Organisation (2)
what are tissues made up of?
similar cells working together to carry out a particular function. This can include more than one type of cell
what are organs made up of?
a group of different tissues working together to perform a function
what is an organ system?
a group of organs working together to perform a particular function
what do muscular tissues do?
they contract to move whatever they are attached to
what does glandular tissue do?
make and secrete chemicals such as enzymes and hormones
what does epithelial tissue do?
covers parts of the body such as the inside of the gut
what does the digestive system do?
break down and absorb food
what are the organs in the digestive system?
Glands - pancreas & salivary glands
Stomach
Small intestine
Liver
Large intestine
gullet
gall bladder
rectum
name the glands and what they do
the salivary gland and pancreas produce digestive juices. Ghe salivary gland produces amylaze enzymes in the saliva, the pancreas produces protease, amylase and lipase and releases them into the small intestine
how does the stomach digest food?
- it pummels the food using its muscular walls
- it produces protease (pepsin)
- it produces hydrochloric acid to kill bacteria and give the right pH for protease to work (pH2- acidic)
what are the 2 functions of the small intestine?
producing enzymes to complete digestion and absorbing soluble food molecules into the blood
what does the liver do?
produce bile
what does the large intestine do?
absorb water from undigested food, leaving faeces
name a biological catalyst
enzymes
what is a catalyst?
a substance which increases the speed of a reaction without being changed or used up
what is the active site of an enzyme?
the side of the enzyme with a unique shape that can only be fit by the specific substance involved in the specific reaction that enzyme catalyses
whats the name for the substance an enzyme acts upon
substrate
what happens if the temperature becomes too high for an enzyme?
the bonds holding the enzyme together break, changing the shape of the active site, meaning the substrate will no longer fit, therefore the enzyme is denatured
what are the 2 tjings affecting the rate of enzymes?
temperature and pH
what happens if the pH is too high or low for an enzyme?
this interferes with the bonds holding the enzyme together, this changes the shape of the active site and denatures the enzyme
how do you calculate the rate of reaction?
rate = 1000 divided by time in seconds
OR
rate = change (eg. amount of product formed) divided by time
What do enzymes do?
break down big molecules into smaller ones so they can pass more easily through the walks of the digestive system, allowing them to be absorbed into the bloodstream
what does protease do?
convert proteins into amino acids
where is protease made? name 3
stomach
pancreas
small intestine
what do lipases do?
covert lipids into glycerol and fatty acids
what are lipids
fars and oils
where are lipases made? name 2
pancreas
small intestine
what do carbohydrases do?
convert carbohydrates into simple sugars
name a type of carbohydrase?
amylase
what does amylase break down?
starch into sugars such as maltose and dextrins
where is amylase produced? name 3
salivary glands
pancreas
small intestine
what does bile do?
neutralise stomach acids and emulsifies fats
what dies the rectum do?
where the faeces (indigestible food) is stored before being pood out
what is the function of the gall bladder?
where bile is stored before being released into the small intestine
how do you prepare a food sample?
-break it up using pestle and mortar
- transfer to beaker and add distilled water
- stir mixture to dissolve food
- filter the solution using a funnel lined with filter paper
how do you ise Benedicts test to test for sugars?
- prepare food sample and transfer 5cm3 to a test tube
- prepare a water bath to 75°C
- add 10 drops of benedicts solution using a pipette
- place test tube in water bath and leave it fir 5 min. ensure test tube is pointing away from you
- if food sample contains reducing sugar, the solution will turn from blue to green yellow or brick red depending how much sugar is in the food
how is iodine solution used to test for starch?
- transfer 5cm3 of your food sample to a test tube
- add a few drops of iodine solution and gently shake tube to mix contents
- if the sample contains starch the colour of the solution will change from browny orange to black or blue black
how is the biuret test used ti test for proteins?
- prepare a food sample and transfer 2cm3 of sample to test tube
- add 2cm3 of biuret solution to sample and mix cintents by gently shaking
- if the food samole contains protein the solution will change from blue to purple
how do you use the sudan III test to test for lipids?
- prepare a food sample without filtering
- transfer 5cm3 to test tube
- use a pipette to add 3 drops of sudan III stain solution to the test tube and gently shake the tube
- the sudan solution stains lipids.
- if any are present, the solution will separate out into 2 layers and the top layer (lipids) will turn bright red.