B3 Flashcards
Levels of organisation
Cells, tissue, organ, organ system, organism
Tissue
A group of similarly structured cells working together.
Organ
Several tissues which together, perform a function
Oesophagus
Has muscles init’s walls which contract to push food down in a process called ‘peristalsis’
Liver
Produces ‘bile’, which travels to the small intestine to digest fat in food.
Stomach
Food is broken into ‘chyme’ and is mixed with stomach acids, so protien enzymes can digest at the best PH
Pancreas
Creates hormones which control glucose levels in blood
Gall bladder
Stores bile, travels from here to small intestine
Large intestines
Made up of colon, appendix and rectum. The colon absorbs water into the blood and any undigested material builds up in the rectum to leave via the anus.
Small intestine
Food is kept moving through here and is digested by enzymes and bile.
Carbohydrates
Contain simple sugars like glucose and sucrose and provide us with energy as glucose is used for resparation.
Lipids
Fats (solids) and oils(liquids). Most important energy store, important for diet, cell membranes, hormones and nervous system. Made up of three fatty acids and glycerol.
Proteins
Build cells and tissues and are the basis for enzymes, made up of chains of amino acids.
Testing for starch
Place food on spotting tile, Use iodine on the food, solution turns blue-black if starch is present.
Testing for sugar
Place food in test tube, add benedict’s solution to the food, place in warm water for 10 mins, benedict’s solution turns brick red if sugar is present.
Test for lipids
Place food in test tube, add ethanol, shake test tube and leave for 1 min, pour solution in water and solution turns cloudy white if lipid is present.
Test for protein
Place food in test tube, add biuret reagent. If protien is present, solution turns purple.
Enzymes
Enzymes are biological catalysts (speeding up the reaction). They are specially shaped to break down food macromolecules.
Active site
The part of an enzyme which is the correct shape to split substrates into products.
Amylase
Breaks down carbohydrates into simple sugars in the mouth and the small intestine. Produced in the pancreas and the small intestine
Pepsin
Breaks up protein molecules into it’s amino acids in the stomach. Is produced in the stomach, small intestine and the pancreas.
Bile
Breaks down fat globules in the small intestine. Is produced in the liver and stored in the bile duct
Lipase
Breaks down triglyceride molecules (fat) in the small intestine. Produced by the pancreas.
How does temperature affect enzyme action?
Increases in temperature gives the enzymes more kinetic energy and thus digest faster however temperatures above 40 degrees will denature enzymes in most organisms.
How does PH affect enzyme action?
A PH too high or too low can cause enzymes to denature. Best PH for amylase is about PH 4.0.
Role of acid in digestion
In the stomach, PH 2.0 is the best for protease digestion
Role of Bile
When food enters the small intestine it is covered in stomach acid but bile neutralises the acid. Fat gloubules before bile is added are too large to be digested by lipase but the bile emulsifies it, breaking it up to have a larger surface area
