Topic 1- Water Flashcards
Where do all metabolic reactions take place in cells?
In water
As 71% of the Earth’s surface is covered in water it is a major 1._____ for organisms
1.habitat
70% to 95% of the 1._____ of a cell is water
1.mass
What is water composed of?
Hydrogen and oxygen atoms
One atom of oxygen combines with two atoms of hydrogen by sharing 1.______ (covalent bonding)
1.electrons
The oxygen atom attracts the electrons more strongly than the hydrogen atoms resulting in what?
A weak negatively charged region on the oxygen atom and a weak positively charged region on the hydrogen atoms
What is a dipole?
separation of charge due to the electrons in the covalent bonds being unevenly shared
What is a polar molecule?
When a molecule has one end that is negatively charged and one end that is positively charged
Is water a polar molecule?
Yes
Why do hydrogen bonds form between water molecules?
Because they are polar
Why do hydrogen bonds only form a strong structure when they are in large numbers?
As they are weak
What are some properties of water?
-An excellent solvent – many substances can dissolve in water
-A relatively high specific heat capacity
-A relatively high latent heat of vaporisation
-Water is less dense when a solid
-Water has high surface tension and cohesion
-It acts as a reagent
-Polar
-presence and number of hydrogen bonds between water molecules
Why is water a good solvent?
-Polar molecule
-Ions and covalently bonded polar substances will dissolve in it
-Metabolites can be transported efficiently
What is specific heat capacity?
he amount of thermal energy required to raise the temperature of 1kg of that substance by 1°C
What is waters specific heat capacity?
4200 J/kg°C
Does water have a high or low specific heat capacity?
High
Why dos water have a high specific heat capacity?
-Many hydrogen bonds
-Takes a lot of thermal energy to break these bonds
High specific heat capacity is useful for living organisms, why?
-Provides suitable habitats
-Able to maintain a constant temperature as it is able to absorb a lot of water without fluxuating in temp
-Temps are maintained for enzyme activity
Water in 1.____ _____ is also vital in transferring heat around the body, helping to maintain a fairly constant temperature
Water in 2.___ ____ also plays an important regulatory role in maintaining a constant body temperature
1.blood plasma
2.tissue fluid
What needs to be broken for water to change state?
Hydrogen bonds
Why is latent heat of vaporisation an advantage?
-only a little water is required to evaporate for the organism to lose a great amount of heat
-This provides a cooling effect for living organisms
Hydrogen bonds between molecules allow for what?
strong cohesion between water molecules
Why is strong cohension useful?
-allows columns of water to move through the xylem of plants and through blood vessels in animals
-Enables tension
What is meant by adhesion? What does this allow for?
Water is also able to hydrogen bond to other molecules, such as cellulose- Allowing for transpiration
