A1.1 Water

Question 1

Water structure

Answer 1

Water (H2O) is made up of 2 hydrogen atoms covalently bonded to an oxygen atom.

Water is described as polar because the oxygen atom is slightly negative (δ–) while the hydrogen atoms are slightly positive (δ+).

Water can form hydrogen bonds with other water molecules (between a δ+ hydrogen and a δ– oxygen of two molecules).

Question 2

Water properties

Answer 2

Solvent properties
Cohesion
Adhesion
High heat capacity
High latient heat
theramal conductivity
buoyancy
viscosity

Question 3

solvent properties

Answer 3

• Able to dissolve charged particles (due to the partially positive H and partially negative O)

Act as a good metabolic and transport medium.

Question 4

cohesion

Answer 4

• Strong hydrogen bonds between water molecules, creating surface tension
• Allowing organisms to walk on water surface

Question 5

adhesion

Answer 5

• Water molecules weakly stick onto the walls of container
• Allowing capillary effect in the xylem tube

Question 6

High heat capacity

Answer 6

• It takes a lot of energy to change the temperature of water
• Keeping a relatively stable aquatic temperature

Question 7

High latentheat

Answer 7

• It takes a lot of energy to evaporate_water
• Useful as a_coolant_(e.g. sweating)

Question 8

Thermal Conductivity

Answer 8

• Water absorbs and transfers heat more readily than air as water particles are packed tightly together
• blood transport heat around the body, water currentdistributing heat around the globe

Question 9

Buoyancy

Answer 9

• Water applies a greater upward force_than air
• Allows organisms to float_ in water

Question 10

Viscosity

Answer 10

• Water is more viscous_than air
• Increase the friction of flowing molecules

Question 11

Examples of the Biological Consequences of Water

Answer 11

Black-throated loon
Ringed Seal

Question 12

Black-throated loon

Answer 12

Buoyancy: hollow bones and are less dense, allowing loon to float

Viscosity: Legs are _located at the rear_to better propel them through water

Thermal conductivity: Feathers form an _interlocking structure_that functions as a barrier to water, _preventing heat loss_by the current

Question 13

Ringed Seal

Answer 13

Buoyancy: _denser bones allowing it to stay submerged upon diving

Viscosity: streamlined body to better propel them through water

Thermal conductivity: _outer coat of fur that traps air and thick layer of blubber to present heat loss in water

Specific heat capacity: Do not have many __effective calling mechanisms_because water temperature are generally stable.

Question 14

The Origin of Water on Earth

Answer 14

Hypothesis:

• Early stage of earths surface was nothing other than magma
• Over very long periods of time earth cold and numerous asteroid struck the earth bringing hydrated minerals that released water
• The asteroids became part of the earths crust