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B2- organisation - Coggle Diagram
B2- organisation
food tests - required practical
take the food sample and grind it with distilled water using a mortar and pestle - make a paste
transfer the paste into a beaker and add more distilled water, stir so the chemicals in the food dissolve in the water
filter solution to remove any suspended food particles
testing for starch
place 2cm3 of food solution into a test tube
add a few drops of iodine solution
if starch is present then the solution will turn black/blue
if no starch is present then iodine will stay orange
testing for sugars
place 2cm3 of food solution into a test tube
add 10 drops of benedict's solution
place test tube into a beaker and half fill the beaker with hot water from a kettle
leave for around 5 mins
if sugars are present then solution will change colour
a green colour tells us there is a small amount of sugar present
yellow - more sugar is present
brick - red tells us there is a lot of sugar present
this only works for certain sugars such as glucose
testing for proteins
take 2cm3 of food solution
add biuret solution which is blue
if protein is present then it will change from blue to a purple/lilac
testing for lipids
food solution in a test tube - add a few drops of distilled water
add a few drops of ethanol
gently shake the solution
if lipids are present then a white cloudy precipitate forms
digestive enzymes
large food molecules are digested by enzymes into smaller molecules
the products of digestion are absorbed into the bloodstream
enzyme catalysts speed up the reaction
enzymes are large protein molecules and they have a groove on their surface- an active site
the active site is where the substrate attaches to
the enzyme breaks down the substrate into different products
enzymes are specific and the substrate must fit perfectly into the active site
digestive system
larger molecules are broken down into smaller molecules by enzymes
how the small intestine is adapted for absorbing products
its very long (5m)
provides a large surface area
the interior is covered with millions of villi
increases surface area
the have a thin membrane - makes diffusion quicker
has capillaries
gas exchange in the lungs
the heart pumps blood to the lungs where the blood collects oxygen