Biology - Digestion Revison Cards Flashcards
How would somebody test a food for starch?
Place iodine solution on the food and if it turns from yellow red solution to blue black starch is present.
How would somebody test a food for sugar?
Add enough Benedict’s solution to cover the food where it is in a test tube, place the tube in warm water for 10 mins and it will turn brick red if sugar is present.
How does somebody test for lipids (fat) in foods?
Place the food in a test tube, add a few drops of ethanol shake the test tube and leave it for a minute, pour the solution into a test tube of water, lipids are present if a cloudy white layer forms.
How would somebody test for protein?
Add a small amount of Biuret solution to food in a test tube alternatively you could add 1cm cubed of sodium hydroxide solution and a few drops of copper sulphate solution. It will turn purple if protein is present.
State 2 ways in which temperature can effect enzymes
If you increase the temperature the rate of the reaction increases as enzymes and substrates collide more frequently
Optimum temperature means that enzymes can be denatured and broken down where it can’t fit its substrate if the temperature is raised too much.
State 2 effects of Ph on enzymes
In conditions with a lower or higher Ph it can interfere with bonds that hold the enzymes in the correct shape.
This can change the shape of the enzyme meaning no enzyme substrate complexes can form within the nutrients.
Carbohydrate digestion
Carbohydrase enzymes are respnsible for the break down of the large cahbohydrates molecules into the small ones. We need glucose in our cells for the process for respirtaion. We get the glucose we need by breaking down starch using carbohydrase enzyme amylase.
Protein digestion
Proteins are large molecules made from amino acids. They contain carbon, oxygen, nitrogen and sulphur. We need amino acids to build proteins in the body so it can grow and repair. Special protease enzymes break down the large protein molecules to amino acids.
Fats (lipids) digestion
In order to digest large fat molecules into into the component fatty acid molecules and glycerol, bile and a lipase enzyme are needed. When your put fats into large globules are for formed which give a small surface enzyme for the area to attack. Bile, formed in the gall bladder, helps break up the fat into small droplets and then coats the droplets to orevenf the, sticking together again. This increases the surface area and allows the enzymes to reach all the fat droplets.
