B3-Organisation And The Digestive System Flashcards
What is a tissue?
A group of similar cells working together
What is an organ
A collection pf dofferent tissues working together to preform a function
What is an organ system?
A collection of organs working together
What is an organism?
A collection of organ systems working together
What is the function pf the mouth in the idgestuve system?
- Teeth grind the food up
- Food is mixed with saliva (saliva contains a digestuve enzyme called amylase)
- Tongue pushes food to back of throat to be swallow
What is the use of the stomach in the digestive system?
- Temporary storage facility for food that is being digested
- Stretchy, muscular bat
- Muscles create churning pattern to mix food with digestive enzymes
- Acid activates the protease enzymes to break up large protein molecules
What is the function of the large intestine innthe digestive system?
- Any undigested food now enters the large intestine
- No digestion takes place but over 90% of water absorbtion occurs
- This forms faeces which move tot he rectum throught he process of peristalsis
What is the function of the small intestine in the digestive system?
- Partly digested food enter small instestine from stomach
- Bile and pancreatic juices are added to neutralize acid from stomach
- The pancreatic juices contain enzymes to break down fats, carbohydrates and proteins
- Proteins and nutrients are absorbed by the villi into the blood
What is the role of lipids in our body and whcih food are a good source of this nutrient?
They are the most efficent energy store in the body and an important source of energy in the diet. They are also important within cell membranes, and nervous system
* All oils (eg: olive oil and corn oil)
* Butter
* Margarine
* Cheese
* Cream
What role does carbohydrates play in the body and which foods are a good source of this nutrient?
Carbohydrates provide us with the fuel that makes all other reactions of life possible. They act as an energy source and help control blood glucose metabolism
* Bread
* Potatoes
* Rice
* Pasta
Why role does protein play in the body and which foods are a good source of this nutrient?
Proteins are used for growth of cells to repair tissues as well as the basis for all enzymes, used within the digestuve system to break down foods for the absorbtion of nutrients. They also act as antibodies and hormones such as insulin
- Fish
- Meat
- Cheese
- Eggs
- Pulses
What are the individual parts of a lipid?
Glycerol molecule, 3x fatty acid chains
What are the individual parts of protein and what is the entire protein chain called
Individual amino acids, polypeptide chain
What are the individual parts of carbohydrates and what is the entire carbohydrate chain called
Individual glucose molecules
A starch molecule (complex carbohydratej
What is the chemical used for starch?
Iodine solution
What is the chemical used for sugar?
Benedict’s solution
What is the chemical used for protein?
Biuret solution
What is the chemical used for lipds/ fats?
Ethanol
What is the method of test for starch?
1 Place a small amount of food on the spotting tile.
2 Add a few drops of iodine solution to the food on the spotting tile.
3 Yellow–red iodine solution turns blue–black if starch is present.
4 Record your result in the results table.
5 Repeat steps 1–4 for other types of food.
What is the method of test for sugar?
1 Place a small amount of food in a test tube.
2 Add enough Benedict’s solution to cover the food.
3 Place the test tube in a warm water bath for 10 minutes.
4 Blue Benedict’s solution turns brick red on heating if a sugar such as glucose is present or green if little sugar is present
5 Record your result in the results table.
6 Repeat steps 1–5 for other types of food.
What is the method of test for lipids/ fats?
1 Place a small amount of food into a test tube.
2 Add a few drops of ethanol to the test tube.
3 Shake the test tube and leave for 1 minute.
4 Pour the solution into a test tube of water.
5 Ethanol added to a solution gives a cloudy white layer if a lipid is present.
6 Record your result in the results table.
7 Repeat steps 1–6 for other types of food.
What is the method of test for protein?
1 Place a small amount of food in a test tube.
2 Add 1 cm3 of Biuret reagent. Alternatively add 1 cm3 of
sodium hydroxide solution and then add a few drops of copper sulfate solution.
3 Blue Biuret reagent turns purple if a protein is present.
4 Record your result in the results table.
5 Repeat steps 1–4 for other types of food.
What are enzymes?
Enzymes are special proteins that are involved in metabolism (reactions in the body). They are catalysts and can build, break or change molecules.
What are digestive enzymes?
Digestive enzymes break food into small soluble molecules that can be absorbed into the blood and delivered around the body
What is the active site?
The area of the enzyme that is complementary to the substrate
What is it called when the enzyme binds to the substrate?
Enzyme substrate complex
What is the name of enzyme which breaks carbohydrates down?
Carbohydrase
Area: in the mouth and small intestine
Product: Glucose
What is the name of enzyme which breaks proteins down?
Protease
Area: Stomach, small intestine
Product: Individual amino acids
What is the name of enzyme which breaks lipids/ fats down?
Lipase
Area: Small intestine
Product: Glycerol molecule and fatty acids
Explain why enzyme activity increases as temperature increases (up to an optimum)
As temperature increases, there is greater thermal energy resulting in greater kinetic energy. This results in a higher frequency of collisions between the enzymes and substrate and collidisions with greater energy. This results in more enzyme substrate complexes, therefore, increasing enzyme activity.
Explain why enzyme activity rapidly decreases with increasing temperature beyond the optimum?
Enzyme activity rapidly decreases with increasing temperature beyond the optimum temperature as vibrations within the enzyme caused by kinetic energy break the intermolecular forces between the protein chains, resulting in the enzymes becoming denatured. This means the substrate can no longer fit into the enzyme as it is no longer complememtary to the substrate and an enzyme substrate complex cannot be made. As a result of this, enzyme activity rapidly decreases.
Explain why enzyme activity decreases as the pH increases above/ decreases below the optimum pH
Within enzymes, the amino acids attract eachother as they have different, opposite charges. However, changin the pH scale will affect the charges of the amino acid molecules. Extremes of pH therefore denature the enzyme-substrate complex as the active site is no longer complementary to the substrate, resulting in low enzyme activity.
Why does pH affect the way an enzyme works?
pH affects the enzyme works as it interupts the hydrogen bonds between molecules within the enzyme. This changes the specific formation of the enzyme and it denatures, so the active site is no longer complementary to the substrate and enzyme activity decreases. However thos occurs at different pHs for each enzyme.
Why is it important to add the buffer to the enzyme before adding the starch?
It is important to add the buffer to the enzyme before adding the starch because it means the reaction will start as soon as the enzyme meets the starch. If the buffer is not already in before adding starch, the pH changes after the reaction has started and so the results will be invalid.
Explain what would have happened if, after taking 50 samples of amylase/buffer/starch
mixture, the iodine solution still continued to turn blue/black.
After taking 50 samples of the mixture, if the iodine solution continues to remain blue/black, it suggests the buffer solution cannot break down the starch as it us either too high or low, relative to the optimum pH. We can conclude from this the the enzyme amylase has denatured as the active site is no longer complementary to the substrate, resulting in low enzyme activity.
Why is it difficult for lipase enzymes to act on fat?
The fats that you don’t mix with all the watery liquids in your digestive system remain as large globules, making it difficult for lipase enzymes to act
What does bile do to help with the digestion of fat?
Bile emulsifies the fats in your food; bile physically breaks up large drops of fat into smaller droplets
Why is fat digestion difficult without bile?
Because the fat stay as large globules, making it difficult for lipase enzymes to act due to its smaller surface area
What is bile?
Bile is a green/ yellow alklali liquid produced by the liver and stored in the gall bladder.
Where is bile made?
The liver
Where is bile stored?
The gall bladder
What is another important job of bile other than emulsification?
Bile also neutralises the acid that was added to the food in the stomach, providing alkali conditions for the enzymes in the small intestine to work effectively.
What is the method for test8 g the effects on pH on amalyse?
1 Take a test tube containing 1 cm3 of pH buffer solution. Use a pipette to add 1 cm3 of amylase solution.
2 Place the test tube into a water bath set at 30 C and leave for 5 minutes.
3 While waiting, add a drop of iodine solution into each dimple of a spotting tile.
4 After 5 minutes, use another syringe to add 1 cm3 of starch to the amylase/buffer solution, immediately start the stop clock and leave it on throughout the test. Mix using a plastic pipette.
5 Remove a drop of the amylase/starch/buffer mixture after 20 seconds and add to the first drop of iodine on your
spotting tile.
6 Wait another 20 seconds. Then remove a second drop of the mixture to add to the next drop of iodine.
7 Repeat step 6 until the iodine solution and the amylase/buffer/starch mixture remains orange.
8 Record the time taken for the amylase to fully digest the starch.
10 Repeat the whole procedure with a different pH buffer.
