Properties of Water
Water Water is by far the most abundant component of organisms. Like all living organisms, humans depend on water and it makes up 60-70% of the human body, or about 40 litres, of which 25 litres are inside the cells and 15 litres outside (12 litres in tissue fluid, and 3 litres in blood plasma). A loss of 4 litres may cause hallucinations; a loss of 8-10 litres may cause death. About 1.5 litres a day are lost through breathing, sweating, and in faeces, and the additional amount lost in urine is the amount needed to keep the balance between input and output. In temperate climates, people cannot survive more than five or six days without water; this is reduced to two or three days in a hot environment. Often overlooked by many as the most important substance the body needs, water is involved in every aspect of maintaining the human body from forming nucleic acids in it to transporting various substances around it. The root of these special characteristics lies in the properties of water itself. The Properties of Water This liquid is such a good solvent that almost anything will dissolve into it and it is therefore known as the universal solvent. Its properties as a solvent depend on the fact that it is a polar molecule. A polar molecule is one which has an unevenly distributed charge. Water is made up of 2 oxygen atoms and one hydrogen atom. Oxygen has a bigger nucleus and
Osmosis in plant tissue.
Osmosis in plant tissue Introduction In this experiment I am going to find the water potential of a chip, by immersing it in different concentrations of sucrose solutions using the theory of osmosis, the gain or loss in length of the chip can be measured, in osmosis water molecules move down a gradient from a concentrated area to an area where they are less concentrated. In the first half of the experiment, half an hour should be sufficient to find the water potential of the chip. The process of this is also known as graded osmotion and the chip will shrink due to plasmolysis of cells. The equipment that I needed for this experiment is as follows Equipment: 5 petri dishes Sucrose Distilled water to make up the sucrose solution 0 chips cut up to be 40 millemetres in length Paper towel to mop up spills Ruler to measure chips My predictions In this experiment I predict that the more concentrated the sucrose solution the shorter the chip will become in length, e.g. a chip with a sucrose concentration of nil will be a lot longer than a chip which has been in a solution with a concentration of 0.8, this is because the sucrose fills in the gaps of the water and the water molecules move down a concentration gradient to an area where they are less concentrated. This diagram shows how sucrose affects the concentration gradient of water. Plan: I plan to find the
Osmosis in Potato cells
ACCESS HUMAN BIOLOGY UNIT A Practical Assignment - Osmosis in potato cells Planning The aim of this experiment is to investigate the movement of water in and out of plant cells. The plant cells that we will use are potato cells. Osmosis is defined as the passage of water from a region of high concentration of water, to a region of low concentration of water through a semi permeable membrane. A semi permeable membrane is defined as a thin layer of material that allows some materials to pass through (such as water or some proteins) and prevents other materials from passing through (such as sugar or salt). The diagram below demonstrates osmosis taking place through a semi permeable membrane. Diagram taken from http://fig.cox.miami.edu/~lfarmer/BIL265/BIL2001/osmosis.JPG Plant cells are constructed with a thick cell wall and a central cavity filled with fluid, this can occupy over 80% of the volume of the cell. When osmosis takes place and water passes through the semi permeable membrane into the cell, the vacuole swells in size, pushing the cell contents against the thick cell walls and the cell becomes hard, this is known as becoming "turgid". The strong cell wall surrounding the cell prevents it from bursting. When the internal pressure is at its highest, the plant cell cannot accept any more water. This works against osmosis as it prevents further intake of
Osmosis in Potatoes.
Osmosis in Potatoes Osmosis is a special type of diffusion where water moves across a semi permeable membrane from an area of low solute concentrating to an area of high solute concentrating. Osmosis is an important in plant cells as it makes the cell turgid. Turgidity is when no more water can enter the cell and therefore helps to keep the plant firm and upright. Variables: Some parts of the experiment will have to be kept the same while one key variable is changed. Some of the variables I am going to control are: * Time left in solution - If the chips were left longer in the solution than others, more time would be allowed for osmosis to occur. * Surface area of potato chip - If the surface areas are larger on some chips than others there would be larger and there would therefore be more space for osmosis to happen. I have chosen to change the concentration of the sugar solution. If any of the non-variables aren't kept constant it would mean it would not be a fair test. Apparatus: Test Tube Rack - We used this to put the test tubes in so they wouldn't fall over. 5 Test Tubes - We used these in order to put our chips and the sucrose solution in. Measuring Cylinder - We used this in order to measure accurately the amount of Sucrose Solution being put into the test tubes. Chipper - This was used in order to cut the chips to the same size so that all the chips
Osmosis in potatoes.
Osmosis in potatoes. Osmosis is the diffusion of water from a weak solution (lots of water) to a strong solution (little water) through a selectively permeable membrane, going down a concentration gradient. A plant cell has a weak solution in it but not as weak (or pure) as water. When placed in water then, a plant cell becomes turgid because the water diffuses into the cell because there is a lower concentration of water inside the cell. Therefore, when put in a sucrose (sugar) solution, the plant cell becomes flaccid (or plasmolysed), this is because the solution in the cell diffuses out where the concentration of water is lower. Potatoes are made up of plant cells because it is a type of plant for the reason that it comes from the ground. Therefore, when put in water it will take it in by diffusion and become turgid and then in a sucrose solution it will become flaccid (or plasmolysed). Plasmolysis is when a cell (in this case a plant cell) loses its solution from the vacuole by osmosis and become limp or floppy. We say it is flaccid. As more water leaves the cytoplasm the cell membrane peels away from the cell wall and collapses with the vacuole to make the cell flaccid. Turgid is when a cell is so filled with water it can't take any more in. an animal cell would eventually burst but because the plant cell has a cell wall it doesn't burst. Water diffuses into the
Osmosis Investigation.
Osmosis Investigation Aim My aim during this investigation is to vary different amounts of sugar solution and to see how this will affect a potato, with a process of osmosis. I will also record the weight at the start of the experiment, and at the end after the chip has been placed into the solution. General knowledge Osmosis is the movement of liquid from one solution into another, through a membrane that separates them. This process mainly applies to the survival of living things, and is essential. For example, plant absorbs most of its water by the process of osmosis. In animals, osmosis helps continue the flow of water between body cells. The process of osmosis works with a mixture of substances that cannot be separated. This is known as a solution. Inside a liquid solution, is a dissolved substance called a solute and a liquid called solvent. During osmosis some of the solvent moves to another solution through a membrane. This membrane is known as a semi-permeable. It allows some substances to pass through but no others. The solvent would be able to move to different solutions, according to the temperature and pressure of each solution. In normal osmosis it is the diffusion of water molecules from a region of higher water concentration to a region of lower water concentration. Inside cells outside cells LOW WATER
Investigating osmosis in plant tissue.
Investigating osmosis in plant tissue Introduction Osmosis is the movement of water particles along a concentration gradient, from a high concentration to a low concentration through a selectively permeable membrane. Osmosis can happen anywhere where there is a selectively permeable membrane and water, however can only move along the concentration gradient. For example if a red blood cell were to be placed in water, then water would travel through diffusion into the red blood cell as the water concentration inside a red blood cell is quite low. However animal cells only have a cell membrane, so the blood cell would fill and fill, and keep on filling until the membrane could hold it no longer and it would burst. Whereas with a plant cell, it has a cell wall, so instead of bursting, a plant cell will merely become turgid, or swollen and hard. This is where the pressure inside the plant cell increases and increases until no more water can enter and the cell is turgid. This is the pressure is called turgid pressure and keeps plants standing up, and why plants wilt when not enough water is consumed by the plant, this is called flaccid. We have done an experiment to try and investigate osmosis further; we performed an experiment with visking tubing and a glucose solution. We filled up a visking tubing with water, and weighed it, we then placed the visking tubing inside a
Investigate the movement of osmosis through a selectively permeable membrane, in this case potato.
Osmosis in Potatoes Aim: Investigate the movement of osmosis through a selectively permeable membrane, in this case potato. Introduction: Osmosis is the movement of water through a semi permeable membrane. The water passes from an area of high concentration to an area of low concentration, until the two concentrations are equal in concentrations of water. Many cell membranes behave as semi permeable membranes, and osmosis is a vital part in the movement of liquids in living organisms, for example, in the transport of water from the soil to the roots in plants. If a cell is in contact with a solution of lower water concentration than its own contents, then water leaves the cell by osmosis, through the cell membrane. And if the cell is in contact with a solution of high water concentration than its own then water goes into the cell. If you put a plant cell in water, water enters by Osmosis, then it swells up. However, the cell will not burst. This is because the cell walls are made from something which is extremely strong. Eventually, the cell stops swelling, and when this happens, we say the cell is turgid. This is important, because it makes plant stems strong and upright. Osmosis: Preliminary Work: For my preliminary work, I used 30mm of potato. To begin, I used 25mls of Sucrose solution. The first thing I needed to see was how different concentrations affected the
'Factors affecting the rate of respiration in immobilised yeast'.
Biology Coursework James Wyatt 'Factors affecting the rate of respiration in immobilised yeast' Variables The input variable that we will be investigating will be the temperature of the glucose solution that the yeast ball rises quickest in. This will be measured at regular intervals. The output variable is the time taken for the yeast balls to respire and rise to the top of the glucose solution. They will respire by the carbon dioxide from the solution entering the yeast balls, causing them to rise. The variables that will be controlled and kept the same are the volume of water, the amount of glucose, the concentration of the glucose and the size and mass of the beads. All of these will be controlled to keep a fair test. We will try and keep the beads the same size although it may be little tricky. Should this not be kept identically, it should not affect the results in a drastic way. If there was more glucose in one solution than another then there would be and unfair test and there would be more carbon dioxide to respire. I don't think that the yeast balls' mass or size will differ enough to change the results, as they would only differ in .01 of a gram, which is only a slight difference. Prediction I predict that the rate of respiration in the immobilised yeast will increase as the temperature increases until the temperature reaches a certain point. I predict
Diabetes mellitus.
Diabetes mellitus is a condition in which the amount of glucose in the blood is too high because the body cannot use it properly. Glucose comes from the digestion of starchy foods such as bread or potatoes, from sugar and other sweet foods, and from the liver which makes it and passes it into the blood stream. Insulin, a hormone produced by the pancreas, helps the glucose to enter the cells where it is used as fuel by the body. The main symptoms of untreated diabetes are increased thirst, passing large amounts of urine, extreme tiredness, blurred vision, and weight loss. Insulin dependent diabetes (also known as Type 1 diabetes) develops when there is a severe lack of insulin in the body because most or all of the cells which make it have been destroyed. This type of diabetes usually appears before the age of 40. It is treated by insulin injections and diet. Non insulin dependent diabetes (also known as Type 2 diabetes) develops where the body can still make some insulin, though not enough for its needs, or when the insulin that the body does make is not used properly. This type of diabetes usually appears in people over the age of 40. It is treated by diet and tablets or, sometimes, by diet and insulin injections. The main aim of treatment is to achieve near normal blood glucose levels, which, together with a healthy lifestyle, will help to improve well being and
