The aim of this experiment is to investigate the movement of water into and out of plant cells by osmosis. The cells chosen for study will be taken from potato tubers as they provide a ready supply of uniform material.
Aim The aim of this experiment is to investigate the movement of water into and out of plant cells by osmosis. The cells chosen for study will be taken from potato tubers as they provide a ready supply of uniform material. Background Information Any substance dissolved in water is called a solute; a solvent is a liquid that is able to dissolve another substance, (a solute), to form a solution. The water content of plants varies depending on environmental conditions. In land plants it plays a vital role in structural support and mineral transport and thus a lack of water may lead to wilting or possibly death. Water is mainly absorbed through the roots, which are covered in specially adapted root hair cells, with large surface areas and thin cell walls to aid absorption by osmosis. The evaporation of water through stomata on plant leaves causes a transpiration stream, causing the water to be drawn up through xylem vessels. Osmosis is the flow of water molecules by diffusion through a partially permeable membrane from areas of high water potential (low solute concentrations) to regions of low water potential (high solute concentrations). All plant cell membranes are partially permeable, which means they allow some substances to penetrate them but not others. Whether water enters the cell by osmosis will depend on the balance between external and internal solute and water
How did the Dinosaurs become Extinct?
The Asteroid Theory One of the most well-known and intriguing theories suggested for dinosaur extinction is the asteroid theory. In the 1980, the father-son team of Luis and Walter Alvarez discovered a layer of iridium in the K-T boundary. Iridium is rare on earth, but abundant in meteorites. The Alvarezs' suggested that a huge asteroid or comet, perhaps miles in diameter, hit the Earth at that time. The result of such an impact would be an enormous explosion that would throw dust clouds into the sky, darkening the planet. Massive forest fires, triggered by the hit, would add smoke to the sky. This would cool the planet causing the climatic changes observed. A crater, now worn down and partly under the ocean, was found along the Mexican Yucatan Peninsula and its creation coincides nicely with the K-T boundary. NASA scientists estimate that the asteroid that made Chicxulub Crater, as it is now known, would have been about 6 to 12 miles in diameter. The crater is about 130 miles across. Scientists at the Southwest Research Institute in Boulder, Colorado, have even been able to trace the path of that asteroid back into space. According to their calculations, 160 million years ago a collision between a 100-mile-wide asteroid, named Baptistina, and a smaller unnamed asteroid out beyond the orbit of Mars, shattered the larger object and sent pieces of it into the inner solar
The Effects Of Changing Light levels on the Rate of Photosynthesis
The Effects Of Changing Light levels on the Rate of Photosynthesis Aim: To investigate a factor that affects the rate of photosynthesis. Outline: A piece of pond weed will be cut and placed into a beaker containing water and sodium hydrogen carbonate. A lamp will be shined on to the pond weed and the amount of bubbles released from the plant will be counted. The lamp will be adjusted to different distances from the plant to try and obtain different results. Photosynthesis Equation: 6CO2 + 6H2O light energy & chlorophyll C6H12O6 + 6O2 Variables: Experimental Variable- Light intensity is to be the variable explored in this investigation. Light intensity can be changed by increasing or decreasing the distance from the light source to the plant. Fixed Variables- Carbon Dioxide- CO2 concentration can affect the rate of photosynthesis since the more CO2 in the air, the more CO2 that can diffuse into the leaf. This variable can be fixed by adding a fixed amount of sodium hydrogen carbonate to the beaker and plant. Water- Water is required in the photosynthetic reaction. When plants lack water, their stomata close to prevent further water loss. At the same time, closing the stomata cells doesn't allow CO2 to diffuse into the leaf. Water is also linked to the carbon dioxide factor. Water can be kept a constant by keeping the same amount of water in the beaker. Temperature-
How the concentration of salt-water affects the rate of osmosis.
How the concentration of salt-water affects the rate of osmosis. Aim: To find out how the concentration of salt-water affects the rate of osmosis in a potato. Prediction: My prediction is when the concentration of salt-water gets higher the mass of the potato will get smaller. The reason for this is because when the concentration of salt is low the concentration of water will be high. The water moves from a high concentration to a low concentration. The potato has a low concentration of water so the water passes through the semi permeable membrane and the potato gains water through osmosis, increasing the mass of the potato. If the concentration of salt is high then the concentration of water will be low. The water passes from high concentration to a lower concentration so if the concentration of water outside the potato is lower than inside the water passes out of the potato reducing the mass of the potato. Method: Variables: The variables that could affect the results are: * The time the potato is exposed to the water because the experiment may not be left long enough to show any affect. * The volume of salt-water will affect the potato because there is more water and sugar and so more water will want to move making the test unfair. * The size of the potato because if they are different sizes the potato may gain more water because it can hold more making the
Investigating antacids.
Investigating antacids Aim: To discover the most effective and useful base for use as an antacid using both chemical and medical evidence to make a final judgement. The formulae for the neutralisation of each base are as follows: Mg(OH)2 + 2HCl › MgCl2 + 2H2O Mr: 92 + 80 = 172 0.2g + 1.8g = 2g 0.0022 + 0.0225 CaCO3 + 2HCl › CaCl2 + CO2 + H2O Mr: 100 + 80 = 180 0.2g + 1.8g = 2g 0.0020 + 0.0225 MgCO3 + 2HCl › Mg(Cl)2 + CO2 + H2O Mr: 84 + 80 = 164 0.2g + 1.8g = 2g 0.0023 + 0.0225 MgO + 2HCl › MgCl2 + H2O Mr: 40 + 80 = 120 0.2g + 1.8g = 2g 0.005 + 0.0225 NaHCO3 + HCl › NaCl + CO2 + H2O Mr: 84 + 37 = 71 0.2g + 0.9g = 1.1g 0.0023 + 0.0243 We are using 0.5M Hydrochloric acid for the titration and we would therefore expect that 0.9g of HCl is being neutralised throughout. (0.05l x 18g = 0.9g HCl) You would expect that the magnesium based compounds would be the most efficient antacids because they have high formula masses that are greater than or close to the amount of HCl being neutralised, in particular MgO which has a formula mass of 0.005 and is neutralising HCl of 0.0225. Apparatus: 50ml burette and stand, burette funnel, glass beaker, pipette, conical flasks, Hydrochloric acid (0.5M), selection of bases (Magnesium hydroxide, Calcium
length of a simple pendulum affects the time
. Plan Aim To investigate how the length of a simple pendulum affects the time for a complete swing. Variables length The length of the pendulum has a large effect on the time for a complete swing. As the pendulum gets longer the time increases. size of swing Surprisingly, the size of the swing does not have much effect on the time per swing. mass The mass of the pendulum also does not affect the time. air resistance With a small pendulum bob there is very little air resistance. This can easily be seen because it takes a long time for the pendulum to stop swinging, so only a small amount of energy is lost on each swing. A large and light pendulum bob would be affected by a significant amount of air resistance. This might change the way the pendulum moves. gravity The pendulum is moved by the force of gravity pulling on it. On the Moon, where the pull of gravity is less, I would expect the time for each swing to be longer. Theory When the pendulum is at the top of its swing it is momentarily stationary. It has zero kinetic energy and maximum gravitational potential energy. As the pendulum falls the potential energy is transferred to kinetic energy. The speed increases as the pendulum falls and reaches a maximum at the bottom of the swing. Here the speed and kinetic energy are a maximum, and the potential energy is a minimum. As the pendulum rises the
Investigation into the energy produced per mole when burning different alcohols to heat up water.
Investigation into the energy produced per mole when burning different alcohols to heat up water. Plan The aim of this investigation is to find out how much energy is produced per mole of alcohol when burning the alcohol to heat up water to a certain temperature rise. Equipment 5 Alcohol Burners: Methanol, Ethanol, Propanol, Butanol, Pentanol, Bunsen Burner, Splints, Wooden Board, Safety Glasses, 200ml beaker, Water, Thermometer, Clamp Stand, Ruler, Scales, Measuring Cylinder, Method Set up all the equipment as shown above. First weigh the alcohol burner, so that the amount of alcohol that has been burnt can be worked out after the experiment has been carried out. Then fill up the beaker with 100mls of water, using the measuring cylinder for greater accuracy. The water used will always be around room temperature, because it is from the tap. Place the alcohol burner on to the wooden board next to the clamp stand, and then attach the beaker with water in, to the clamp stand, directly above the alcohol burner and 15cm from the board, and put the thermometer into the water. Now record the temperature of the water. It should be around 20°C, because that is the normal room temperature. Now light the Bunsen burner. Using the splint, light the first alcohol burner, which is methanol. Let the flame from the alcohol burner, burn until the temperature of the
Human activities pollute air, water and land in different ways.
By Arran Roberts Contents Page Title 2 ..........................................................Contents 3..........................................................Loss Of Habitat 5...........................................................Human Activities 7............................................................Solutions Loss of Habitat The amount of land available for animals and plants is reduced by Man's land use, mainly activities such as quarrying, building, farming and dumping waste. Quarrying is a major threat to plants which grow specifically in rocky areas, such as yellow larkspur and American Hart's-Tongue Fern. Plants of this nature are becoming more difficult to find as more quarries appear. (Lakeside daisy threatened by limestone quarrying) Building is a large cause of loss of habitat, towns and cities are outwardly expanding and more land is being used for housing and other large scale building projects such as shopping malls and new roads. Draining of swamps and wetlands and deforestation are also greatly contributed to by building. Loss of habitat and habitat fragmentation are areas of major concern in species conservation, building often results in large areas of habitat being broken up into a series of smaller areas, each of which will support fewer species. (Building site) Farming and agriculture reduce amounts of
An investigation to determine the factors which affect the rate of reaction between Calcium carbonate (marble chips) and the concentration of Hydrochloric acid.
An investigation to determine the factors which affect the rate of reaction between Calcium carbonate (marble chips) and the concentration of Hydrochloric acid. Background knowledge Collision theory- In order for any reaction to occur the reacting particles needs to collide with sufficient energy to overcome the activation of he reaction. To make a reaction happen more quickly we either need to: > Increase the chance of collision occurring > Increase the energy collision > Both Aim The aim of the investigation is to determine the effect of varying the concentration, in the reaction between Calcium carbonate and Hydrochloric acid. The equation for the reaction is: Hypothesis A reaction can only take place when particles collide. This process is based on random particle movement. So therefore, if you have more particles in a given volume the more likely they are to collide with one another. Resulting in a faster rate of reaction. The above hypothesis can be investigated by comparing the rate of reaction between the marble chips and hydrochloric acid using different concentration of hydrochloric acid. The hypothesis will be supported if the rate of reaction increases with increase in concentration of the hydrochloric acid. Factors which affect the rate of reaction: * Temperature * Surface area * Concentration * Catalyst * Stirring I will be looking
Investigating the reaction between magnesium ribbon and hydrochloric acid
Investigating the reaction between magnesium ribbon and hydrochloric acid Introduction Magnesium reacts with hydrochloric acid and as magnesium is a more reactive element than hydrogen it extracts the chloride from the hydrochloric acid and joins with it to make magnesium chloride. Hydrogen gas is then given off as it has now left its compound state and become an element. Magnesium + Hydrochloric Acid Magnesium Chloride + Hydrogen Mg + 2HCl MgCl2 + H2 There are four main factors which can affect the rate of reaction. These are: temperature, concentration, surface area and if a catalyst is present. A catalyst is a chemical which increases the rate of reaction by lowering the energy activation level causing more collisions per second and therefore more successful collisions every second. A catalyst can not be used up or changed and can be recycled. An enzyme is a biological catalyst. A greater surface area increases the rate of reaction by allowing the particles around it in the solution more area to react with and therefore more collisions every second hence more successful collisions every second. A greater concentration increases the rate of reaction as there are more particles in every centimetre cubed to react. This causes more reactions every second so there are more successful collisions every second. The greater the temperatures the
