Organisation- Digestive System Flashcards
The digestive system is an _____ _______. Several organs work together to digest and absorb _________.
The digestive system is an organ system. Several organs work together to digest and absorb nutrients.
Enzymes are ___________ ________ used in the digestive system. Enzymes are biological _________.
Enzymes are specialised proteins used in the digestive system. Enzymes are biological catalysts.
Enzyme function can be described as the ‘____ and ___ model’.
Enzyme function can be described as the ‘lock and key model’.
The _________ binds to the active site on the enzymes.
The substrate binds to the active site on the enzymes.
An enzyme _________ when the active site changes _____ and the substrate can no
longer bind to the enzyme.
An enzyme denatures when the active site changes shape and the substrate can no
longer bind to the enzyme.
High ____________ and the wrong __ denature enzymes.
High temperatures and the wrong pH denature enzymes.
Carbohydrase enzymes break down _____________ into ______ _______.
Carbohydrase enzymes break down carbohydrates into simple sugars.
________ is a type of carbohydrase which breaks down starch into sugars
Amylase is a type of carbohydrase which breaks down starch into sugars
Lipase enzymes break down ____ into _____ _____ and ________.
Lipase enzymes break down fats into fatty acids and glycerol.
Protease enzymes break down _______ in to _____ ______.
Protease enzymes break down protein in to amino acids.
Bile is made in the _____ and stored in the ____ _______.
Bile is made in liver and stored in the gall bladder.
____ neutralises the substances from the stomach and helps to emulsify fats.
Bile neutralises the substances from the stomach and helps to emulsify fats.
Different chemicals test for different nutrient groups. Which chemical tests for starch? What’s the colour change?
Iodine tests for starch – pale yellow to blue/black
Different chemicals test for different nutrient groups. Which chemical tests for sugar? What’s the colour change?
Benedicts tests for sugar – blue to brick red
Different chemicals test for different nutrient groups. Which chemical tests for protein? What’s the colour change?
Biuret reagent tests for protein – blue to purple
Different chemicals test for different nutrient groups. Which chemical tests for fats? What’s the colour change?
Ethanol tests for fats – clear to cloudy
what are the three main nutrients found in food
carbohydrates protein and lipids
are these nutrients large or small molecules
large meaning they have to be digested
During digestion what breaks down the large molecules into smaller molecules
enzymes
What happens in the mouth when digesting food
The food is chewed and the saliva begins to digest the starch into smaller sugar molecules
After the mouth where does the food go and what happens here
food passes through the oesophagus and into the stomach and the enzymes then start to digest the proteins
what acid is found in the stomach to help the enzymes to digest the proteins
hydrochloric acid
true or false?
the food spends several hours in the stomach
true
What happens in the stomach to help turn the food into a fluid
The stomach muscles contract to create a churning motion which increases the surface area for enzymes to digest
where does the fluid go after the stomach and what happens
small intestine and chemicals are produced from the liver and pancreas
the pancreas releases enzymes, what does this help the digestion of?
starch, protein and lipids
what does bile do
speed up the digestion of lipids
and neutralises the acid released from the stomach
what does the small intestine do to help the digestion of protein and lipids?
the walls release enzymes
How are the small food molecules absorbed into the blood stream by the small intestine
by active transport or diffusion
what happens in the large intestine
water is absorbed into the bloodstream
and the faces is released from the body
true or false?
enzymes are not specific and can break down many things
false
enzymes are very specific and can only fit perfectly to one active site
where do you find proteases
stomach, pancreas, small intestine
what are proteins
long chains of chemicals called amino acids
what happens when we digest proteins
the protease enzyme convert the protein back to the individual amino acids which are then absorbed into the blood stream
how are human proteins made
when the amino acids are joined together in a different order
what is starch made of
starch consists of a chain of glucose molecules
where is amylase found
saliva, and in the pancreatic fluid
what is a lipid molecule made of
a molecule of glycerol attached to three molecules of fatty acids
where is lipase found
in the pancreatic fluid and the small intestine
bile emulsifies the Lipid
why is this good?
it massively increases the surface area of the lipid droplets
why can bile neutralize the stomach acid
because it is alkaline
what happens tp the reaction if you increase the temperature
the activity of the enzymes increase meaning the reaction rate increases
why does a rising temperature increase the rate od reaction
the enzyme and substrate are moving quicker and so there are more collisions per second between the substrate and the active site
what’s the optimum temperature
the temperature in which the enzymes are working st the fastest possible rate
for human enzymes what’s the optimum temperature
37 degrees celsius (human body temp)
what happens once you increase the temperature past the optimum
activity of the enzyme rapidly decreases to 0
why is this?
at high temperatures, the enzyme molecule vibrates and the shape of the active site changes
what is it called when the active site no longer fits the substrate
the active site has denatured
what happens to the active site of an enzyme if conditions are too acidic or to alkaline
the activity drops to 0
true or false?
each enzyme has the same optimum ph
false
each enzyme has a specific optimum ph and work better or worse depending on it
required practical : effect of ph on amylase
- place 1 drop of iodine into each well of a spotting tile
- take 3 test tubes and place 2 cm^3 of startch solution into the first, amylase into the second and a buffer solution into the third
- place all 3 test tubes into a water bath at 30 degrees celsius and leave for 10 minutes
- combine 3 test tubes into 1 and stir with a stiring rod, keep in water bath and start stop watch
- after 30 seconds use a stirring rod to transfer 1 drop of the solution into each well of the spotting tile
- the iodine will turn blue/ black if the startch is present
- take a sample every 30 seconds and when the iodine remains orange that means all the starch has been used up - this means the reaction has finished
- repeat the experiment multiple times but use different ph buffer solutions
what are the problems with this practical
- only taking samples every 30 seconds meaning we only have an appointment time for the reaction to complete
- it is not always obvious when the reaction has stopped as the colour change can be subtle
required practical: food tests
- take the food sample and grind this with distilled water using a mortar and pestle - you want to make a paste
- transfer the paste to a beaker and add more distilled water. stir so the chemicals in the food dissolve in the water
- filter solution to remove suspended food particles
- add 2cm^3 into a beaker and add your indicator
how do you test for sugar
place 2cm^3 of you food solution. add 10 drops of benedict solution which is a blue colour. place the test tube containing the solution into a beaker with half filled hot water. leave this for 5 minutes. if sugar is present then the benedict’s will change colour.
when testing for sugar, what does it mean if the benedict’s solution turns green
that there’s a small amount of sugar
when testing for sugar, what does it mean when the benedict’s solution turns yellow
there’s more sugar present
when testing for sugar, what does it mean if the benedict’s solution turns brick red
that there’s lots of sugar present
what sugars does benedict’s solution work for
reducing sugars
how is the small intestine adapted for absorption
- length of around 5m - large surface area for absorption
- interior covered in villi which increase the surface area for the absorption of molecules
