B2 - Organisation Flashcards
What are:
- cells
- tissues
- organs
- organ systems
Basic building blocks of all living organisms
A tissue is a group of cells with a similar structure and function.
Organs are aggregations of tissues performing specific functions.
Organs are organised into organ systems, which work together to form organisms
Define catalyst
substance which increases speed of reaction by providing an alternate pathway without being changed or used up in the reaction
What is an enzyme
Chemical which speeds up the rate of reaction
Is a protein
Explain the lock and key theory (3 marks)
Enzyme is the lock, substrate is the key
Every enzyme has an active site with a unique shape that fits onto the substance involved in a reaction
For an enzyme to work, substrate has to fit into its active site
Vice Versa
Formula for rate of reaction
1000/time
What does change equal to
Other equation
amount of product formed
Change/time
What is the digestive system
An example of an organ system in which
several organs work together to digest and absorb food.
Explain how temperature and affect enzymes (4 marks)
Changing temperature changes the rate of an enzyme-catalysed reaction
As temp increase, rate increases up until a point
If it gets to hot, some of the bonds holding the enzyme together will break - changes shape of enzymes active site, substrate won’t fit anymore - denatured
Explain how pH affects enzymes ( 3 marks)
If pH gets too high or too low, pH interferes with the bonds holding enzymes together - changes the shape of the active site - denatures
What pH do enzymes work at
But what is the name of the other enzyme used to break down proteins in the stomach and what is its optimum pH
7
Pepsin - pH2
How to investigate effect of pH on Enzyme activity (6 marks)
Put a drop of iodine solution in a spotting file
Place Bunsen burner on a heat proof mat, and place tripod and gauze over it
Using a Bunsen burner, heat up a beaker of water to 35 degrees - keep constant
Using a syringe add 1cm^3 of amylase solution and 1mc^3 of buffer solution pH5 to the boiling tub. Put this boiling tube into the beaker of water and wait 5 minutes
After 5 minutes, add 1cm^3 of starch solution to the boiling tube using a different syringe
Immediately mix the contents and start a stopwatch
Every 10 seconds, put a drop from the boiling tube into a spotting file using a pipette
When the iodine solution remains brown-orange, there is no more starch present
Repeat with different pH of buffer solution to see how pH affects rate of reaction
Keep concentration and volume of amylase solution constant throughout the experiment
Where is Amylase found
Converts what to what
Salivary glands pancreas s.i
Carbohydrates into maltose
Amylase is an example of ..
carbohydrases
Where is protease found
Converts what to what
Stomach Pancreas S.I
Proteins into amino acids
Where is lipase found
Converts what to what
Pancreas S.I
Lipids into glycerol and fatty acids
What is the purpose of digestive enzymes
Digestive enzymes convert food into small soluble molecules that can be absorbed into the bloodstream
Where is bile made and stored
Made in liver
Stored in gall bladder
What is the purpose of bile and how does bile emulsify fats (4 marks)
Alkaline to neutralize hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase
What is the role of digestive enzymes
Break down large food molecules into smaller, soluble ones that can be absorbed into the bloodstream
Function of:
Muscular tissue
Glandular tissue
Epithelial tissue
Moves the stomach wall to churn up the food
Makes digestive juices to digest food
Covers the outside and inside of the stomach
Function of:
Glands
Stomach
Liver
S.I
L.I
Produce digestive juices
Digest food
Produce bile
Absorb soluble food molecules
Absorbs water from undigested food - leaving faeces
How do you prepare each food sample
( 4 marks)
Get a piece of food an break it up using pestle and mortar
Transfer the ground up food to a beaker and add some distilled water
Give the mixture a good stir with a glass rod to dissolve some of the food
Filter the solution using a funnel lined with filter paper to get rid of the solid pieces of food
Benedict’s test for sugars
(6 marks)
Prepare food sample and transfer 5cm^3 to a test tube
Prepare a water bath set to 75 degrees
Add 10 drops of benedict’s solution using a pipette to the test tube
Place test tube in water bath using a test tube holder and leave for 5 minutes
Make sure tube is pointing away from you
Blue to green, yellow or brick-red contains sugar
Iodine test for starch
( 3 marks)
Make a food sample and transfer 5cm^3 of sample to a test tube
Add a few drops of iodine solution and gently shake tube to mix contents
Browny-orange to black or blue black contains starch
Test for proteins
( 3 marks)
Prepare a food sample and transfer 2 cm^3 of sample to test tube
Blue to purple - contains protein
Stays blue if protein is not present
Sudan III test for lipids
( 4 marks)
Prepare a food sample - no need to filter
Transfer 5 cm^3 into a test tube
Use a pipette to add 3 drops of Sudan III stain solution to the test tube and gently shake the tube
Mixture with separate out into two layers - top layer bright red - lipids present
