B2- Organisation

• What do cells form in multicellular organisms?


  Tissues
• What occurs during the development of a multicellular organism?

  Differentiation
• What are cells considered in living organisms?


  Building blocks
• What type of cell is described as unspecialised?


  Stem cell
• What do specialised cells form?


  Tissues
• What is a group of similar cells that work together called?

  Tissue
• What is the function of tissues?


  To carry out a particular function
• What are examples of tissues in mammals?

  • Muscular tissue: contracts to move attached structures
  • Glandular tissue: makes and secretes chemicals like enzymes and hormones
  • Epithelial tissue: covers parts of the body, e.g., the inside of the gut
• What do organs consist of?


  A group of different tissues
• What is an example of an organ?


  The stomach
• What tissues make up the stomach?

  Muscular, glandular, and epithelial tissues
• What do organ systems consist of?


  A group of organs working together
• What is the function of the digestive system?


  • Breaks down food
  • Absorbs nutrients
  • Made up of organs like:
  • Glands (e.g., pancreas & salivary glands)
  • Stomach
  • Small intestine
  • Liver
  • Large intestine
• What is the role of glands in the digestive system?


  To produce digestive juices
• What does the stomach do in digestion?


  Churns food and produces digestive juices
• What is the role of the liver in digestion?


  Produces bile
• What does the small intestine do?


  Absorbs soluble food molecules
• What is the function of the large intestine?


  Absorbs water from undigested food
• What happens to faeces in the rectum?


  They are stored before being expelled
• What is the optimum temperature for enzymes?


  It varies, but enzymes have a specific optimum temperature
• What happens to enzymes at high temperatures?


  They denature and lose their function
• What is the active site of an enzyme?


  The region where substrates bind to the enzyme
• What is the lock and key theory in relation to enzymes?


  It describes how substrates fit into the active site of an enzyme
• What are the steps in the practical to test the effect of pH on enzyme activity?


  1. Prepare iodine solution in wells.
  2. Heat water to 35°C.
  3. Mix amylase and buffer solution in a boiling tube.
  4. Add starch solution and start timing.
  5. Sample every 30 seconds to check for starch breakdown.
  6. Repeat with different pH values.
  7. Control variables for a fair test.
• How do you calculate the rate of reaction in the enzyme experiment?


  Rate = $\frac{1000}{time}$
• What do digestive enzymes do to large molecules?


  They break them down into smaller molecules
• What are the smaller molecules produced by digestive enzymes?


  Sugars, amino acids, glycerol, and fatty acids
• Where are digestive enzymes produced?


  By cells in glands and the gut
• What happens to smaller, soluble molecules in digestion?


  They pass through the walls of the digestive system into the bloodstream
• What are the types of enzymes involved in digestion and their functions?


  • Carbohydrases: convert carbohydrates into simple sugars (e.g., amylase)
  • Proteases: convert proteins into amino acids (e.g., pepsin)
  • Lipases: convert lipids into glycerol and fatty acids
• What is the function of bile in digestion?


  It neutralizes stomach acid and emulsifies fats
• Where is bile produced and stored?


  Produced in the liver and stored in the gall bladder
• What is the role of the small intestine in digestion?


  It completes digestion and absorbs digested food
• What are the functions of the stomach in digestion?


  • Pummels food with muscular walls
  • Produces protease enzyme (pepsin)
  • Produces hydrochloric acid to kill bacteria and provide the right pH for protease
• What are the functions of the pancreas in digestion?


  • Produces protease, amylase, and lipase enzymes
  • Releases these enzymes into the small intestine
• What is the role of the large intestine in the digestive system?


  • Absorbs excess water from food
  • Prepares waste for excretion
• What is the role of salivary glands in digestion?


  • Produce amylase enzyme in saliva
• What is the role of the rectum in the digestive system?


  • Stores faeces before excretion
• What is the importance of controlling variables in enzyme experiments?


  • Ensures a fair test
  • Allows for accurate comparison of results
• What is the role of enzymes in the digestive system?


  They catalyse the breakdown of different food molecules.