Organisation Flashcards
What is meant by a cell?
A basic building block of all living organisms.
What is meant by a tissue?
A group of cells with a similar structure and function.
What is meant by an organ?
A group of tissues performing specific functions.
What is meant by an organ system?
A group of organs working together to perform specific functions within an organism’s body.
What are the three main nutrients within food?
Carbohydrates (starch and sugars)
Protein
Lipids (fats and oils)
Why do :
Carbohydrates (starch)
Protein
Lipids (fats and oils)
Have to be digested?
Because they are large molecules. Too large to be absorbed into the blood stream, so are digested so they can be absorbed by bloodstream.
What occurs during digestion? Define digestion.
Process where large and complex molecules in food are broken down into smaller and simpler molecules so that nutrients from this can be absorbed into the bloodstream.
Role of the mouth in the digestive system
-Where food is chewed.
- Saliva in the mouth contains enzymes (salivary amylase) which begin to digest the starch into smaller sugar molecules.
Role of the oesophagus in the digestive system
Where food that is chewed by the mouth passes thru before reaching the stomach.
What are the things the stomach does in digestion?
- The stomach begins the digestion of protein through the enzyme pepsin which it contains.
- Contains HCL which:
> Kills bacteria in food.
> Provides optimal acidic conditions/pH for enzyme activity to aid digestion. - Has stomach muscles - these contract to create a churning action which turn the food to a fluid to INCREASE SURFACE AREA FOR ENZYMES TO DIGEST.
What two types of breakdown does digestion rely on?
Physical breakdown
Chemical breakdown
Role of HCL in the stomach.
> Kills bacteria in food.
Provides optimal acidic conditions fo enzyme activity to aid digestion
After food has been digested by the stomach, where does it go and what happens next?
Food Fluid after spending several hrs in the stomach passes into the small intestine.
Chemicals from pancreas and liver are released into the small intestine:
PANCREAS - releases pancreatic juice which contains enzymes which continue digestion of protein and carbs and BEGIN digestion of lipids.
LIVER and GALL BLADDER-
Gall bladder releases bile produced by the liver. The role of bile is to speed up the digestion of lipids by emulsifying them into small droplets = BIGGER SA for digestive enzymes to work on - and neutralise stomach (HCL) acid bc bile is alkaline.
Next, food fluid passes down the rest of small intestine and the WALLS release enzymes which continue the digestion of proteins and lipids
Now, small food molecules are absorbed into the bloodstream via diffusion or active transport.
What organ does most digestion occur?
Small Intestine.
Role of bile
LIVER and GALL BLADDER-
Gall bladder releases bile produced by the liver into small intestine through a tube. The role of bile is to speed up the digestion of lipids by emulsifying them into small droplets = BIGGER SA for digestive enzymes to work on - and neutralise stomach (HCL) acid bc bile is alkaline.
1 - To speed up the digestion of lipids bc it emulsifies fats (breaking big molecules into smaller droplets) - makes a larger SA for enzymes to work on.
2 - To neutralise stomach acidi food in small intestine bc bile is alkaline fo enzymes in SI to work effectively.
(remember to always mention both roles)
True or false, bile is an enzyme?
False.
What happens after the useful small molecules from food is absorbed by the bloodstream (from small intestine)?
Remainder of fluid food passes into large intestine which absorbs the excess water, producing faeces which is stored in the rectum until removed via egestion.
What are the products of digestion used for by the body?
To produce new carbs, proteins and lipids in body, eg protein for enzymes.
Some glucose is used for respiration.
digestive system labelled
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What is meant by an enzyme?
A biological catalyst that speeds up chemical reactions in living organisms without being consumed or permanently altered in the process.
Enzymes a proteins, protein is a polymer made up of small molecules called?
Amino acids.
What type of molecule is an enzyme?
A large protein molecule.
What is meant by the active site of an enzyme.
The active site is where the substrate attaches to.
What is meant by a substrate?
The molecule the enzyme is breaking down.
Summarise the lock and key theory.
- Enzymes have a specific active site which is complementary to their substrate so they can bind to the substrate to form an enzyme-substrate complex, and break substrate molecule in to smaller ones to be absorbed by bloodstream.
True or false enzymes are specific.
True, their active site is specific to their substrate
What is protease and explain its role.
Protease is the enzyme that breaks down proteins.
Proteins are made up of long chains amino acids. When digested, proteins are converted by protease back to individual amino acids. When amino acids are absorbed by body cells, they are joined together in a different order to make human proteins.
Where is protease found?
Stomach
Small intestine
Pancreatic fluid in pancreas.
What is starch?
A type of carbohydrate consisting of a chain of glucose molecules
What type of enzymes are carbohydrates broken down by.
Carbohydrases.
- Eg - amylase is a type of carbohydrase that breaks down starch to glucose, a type of sugar.
What enzyme breaks down starch?
Amylase.
Where amylase found?
Pancreatic fluid
Saliva
small intestine
Amylase breaks down starch to produce?
Simple sugars such as glucose
Carbohydrase breaks down carbohydrate to produce?
Glucose and simple sugars
Protease breaks down proteins to produce?
Amino acids.
A lipid molecule consists of how many molecules of glycerol and fatty acid?
1 lipid molecule =
1 molecules of glycerol and 3 molecules of fatty acids.
What enzyme breaks down lipid molecules?
Lipase.
Lipase breaks down lipid molecules to produce?
Glycerol and fatty acids.
Where is lipase found?
Pancreas
Small intestine
What also, as well as lipase aids the digestion lipids?
Bile.
- emulsifies lipid molecules, making them into smaller droplets to increase SA for lipase action.
- Is alkaline - neutralises stomach acid = optimum alkaline conditions for lipase
^^ Increasing the rate of lipid digestion by lipase.
Describe the affect of temperature on an enzyme using stages 1 2 and 3 (look at diagram).
Stage 1,
As temp increases so does enzyme activity
Bc there is more energy supplied meaning enzyme and substrate are moving faster.
This means there are more collisions per seconds between enzyme and active site
Stage 2, at the peak is the optimum temperature. This because enzymes are working at the fastest rate possible. This is because there is a max, frequency of collisions between substrate and active site.
Stage 3, When temperature is raised past optimal level, enzyme activity rapidly decreases to zero (enzymes stop working). This is because they begin to vibrate and shape of active site changes - so substrate can no longer fit in. Enzyme has denatured.
What is the optimum temperature in humans?
37 deg celcius
Describe the effect of altering pH of an enzyme.
- Every enzyme has an optimum pH, if pH is increased (more alkaline) or decreased (more acidic) the enzyme activity will fall as the active site changes shape/denatures.
An enzyme’s optimum pH is acidic, what enzyme could this be?
protease enzyme
carbohydrase enzyme
An enzymes optimum pH is alkaline, what enzyme could this be?
Lipase
An enzymes optimum pH is slightly alkaline and slightly neutral, what enzyme could this be?
Amylase.
Describe how to prepare food sample when conducting chemical tests for nutrients.
- Take food sample and add distilled water.
- Grind the mixture w a mortar and pestle to make a paste.
- Transfer paste into a beaker and add more distilled water.
- Stir so chemicals in food dissolve into the water.
- Filter the solution to remove suspended food particles and for a clearer colour change to be seen.
Test for carbohydrates:
Starch = Iodine test
Reducing sugars = Benedict’s
Test for protein:
Biuret’s reagent (Copper II sulfate and sodium hydroxide).
Test for lipids:
Ethanol emulsion test.
Sources of error when conducting chemical tests for nutrients.
Colour change may be subtle and difficult to judge if the concentration of the test molecule is low (we can get many ppl to check).
Safety precautions when conducting chemical tests for nutrients.
- Tie hair back and when using open flame eg Bunsen burner when performing Biuret’s test and water bath when performing Benedict’s test .
- Handle Biuret’s reagent w care as it contains copper II sulphate which is poisonous and sodium hydroxide which is corrosive. WEAR GLOVES, and wash immediately if it comes in contact w skin.
- Keep ethanol solution away from flames bc its highly flammable.
Describe test for starch
What test?
What do we do?
Positive colour change - from __ to __
IODINE TEST:
Add prepared food sample (2cm^3) into a test tube
Add a FEW drops of iodine solution into test tube using a pipette and mix.
If starch is present, the iodine solution will turn from brown to blue-black.
(note any colour change in a table of results)
Describe test for reducing sugars
Add prepared food sample (2cm^3) into a test tube.
Add an equal volume of Benedict’s reagent (10 drops) using a pipette to the test tube containing the food sample solution.
Heat the test tube in a water bath at around 75°C for a few minutes.
If reducing sugars are present, the solution will change from blue to:
brick-red,
orange,
yellow
or green,
Indicating the presence of reducing sugars depending on the concentration ^^ respectively, most conc = brick-red.
note any colour change in a table of results.
Describe test for protein
Add a 2 cm^3 of Biuret’s reagent to food sample (2cm^3) in a test tube, using a pipette.
Shake solution carefully to mix and wait for a few minutes.
If protein is present, the solution turns from blue to purple.
Describe the test for lipids
Add a few drops of cm^3 of ethanol and distilled water using a pipette to food sample (2cm^3) in appropriate apparatus.
DON’T FILTER WHEN PREPARING - bc lipid molecules can stick to filter paper.
Pour mixture into test tube with equal volume of distilled water.
If lipids are present, a white emulsion is formed on the surface of the mixture.
- ethanol is highly flammable, ensure no naked flames are present.
Positive result for starch
Brown to Blue black.
Positive test for reducing sugars
Blue to any colour of rainbow depending on conc: brick red, orange, yellow, or green.
In an exam say brick-red when necessary.
Positive test for protein
Blue to purple.
Postive test for lipids (ethanol emulsion test)
White emulsion is formed on surface of mixture.
Positive test for lipids (Sudan III Test)
2 layers formed -
top layer = bright red
bottom layer = colour of original mixture
Describe test for lipids (sudan III)
Using a pipette 3 drops of Sudan III stain solution to prepared food sample (5cm^3) in a test tube.
DON’T FILTER WHEN PREPARING - bc lipid molecules can stick to filter paper.
Gently shake the tube in order to mix the mixture,
Sudan III stain solution stains lipids. If lipids is present in sample, mixture will form 2 layers; the top layer will be bright red (if no lipids present, mixture doesn’t form two layers).
True or False, Benedict’s test works for non-reducing sugars eg sucrose?
FALSE. no colour change will occur if we try.
Why don’t we filter when preparing our food sample to check for presence of lipids?
bc lipid molecules can stick to filter paper which will affect results.
Structure of proteins, starch and sugars
Draw
Describe how to investigate the effect of pH on the rate of reaction of the enzyme amylase.
- Place one drop of iodine solution using a pipette, into each well of a spotting tile.
- Take 3 test tubes, and in the 1st there’s 2cm^3 starch solution, in the 2nd there’s 2cm^3 of amylase solution and in the 3rd there’s 2cm^3 of pH 5 buffer solution (SAB).
- Place all three test tubes in a water bath at 30 deg Celsius and leave them to heat for 10 mins to allow solutions reach 30 deg.
- Combine 3 solutions into a new test tube and mix with a stirring rod.
- Immediately return the test tube containing the mixture into water bath and start a stop watch for 30 secs.
- After 30 secs, use stirring rod to transfer 1 drop of solution into each well in spotting tile containing iodine solution.
- Iodine should turn blue-black if starch is present.
- Take a sample every 30 seconds and continue until iodine remains brown/orange.
- When iodine remains brown, it means starch is no longer present in solution (reaction has completed)
- Record the time that the reaction completed within in a table.
- Repeat this experiment for different pH buffers (6, 7 and 8).
- Plot a graph for rate of enzyme reaction against pH
- Calculate rate of reaction: rate = change/time
What does amylase break down starch to?
Maltose.
What is buffer solution used for?
A buffer solution is used to maintain a stable pH level in a solution, resisting changes in pH when small amounts of acid or base are added.
- we can use them to alter pH.
What issues are there when investigating the effect of pH on the rate of reaction of the enzyme amylase.
- INTERVALS BETWEEN TESTING MAY BE TOO LONG TO ACCURATELY FIND THE TIEM TAKEN FOR STARCH TO BE COMPLETELY BROKEN DOWN: We take sample every 30 seconds meaning we only have an approximate time which reaction finished - instead we should take sample every 10 seconds to be more specific.
- When we look for the time iodine doesn’t become blue-black from brown, it isn’t always obvious as colour change is gradual, one well may have blue mixed w v little brown - so ask many ppl to check to see when reaction has finished.
Safety precautions when investigating the effect of pH on the rate of reaction of the enzyme amylase.
- Be careful when using Bunsen burner; tie hair back and use goggles.
-
Order of digestive system.
Mouth
Osophagus
Stomach
Small intestine (liver and pancreas come in)
Large intestine
Rectume
Adaptations of the small intestine for absorption of products of digestion.
1) Very Long. This provides a large SA for products of digestion to be absorbed (faster diffusion/AT).
2) Interior of small intestine is covered in villi. This increases SA for products of digestion to be absorbed by bloodstream.
3) Villi is covered in microvilli on their surface. This further increases SA for absorption.
4) Villi have a good blood supply. Blood rapidly absorbs products of digestion - this maintains a steep conc gradient increasing rate of absorption.
5) Villi have a thin membrane; short diffusion path for absorption.
If products aren’t absorbed by diffusion they are absorbed by AS.
True or false, fish have a single circulatory system?
TRUE:
Heart - Gills - Organs.
blood passes through the heart once during one complete circuit through the body.
What is the issue with a single circulatory system?
Blood loses pressure so blood travels slowly, so a great deal of oxygen cannot be delivered to organs in a specific time - less O2 for respiration - more anaerobic respiration.
Do humans have a double circulatory system?
YES.
blood passes through the heart twice during one complete circuit through the body
Why do humans have a double circulatory system?
We are relatively larger organisms, smaller SA:VOL so humans have a double circulatory system to efficiently separate oxygenated and deoxygenated blood, ensuring optimal oxygen delivery to ALL body tissues and effective removal of carbon dioxide rapidly, in a given time.
draw timeline diagram.
What is meant by the heart?
The heart is an organ consisting of mainly muscle tissue that pumps blood around the body in a double circulatory system.
How many chambers does the heart have?
4 chambers.
Right and Left atrium.
Right and Left ventricle.
What are atria separate from ventricles by?
Valves.
