Pracs pt 1 Flashcards
What are reducing sugars?
Sugars that can donate an electron to another molecule
What sugars are reducing sugars?
All monosaccharides an some disaccharides (e.g. Maltose & Lactose)
Give examples of monosaccharides 3
glucose, fructose and galactose
give examples of disaccharides 3
Maltose, sucrose and lactose
How do you test for reducing sugars? 3
Place 3cm^3 of food solution into boiling tube & 3cm^3 of Benedict’s solution
Place boiling tube into beaker of boiling water
It will go from blue to warmer colour if reducing sugar is present
How to test for non-reducing sugars? 7
Add 3cm^3 of food solution into boiling tube
Add 3cm^3 of dilute hydrochloric acid
Gently boil the solution for 5 minutes
Add 3cm^3 of a dilute alkali like sodium hydroxide solution
Use pH paper to check if solution is alkaline
Add 3cm^3 Benedict’s solution and heat in boiling water for 5 minutes
Positive test will show warmer colour change
When would you test for non-reducing sugar?
When there is either no reducing sugar or a very small amount
What do you use to test for starch?
Iodine solution
How do you test for starch? 2
Add drop of iodine to food sample
Solution will turn blue/black if starch is present
What do you use to test for proteins?2
Biuret solution, which contains copper(II) sulfate and sodium hydroxide
How do you test for proteins? 3
Add drops of sodium hydroxide to each sample
Add drops of copper(II) sulfate solution to each sample
Colour change from blue to lilac if protein present
Draw a table of a simple dilution. You are given 1% concentration of HCL solution, make 5 concentrations of this solution, each with a volume of 10cm^3
On layer
Draw a diagram of the simple dilution you made a table of
On Layer
Draw a diagram of a serial dilution of 1% HCL solution, reducing by a factor of 10 each time
On LAyer
Draw a diagram of a serial dilution of 1% HCL solution, reducing by a half each time
On layer
