B3 Flashcards
What is a cell
It is the basic building block of life.
What is a tissue?
A tissue is a group of cells of the same type.
What is an organ?
It is a group of tissues that work together to perform a function.
What is an organ system?
It is a group of organs working together for e.g. circulatory system
What is a organelle?
It is a smaller thing in a cell for e.g. mitochondria
What is digestion?
Digestion is the process where large molecules are broken down into smaller molecules to be absorbed into the blood.
What is the order of the digestion system?
1) Digestion starts in the mouth - where food is chewed and saliva added.
2) Food goes down the oesophagus and enters the stomach.
3) The stomach churns the food and hydrochloric acid is added.
4) Then it enters the small intestine where digested food is absorbed into the blood stream.
5) Anything remaining enters the large intestine where water is absorbed.
6) Finally any undigested food exits via the anus.
What do the villi do in the small intestine?
The villi provide the small intestine with a large surface area so more digested food can be absorbed into the blood stream.
Villi also have a good blood supply to assist quick absorption
They also have a one cell thick wall so that the nutrients have a shorter distance to diffuse over
What is the function of a liver?
It produces bile
What is the function of the stomach?
Breaking down large insoluble molecules into smaller soluble molecules
What is the function of the small intestine?
It produces protease, lipase and amylase enzymes
It is also the place where digested food is absorbed into the blood
What is the function of the large intestine?
It absorbs excess water from the food
Give an example of a simple sugar
Sucrose, glucose
What are lipids?
They are fats and oils
What do the salvary glands produce?
Amylase enzyme in the saliva
What does the pancreas produce?
Protease, amylase and lipase enzymes
What is a protein?
A molecule that is made up of long chains of amino acids
What is an enzyme?
Its a biological catalyst
Whats another thing that the stomach does?
-It pummels the food with its muscular walls
-It produces the protease enzyme, pepsin.
-It produces hydrochloric acid
What enzyme catalyses starch and what does it break it into?
Amylase(carbohydrase) catalyses starch and turns it into maltose
What is a catalyst?
It is a substance that speeds up a chemical reaction without getting used up or changed
What enzyme catalyses protein and what does it break it into?
Protease catalyses protein and breaks it up into amino acids
What enzyme catalyses lipids and what does it break it up into?
Lipase catalyses lipids and breaks it up into glycerol and fatty acids
What does bile do and where is it stored and produced?
Bile neutralises the stomach acid and emulsifies fats
Bile is produced in the liver
It is stored in the gall bladder before its released into the small intestine
It breaks down lipids into smaller droplets so that the lipase enzyme has a bigger surface area to work on so it breaks down lipids quicker.
It neutralises stomach acid so that the lipase is at its optimum pH to break down fat
What does every enzyme have?
Every enzyme has a active site
What is the thing called that binds to the active site?
Substrate
What 2 things can change the rate of an enzyme-catalysed reaction?
Temperature and pH
What happens if the temp gets too hot on the enzyme?
Some of the bonds holding the enzyme together will break and this changes the shape of the enzymes active site making the substrate not fit anymore. The enzyme is said to be DENATURED. This is the same with pH
At what temp and pH do most enzymes work best at?
Temp-37, pH-7
At what pH does pepsin (the enzyme that breaks down proteins) work best at?
pH 2 because it lives in acidic conditions
How do you calculate the rate of reaction?
Rate=1000/time
How can you investigate the effect of pH on enzyme activity (required practical)?
1 ) Use the syringe to place 2 cm3 of amylase solution into a test tube.
2 ) Use another syringe to add 1 cm3 of pH buffer solution to the test tube.
3 ) Place the test tube into a water bath set at 30 C and leave for 5 minutes.
4 ) Whilst waiting, add a drop of iodine solution into each dimple of a spotting tile.
5 ) After 5 minutes, use another syringe to add 2 cm3 of starch to the amylase/buffer solution, start the stop clock and leave it on throughout the test. Mix using a plastic pipette.
6 ) Remove a drop of amylase/starch/buffer mixture after 30 seconds and add to the first drop of iodine on your spotting tile.
7 ) Wait another 30 seconds. Then remove a second drop of the mixture to add to the next drop of iodine.
8 ) Repeat step 6 until the iodine solution and the amylase/buffer/starch mixture remains orange.
9 ) Record the time taken for the amylase to fully digest the starch.
10 ) Repeat the whole procedure with a different pH buffer.
What can you use to test for sugars? And what colour will the food change?
Benedict’s solution and it will change from blue to green to yellow to brick-red depending on how much sugar is in the food
How do you test for starch? And what colour will the food change?
Use Iodine solution and the food will change from browny-orange to black or blue-black
How do you test for proteins? And what colour will the food change?
Use Biuret test and the food will change from blue to purple
What do you use to test for fats? And what colour will the food change?
Ethanol and the ethanol will change from colourless to milky white
How does an enzyme catalyse a reaction (lock and key method) ?
First the substrate would bind to the enzymes active site because the shape of the active site and substrate would complimentary. This would cause bonds between the substrate molecules to break to produce smaller molecules
