Water Flashcards
(6 cards)
Structure of water?
1 oxygen molecule covalently bonded to 2 hydrogen molecules. Oxygen has a slightly negative charge while hydrogen has a slightly positive charge allowing weak hydrogen bonds to form between water molecules.
4 roles of water?
- Metabolic reactions
- Solvent
- Temperature regulation
- Support (internal & external).
Describe and explain the properties and functions of water in metabolic reactions.
Metabolite in many metabolic reactions:
- condensation & hydrolysis
- photosynthesis
- metabolic product of respiration, important for dry desert organisms.
Describe/explain the properties/functions of water as a solvent.
- Transporting nutrients (glucose in blood, sucrose in phloem)
- Removing excretory products (urea, ammonia)
- Medium in which metabolic reactions occur.
Describe/explain the properties/functions of water in temperature regulation.
HIGH HEAT CAPACITY (needs lots of energy to increase temp. of 1kg by 1C as energy is absorbed by hydrogen bonds):
- water is a buffer in temp. changes
- minimises temp. increase within cells due to biochemical reactions
- maintains aquatic habitats safe as dangerous temp. fluctuations are prevented.
LARGE LATENT HEAT OF VAPORISATION:
- cooling effect with little loss of water through evaporation
- helps animals maintain constant body temp.
- cooling effect in plants via xylem (transpiration).
Describe/explain the properties/functions of water in support.
INTERNAL SUPPORT:
- hydrogen bonds -> water molecules stick together -> COHESION. This allows for water columns in xylem -> transport from roots to leaves.
- water is not easily compressed so provides support in plants via turgor pressure, & in some animals like worms.
EXTERNAL SUPPORT:
- COHESION produces surface tension where water meets air -> creates habitats for insects e.g., hanging beneath surface or pond skaters walking on water.
- water provides buoyancy for aquatic organisms e.g. whales.
