Animal cells initially have a mean volume of 120 arbitrary units. After the surrounding fluid becomes more concentrated, their mean volume falls to 90 arbitrary units.
Which statement correctly describes the change and its cause?
a 25%25\%25% decrease because water enters the cells by osmosis
a 33.3%33.3\%33.3% decrease because water leaves the cells by osmosis
a 25%25\%25% decrease because water leaves the cells by osmosis
a 33.3%33.3\%33.3% decrease because water enters the cells by osmosis
44 exam-style questions on Edexcel GCSE Biology 7.3 Homeostasis and thermoregulation, covering 7.3.1 Importance of a constant internal environment, 7.3.2 Importance of homeostasis, 7.3.3a Thermoregulation via the skin and hypothalamus, and 7.3.3b Vasoconstriction and vasodilation in thermoregulation. Each one has a worked solution and a mark scheme showing where the marks go.