3. exchange and transport systems

• what are the 2 major adaptations of gas exchange systems?

  large surface area and thin
• fish use a counter-current system for gas exchange
• insects use tracheae to exchange gases
• what are examples of xerophytic plant adaptations to limit water loss?

  stomata sunk into pits, layer of 'hairs' on the epidermis, curled leaves with stomata inside, reduced number of stomata, waxy and waterproof cuticles
• what breaks down carbohydrates?

  amylase and membrane-bond disaccharidases
• what breaks down lipids?

  lipase and bile salts
• monosaccharide can be transported across the cell membranes of the ileum epithelial cells via specific transporter proteins
• what do lipids get broken down into?

  Fatty acids and glycerol.
• what breaks down proteins?

  endopeptidases and exopeptidases
• difference between endopeptidases and exopeptidases?

  endopeptidases hydrolyse peptide bonds within a proteins, exopeptidases hydrolyses peptide bonds at the ends of a proteins
• how is glucose absorbed across cell membranes?

  via active transport with sodium ions via con-transporter proteins
• how is galactose absorbed across cell membranes?

  facilitated diffusion using co-transporter protein
• how are monoglycerides and fatty acids absorbed across cell membranes?

  Passive diffusion as lipid soluble
• how are amino acids absorbed across cell membranes?

  Facilitated diffusion and active transport
• haemoglobin is a large protein with a quaternary structure that is made up of four polypeptide chains
• each haemoglobin molecule can carry 4 oxygens
• haemoglobin + oxygen = oxyhaemoglobin
• partial pressure of oxygen is a measure of oxygen concentration
• a dissociation curve shows how saturated the haemoglobin is with oxygen and any give partial pressure
• arteries carry blood from the heart to the rest of the body
• veins take blood back to the heart under low pressure
• capillaries exchange substances between the blood and body tissues
• tissue fluid is formed by pressure filtration
• xylem tissue transport water and mineral ions up the plant
• phloem tissue transport organic substances up and down the plant
• transpiration is the loss of water from a plant surface
• what 4 factors affect the rate of transpiration?

  light, temperature, humidity, wind
• translocation is the movement of solutes
• the bohr effect shifts the dissassociation curve to the right
• organisms that live in an envrionment with low concentrations of oxygen have a dissociation curve to the left of humans
• organisms with high oxygen demands have a dissociation curve to the right of humans
• structure of an artery?

  elastic tissue in wall, thick muscular layer, folded endothelium, small lumen
• structure of a vein?

  large lumen, thin muscle wall, enothelium
• in an artery, the muscular walls have elastic tissue that stretch and recoil as the heart beats so that pressure is maintained
• in an artery, the endothelium is folded so that it can stretch
• what are 3 adaptations of capillaries?

  one cell thick, near cells, large in number