Paper 2 biology

• the pancreas is an exocrine gland that secretes digestive enzymes into the small intestine
• the liver produces bile which helps to emulsify fats, it also stores glucose as glycogen and detoxifies poisons.
• bile is produced by hepatocytes (liver cells) and stored in the gall bladder until needed.
• the liver produces bile which helps to emulsify fats, it also stores glucose as glycogen and converts excess amino acids into urea.
• the stomach has three layers; mucosa, submucosa and muscularis externa.
• the stomach has three layers - mucosa, submucosa and muscularis externa.
• the mucosa contains gastric glands with parietal cells that produce hydrochloric acid and chief cells that produce proteolytic enzymes.
• the mucosa contains parietal cells which secrete hydrochloric acid and chief cells which produce protease enzymes.
• the pancreas secretes digestive juices containing enzymes such as lipase, amylase and trypsin.
• hydrochloric acid kills bacteria and activates pepsinogen to form pepsin.
• the large intestine absorbs water from food waste and forms faeces.
• the small intestine consists of the duodenum, jejunum and ileum.
• pepsin breaks down protein molecules into smaller peptides.
• the large intestine consists of the caecum, colon and rectum.
• lipase is an enzyme that breaks fats down into fatty acids and glycerol.
• lipase breaks down fats into glycerol and fatty acids.
• the stomach has three layers - muscularis externa (outer layer), submucosa (middle layer) and mucosa (inner lining).
• amylase is an enzyme that breaks starch down into maltose.
• bile is stored in the gall bladder until needed.
• the liver produces bile salts which emulsify fats into smaller droplets so they can be digested by lipases.
• enzymes are biological catalysts that speed up chemical reactions without being used up themselves.
• amylase is produced by the salivary gland and small intestine and it breaks down starch into maltose.
• the large intestine reabsorbs water and electrolytes from chyme using osmosis and active transport.
• the pancreas produces digestive juices which are released into the small intestine via the pancreatic duct.
• the small intestine absorbs nutrients from food through diffusion or active transport across epithelial cell membranes.
• bacteria break down carbohydrates using amylase.
• amylase converts starch into maltose.
• the small intestine is the site where most absorption occurs due to its large surface area provided by villi and microvilli.
• proteins are made from amino acids joined together with peptide bonds.
• lipases break lipids (fats) down into fatty acids and glycerol.