A group of cells with similar structure working together for a specific function
A group of tissues working together for specific functions
Reorder the following in increasing size order: Organ, cell, tissue, organ system, organism
Cell < Tissue < Organ < Organ system < Organism
State the function of the salivary glands.
Produce digestive enzymes (eg. Amylase)
Name the tube that carries food from the mouth to the stomach.
State the function of the stomach.
Releases digestive enzymes to digest food
State the function of the liver in the digestive system.
Produces bile for lipid digestion
State the function of the small intestine.
Digest food and absorb nutrients from digested food
State the function of the large intestine.
Absorb water from digested food
State the the function of the pancreas.
Produces/Releases digestive enzymes
State the function of the gall bladder.
Store bile before release into small intestine
What are carbohydrates made up of?
State the chemical formula of glucose.
Name a complex carbohydrate that is made up of glucose.
State the importance of having carbohydrates in our diet.
Energy source - Break down glucose in respiration to release energy for metabolic reactions
What elements make up carbohydrates?
C, H, O
What are lipids made up of?
1 glycerol + 3 fatty acids
State the importance of having lipids in our diet.
Energy store/Make up cell membranes/Steroid hormones
What elements make up lipids?
C, H, O
What are proteins made up of?
State the importance of having proteins in our diet.
What elements make up proteins?
C, H, O, N
Name the reagent used to test for starch.
What is a positive result for starch test?
Starch turns iodine from brown-red to blue-black
Name the reagent used to test for sugars.
What is the positive result for sugars?
Benedict’s solution turn from clear blue to brick-red (precipitate)
What is the reagent used to test for proteins?
What is the positive result for proteins?
Biuret turns from blue to purple
What is the reagent used to test for lipids?
What is the positive test for lipids?
White milky layer
State a hazard in doing food tests.
Ethanol is flammable/Biuret is corrosive
A substance that speeds up chemical reactions but don’t get used up
Biological catalysts that speed up chemical reactions
What kind of molecule are enzymes - carbohdyrates, lipids or proteins?
Define ‘active site’.
The site on an enzyme where the substrate binds
Any substance can fit into the active site of an enzyme. True or false?
Briefly describe the lock- and-key model.
Substrate fits into the active site to form enzyme-substrate complex –> Reaction occurs –> Enzyme releases products and binds to another substrate
Sum of all reactions in a cell/body
Loss of active site
How does temperature affect enzymes’ rate of reaction?
As temp increases, RoR increases until after optimum
Why do enzymes stop working past their optimum temperature?
Denatured (substrate can no longer bind to active site)
Why do enzymes not work well at lower temperatures?
Inactive (not enough KE to collide and bind to active site)
How does a change in pH affect enzyme structure?
pH change affects forces holding enzyme structure together, causing it to denature
Define ‘ digestion’.
Breakdown of large insoluble molecules into smaller soluble substances
Name the type of enzyme that digests carbohydrates.
Name the enzyme that digests starch.
Name the product of the breakdown of starch.
Name the type of enzyme that digests proteins.
Name the protease that works well in the stomach.
Name the product of the breakdown of proteins.
Name the type of enzyme that digests lipids.
Name the products of the breakdown of lipids.
Glycerol and fatty acids
Which organs produce amylase?
Salivary glands and pancreas
Which organs produce proteases?
Stomach, pancreas, small intestine
Which organs produce lipases?
Pancreas and small intestine
Where does starch digestion occur?
Mouth + Small intestine
Where does protein digestion occur?
Stomach + Small intestine
Where does lipid digestion occur?
How are the nutrients carried away from the gut?
Absorbed into bloodstream through small intestine
State an observation to determine when the amylase has completed its digestion of starch.
Iodine remains brown-red rather than turning blue-black
State a reason for setting the amylase solution, starch solution and the buffer in the water bath before the experiment.
To ensure all of the same temp, so that temp will not affect the results (fair test)
How does the hydrochloric acid in the stomach help with digestion?
Provides optimum pH for pepsin to digest proteins
Apart from digestion, what is another function of hydrochloric acid in the stomach?
Kill pathogens in food
How is the stomach adapted to protect itself from the hydrochloric acid?
Thick mucus layer/quick renewal of epithelial layer
State the two functions of bile.
Emulsifies fats + Neutralises food from stomach (HCl)
What is emulsification?
Physically breaking down large oil drops into smaller droplets, increasing surface area for lipases to work on
Bile is an enzyme. True or false?
Hydrochloric acid in the stomach breaks down food. True or false?
FALSE - provides optimum pH for pepsin and kills bacteria, NOT digest food
State the importance of the neutralising role bile has.
Small intestine does not have protective mucus layer + Enzymes will denature in small intestine