Diet + Nutrition Flashcards
3 reasons we need food
- ‘fuel’ for energy
- provide materials for growth and repair of tissues
- help fight against disease and keep bodies healthy
5 groups of food substance you NEED as well as water and fibre and at the right amounts to be balanced
carbohydrates lipids proteins minerals vitamins
what is the bodes main fuel
carbohydrates
how do cells release energy from carbs
by oxidising a sugar called glucose (respiration)
glucose is found in what
sweet tasting foods like fruits and veg
different types of sugar other than glucose
fructose and lactose and sucrose (table sugar)
2 physical properties of sugar
taste sweet
can dissolve in water
many processed foods contain added sugar which causes common problems today like
tooth decay
obesity
diabetes
most carbs found in our diet come from
starch
what is starch
large insoluble molecule found in carbs, because insoluble found as a storage energy in things like potatoes and rice
what is starch’s structure
a polymer of glucose, made up of long chains of hundreds of glucose molecules
starch is found in only plant cells so what is found in animal cells which is very similar
glycogen (another polymer of glucose), store of energy in muscles etc
there is an enzyme our body does NOT produce to breakdown … into simple sugars for our blood or as an energy source
cellulose (another polymer of glucose)
if we cannot digest cellulose why do we need it
forms dietary fibre for us –> gives the muscles of the gut something to push against as the food is moved through the intestine (avoiding constipation and preventing bowel diseases)
lipids contain the same elements in their molecules as carbohydrates which are
carbon
hydrogen
oxygen (less of this in lipids)
animal fats are usually solid at room temperature and what are plant fats state at room temperature
usually liquid (oils)
why are lipids important for humans
make up about 10% of our body mass and form an essential part of the structure of all our cells
what is the fatty layer under our skin useful for
used for insulation, reducing heat loss at the surface of our body
what are the chemical building blocks of lipids
glycerol (oily liquid) and fatty acids
explain the structure of glycerol
joined to three fatty acid molecules
too much lipids however can cause what
heart disease from too much saturated fat or high cholesterol
how much of our body mass do protein make sup
18% –> second largest fraction after water
why are proteins important for us
all cells contain them so needed for growth and repair of tissues, enzymes are made up of them
what are products that are rich in proteins
animal products like meat, fish, cheese, eggs and then beans, peas and nuts
doctors recommend a daily intake of protein of 70g, but in poorer countries they suffer from a lack of protein leading to
kwashiorkor
what is proteins structure like
20 different sub-units called amino acids
what do amino acids contain
carbs/fats and nitrogen
two also contain sulphur
what are amino acids structure like
linked together in a long chain which are folded/twisted into spirals with cross-links holding the chains together, all in any order resulting in thousands of different structures and specialist cells
explain calciums roll as a mineral in our body
making teeth and bones, 100g in an adults body, comes from dairy products, fish, bread and vegetables
explain irons roll as a mineral in our body
part of haemoglobin in red blood cells, helps carry oxygen, 3g found in an adults body, found in red meat, liver, eggs and some vegetables
what happens if a person fails to intake the required amount of minerals
start to show symptoms of mineral deficiency disease and could lead to rickets or anaemia
Use in the body, effect of deficiency, some foods that have a lot of it: Vitamin A
making a chemical in the retina; also protects the surface if the eye
night blindness, damages cornea of eye
fish liver oils, liver, butter, carrots
Use in the body, effect of deficiency, some foods that have a lot of it: Vitamin B1
helps with cell respiration
beri-beri
yeast extract, cereals
Use in the body, effect of deficiency, some foods that have a lot of it: Vitamin B2
helps with cell respiration
poor growth, dry skin
green veg, eggs, fish
Use in the body, effect of deficiency, some foods that have a lot of it: Vitamin B3
helps with cell respiration
pellagra
liver, meat, fish
Use in the body, effect of deficiency, some foods that have a lot of it: Vitamin C
sticks together cells lining surfaces such as the mouth
scurvy
fresh fruit and vegetables
Use in the body, effect of deficiency, some foods that have a lot of it: Vitamin D
helps bones absorb calcium and phosphate
rickets, poor teeth
fish liver oils, sunlight
test for starch
- starch powder placed on spotting tile
- drop of dilute iodine solution added to starch
- reacts with starch forming very dark blue or blue/black
- can use any starchy substance
- will stay iodine colour if no starch is present
test for glucose
- glucose is called a reducing sugar as the test for it involves reducing an alkaline solution of copper(II) sulcate to copper(I) oxide
- small spatula placed in test tube (add a little water)
- dissolve the glucose
- add several drops of Benedict’s solution to the test tube
- it will go blue
- place the tube in a boiling water bath
- the blue colour gradually changes colour to orange in a few seconds or brick red precipitate of copper(I) oxide
- this works with all types of sugars except sucrose (table sugar)
who needs for calories per day: male or female
male
who needs for calories per day: new born baby or 2 year old child
2 year old
who needs for calories per day: girl aged 12-14 or girl aged 15-17
the same
who needs for calories per day: boy aged 12-14 or boy aged 15-17
boy ages 15-17
who needs for calories per day: girl aged 15-17 or boy aged 12-14
boy aged 12-14
who needs for calories per day: heavy manual worker or pregnant woman
heavy manual worker
who needs for calories per day: breast-feeding woman or pregnant woman
breast-feeding woman
who needs for calories per day: heavy manual worker or breast-feeding woman
heavy manual worker
how to measure the energy content of a food
- weigh the mass of a food sample
- place a measured amount of water in a boiling tube, clamp it on a base
- measure temp of water
- pierce the food on the end of a mounted needle and put it over a burning bunsen
- once its lit hold it under the test tube
- once completely burnt measure the new temperature of the water
- remember 4.2 joules of energy is the equivalent to 1 gram of water raised in temperature by 1 degree
- 1cm(cb) water has the mass of 1g
- use the equation to find the answer:
energy in joules per gram =
(final temp -start temp) x 20(g) x 4.2 (J per degree C) /mass of food (g)
