organisation gcse biolgy

• What are cells?

  basic building blocks that make up all living creatures
• What are specialised cells?

  Cells that carry out specific function
• What is the process of becoming specialised called?

  differentiation
• What is a tissue?

  Group of similar cells that work together to carry out particular function
• What are examples of tissues?

  muscular tissue which contracts, glandular tissue that makes and secretes hormones and enzymes, epithelial tissue that covers some parts of the body
• When does differentiation happen?

  during development of a multicellular organism
• What is an organ?

  A group of different tissues that work together to perform a certain function
• What tissues is the stomach made up of and what do they do?

  Muscular tissue: moves stomach wall and churns up food, Glandular tissue: makes digestive juices to digest food, Epithelial tissue:covers inside and outside of stomach
• What is an organs system?

  Group of organs working together to carry out particular function
• What is an example of an organ system and what does it do?

  Digestive system- breaks down and absorbs food
• What are enzymes?

  Biological catalysts that speed up the rate of reaction without being changed or getting used up
• Why are enzymes useful?

  Reduces need for high temperatures
• What are enzymes made from?

  large proteins made from chains of amino acids
• What does every enzyme have?

  An active site that is only complementary to one specific substrate
• What is the lock and key theory?

  Substrate binds to active site of enzyme because shape of active site is complimentary to the substrate
• What effect does changing the temperature have on the rate of reaction

  (at first)?

  increases rate of reaction because the enzyme and substrate molecules collide more often
• What happens if the temperature gets too hot?

  Bonds holding enzyme together break and enzyme becomes denatured and active site of enemy is no longer complimentary to active site of substrate
• What is the optimum temperature?

  The temperature the enzymes work best at
• What happens if the pH is too high or too low?

  pH interferes with bonds holding enzyme together and changes the shape of the active site of the enzyme and denatures it
• What is the optimum pH for enzymes?

  normally pH 7
• Why is Pepsin's optimum pH 2?

  Breaks down protein in stomach where the conditions are very acidic
• What do digestive enzymes do?

  Break down big molecules into smaller soluble molecules that can pass through the walls of the digestive system and be absorbed into the bloodstream
• What do carbohydrases break down?

  Carbohydrates into simple sugars e.g. glucose
• Where is amylase made?

  salivary glands, pancreas, small intestine
• What does protease break down?

  proteins into amino acids
• Where is protease made?

  stomach(pepsin), pancreas, small intestine
• What does lipase break down?

  breaks down lipids into fatty acids and glycerol
• Where is lipase made?

  pancreas, small intestine
• Where is bile produced and stored?

  Bile is produced in the liver and stored in the gall bladder before it is released into the small intestine
• Why is bile alkaline?

  To neutralise acidic pH from stomach for enzymes in small intestine to work properly
• How does bile help the body to digest fats?


  Bile emulsifies fats giving them a large surface area to volume ratio to increase lipase enzyme action
• What do the salivary glands produce?

  amylase in saliva
• What does the oesophagus do?

  walls of oesophagus contract and relax to push food and liquids to stomach
• What happens In the liver?

  Bile produced, Bile neutralises stomach acid and emulsifies fats
• What does the stomach do?

  pummels food with muscular walls. Contains hydrochloric acid to kill bacteria. Releases digestive juices that contain protease. Hydrochloric acid also gives acidic pH for protease
• What does the gall bladder do?

  stores bile before it Is realised into small intestine
• What does the pancreas do?

  produces amylase, protease and lipase, releases enzymes into small intestine
• What does the pancreas have a lot of ?

  mitochondria to release lots of energy to release enzymes
• What does the large intestine do?

  Has large surface area for excess water from food to be absorbed
• What does the small intestine do?

  produces protease, amylase and lipase for food to be further digested. Food is absorbed by small intestine wall into bloodstream