Find the relationship between amount of fat and amount of energy produced in different foods.

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July 2001

Biology Coursework Year 10


Find the relationship between amount of fat and amount of energy produced in different foods.


I am going to ignite different foods and see how much heat energy they give out. The food that causes the biggest amount of change in temperature will have the most amount of energy. However, calculations have to be carried out to create an average energy output per gram.


Independent Variables: This will change from food to food, thus giving me a range of different results. In this experiment it will be type of food.

Dependant Variable: This is the amount of Energy per gram which can be calculated

Controlled Variables: These are the things that will keep the same, in order to sustain a fair test. These are;

* Apparatus

* Type of boiling tube

* Distance of boiling tube from Bunsen burner

* Distance of food from boiling tube

* Amount of time taken to move ignited food to boiling tube

Fair Test

It is essential that I keep it a fair test in order to sustain accurate results for comparison at the end. To ensure a fair test, I must keep the controlled variables for every test I do.

The apparatus must all be kept the same because there may be some minor differences in insulation properties, or measure of accuracy between them. If this were to happen, it would prevent me from sustaining accurate results.

The same type of boiling tube must be kept constant because, every boiling tube may have different conducting properties. If it were not as dense as a previous test tube, it would heat up more quickly, and if it were denser, I would get the opposite affect. This is why it is essential that all the boiling tubes are identical as it could lead to totally false results.

The boiling tube must be changed for each test though, because a previous boiling tube may have retained heat from a previous experiment. This would cause a false rise in temperature.

The distance of the boiling tube from the Bunsen burner must be kept constant. The Bunsen burner provides heat and different distances from it would be at different temperatures. This could cause the temperature of the water to rise falsely, and would again produce anomalies.

The distance of food from the boiling tube must also be kept constant. There is a different temperature at different points of a flame. The tip of a flame is the hottest part. If the distance were altered, it would apply different amounts of heat to the boiling tube. Again, this would lead to inaccurate results.

The amount of time taken to move ignited food to the boiling tube must be as quick as possible. If there were a delay, the heat energy produced by the food would be wasted. All of the energy produced must be used to heat up the water.


The two types of errors usually made in an experiment are either variable or constant. Variable errors are just general mistakes by the scientist. These can be avoided by making sure that all of the above procedures to ensure a fair test are followed accurately. Constant errors cannot be controlled.

To ensure accurate results, I must make sure that I carry out all of the procedures to ensure a fair test.

The only other measures of accuracy are letting the thermometer stabilise before the next experiment is carried out. Also, when using electronic scales, you must let them stabilise, before the food is taken off of them to ensure an accurate measure of weight.

It is essential that every experiment is repeated at least twice. This way, if there are anomalous results, they will be exposed and shan't affect my overall result.


Safety is extremely important in every experiment and is mandatory. In this experiment, as we will be in contact with hot foods and naked burning flames, it is essential that I carry out all of the safety features.

As we will be using a Bunsen burner, it is essential that goggles are worn at all times. The excessive heat can cause water or other substances to spit. This is why eye protection must be worn at all times.

Also, because of the naked flame, all hair must be tied back, and all loose clothing must be tucked away. If nail polish is being worn, it may be a good idea to wear gloves, as all solvents are flammable, including hairspray and deodorant. All loose clothing must be tucked as they too can catch fire but can also knock over dangerous equipment off of benches.

When and experiment has been carried out, the boiling tube will be very hot from the bottom. Therefore, it must be carried from the top to avoid scalding. Gloves may be appropriate for extra safety.

The benches are made of wood, and therefore are flammable. It is essential that two asbestos mats are used. One should be under the Bunsen burner, the other, under the boiling tube. This is because if ignited food were to fall, it would not cause any hazards to the benches.
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When the food is being burnt, it is held on a needle. It is very important that the needle is held from the wooden handle and that it's wrapped slightly in foil. The foil is there to stop the wood from catching fire. It must be held from the wooden handle, as wood is a good insulator of heat, and will not cause scalding.

The food presented must not be consumed as it may have been accidentally contaminated. The labs are filled with harmful chemicals, and the food is not for consumption, but is for experimental ...

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A good account of the investigation including detailed discussion of unexpected results. There are too many incorrect references to energy being produced or created. 4 Stars