What factors affect osmosis?
What factors affect osmosis? In my investigation I am going to attempt to discover if osmosis is affected by a certain factor. Osmosis is the movement of water from an area of high water concentration through a semi-permeable membrane to an area of low water concentration. Osmosis is affected by water potential which is the term used to describe the movement of a concentration of water, and as a general rule water always falls from an area of high water concentration to an area of low water concentration in a similar way to gravitation or electrical potential. In simple terms, it is sometimes referred to as the diffusion of water. I am going to find out how the concentration of a solution affects osmosis in an investigation using potatoes and sucrose solution. Osmosis depends upon a semi-permeable membrane because this allows water to pass both ways through the membrane but not other solutions with larger molecules, for example sucrose solution (see diagram to the right). A number of factors could affect osmosis such as; type of plant material, temperature, type of solution or concentration of solution. I could have chosen to investigate any of these factors effect on osmosis but instead I chose to investigate the concentration of solution, as I believe it will have the greatest effect on osmosis and will allow me to show a higher level of scientific knowledge and I chose
The effect of antibiotics on the growth of bacteria.
The effect of antibiotics on the growth of bacteria. The Aim: The aim of this investigation is to find out what effect out of two antibiotics, penicillin and streptomycin has on the growth and multiplication of two different species of bacteria. The two different types of bacteria we will be using are E-coli and micrococcus luteus. The Apparatus: * Four sterilised Agar plates, * Glass spreader, * Masking tape, * Wax pencil, * Lab roll, * A beaker with 70% alcohol, * E- coli (Culture) * Micrococcus luteus (culture), * Penicillin (antibiotics), * Streptomycin (antibiotics). Scientific Knowledge: E-coli: E-coli are a common type of bacteria and are short for the medical term Escherichia coli. This normally lives inside your intestines, where it helps your body break down and digest the food you eat. E. coli bacteria was discovered by a German bacteriologist Theodor Escherich in the 1885.The organism can be found on a small number of cattle farms and can live in the intestines of healthy cattle. But also we need it in our bodies to keep them healthy we pretty much depend on E-Coli in our intestines to provide us with Vitamin K and B complex vitamins which play a vital role in keeping us strong and healthy. Penicillin: Penicillin was the first naturally-occurring antibiotic discovered and was the first one to be used therapeutically Penicillin was discovered by
Determine the penetrating power and the range in air of the three radioactive emissions (Plutonium 239 for alpha, Strontium 90 for beta and Cobalt 60 for gamma).
Aim To determine the penetrating power and the range in air of the three radioactive emissions (Plutonium 239 for alpha, Strontium 90 for beta and Cobalt 60 for gamma). Method 1 The apparatus were set up as in the diagram below to measure the range in air up to 50 cm for each source. Before the experiment took place the background radiation was measured as 80 counts in 5 minutes therefore 16 counts per minute. Experimental precautions were: The radioactive source is aligned with a ruler to the GM tube as accurately as possible so that the maximum radiation is measured A set square was used to measure the exact point at which the source and tube were placed The counter was reset each time so the counter read zero so this would reduce zero error in the experiment and the hold button was pressed to freeze the measurement Thirty seconds were left between the start of the count and the recording so the reading would be less instantaneous and more reliable Everything was kept constant for all three experiments and the counts were recorded at regular intervals of 5 cm. Safety precautions included removing the sources from a secure wooden box using thongs and tweezers and placed in plasticene, the set square was held using thongs and all those carrying out the experiment stood behind the source to minimise any direct radiation exposure. Method 2 The equipment was set up
Experiment Report: Studying a simple harmonic oscillator.
Name: Yu Wai So (19) 6S Experiment Report: Studying a simple harmonic oscillator Objective The simple harmonic motion of a pendulum can be studied by attaching a ticker-tape to a pendulum bob and analyzing the dots marked on the tape. Theory In this experiment, a string was used to suspend a 0.5 kg mass. Refer to the diagram above, Considering the tangential force on the mass, ?The oscillation is simple harmonic. Therefore, we can find out more on simple harmonic motion by analyzing the ticker-tape we obtained after the experiment. Apparatus . 0.5 kg ringed mass 2. 1.5 m length of string 3. Ticker-tape timer 4. Ticker-tape 5. Low voltage power supply (a.c.) 6. Retort stand and clamp Procedure . The apparatus as shown in the figure was set up. A pendulum was suspend by a string and was attached to a retort stand and clamp. A ticker- tape was attached to the mass and was inserted to the ticker-tape timer. The mass was pulled to one side. The timer was switched on and the mass was allowed to swing to the other side. 2. After the pendulum reached its highest position, the ticker-tape timer was switched off and the ticker-tape was detached from the mass. The dots marked on the tape were examined. During the oscillation, the pendulum bob accelerated and then decelerated when it was approaching its highest position. The acceleration of the bob was always
Hydrocarbons and the importance of oil as a power source.
Importance of OIL BY: Shivaans Doshii Grade: 9.1 Chemistry Essay PART 1 Fossil fuels are a source of energy that comes from once-living things. When living things die, they are broken down and covered by dust, soil or sand. As they are covered over by once-living things and by more layers of soil, sand and rock, they get buried deeper and deeper below Earth's surface. These layering of once-living things, sand and soil are eventually subjected to very high pressure and to very high temperature. When the pressure is great enough, the sand and soil change into rock. And at just the right temperature, the once-living things change into liquid called oil and a gas called natural gas. This oil and gas are found in porous rocks. Crude oil is separated into fractions by fractional distillation. The fractions at the top of the fractionating column have lower boiling points than the fractions at the bottom. The heavy bottom fractions are often cracked into lighter, more useful products. All the fractions are then processed further. The fractions at the top have a lower boiling point. The fractions at the bottom have a higher boiling point Some fractions from the distillation tower need to be transformed into new components. This is where a refinery
To find out how current affects the rate of electrolysis
Electrolysis experiment. Aim: To find out how current affects the rate of electrolysis. Pre-test: Pre-test Apparatus: . Power Pack 2. Stop watch 3. 3 wires 4. Amp meter 5. A piece of Card 6. stop watch 7. Top pan balance Pre-test Method: . Check to see if all the apparatus work by forming a small circuit with a bulb 2. Collect apparatus and set them out like the diagram below. Ensure that the positive wire leads to the anode and the negative leads to the cathode. 3. Measure out 50 ml of copper sulphate 4. In to a small class beaker 5. Weigh cathode on top pan balance 6. Slide anode and cathode in to piece of card and place in electrolyte 7. Turn on the power pack 8. Time until two minutes 9. Weigh cathode make sure you do not scrape off any copper 0. Repeat three times 1. Repeat for each current Pre-test Findings: By doing this pre-test I have learnt that: * The analog amp meter is very unreliable it * To be very accurate I need to use a multi meter * To be careful not to scrape of copper when measuring weight * Make sure that the anode and the cathode do not touch during the experiment * Make sure wires and power packs are working before you start * To change the electrolyte after each experiment * To use a stop watch instead of a clock as it is more accurate * To use a variable resistor to get the exact current you need Research: There are
An investigation into the effect of temperature on a squash ball
An investigation into the effect of temperature on a squash ball For my experiment I will be using a blue spotted squash ball. This is because the blue spotted ones are designed to have the most bounciness. This is will make it a lot easier to judge the height of the ball's bounce making my experiment more accurate. I'll set up my equipment to the diagram below. Then I'll put the squash ball in a beaker and then put the beaker in a water bath. The water will obviously be heated with a Bunsen burner which will then heat the ball up. I've chosen this method so the ball doesn't get wet, and the experiment is fair. I will then drop the ball from a height of 2 meters. It will be landing onto a piece of MDF (Medium Density Fibreboard) to make sure the surface won't affect my results, so it's more of a fair test. To judge how high the ball has bounced, I will be using my eyesight. Diagram Equipment list 4 different coloured squash balls Beaker Water bath 2, 1 meter rulers MDF Kettle Ice Thermometer Stopwatch Tongs I did a preliminary experiment to see if my method would work and if there were any problems with the way I will conduct my experiment. Preliminary Results Temperature (ºC) Distanced Bounced (Cm) 90 81 40 68 0 20 Factors affecting my experiment * If I use different squash balls of different elasticity it will affect the bounciness of the
Investigating the effects of surface area on the rate of enzyme reactions.
AS Biology Coursework assignment Investigating the effects of surface area on the rate of enzyme reactions By Scott Humm Introduction Enzymes basically are biological catalysts. What this means is they have the ability to speed up reactions without actually being used up themselves. Enzymes are globular proteins and they have a three-dimensional shape, which is very precise and never varies between two examples of the same protein. The active site for all molecules of the same enzyme will be made up of the same arrangement of amino acids. This exact shape and arrangement of amino acids enables the enzymes to be highly specific and this defines which substrate they bind to in the active site. Because they are so specific, enzymes are thought to catalyse substrate into two different products by the "Lock and Key hypothesis". Diagram taken from http://schools.moe.edu.sg/chijsjc/Biology/Enzyme/enzyme.htm This diagram shows how enzymes catalyse the breakdown of a substrate molecule into two products. The only way that another molecule can bind with an enzyme's active site is if it is an inhibitor. Inhibitors are molecules that can bind with the active site briefly causing competition between itself and any substrate molecules. When there is a very high concentration of inhibitors, substrate molecules do not bind with active sites as easily because there are less of them.
Thermal insulators.
Zeadon Jamil Thermal insulators Aim To investigate different materials for the most effective thermal insulator for a house. Introduction Heat transfer is the gain and loss of energy. There are three ways in which thermal energy can be transferred: * Conduction * Convection * Radiation Conduction - this is when energy travels from molecule to another. When one molecule receives energy it begins to vibrate and hits other molecules and makes them vibrate. And will spread throughout the object. Convection - this will only occur in gases and liquids. When heat is applied to the bottom of the substance, it will heat it up. When it heats up, it will rise to the top, forcing colder areas towards the heat source and then they will receive energy and rise to the top, etc. Radiation - it travels in waves. When it hits a molecule it makes it vibrate. I will be concentrating on conduction, as this is the main way in which thermal energy is transferred lost from housing. Which means that I need something that is a bad thermal conductor (good thermal insulator) to keep the amount of conduction to a bare minimum? Plan I am planning to test five materials (paper, cling film, cloth, bubble wrap and plastic) and one control, three times and find the average (to ensure accuracy). Whichever material changes the temp of the water the least is the best insulator. I will wrap
The Process of Human Digestion
The Process of Human Digestion Digestive System, series of organs put together that purpose is to break down, or digest, the food we eat. Food is made up of large things called, complex molecules, which the digestive system breaks down into smaller things called simple molecules that get absorbed into the bloodstream. The bloodstream is our blood. The simple molecules travel through the bloodstream to all of the parts of the body, which we use for growth, repair, and energy. All living things that eat to get energy have a digestive system, a feature that makes us different from plants. Plants make their own food in a process called photosynthesis, photosynthesis is when plants make sunlight to convert water and carbon dioxide into simple sugars. But animals, including humans, must take in food in the form of organic matter, such as plants or other animals. Digestion generally involves two parts: a mechanical part and a chemical part. In the mechanical part, teeth physically break down large pieces of food into smaller pieces. In the chemical part, digestive chemicals called enzymes break apart individual molecules of food to yield molecules that can be absorbed and distributed throughout the body. These enzymes are secreted by glands in the body. The digestive system of most animals consists mainly of a long, tube called the alimentary canal, or digestive tract. This canal
