Digestion and absorption

• What is the definition of digestion?

  Digestion is the process where large insoluble molecules are hydrolyzed into smaller soluble molecules that can be absorbed.
• What are the three main types of macromolecules involved in digestion for AQA Biology?

  • Carbohydrates
  • Lipids
  • Proteins
• What are the two types of enzymes mentioned that are important for digestion?

  Amylases and membrane-bound disaccharidases.
• What does the suffix "ase" indicate in biology?

  The suffix "ase" indicates that the word refers to an enzyme.
• Where is amylase produced?

  Amylase is produced in the pancreas and the salivary glands.
• Where does the digestion of carbohydrates begin?

  The digestion of carbohydrates begins in the mouth.
• What is the role of amylases in carbohydrate digestion?

  Amylases hydrolyze carbohydrate polysaccharides into disaccharides by breaking glycosidic bonds.
• What is the first part of the small intestine where digestion continues?

  The duodenum.
• What do membrane-bound disaccharidases do?

  They hydrolyze disaccharides into monosaccharides.
• Give two examples of membrane-bound disaccharidases.

  Sucrase and lactase.
• What is the function of sucrase?

  Sucrase hydrolyzes sucrose into fructose and glucose.
• What is the function of lactase?


  Lactase hydrolyzes lactose into galactose and glucose.
• What are endopeptidases and their function?

  Endopeptidases hydrolyze peptide bonds between amino acids within the center of the polymer chain.
• What are exopeptidases and their function?

  Exopeptidases hydrolyze peptide bonds between amino acids at the ends of the polymer chain.
• What are dipeptidases and their function?

  Dipeptidases hydrolyze the peptide bond between two amino acids.
• Where does protein digestion start?

  Protein digestion starts in the stomach.
• What is the role of lipase in lipid digestion?

  Lipase hydrolyzes the ester bonds in triglycerides.
• Where is lipase produced?


  Lipase is produced in the pancreas.
• What is the function of bile salts in lipid digestion?

  Bile salts emulsify lipids, splitting large droplets into smaller ones.
• Why is emulsification advantageous for digestion?

  Emulsification increases the surface area for faster hydrolysis by lipase.
• How do micelles form during lipid digestion?

  Micelles form from fatty acids, monoglycerides, and bile salts after lipid digestion.
• What is the role of micelles in absorption?

  Micelles deliver fatty acids and monoglycerides to the epithelial cells in the ileum.
• Where does absorption of digestive food molecules occur?

  Absorption occurs in the cells lining the ileum.
• What structures increase the surface area for absorption in the ileum?

  • Villi: folds of the ileum surface
  • Microvilli: further foldings on the villi
• What is the function of the capillary network in the villi?

  The capillary network maintains the concentration gradient and provides a short diffusion distance.
• How are monosaccharides and amino acids absorbed?

  They are absorbed by co-transport, a type of active transport.
• What happens to fatty acids and monoglycerides after they enter the epithelial cells?

  They are reformed into triglycerides inside the Golgi apparatus or endoplasmic reticulum.
• What is a chylomicron?


  A chylomicron is a triglyceride combined with a protein.
• How are chylomicrons released from the epithelial cells?

  Chylomicrons are released by exocytosis from the Golgi vesicle.
• What is the role of lacteals in lipid absorption?

  Lacteals absorb chylomicrons and transport them in the lymph system.
• How do chylomicrons eventually enter the bloodstream?

  Chylomicrons drain into the capillary system from the lymphatic system.
• What are the key processes involved in digestion and absorption?

  • Digestion: hydrolysis of macromolecules
  • Absorption: uptake of nutrients into the bloodstream
• What are the three main macromolecules involved in digestion that students need to know for AQA biology?

  Carbohydrates, lipids, and proteins.
• What is the definition of digestion?

  It is the process where large insoluble molecules are hydrolyzed into smaller soluble molecules that can be absorbed.
• What are the two types of enzymes mentioned that are involved in carbohydrate digestion?

  Amylase and membrane-bound disaccharidases.
• Where is amylase produced?

  In the pancreas and salivary glands.
• Where does the digestion of carbohydrates begin?

  In the mouth.
• What happens to starch during carbohydrate digestion?

  It is hydrolyzed into disaccharides such as maltose.
• What is the role of membrane-bound disaccharidases in digestion?

  They hydrolyze disaccharides into monosaccharides.
• What are the two examples of membrane-bound disaccharidases mentioned?

  Sucrose and lactose.