died and his aunt ester was whipped. When he was a bit older he lived in Baltimore he had a new master Hugh Auld who was a ship carpenter. Fredrick says that he was treated like a pig on the plantation. His master’s wife was teaching him how to read and when his master found out he wanted it stopped immediately. He thought that slaves should know nothing.In the chapters 13-20 at the age of 15 is when he fially escapes freedom. â€Å"One trouble over, and on comes another,† Douglass says â€Å"The slave’s life is full of uncertainty† (pg 170 his particular period of uncertainty begins wit h the death of Captain Anthony, who, Douglass notes, had remained his master â€Å"in fact, and in law,† though he had become â€Å"in form the slave of Master Hugh. Captain Anthony’s death necessitates a division of his human â€Å"property,† and soon afterwards, Hugh Auld sends Douglass to work at his brother Thomas’s plantation ). When Master Thomas finds that severe whippings do not cause â€Å"any visible improvement in [Douglass’] character,† he hires the young slave out to Edward Covey, who is reputed to be â€Å"a first rate hand at breaking young negroes† (pg 203).. The oxen run away, and Covey punishes Douglass harshly. But Douglass does not intend to be broken either, and his year with Covey culminates in a violent fistfight with the overseer. In 1835, Douglass leaves Covey to work for William Freeland, â€Å"a well-bred southern gentleman,† noting that â€Å"he was the best master I ever had, until I became my own master† (pgs 258-268). After an uneventful year, Douglass devises his first escape plan, conspiring with five other young male slaves (pg 279). However, their scheme is detected, Douglass is imprisoned for a time, and finally Thomas Auld sends him back to live with Hugh (pg 303).While working in a Baltimore shipyard as a hired laborer, Douglass is savagely beaten and nearly killed by four white ship  carpenters. Nevertheless, the job allows Douglass to save some money, finally enabling him to make his escape in September 1838. Douglass does not reveal the full details of his escape in My Bondage and My Freedom, fearing that he might â€Å"thereby [prevent] a brother in suffering [from escaping] the chains and fetters of slavery† (p.323). (He narrates his escape in Life and Times of Frederick Douglass, published well after emancipation). Instead, Douglass skips to his first impressions of life in New York: â€Å"less than a week after leaving Baltimore, I was walking amid the hurrying throng, and gazing upon the dazzling wonders of Broadway† (p. 336)Chapter 24 describes Douglass’ tumultuous Atlantic crossing on a ship full of slave-owners, his exploits as a traveling lecturer in England, Ireland, Scotland, and Wales, and the â€Å"many dear friends† abroad who collaborate to purchase Douglass’s freedom from Thomas Auld in 1846 (p 373). Chapter 25 recalls Dou glass’s plan to start a newspaper after returning to the United States, which he realizes with the help of his â€Å"friends in England† despite some unexpected resistance from his abolitionist â€Å"friends in Boston† (p 392-393). This difference of opinion was emblematic of a larger rift between Douglass and the followers of William Lloyd Garrison over various points of political philosophy. Determined to circulate his newspaper from a neutral location, Douglass begins printing The North Star in December 1847 and moves his family to Rochester, New York, in 1848. He concludes My Bondage and My Freedom with a revised mission statement: â€Å"to promote the moral, social, religious, and intellectual elevation of the free colored people . . . to advocate the great and primary work of the universal and unconditional emancipation of my entire race† (p 306)

The Anti- Corruption Of Bangladesh - 1510 Words

Since the independence, Bangladesh has achieved commendable progresses in terms of socio-economic and governance. Corruption is still a major obstacle towards development and good governance. There have been several institutions in the country established to fight corruption in the country. The Bureau of Anti-Corruption (BAC) was established in 1957, during which Bangladesh was East Pakistan. This bureau was the first institution established to fight corruption. Corruption was identified as a crime under the Code of Criminal Procedure, 1898 as well as Prevention of Corruption Act 1947 and the Anti-Corruption Act 1958. Unfortunately none of the above was effective to address the issue of corruption in the country. During 1990’s and 2000s†¦show more content†¦According to this amendment the organization had to seek government approval to investigate and file a case, therefore it limited the operational capacity of the commission. Based on the complaints from the lawmake rs from all over the country, an amendment was made that allowed the commission to be more independent and not subjected to the government approvals for their investigation. Although the commission is independent by law, in practice the politicians and civil society have turned their attention to the selection process of the commission leadership. (Global Integrity, 2010) According to Hechler et.al (2011), the commission has been active during the tenure of the caretaker government and has filed many cases including top political leaders. However, due to the elections in December 2008, many cases were dropped. In 2010 a set of recommendations were proposed that could limit the powers of the commission by providing a provision of seeking approval from the government prior to the investigation, which was withdrew through campaigns by civil society and media. (Transparency International, 2012) The Office of Comptroller and Auditor General (OCAG), the Supreme Audit Institution (SAI) of Bangladesh is tasked to audit government receipts, and public spending and to determine if the expenditures have produced value for money in government offices, public bodies and statutory organizations. The Comptroller and