Researchers grow collecting duct cells as a thin layer between artificial filtrate and a surrounding solution representing blood. The artificial filtrate has a higher water concentration than the surrounding solution. ADH is added to the surrounding solution. The rate at which water leaves the artificial filtrate then increases.
Which explanation is most consistent with the result of this study?
ADH increased the permeability of the collecting duct cell layer to water, so more water moved from the artificial filtrate into the surrounding solution by osmosis
ADH increased the water concentration of the artificial filtrate, so more water crossed a cell layer whose permeability did not change
ADH entered the artificial filtrate and carried water molecules with it across the collecting duct cell layer into the surrounding solution
ADH caused active transport of water across the collecting duct cell layer from the artificial filtrate into the surrounding solution
94 exam-style questions on Edexcel GCSE Biology 7.4 Blood glucose and the urinary system, covering 7.4.1 Insulin and blood glucose control, 7.4.2 Glucagon and blood glucose regulation, 7.4.3 Type 1 and type 2 diabetes, 7.4.4 Structure of the urinary system, 7.4.5 Structure and function of the nephron, 7.4.6 ADH and water regulation, 7.4.7 Treatments for kidney failure, and 7.4.8 Production of urea in the liver. Each one has a worked solution and a mark scheme showing where the marks go.