Chapter 3 Biology GCSE

• The function of the mouth is to mix food with saliva so it's easy to swallow.
• The function of the oesophagus is too connect the mouth to the stomach
• The function of the stomach is to churn down the food and mix it with acid to be broken down chemically.
• The function of the liver is to make bile
• The function of the gall bladder is too store bile.
• The function of the bile is to help digest lipids and neutralise stomach acid.
• The function of the pancreas is to make enzymes for digestion
• The function of the small intestines is to absorb nutrients from food.
• The small intestine increases its surface area through its length, microvilli, and villi.
• The function of the large intestine is to absorb water into food and to remove undigested food.
• The function of the rectum is to hold faeces until it can be passed out of the body.
• The function of the anus releases feaces.
• Protein must be broken into smaller molecules so that it can enter the cell.
• Digestion is the process of breaking down large food molecules into smaller ones that can be absorbed into the bloodstream.
• peristalsis is triggered when food travels down the oesophagus.
• Carbohydrates are needed for respiration.
• Proteins are needed to make cells/tissues
• lipids are used as energy stores and make hormones and cell membranes.
• Carbohydrates are broken down by carbohydrase.
• Lipids are broken down lipase.
• proteins are broken down by protease.
• A simple carbohydrate is starch or cellulose
• A complex carbohydrate is glucose or sucrose.
• Carbohydrase breaks down starch / carbohydrates into glucose.
• Protease breaks down protein into amino acids.
• Lipase breaks down lipids into fatty acids and glycerol.
• To test for sugars you have to use Benedict's reagent which turns red after a hot water bath if sugar is present.
• The test with benedicts reagent is a semi-quantive test.
• To test for starch you must use iodine which turns a black colour if present.
• To test for lipids you must use ethanol (and water) which turns a cloudy white colour if present.
• To tets for protein you must use biuret soloution which turns purple if present
• Epithelial tissues covers your organs and lines your body.
• Glandular tissue produces digestive juices that break down food.
• Muscular tissues churns food and digestive juices together.
• Enzymes are bio-catalysts.
• A catalyst speeds up a chemical reaction without using any energy.
• Active site is a region along the enzyme that the substrate attaches itself too.
• A theory to describe enzymes is the lock and key theory.
• Factors that affect enzyme activity are temperature and pH
• The optimum temperature/pH means that is when there is maximum enzyme activity.