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Lesson: Chapter 1 — The Chemical Basis of Life

1.5. Water 3 of 3

Water, heat and habitat

Water's other two special properties are both about heat.

1. Regulating body temperature

Water has a high specific heat capacity. That means a large amount of heat is needed to raise its temperature by even one degree.

What a living thing gains from this

Since most of the body is water, body temperature does not rise and fall quickly when the environment changes. It is why your internal temperature stays steady in the midday sun and the night-time cold alike.

2. A habitat for aquatic life

Most substances get denser as they solidify. Water does not — ice is less dense than water.

  1. When water freezes, the ice floats to the surface
  2. That surface layer of ice acts as an insulator
  3. So the water beneath stays liquid

In cold countries a lake may be frozen on top while fish and other aquatic life carry on below.

Extra knowledge — what if ice were denser than water?

What if ice were denser than water? The blocks of ice would sink. The lake would freeze from the bottom upwards until it was solid all the way through — and nothing living in it could survive the winter.