Graph

• Glucose filtration and re-absorption rates increase proportionally (same rate) to blood glucose concentration up to a threshold; above it, filtration rate increases proportionally to glucose concentration but re-absorption plateaus (maximum rate - determined by number of co-transport protein)

  
• Molecule/ion concentration depends on their relative number to water molecule number; if Na^+ concentration is the same, top to bottom of PCT, means Na^+ is re-absorbed at same rate as water molecules while filtrate passes downe tubule