Topic 1/Conditions for life on Earth - WATER
- Created by: SJC
- Created on: 26-09-16 15:57
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- Water is important because
- It is a solvent for substances involved in metabolism, including food compounds, mineral nutrients, chemical signals and waste products
- It is essential for metabolic activity to occur- such as photosynthesis
- It is a transport medium for dissolved compounds, moving them in and out of cells, as well as around the organism, for Example the Xylem of plants or as the major component of blood
- It is important in the structure and support of cells. Cells are 60% to 70% water
- Water is a high heat capacity, absorbing or releasing large amounts of heat energy and moderating temperature fluctuations, e.g. oceans prevent large fluctuations between day and night
- As water freezes it expands and floats because it is less dense than liquid water. The ice layer insulates the water the water underneath, keeping it liquid and allowing organisms to survive
- Water is a coolant that prevents overheating. It evaporates from surfaces by absorbing heat energy and changing into water vapor, cooling the surface, for example in sweating or panting
- It provides an aquatic habitat for aquatic and semi-aquatic organisms, in areas such as ponds, rivers and oceans
- It is transparent, allowing light to penetrate for photosynthesis by plant and algae
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