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GCSE: Life Processes & Cells

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  1. Marked by a teacher

    How does the concentration of salt solution affect osmosis in potatoes?

    4 star(s)

    Therefore, the potato piece will stay the same size. Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty. A cell can only become flaccid by losing water. The chain of events starts with water leaving the cell through the cell membrane by osmosis because the water concentration outside is lower than that in the cell. As water is lost the vacuole gets smaller as it is used to top the cytoplasm up.

    • Word count: 1042
  2. Marked by a teacher

    Science GCSE coursework: osmosis

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    The water is stored in the vacuole in the cell of the potato chip and as that expands then so does the mass of the potato chip. Method The following apparatus were used: * Scales * Potato chip * Water solution * Measuring jugs + beakers * Thermometer * Boiling tubes * Stop clock * Knife * Pipette Salt Concentration (m) Volume of water (cubed cm) Volume of salt solution (cubed cm) 0 30 0 0.2 27 3 0.4 24 6 0.6 21 9 0.8 18 12 1.0 15 15 1.2 12 18 1.4 9 21 1.6 5 24 1.8 3 27 2.0 0 30 * Firstly, cut the potato chip to the size 35mm.

    • Word count: 1031
  3. Marked by a teacher

    An investigation into the factors affecting osmosis

    4 star(s)

    Whereas 1.0 and 2.0 molar solutions decreased the onion in size and mass. We found out that the ones that we couldn't really see any particular difference in we would have too look in specific detail so we decided to look between 0.2M and 0.4M. I will plot my results in a table that looks like this: Concentration of solution (M) Length before (mm) Length after (mm) Change in length (mm) Percentage Change in length Mass before (g) Mass after (g)

    • Word count: 3954
  4. Marked by a teacher

    An Experiment to determine Water Potential in Potato Tissue.

    4 star(s)

    Water potential is affected by two main factors: 1. Solute potential 2. Pressure potential. The effect of dissolving solute molecules in pure water causes it to reduce the concentration of water molecules and therefore lowers the water potential. This means that all solutions have lower water potential than pure water. The amount of this lowering is called solute potential. The solute potential is a measure of the change in water potential because of the presence of solute molecules. The other factor that affects the water potential is pressure potential. As the pressure increases onto pure water or a solution, its water potential increases.

    • Word count: 3753
  5. Marked by a teacher

    An experiment to investigate how the effect of varying concentrations of salt solutions play on the movement of water in a potato.

    4 star(s)

    Mc McCarthy Bottle I have drawn a diagram of what the experiment will look like seen above. I have been given the best equipment to carry out this investigation thoroughly. Within each of the McCarthy bottles contains the different molar solutions with the potato cylinder as you are able to see above. I will be using the concentrations of 0 Molar, 0.5 Molar, 1 Molar, 1.5 Molar and 2 Molar. The experiment will take place over the time-span of twenty-four hours.

    • Word count: 6185
  6. Marked by a teacher

    "Osmosis" - The Potato Experiment.

    4 star(s)

    The inward pressure is called turgor pressure and the outward force is called osmotic pressure. The opposite of being turgid is being flaccid. This occurs if the plant is placed in solution that is hypertonic to its contents. So basically, when the solution outside the cell is more concentrated. The cell loses the water content via the process of osmosis. The cytoplasm will eventually cease to exert any force on the cell whatsoever and so the cell becomes flaccid. In the experiment, the pieces will either become flaccid, stay the same or become turgid depending on the concentration of the solute inside and outside the cells.

    • Word count: 2288
  7. Marked by a teacher

    Investigate the effect of surface area on osmosis in potato tissue.

    4 star(s)

    Osmosis takes place until the concentration of water on the outside of the cells is the same as the concentration of water on the inside of the cells, therefore, if the pieces of potato are left in 100% pure water then it will take a long time for the concentration of water in the cells to equal that of the water around them. Osmosis between pure water and a plant cells is quicker then osmosis between 1molar sucrose solution and a plant cell.

    • Word count: 2288
  8. Marked by a teacher

    What factors affect osmosis in potato cylinders?

    4 star(s)

    * Time- if one cylinder was left to perform osmosis for 24 hours and another for only 2 hours, this would be an unfair test so all cylinders must be measured for the same length of time to succeed in making it a fairer test. I have chosen to investigate how the strength of the sugar solution affects osmosis in potato cylinders. For this investigation the input variable will be the strength of sugar solution, the dependant variable will be the weight change because water molecules will either be lost or gained through osmosis.

    • Word count: 1768
  9. Marked by a teacher

    Investigating the effects of surface area on the rate of enzyme reactions.

    4 star(s)

    A different kind of inhibitor binds elsewhere on the enzyme, rather than in the active site. The other binding site is called the allosteric site. The consequence of this is that the specific substrate can no longer fit and no products can be formed. This is known as non-competitive reversible inhibition. The way that enzymes speed up reactions is by lowering the activation energy needed to get the reaction started. When there isn't enough energy, there are no products formed from the substrate and no reaction occurs. When the activation energy is lower, the reaction can occur much more easily, and without as much energy.

    • Word count: 3081
  10. Marked by a teacher

    The aim of this investigation is to find out what effect pH has on the enzyme Catalase in it breaking down Hydrogen peroxide into Oxygen and Water.

    4 star(s)

    If too little substrate is available the rate of reaction is slowed and cannot increase any further. If too much product accumulates, the reaction can also be slowed down. So it is important that the product is removed. The pH must be correct for each enzyme. If the conditions are too alkaline or acidic then the activity of the enzyme is affected. This happens because the enzyme's shape, especially the active site, is changed. It is denatured, and cannot hold the substrate molecule. Temperature is a key factor too. If it is too cold the enzymes will move around slowly to meet the substrate molecules, so the reaction rate is slow.

    • Word count: 3675
  11. Marked by a teacher

    Osmosis Investigation - How Does Salt Solution Concentration Affect The Mass Of Potatoes?

    4 star(s)

    If plant cells lose water the cells become limp and flaccid. Water is essential for support in plants. Prediction I think that when the potato is placed in distilled water the potato mass will increase. This is because water, has, if pure, a weaker concentration than the potato, and the water molecules move in through a partially permeable membrane by osmosis. If the potato is in a high concentration salt solution, the potato mass will decrease because the potato is less concentrated than the salt solution, and the water will move through the partially permeable membrane into the stronger solution.

    • Word count: 1172
  12. Marked by a teacher

    To investigate the effect of temperature on enzyme activity. The enzyme used will be catalyse.

    4 star(s)

    The higher the temperature above 45�C, the slower the reaction rate. If the temperature falls below 40�C, the rate of enzyme activity will fall. This is because the lower the temperature, the less kinetic energy the enzymes will have. This means that fewer will be able to react. The lower the temperature below 40�C, the slower the enzyme reaction rate. At low temperature's particles of reacting substances do not have much energy. However, when the substances are heated, the particles take in energy. This causes them to move faster and collide more often.

    • Word count: 1865
  13. Marked by a teacher

    The aim of this investigation is to find out how the concentration of the solution a plant is in affects the rate of osmosis in the plant.

    4 star(s)

    This increases the length and weight of the cell considerably, because it has a bigger area and water content. When there is enough water in the cell, the turgor pressure becomes so high that no more water can enter the cell, stopping osmosis. The more osmosis occurs, the more turgid the plant cell becomes. On the other hand, when there is little water because little osmosis occurs, the plant cell becomes FLACCID (or plasmolysed), decreasing the length and weight. So the less osmosis occurs, the more plasmolysed the plant becomes.

    • Word count: 4718
  14. Marked by a teacher

    Experiment to find the effect of sucrose solution concentration on potato and apple tissue.

    4 star(s)

    As water leaves the cells, their X falls and eventually the X of the cells = X of the solution and there is no further net water loss. If a cell is placed in a solution with the same X as that of the cells there is no net movement of water. This is how I will be able to find the water potential of the apple and potato tissue. Plant cells have a cellulose cell wall that prevents the cells from bursting when they take up water.

    • Word count: 2356
  15. Marked by a teacher

    The Effect of pH on Catalase

    4 star(s)

    This can then be analysed for the effect of pH on catalase to prove or disprove the hypothesis. Alternative: Use yeast, broad beans or liver, instead of potato. Diagram: Brief Method: 1. Set up apparatus as shown in the diagram. 2. Mince and weigh out potato to form a suspension with distilled water. 3. Add buffer solution and warm mixture in water bath to optimum temperature of catalase. 4. Check pH is still correct at the optimum temperature. 5. Inject hydrogen peroxide onto potato and start timer. 6. Record volume of oxygen produced every 10 seconds for the first second, and then every minute thereafter till 4 minutes has passed.

    • Word count: 3649
  16. Marked by a teacher

    Determination of Water PotentialOf Potato Tissue

    4 star(s)

    High water potential is when the water is highly likely to leave. Low water potential is when the water is less likely to leave. The water potential for water potential is arbitrarily given value 0. Solute Potential of cell contents (?s) is only slightly affected by dilution as water enters the cell. Pressure potential (?p) is 0 until the protoplast begins to exert pressure on the cellulose cell wall. If a plant tissue was placed in a hypertonic solution, the plant tissue will increase in size. This happens because this is more concentrated solution, which means that the water will leave the high concentration water and enter the plant tissue, which is low concentrated.

    • Word count: 1612
  17. Marked by a teacher

    Thyroid Cancer Research Project

    3 star(s)

    showing the incidence of thyroid cancer in different races in males and females. Table (2) showing thyroid cancer incidence rates in relation with race Table (3) showing death rates as a result of thyroid cancer in realtion with race Source: http://seer.cancer.gov/statfacts/html/thyro.html Not enough iodine in the diet: The thyroid needs iodine to make thyroid hormone. Thyroid cancer seems to be more common in countries where iodine is not part of the diet. Moreover,thyroid cancer generally has an increasing trend Word count :163 Word Count:144 Figure(6) showing the rate of incidence of thyroid cancer in New Mexico over a period of years.

    • Word count: 2298
  18. Marked by a teacher

    The Vitamin C content in fruits

    3 star(s)

    to make 1ml of DCPIP solution change from blue to colourless.We can add in the juices drop by drop until the DCPIP solution become colourless. The control variables are the temperature,the volume of water used in grinding the fruits and the volume of DCPIP solution used in each test tube.The experiment have to be carried out under constant room temperature because heat destroys the reducing property of vitamin C and the result might vary if the temperature is not constant.The volume of water added and the volume of DCPIP solution used can be measured and control by using pipette.

    • Word count: 738
  19. Marked by a teacher

    Biology Project The Stem Cell

    3 star(s)

    They can be frozen in liquid nitrogen and used at a later date for various purposes. This process is called as stem cell storage. 1 of 6 Biology Project ? The Stem Cell Research Question 2 ? What are the uses of stem cells? Ans. Stem cells can be used for the following ? 1. Drug testing ? Stem cell lines can be used for testing new drugs under controlled laboratory conditions. For example cancer cell lines can be used to test the efficacy and safety of anti ? tumour drugs.

    • Word count: 1350
  20. Marked by a teacher

    Pectinase Lab

    3 star(s)

    Materials: Preliminary Lab:- 1. Apple - 1 2. Pectinase - 8 drops 3. Water - 8 drops 4. Beaker - 4 5. Kettle - 1 6. Measuring Cylinders - 4 7. Digital Thermometers - 2 8. Droppers - 2 9. Test Tubes - 2 10. Mortar and Pestle 11. Spatula -1 12. Cheesecloth - 2 pieces 13. Knife 14. Stopwatch 15. Funnels - 2 16. Stirrer - 2 Final Lab:- 1. Apple Sauce - 15 cm3 2. Pectinase - 8 drops 3. Water - drops 4. Kettle - 1 5. Plastic Bowl - 1 6. Test Tubes - 2 7.

    • Word count: 1723
  21. Marked by a teacher

    Agar blocks

    3 star(s)

    Using a measuring cylinder measure 40ml of hydrochloric acid (1mol) 3. Using tweezers put all of the cubes in a beaker containing 40ml (1 mol) of hydrochloric acid 4. Measure length of time for agar blocks to go from pink to white using stop watch. Effect of concentration on rate of diffusion Procedure #2 1. Six agar blocks are cut into size 1.5cm� using knife 2. 40ml cube of hydrochloric acid (0.75, 0.5 and 0.25 moles each separate) are put into a beaker, different beaker for each concentration.

    • Word count: 890
  22. Marked by a teacher

    Energy content of foods

    3 star(s)

    Boiling tube is attached to the retort stand via a clamp 2. 20cm� of water is measured in a measuring cylinder and put into the boiling tube 3. Inital temperature of water is measured 4. A sample of food substance is weighed and its mass recorded using the measuring scale 5. The food substance is held by a tonge and then ignited 6. The food sample is burnt, underneath the boiling tube at a fixed distance via the marker, untill it turns completley black. 7. The final temprature is then recorded. 8.

    • Word count: 1033
  23. Marked by a teacher

    The Effect of Temperature on Amylase

    3 star(s)

    which results in faster rate of enzymatic reaction. ?The best temperature range for the amylase to work best at is 35-40�c- This is because if the temperature is too low (0-5�c), there will be less collision between the substrate and the active site therefore the reaction is much more slower. And if the temperature is too high (85-90�c), the enzyme will stop it's reaction because if the temperature is too high, the enzymes will denature. Enzymes are protein, and protein breaks down at high temperature. When the active site changes, the substrate will not fit so now it no longer works.

    • Word count: 1283
  24. Marked by a teacher

    Osmosis Coursework

    3 star(s)

    will be used to compare in mass both before and after being placed in the concentrated solution, the samples will also be took using a cork borer. Test Tubes - these will be used for placing each piece of potato in separately, and also for storing equal amounts of solution so the investigation can be carried out. Test Tube Racks - these will be used to store the test tubes in so they don't collapse and smash/spill the solution. Sucrose Solution - this is the name for the solution being used which will be varied in concentration to obtain different results for the rate of osmosis.

    • Word count: 1357
  25. Marked by a teacher

    Agar gel lab report

    3 star(s)

    Syringe- 20 cm3 Variables: Independent * Volume of the agar gel used for each set of readings. Dependent * Time taken for the agar gel to turn white in colour from pink in colour. Constant * The volume of hydrochloric acid used for each reading taken. * The number of readings taken in each set of readings. * The agar gel sample should be the same for each reading for every dimension. Fair Test: * There should be minimal error in measuring the dimensions of agar gel used for each reading. * The agar gel should be dropped in the test tube or beaker as soon as the stopwatch is started.

    • Word count: 1345

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