Food and Digestion Review
A balanced diet should contain 7 types of nutrients.
These are carbohydrates, proteins, fats (and lipids), vitamins, minerals, fibre, water.
A balanced diet has 7 nutrient types which are:
water, minerals, fats, fibre and ...
The best source of protein is...?
What do carbohydrates do for our bodies?
These are tables full of information about what is in our food.
This label is used for a question on the next slide.
Look at the information carefully.
Use the image on the previous slide to answer this question.
How much total sugar is there in a serving of this milk?
Testing for carbohydrates
Can you remember these?
Iodine is added to starch and it turns from brown to blue-black.
Benedicts solution is added to glucose solution and must be heated. A positive test results in a colour change from blue to brick red.
Testing for Protein and Fats
For a protein test, you use Biuret solution and it will change from blue to lilac in the presence of protein.
By mixing ethanol and water with fats or oils and giving it a good shake, a cloudy white emulsion is formed.
Lucy did a food test and these were her results. Which food type was she testing for?
You will need to study this diagram of the human digestive system.
No doubt you will need to label a diagram in the near future!
What is the part of the digestive system labelled with a '3'?
Check out this youtube video:
"The digestive system in the human body for kids - Smile and Learn"
You will need to open another tab and search for this clip; the URL is not linked :(
Where does most of our digestion take place?
Enzymes are proteins that speed up reactions in our bodies. They are really helpful in the digestive system as they break long insoluble molecules of food into smaller soluble molecules that we can absorb.
The keywords you need to remember are:
active site [where the reaction happens]
substrate [the molecule/reactant the enzyme works on]
product [what is made by the enzyme action]
lock and key theory [a specific substrate fits into only one type of enzymes active site - this is why enzymes are specific eg amylase only will digest starch]
optimum [the best an enzyme can work in certain conditions]
Action of amylase
amylase enzyme digests starch, producing smaller sugars
PROTEases digest PROTEins
Smaller amino acids are produced
LIPases digest fats and LIPids
What would happen in this experiment?
The tubing contains starch only.
Iodine and water surround the visking tubing.