2.2 Water Flashcards
How do hydrogen bonds form between water molecules?
Water is a polar molecule. Oxygen and hydrogen share electrons share electrons unequally when they bond. Oxygen has a greater share (more negative), hydrogen have a smaller share (more positive) , oxygen is then attracted to the more positive hydrogen atom.
State important properties of water
- reaches maximum density at 4 degree celcius
- high surface tension
- coolant so resistant to temperature change
- allows movement of substrates and enzymes
- it is a polar solvent
- substrate for some reactions
- high specific heat capacity
- cohesion between molecules
Why is the incompressible nature of water important for organisms?
Provides turgidity to plant cells
Provides hydrostatic skeleton for some small animals e.g. earthworms
Why does ice float on water?`
Ice is less dense than water because H- bonds hold molecules in fixed positions further away from each other
Why is ice floating on water important for organisms?
This insulates water in arctic climates so aquatic organisms can survive, water acts as a habitat
Why is the high surface tension of water important to organisms?
Slows water loss due to transpiration in plants.
Water rises unusually high in narrow tubes, lowering demand on root pressure.
Some insects can “skim” across the surface of water.
Why is water an important solvent for organisms?
Polar universal solvent dissolves and transport charged particles involved in intra and extracellular reactions
why is high specific heat capacity important for organisms?
Acts as a temperature buffer which enables endotherms to resist fluctuations in core temperature to maintain optimum enzyme activity
