water Flashcards
(18 cards)
What percentage of organisms does water make up?
60-95%
What does a water molecule make up?
2 hydrogens and 1 oxygen
What is responsible for many of the properties of water?
Weak hydrogen bonds
Which reactions is water a metabolite?
Condensation and hydrolysis, required in photosynthesis, product of respiration
What is water as a solvent used for?
To transport nutrients, to remove excretory products, as a medium in which metabolic reactions occur
Does water have a high or low heat capacity?
High
What does this mean?
That it can absorb a large amount of heat energy before rising in temperature
What bonds does the energy get absorbed by?
Hydrogen bonds
How is water’s heat capacity useful?
It minimises the increase in temperature within cells as a result of biochemical reactions, it helps to prevent dangerous fluctuations in aquatic habitats
Does water have a large or small latent heat of vaporisation?
Large
Why is this the case?
Energy is required to break the hydrogen bonds
What does this mean for water’s properties?
This allows water to provide a cooling effect with little loss of water through evaporation
How is water’s latent heat of vaporisation useful?
Helps some animals to maintain a constant body temperature through sweating, has a cooling effect via transpiration
How do cohesive forces contribute to internal support?
They support tube-like transport cells of plants allowing transport from roots to leaves
How do cohesive forces contribute to external support?
Produces surface tension where water meets air which enables insects to walk on water
What causes cohesive forces?
Hydrogen bonds between the water molecules
How else does water provide internal support?
Water cannot be compressed easily so can provide support in non-woody plants via turgor pressure and in some animals
How else does water provide external support?
Water provides buoyancy for aquatic organisms
