Water Flashcards
Why is water a polar molecule?
Has an uneven distribution of charges
Oxygen end of the molecule has a slight negative charge
Hydrogen end have a slight positive charge
2 molecules in close contact leads to their opposing charges to attract each other forming a weak hydrogen bond
Describe hydrogen bonding between water molecules
Weak intermolecular forces of attraction form between a lone pair on a negative charged oxygen and a positive charged hydrogen on an adjacent molecule
Describe the role of water as a metabolite
Water is a reactant in photosynthesis and hydrolysis reactions
Water is a product in aerobic respiration and condensation reactions
Why does water have a high specific heat capacity?
A lot of energy is needed to break the hydrogen bonds
Alot of energy is needed to increase the temperature of water
Why is water’s high specific heat capacity important for organisms?
Acts as a temperature buffer
This enables aquatic organisms to resist fluctuations in core temperature
Maintains the optimum enzyme activity
Why does water have a high latent heat capacity?
A lot of heat energy is needed to break the hydrogen bonds
A lot of heat energy is needed to change water from a liquid to a vapour
A lot of heat energy is required for water to evaporate from the surface of an organism
Why is water’s high latent heat of vaporisation important for organisms?
When water evaporates it has a cooling effect
Important in homeostasis
This is because organisms can lose heat through sweating or panting
Heat is removed from the body to evaporate the water molecules
Why is water an important solvent for organisms?
Is a polar universal solvent
Enables chemical reactions to take place withing cells
Examples: transport of materials in the plasma and removal of metabolic waste
Why does water have a high surface tension?
Due to the ordered arrangement
Cohesion of molecules at the surface of water
How does cohesion occur?
Water meets air
Water molecules form hydrogen bonds with other nearby water molecules
But not with molecules in the air
This cohesion causes an uneven distribution of force called surface tension
Why is the high surface tension of water important for organisms?
Enables the transport of water and nutrients through plants stems and small blood vessels in the body
Allows small insects to walk on water
Example: pond skater
Is water less dense in its solid state (ice) compared to liquid water?
Yes
Why is ice being less dense compared to water important for living organisms?
Floats on the surface of water
Forms an insulating layer which allows aquatic organisms to survive in water underneath the ice
Provides a habitat for organisms such as polar bears
Why is water being transparent important for aquatic plants?
Allows light to pass through to underwater aquatic plants
Enables them to photosynthesise effectively
