🥞 Food and Energy 🏃♀️ Flashcards
Starch test
iodine solution.
Colour change starch
- iodine
- yellow-brown blue-black.
Sugar test
Benedict’s reagent
Sugar colour change
Blue to brick-red precipitate.
Benedict’s method
Add Benedict’s solution and heat in a water bath.
Protein test
- add sodium hydroxide, then a few drops of copper sulfate and shake
- biuret test
Protein colour change
- biuret test
- blue —-> purple/ lilac
Fat test method
Shake the fat with ethanol (alcohol), then add an equal amount of water
Fat test colour change
- ethanol
- Colourless —> cloudy white emulsion
Biological molecules
- carbs
- proteins
- fats
What do biological molecules contain?
- carbon
- hydrogen
- oxygen
- nitrogen (protein)
“Simple” carbohydrates
sugars such as glucose and lactose - they are described as ‘simple’ as they are made up of one (e.g. glucose) or two (e.g. lactose) basic sugar units
Glucose use
Glucose is the sugar that is normally used in respiration.
Carbohydrate
biological molecule formed of sugar sub-units
- Carbohydrates differ by having different numbers or types of sugar sub-unit.
Lactose use
Lactose is the sugar and energy source in milk
Sugars
Sugars are ‘fast-release’ energy stores
What can sugars be
quickly metabolised to release energy
Complex carbohydrates
- starch, glycogen and cellulose
- made up of many glucose (sugar) units linked together
What are starch and glycogen important for?
Storage molecules
main storage molecule in plants
Starch
main storage molecule for animals
Glycogen
- liver
- muscles
Structural carbohydrate
Cellulose
- provides support plant cell walls
What does cellulose do?
Provides support in cell walls
Protein
- biological molecule formed of subunits of amino acids
- can differ by:
- containing different types
- numbers of amino acids
- these being arranged in different sequences
1g water = ?
1cm3 water
How can proteins differ?
- dif. link arrangements
- structural (e.g. muscle)
- functional (e.g. enzymes, antibodies)
Sources of protein
- lean meats
- lentils
- fish
Fat
the basic unit of a fat is glycerol and three fatty acids
Why are fats excellent storage molecules?
high in energy (1g of fat contains approximately twice as much energy as 1g of carbohydrate or protein)
What does too much fat in the diet cause?
Health problems
What are lipids?
What fats are also called
food-energy test results (fair test)
When comparing diff. foods:
- use same amount food
- hold burning food same distance from boiling tube
Food-energy test, where does energy go?
- lost in air
- lost heat glass
- left in burned food remains
Food-energy test equation
Energy released in J = water mass (g) x rise in temp. x 4.2
