Biosphere: (The Role Of Water In Cycles)

Question 1

Matter cycles:

Answer 1

-all available matter is on earth
-therefore, water and nutrients must be recycled to sustain life.
-molecules pass between the biotic (living) and abiotic (non-living) worlds.

Question 2

Biogeochemical cycles:

Answer 2

-the use and re-use of materials of the earth is referred to as a biogeochemical cycle.
•1. Hydrologic cycle.
•2. Carbon/oxygen cycle.
•3. Nitrogen cycle.
•4. Phosphorus cycle.

Question 3

Role of water in cycles:

Answer 3

•human body loses and must replace approximately 3% of its total H2O volume daily. (~2L/day or 8 glasses of water/day).
•plants lose H2O through transpiration.
•plants take in H2O from the roots, filter/clean H2O, and transpire through the stomata of their leaves.
•cellular respiration produces metabolic H2O.
•H2O vapour is a greenhouse gas that traps and transfers heat.
•H2O is cycled in the hydrologic cycle.

Question 4

Hydrological cycle:

Answer 4

•evaporation: changing water from a liquid state to a gaseous state.
•transpiration: evaporation of water from plant leaves.
•percolation: movement of water through soil and permeable rock.
•precipitation: rain, snow, hail, etc.
•condensation: collection of water droplets in the atmosphere to form clouds.
-(Too dense clouds = rain).

Question 5

Reservoirs of water:

Answer 5

-oceans.
-rivers.
-lakes.
-streams.
-ground water.
-snow/ice.
-clouds/atmosphere.

Question 6

Water’s unique properties:

Answer 6

-1. Universal solvent. (Kind of).
-2. High melting and boiling point.
-3. High heat capacity.
-4. Special cohesive and adhesive properties.

Question 7

1. Universal solvent:

Answer 7

•water molecules are polar (different charges at each end), resulting in a weak attraction between molecules known as a hydrogen bond.
•this enables water to dissolve a wide variety of substances.
•this process of transporting dissolved materials is referred to as biogeochemical cycling.

Question 8

2. High melting and boiling point:

Answer 8

•melting water (solid—> liquid).
•boiling water (liquid—> gas).
•requires that hydrogen bonds are broken.
•THIS requires A LOT of energy.
•explains why water has high melting point (0 degrees C) and a high boiling point (100 degrees C).

Question 9

Density:

Answer 9

•when water cools, hydrogen bonds strengthen, causing cold or frozen water to have a lower density due to the more spaced out lattice structure.
•when water heats up, these bonds loosen, causing warm water to have a higher density.

Question 10

3. High heat capacity:%

Answer 10

•water has a high heat capacity.
•large amounts of energy are required to increase the temperature of water. (Conversely large amounts of energy are given off when the temperature of water drops).
•large bodies of water (oceans) assist in moderating the temperature of nearby land (example: Vancouver).
•energy from water—> heats the land.
•energy from land—> given to water to cool land.
•water currents, transfer heat from warm equatorial regions to higher latitudes.

Question 11

4. Special cohesive and adhesive properties:

Answer 11

•cohesion— attraction of water molecules to other water molecules.
-important in allowing insects to walk on water.
-keeps organic debris on the water surface, where other organisms can feed on them.
-surface tension.
•adhension— attraction of water molecules to molecules of other substances (examples: glass tube, cell wall).
-important for the movement of water up xylem in plants.

Question 12

Issues affecting water:

Answer 12

•fresh water is a scarce resource (3% of the worlds water).
•many individuals do not have access to clean water.
•increasing global temperatures—> increase rate of evaporation—> increase risk of drought—> decrease photosynthesis—> decrease plant growth/possible plant death and increasing CO2(g) levels.