unit 2 - digestive system (y8) Flashcards
1
Q
What are the seven types of nutrients?
A
- carbohydrates - provide short term energy
- lipids - e.g fats and oils provide long term energy
- protein - used for growth and repair
- vitamins - keep you healthy
- water - needed in all cells and bodily fluids
- fibre - provides bulk to food to keep it moving in the gut
2
Q
simple carbohydrates
A
- are simple sugars
- provide a quick source of energy
- e.g fruit
- one sugar unit
3
Q
complex carbohydrates
A
- they have to be broken down by the body
- energy is released more slowly
- chain/polymer of simple sugars
- e.g pasta, bread
- e.g starch, storage molecule in plants, or glycogen, storage molecule in animal cells
4
Q
lipids
A
- includes fats and oils
- provides source of energy
- protects organs like kidneys and heart from damage
- keeps you warm - provides insulation
5
Q
proteins
A
- needed to make new cells for growth and to repair tissues
- building blocks (monomers) of protein are amino acids
6
Q
dietary fibres
A
- needed for intestinal health and to keep moving along the bowels (we can’t actually digest fibre)
- as humans don’t have the cellulose enzyme, we cannot digest the food. Cellulose is in the cell walls of plants
7
Q
vitamins and minerals
A
are needed in small quantities to maintain health, e.g
* vitamin a - good eyesight
* vitamin d - helps body absorb calcium
* calcium - helps maintain healthy teeth and bones
* iron - needed to make haemoglobin in red blood cells
8
Q
a balanced diet
A
one which provides the right amount of each nutrient and energy of a person’s needs
9
Q
independent variable
A
the variable someone changes in an experiment
10
Q
dependent variable
A
what we measure during the experiment
11
Q
control variable
A
the variable that stays the same throughout the experiment
12
Q
testing for starch:
A
- add iodine solution
- iodine solution will turn from orange-brown to blue-black
13
Q
testing for simple sugars:
A
- sugars react with Benedict’s solution to turn it from blue to orange-red
- it is slow reaction, so needs heating up by placing in a hot water bath
- green - low conc., orange - medium conc., red - high conc., blue - negative
14
Q
testing for lipids
A
- grind up the food if necessary and put in test tube
- add 2cm³ ethanol and shake
- add 2cm³ water and shake again
- if fat is present, ethanol will turn from clear to cloudy white when water is added
15
Q
testing for proteins:
A
- put some food in a test tube and add a few drops of Biuret reagent (the smaller the pieces of food are, the quicker the reaction)
- if positive, will turn from blue to purple-lilac
