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  • Published on: 15th October 2019
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Biuret test

Testing for proteins in foods

Bread Cheese Biscuit

Non-positive Very positive result Non-positive

In this test we used the blue copper sulphate as an indicator. It would turn to a purple colour if the food had protein inside of it. This result if what I was expecting.

Benedict’s test

Testing for reducing sugars inside of food

Bread Cheese Biscuit

Little change No change Positive results for reducing sugars

Some of the simple sugars which include the common one glucose can be made to reduce the copper sulphate which is blue to red copper oxide. This reaction which is known as the benedict test, the test allows the show of reducing sugars in food by changing the colour from blue to a yellow/red colour. These results I expected

Flame test

Shows the presence of inorganic ions

Sodium chloride Potassium chloride Lithium chloride

Bright orange orange red

The flame test allows to determine what ions are in the compounds we tested, this is because when heated they produce different colours. These results I expected

Iodine test

Testing food for starch

Cheese Bread Biscuit

No starch Starch present Starch present

When iodine is mixed with starch it turns from a brown to a dark blue-black colour. This is how you will be able to know if the food has starch or not. These results I expected

Ascorbic acid

Testing food for vitamin C

Cheese Bread Biscuit

No vitamin C No vitamin C No vitamin C

Dcpip which is a blue substance is used as an indicator. It changes its colour from a blue to a red colour with the presence of acid. One of these acids is Vitamin C, DCPIP therefore allows to test for the presence of Vitamin C in food. These results I expected

Grease spot test

Testing for fat by using ethanol

Cheese Bread biscuit

Present Present present

 We’re able to test for fat in foods with the use of ethanol, ethanol leaves a mark on what it is placed on. In some different liquids it takes different amounts of time to disappear. Water takes a minute to disappear, alcohol takes a couple of seconds and finally oil leaves a grease stain which is there permanently. Allowing to distinguish between liquids and oil. These results are what I expected


Carbohydrates are commonly found in foods such as bread, vegetables and cereals such as Weetabix. They are a very important source which is needed by the body, when digestion occurs involving carbohydrates a series of reactions including enzymes occurs. The main aim that is in these reactions is to break down the carbohydrates into smaller molecules for easier digestion which are then absorbed into the blood stream much easier. There are different types of enzymes which are used in the breaking down of carbohydrates reaction. These include maltase, lactase and sucrase. These all serve different functions. First of all maltase breaks down the maltose, lactase breaks down the lactose and the sucrase breaks down the sucrose. However these enzymes listed don’t actually break down the whole molecule itself they break down the bond which is known as the glycosidic bond. This bond is what holds together the molecule itself and all the other molecules. For example the bond is broken and it is made easier to digest. The chemical equation for the digestion of carbohydrates is; Starch+ water+ (amylase)>Maltose


Proteins are a vital nutrient which our body needs to create structures and also repair cells, not only that but proteins allow the build-up of muscle cells. When proteins enter the digestive system they are broken down into their more basic form which is amino acids. The amino acids are absorbed by the intestine walls as they’re very small. The enzyme which is known as pepsin is the most active protein  digesting enzyme which is located inside of the stomach. When the pepsin acts on the proteins it breaks the bonds in the proteins, when the bonds are broken the amino acids join together into a compound known as polypeptides. The polypeptide compound then moves on into the small intestine where the proteins are broken down more with the aid of pancreatic enzymes these help the aid of digesting proteins. Therefore from this the chemical equation which is used for the digestion of proteins is; Protein+ Pepsin> amino acids


Fats are an important nutrient needed in the body, however too much of it can cause health problems. Fats come in foods such as meats, dairy, nuts and oils. They’re also known as lipids, lipids are known like a molecule of fat however they don’t dissolve in water, this is able to cause an effect on the digestive system and the body. Fats are known to clump up together which is dangerous in the body due to the ability to build up and cause harm. When the fat clumps that have joined together reach the small intestine they are broken down by the bile which is produced this is because the bile inside of the liver contains salt which breaks it down. The surface area of the fats is best when it is large as possible as the pancreatic lipase are then able to break it down easier, when the fat has broken down it results in two smaller forms that are easier absorbed by the small intestine, these are known as fatty acids and then the least known monoglycerides. The chemical equation for this is; Fat +Water+lipidsglycerol+ fatty acids


Micronutrients consist of mainly vitamins and minerals. They are found naturally in plant and animal based food, however unnaturally they can be made up inside of  a lab. Micronutrients aren’t needed as much as macronutrients, however they still are very important and needed for a balanced and healthy diet. With the lack of micronutrients they’re able to cause many different types of physical and mental problems such as blindness and mental retardation, therefore to avoid these they are vital. One main example which is known to be needed, especially at a young age is the element known as calcium. This element is needed to improve teeth and bone development and make them stronger. Also another thing which is needed especially for metabolism is iron. Another element which is included is magnesium, this is important as it helps prevent heart problems and diseases. Micronutrients are essential for growth and also development.


Macronutrients are very important and needed for growth and other body functions. The 3 main macronutrients are different to the micronutrients, the 3 are fats, carbohydrates and fats. These are important for giving the body the required nutrients. Carbohydrates the first main example are very important as when they get broken down they’re the bodies main source of energy. Muscles, liver and most important the heart all need carbohydrates to survive and be able to function properly. Fibre is one form of carbohydrates. Fibre is unable to be broken down and used in the body for nutrients, therefore because of this fibre just flows right through the body. Diets which are high in fibre tend to reduce the chance of heart disease, obesity and the build-up of cholesterol this is because due to fibre flowing though the body it also picks up harmful waste products which are then excreted.

The next example are proteins, these are important due to them being needed for growth and repair of cells, not only that but protein helps the growth of muscles that’s why some people tend to have high protein diets. Proteins also help the enzymes inside of the body by creating them, they make enzymes for protection, digestion and immunity. Proteins are broken down from foods such as dairy and meat into amino acids, 21 amino acids to be exact, however it’s been proven that there are only 9 which the body need essentially to survive.

Finally fats which can be found in foods such as oils and meats, these are a big nutrient that is very important for the body to survive off. In a balanced diet there should be at most 35% eaten for the body to get the correct amount of nutrients from them, however too many fats and the body can become unhealthy and start to form obesity. They allow us to absorb some nutrients, therefore they are extremely important. Also lipids are essential for the body as they provide cushioning for the organs. They give us taste, consistency and make us full after eating so many.

Structures of Nutrients and their role in the metabolism

The structure of the 3 main nutrients; fats, carbohydrates and proteins are very different from one another. To start off with carbs are polymers of sugars and proteins are polymers of amino acids. Whereas fats are a combination of glyercol and fatty acids. There are two different type of molecules, there are structural molecules which make up components such as bones and also connective tissues and the other molecule which is regulatory molecules such as hormones and enzymes.

Carbohydrates on the other hand, the polymers made up of glucose are digested by the amylase into 2 part molecules which have a scientific name known as disaccharides. There are different types of these molecules that determine how much it will go onto break down the carbs. The molecules which are formed from carbs are used in the regulatory process this is due to glucose being in carbs as glucose is a compound which the body is able to get energy from. The main examples are active transport and nerve and muscle cell conduction.

Secondly proteins have are used in different sections of the body. In the small intestine the peptides are broken down further than the stage before which occurs in the stomach into one amino acid thus allowing easier absorption. Amino acids mainly form structural molecules such as collagen. Collagen is only 25% of proteins and serves the purpose of providing structure and support for tissues. And for other organs it helps create and strengthen bones, tendon and cartilage. Furthermore proteins help serve a large purpose with the production of insulin.

In the metabolism lipids are used as structural molecules which form membranes. One fatty acid which the body uses from fat nutrients helps control the level of blood pressure, but has the side effect of leading to breast cancer.

Roles of vitamins and minerals in the enzyme system

Vitamin C

This vitamin is a crucial vitamin which is needed for both growth and development. It is used in the body to heal cuts and wounds and also produce collagen for the tissues and bones.

Vitamin D

This vitamin is very important for the body and the development this is because this vitamin alone allows the body to absorb calcium which is needed for the strengthening and improvement of bones in the body. Vitamin D triggers a hormone which allows the cells to be created to absorb the calcium this hormone is known as calcitriol.

Vitamin B12

Finally the last vitamin which is vitamin B12 is needed as it maintains the nerve cells. It also helps the production of DNA and also RNA, these obviously are massively important for the body. Furthermore Vitamin B12 allows the body to create red blood cells. The vitamin B12 can be found on a binding protein as this is how it is transported around towards the small intestine.



Iron which is one of the main three minerals in the body that are used is needed for helping the transportation of oxygen on red blood cells. It is also involved in turning blood sugar into energy.


The minerals that are inside of magnesium are highly important as they are needed in protein synthesis, muscle and also nerve function and correcting blood pressure. Magnesium minerals are absorbed through villi inside the intestine.  Magnesium is also needed for DNA and RNA


This final mineral is one of the most important in the body as it maintains blood pressure. Sodium also holds the contents of water for extending amounts of time which increases the pressure and volume of blood therefore can be a bad thing. Sodium is important for muscle and nerve functions. Sodium gets absorbed by the body through glucose and amino acids, due to this being the case the amount of sodium which is absorbed can be affected by protein.

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