1255 results found

#### Osmosis - how does the concentration of water affect the mass of a potato?

Biology Coursework Osmosis- how does the concentration of water affect the mass of a potato? Abubakar Hatimy Aim: - My aim is to find the percentage change of mass when a small piece of potato is placed in to molar sucrose solution Apparatus: o Molar sucrose solution 0.0 - 0.5 o Potato o Cutting board o Knife o Weighing machine o Glass test tube o Glass test tube holder Plan: - My plan is too find the percentage change of mass of a small piece of potato when placed in to molar sucrose solution by using osmosis. Osmosis is explained below Osmosis Osmosis is the passage of water molecules from a region of their high concentration to a region of their low concentration through a partially permeable membrane. It is best regarded as a form of diffusion in which only water molecules move. For example look at Figure 2. The solute molecules are too large to pass through the pores in the membrane, so the movement of water molecules can only achieve equilibrium. Solution A has the higher concentration of water; so there will be a net movement of water from A to B by osmosis. At equilibrium there will be no further net movement of water. The tendency of water molecules to move from one place to another is measured as the water potential, represented by the symbol

• Word count: 1868
• Level: GCSE
• Subject: Science

#### To Investigate the Effect of Light Intensity on The Rate of Photosynthesis

To Investigate the Effect of Light Intensity on The Rate of Photosynthesis Predication As it is seen in figure 1 that in order for any plant to photosynthesis it need three main raw materials: . Water 2. Carbon Dioxide 3. Light These are also known as 'limiting factors' of photosynthesis (another limiting factor that has not been mentioned above is temperature), therefore if the limiting factors are increased the rate of photosynthesis should also increase. Carbon Dioxide + Water Sugar + oxygen Sunlight Figure 1. Formula for Photosynthesis From figure 1 the fact that without light photosynthesis could not happen could also be concluded. This is proven from a previous experiment, which is set up to compare if light is limited would the plant still produce glucose as food. This is done by setting up a plant that had been given all the raw materials to photosynthesis, compared to a plant that had light limited. As the result of this experiment, when iodine solution, which is used to test for glucose, is added to the decolourised plant, which had all the right raw material to photosynthesis, it turned blue-black which mean glucose had been produced. And when iodine solution is added to the decolourised plant with light limited it stayed reddish brown, which showed that glucose had not been produced as. From here a prediction could be made that if the light

• Word count: 1016
• Level: GCSE
• Subject: Science

#### To experiment with different variables that effect photosynthesis using a computer simulation, and take measurements accordingly.

Photosynthesis - Science Coursework: Task: To experiment with different variables that effect photosynthesis using a computer simulation, and take measurements accordingly. Prediction: I predict that firstly the increased temperature will generate more oxygen, however this will only apply to a certain degree, probably around 35?C to 40?C in my opinion, where I think the equation will be at its optimum heat capacity. And for the additional experiment, I think that an increased in Carbon dioxide levels will again produce greater amounts of Oxygen. Lastly, a higher light intensity, in my opinion will produce increased levels of Oxygen because as the formula states sunlight is essential for the reaction to take place, therefore it is likely the greater this is the more Oxygen is produced. Method: We first decided to find out how the temperature affects the rate of photosynthesis. Using the computer simulation, we tested from 0?C to 50?C, at 5?C intervals. All other variables were set at one certain measure. Take for instance Light Intensity, which was arbitrary at 50 throughout and NaHCO3, which was at 2%. We then let each individual test run for 10 minutes, and then taken the oxygen level produced, measured in mm. As a secondary experiment we tested for the effect of light intensity to the rate of photosynthesis. Again we fixed the amount of NaHCO3 to 2% and left the

• Word count: 710
• Level: GCSE
• Subject: Science

#### Pigment Chromatography Lab

Pigment Chromatography Lab Sahar Rudgar Mr. Wright SBI4U- Per. 4 Tuesday Mar. 22nd, 2005 Purpose: Separation of plant cell pigments by paper chromatography. Materials: * Chromatography paper * Scissors * Test tube * Chromatography tube and solvent * Pencil * Fresh leaf Procedure: .) A test tube was obtained containing developing fluid (9 volumes of petroleum ether / 1 vol. acetone) and a stopper with a hook. 2.) A 15 centimeter strip of Whatman chromatography strip was cut. 3.) One end to a point was trimmed with scissors. A pencil line was drawn just above the point. 4.) The strip on a hard clean flat surface was laid. A fresh leaf was put over the paper and the tissue was crushed onto the pencil line by rolling the edge of a test tube along the leaf surface. The leaf was moved and this was repeated several times. The line of pigment which has been crushed onto the paper was kept as thin as possible. 5.) The paper was immediately hooked onto the hook of the tube stopper so that the tip of the paper was immersed in the developing fluid. The paper was hanging vertically and not touching the sides of the tube. 6.) The tube stood for about 10 minutes. The movement of the solvent front was observed. When the solvent front was within one centimeter of the hook the paper was removed and a pencil line was drawn at the edge of the front (This was done quickly

• Word count: 735
• Level: GCSE
• Subject: Science

#### Investigation to find does light intensity affect the stomata density of leaves.

Investigation to find does light intensity affect the stomata density of leaves. Aim: To find out that does light intensity affect the stomata density of leaves. Leaf stomata are the main means of gas exchange in vascular plants. Stomata are small pores, typically on the undersides of leaves, which open or close under the control of a pair of banana-shaped cells called guard cells. When open, stomata allow carbon dioxide to enter the leaf for synthesis of glucose, and also allow for water, and free oxygen, to escape. In addition to opening and closing the stomata, plants may exert control over their gas exchange rates by varying stomata density in new leaves when they are produced. The more stomata per unit area the more carbon dioxide can be taken up, and the more water can be released. Thus, higher stomata density can greatly amplify the potential for behavioural control over water loss rate and carbon dioxide uptake. Prediction: I think that from the top section of the bush will have more stomata present. I think this is because light stimulates the stomata's to open, and at the top of the bush the leaves are receiving the most light. For photosynthesis to happen the plant needs sunlight and carbon dioxide, so there are more stomata present there to take in the carbon dioxide they need for photosynthesis. I think that at the bottom section of the bush there will be less

• Word count: 1893
• Level: GCSE
• Subject: Science

#### An investigation in to the effect of temperature on the release of pigment from beet root tissue

Nadia Mohamad Rom AT1 Practical investigation An investigation in to the effect of temperature on the release of pigment from beet root tissue Introduction and Hypothesis I think that the increase of the temperature on the beetroot will affect the diffusion of the colour dye in the beetroot. The colour dye is held together by the membrane structure and this maintains the red rich colour in the beetroot. I believe that with the increase of temperature applied onto the plasma membrane, the structure of the membrane will become damaged and the membranes of the protein will eventually denature. Scientists know that cell membrane have the following general characteristics: - * 40% Lipid * 0 - 10% carbohydrate (as prosthetic groups) * 50 - 60% protein. You can see from above that proteins are major constituents of membranes. In membranes there are intrinsic and extrinsic proteins. Intrinsic membrane proteins completely pass through the lipid layers. They have a variety of functions, though many are 'carrier' proteins and channels that assist with transporting molecules through the membrane. These proteins have both an extra and intracellular part. Extrinsic membrane proteins are embedded in the outer phospholipid layer. They are fixed to one side of the bilayer or one depth of the bilayer. They can often act as chemical receptors for the cells. The majority of the

• Word count: 6451
• Level: GCSE
• Subject: Science

#### Primary and Secondary Pollutants:When fuels are burnt in both car exhausts and power stations primary pollutants are released into the atmosphere.

Primary and Secondary Pollutants: When fuels are burnt in both car exhausts and power stations primary pollutants are released into the atmosphere. Secondary pollutants are formed when primary pollutants undergo further reactions. For example Ozone is a secondary pollutant formed when sunlight shines on nitrogen oxides and hydrocarbons. Ozone is a major component of photochemical smog. Primary Pollutants Secondary Pollutants Nitrogen oxides (NOx) Carbon Monoxide (CO) Hydrocarbons (CxHy) Ozone (O3) Peroxyacetyl nitrate (PAN) HNO3 NO2 H2O2 There are 2 main types of primary pollutants responsible for photochemical smog. . Oxides of nitrogen formed when nitrogen in the air reacts with oxygen, under high temperatures and pressure. 2. Hydrocarbons emitted from car exhausts as unburnt fuel. Photochemical smog is formed by the action of the suns rays on these primary pollutants. How are Primary Pollutants formed ? Primary pollutants are formed during the combustion of fuel in coal fired power stations. Carbon dioxide, sulphur oxides and nitrogen oxides are all primary pollutants produced when coal is burnt. When the coal burns the sulphur compounds found in all living organisms are converted to oxides of sulphur, these oxides of sulphur can cause serious environmental damage if they get into the atmosphere. The amount of sulphur in coal depends on the types of

• Word count: 1108
• Level: GCSE
• Subject: Science

#### The effects of light intensity on the rate of photosynthesis.

Biology Investigation The effects of light intensity on the rate of photosynthesis Introduction Photosynthesis involves an energy conversion in which light energy usually in the form of sunlight is converted into chemical energy stored in molecules of carbohydrate. The equation for photosynthesis is: The chlorophyll in the leaves of the plants absorbs the light energy. Some of this energy is used to produce ATP and some is used to split water molecules in the photolysis of water1. Light intensity as a limiting factor The amount of light available affects the amount of chlorophyll, which has excited electrons and therefore the amount of NADPH and ADP produced in the light-dependant stage. If there is a low level of light then insufficient NADPH and ATP will be produced to allow the reactions of the light independent stage to progress at their maximum rate. In this situation light is said to be the limiting factor for the process2. Also, not all wavelengths of light are equally effective at powering photosynthesis. However in my experiment I will be using a bulb, which will produce white light, as I know this, is an effective wavelength because the light from the sun is also white light3. Controlling the other limiting factors in photosynthesis If there is an insufficient supply of carbon dioxide in the reaction then there will not be enough available for

• Word count: 1513
• Level: GCSE
• Subject: Science

#### Investigation of water pollution; comparison of water entering and leaving Newquay zoo.

Investigation of Water Pollution Investigation of water pollution; comparison of water entering and leaving Newquay zoo. Many causes of pollution contain nutrients such as nitrates and phosphates. In excess levels, nutrients over stimulate the growth of aquatic plants and algae. Excessive growth of these types of organisms consequently clogs our waterways, use up dissolved oxygen as they decompose, and block light to deeper waters. This is harmful to aquatic organisms as it affects the respiration ability or fish and other invertebrates that reside in water. Pollution is also caused when silt and other suspended solids, such as soil, wash off ploughed fields, construction and logging sites, urban areas, and eroded riverbanks when it rains. Under natural conditions, lakes, rivers, and other water bodies undergo Eutrophication, an aging process that slowly fills in the water body with sediment and organic matter. When these sediments enter various bodies of water, fish respiration becomes impaired, plant productivity and water depth become reduced, and aquatic organisms and their environments become suffocated. Pollution in the form of organic material enters waterways in many different forms as sewage, as leaves and grass clippings, or livestock feedlots and pastures. When natural bacteria and protozoan in the water break down this organic material, they begin to

• Word count: 875
• Level: GCSE
• Subject: Science

#### To Find Out If Light Intensity Has an Effect On a Plants Rate of Photosynthesis By Varying the Distance From the Light To the Plant

Strand I - Planning Section I intend to find out if light intensity has an effect on a plants rate of photosynthesis by varying the distance from the light to the plant I hope to speed up and slow down the rate of photosynthesis. Safety will be the most important part of my experiment. I will be using glassware, which is liable to break. I will need to dip all my glass tubes and rubber fittings in water before I attempt to connect them. When I connect the pieces, I must hold the two joints very close together so as not to put pressure on the centre of the glass rods. Should any glass break, it will be left where it is for a teacher to clear up. The other major safety issue is using water and electricity together. When conducting this experiment, I will ensure that all my work surfaces are clean and dry and that the lamp never comes in contact with water. Finally, I will make sure that I apply appropriate caution when handling NaHCO3. I will place a set amount of Canadian Pond Weed in a conical flask filled with tap water. I will then put in 1/2 a gram of NaHCO3 before placing the bung on firmly. Next I will place the light source I will then wait for a bubble to reach the beginning of the capillary tube before I begin the 5 minutes in which I will see how far it moves. I will vary the distance between the light source and the experiment. This will be measured as light

• Word count: 3399
• Level: GCSE
• Subject: Science