WaterEdexcel A-Level Biology B: Mind map

Exam questions on Water

1. A pond skater is a small insect that walks and rests on the surface of a pond without sinking, even though its body is denser than water.
   Explain how surface tension arises at the surface of the pond.2 marks
2. In winter the surface of a deep pond freezes, but the water at the bottom stays liquid at about 4 °C and the fish living in the pond survive.
   Explain how the properties of water help the fish in the pond to survive the winter.2 marks
3. Blood plasma is about 90% water. It carries dissolved glucose, mineral ions and urea around the body, and it carries heat from active muscles to the skin. Blood is pumped at high pressure through narrow vessels without any noticeable change in its volume.
   Explain why water is suitable as a solvent for transporting glucose and mineral ions in the blood.3 marks