Food groups Flashcards
What is a lipid
Fats and oils
What’s the structure of a lipid
3 fatty acids, 1 glycerol
Sources of lipids
Meat, cheese, eggs, seeds, peanut
Functions of lipids
- Source of energy (and energy store)
- insulation (electrical for nerve cells and thermal beneath skin)
- form part of cell membrane
- cholesterol used to make steroid hormones
What elements are found in lipids
Carbon, hydrogen, oxygen
What elements are found in proteins
Carbon, hydrogen, oxygen, nitrogen, sulphur
Structure of protein
A long chain of cells called amino acids. The sequence (order) of amino acids determines the shape of the protein molecule. It can be long and thin (eg keratin) or more spherical (eg haemogoblin)
Sources of protein
Meat, fish, eggs, pulses, beans, soya bean
Functions of proteins
- catalyst (enzymes)
- transport (haemogoblin)
- structural material (muscles)
- hormones (insulin)
- defence against natural diseases (antibodies)
Give 2 examples of minerals
Iron, calcium
Source of iron
Red meat, liver, some leafy vegetables
Function of iron
Needed to produce haemogoblin for red blood cells
What happens when you don’t get enough iron (deficiency)
Iron deficiency causes anaemia. The person feels weak as oxygen needed for respiration cannot be transported efficiently
Sources of calcium
Milk, cheese, fish
Functions of calcium
- production and growth of bones and teeth
- involved in the chemical reactions leading to the clotting of blood and
the contraction of muscles
What happens when you don’t get enough calcium (deficiency) ?
Calcium deficiency causes rickets (soft and bendy bones)
Name 3 vitamins
vitamin A (eyes), vitamin D (bones), vitamin C (fibres)
Sources of vitamin A
Liver, dairy, eggs
Function of vitamin A
- used by cells in the retina to produce pigments
- essential for embryos to develop (tells cells where to go and what to
become) - used in the immune system to maintain integrity of skin and mucus
cells in lining of breathing and digestive system
What happens is you don’t get enough vitamin A
Vitamin A deficiency causes poor night vision
Sources of vitamin D
Liver, dairy, eggs, fish oil, sunlight
Function of vitamin D
Helps the body to absorb calcium
What happens if you don’t get enough vitamin D
Vitamin D deficiency causes rickets (soft and bendy bones)
Sources of vitamin C
Citrus fruits (lemon, lime, orange)
Function of vitamin C
Helps cells sticking together in the lining of various organs (production of fibres holding cells together is affected)
What happens when you don’t get enough vitamin C
Vitamin C deficiency causes gum problems (bleeding) and even scurvy (characterised by swollen bleeding gums and the opening of previously healed wounds)
Why do we need water in our diets
Just about every bodily function requires water. We need a constant supply to replace water lost through urinating, breathing, and sweating
Sources of water
All food and drink contains water
Water, watermelon, coconut water
Sources of dietary fibre
Plant material (eg vegetables) contain indigestible fibres Wholemeal bread
Function of dietary fibre (roughage)
- Helps with digestion by providing bulk for gut contents (to be pushed
along) and feces. - prevents constipation.
What is the test for glucose
The bennidicts test (solution is a test for all reducing sugars)
Positive bennidicts test
Solution turns from blue to a brick-red colour and precipitate is formed
Test for starch
Iodine
Positive test for starch (iodine)
Iodine solution goes from yellow to a blue/black colour
Energy released per gram (joules) =
Energy per gram = (mass of H2O) X (temperature rise *C) X 4.18
How to find energy content in food sample
Measure 1g of foodstuff. Measure out a volume of water and take the temperature. Burn the foodstuff under the test tube until all that’s left is ash, measure the temperature rise.
Energy (J) = water mass X temp rise X 4.18
How many joules in 1 calorie
1 calorie = 4200 j or 4.2Kj
What is the function of carbohydrates
They are a good source of energy and are the main fuel of the body as glucose (respiration). It is also used to store starch, glycogen, and cellulose which provide structural support
Sources of carbohydrates
Rice, wheat, barley
What elements do proteins contain
Carbon, hydrogen, oxygen, nitrogen
