The Water Cycle
Diagram:
Transportation
Precipitation
Transportation
Condensation
Precipitation
Sublimation
Condensation
Transpiration
Evaporation
Runoff
Surface Flow
Plant Uptake
Infiltration
Percolation
Ground Water
Questions:
1. Trace the path of a drop of water through the water cycle, explaining what happens to it
each step along the way. Water leaves bodies of water (large or small) through
evaporation as water temperatures rise. As water vapour rises through the
atmosphere it cools and condenses and is transported by air currents and collects
as clouds. Water is then returned to the Earth through precipitation (can be
different forms). Precipitation will either runoff and into a body of water, flow
along the surface of Earth or be infiltrated into the ground. Once in the ground it
can return to a body of water or be taken up by plants through the roots. Water
vapour is lost through the leaves of green plants through transpiration and is
returned to the atmosphere where it can again return to the Earth as
precipitation.
2. How much of the Earth’s surface is covered in water? 75%
3. What is the major component that drives Earth’s weather and climate? Water vapour
4. What is latent heat? Heat obtained by water molecules as it changes state from liquid
or solid to water vapour, heat is released when molecules condense from the
vapour form back into a liquid or a solid, forming cloud droplets or different forms
of precipitation
5. What percentage of Earth’s water is salt water? 96.5% Fresh water? 3.5%
6. Where does freshwater exist? Lakes, rivers, groundwater, frozen forms (snow & ice --ice caps, glaciers, permanent snow, ground ice, permafrost)
7. How much water vapour can a 1 acre cornfield transpire in one day? 4000 gallons
8. What do humans (or other life forms) use water for? Drinking, washing, irrigating and
other uses
9. Describe the changes in Mean Sea Level. Global Mean Sea Level has increased (gone
up) 250 mm since 1870. Explain the change (what is the reason this is happening). This is
happening because they (the seas) are being over-replenished. Even though it is
warmer on our planet and you would expect that there would be less water in the
oceans because of evaporation, there is actually more because of the oceans
warming. When the oceans warm, the water expands and increases in volume. Also,
because of warmer temperatures, water that was previously trapped in glaciers and
ice caps has started to melt and ice shelves have broken off (e.g. Antarctica) also
increasing the volume of water in the seas.
10. Define the following terms:
a. Sublimation – from liquid to gas, does not become a solid in between
b. Evaporation – occurs from the surface of a liquid, when more molecules leave
a liquid for the gaseous state than return from the gas to the liquid
c. Precipitation – any kind of water that falls from the sky as part of the weather,
includes: snow, rain, sleet, freezing rain, hail
d. Surface Flow – water that flows over the surface of the land that has not
infiltrated into the ground
e. Transportation – movement of water in the lower atmosphere
f. Condensation – when more vapour or gas molecules are returning ot the liquid
stat than are evaporating (water condenses on tiny particles of dust, smoke
soot or salt crystals that are suspended in the air)
g. Transpiration – loss of water vapour from land plants into the atmosphere
(movement of water through plant from soil to atmosphere via roots, shoot
and leaves)
h. Ground Water – portion of the water below the surface of the ground
i.
Percolation – downward movement of water through soil and rock
j.
Infiltration – downward movement of water through soil and rock
k. Runoff – water that does not percolate or infiltrate into the soil and rock
The Carbon Cycle
Diagram:
CO2
(from factories
and fossil fuels)
Photosynthesis
CO2
CO2
O2
O2
CO2
Cellular
O2
Respiration
Cellular
Respiration
Secondary
Consumers
Producers
Carbon in Tissues
Dead Organisms
& Wastes
Carbon in Tissues
Primary
Consumers
Dead Organisms
& Wastes
Decomposers
Questions:
1. Trace the path of a molecule of carbon through the carbon cycle, explaining what happens
to it each step along the way. Carbon is found in the atmosphere, it is used by plants
through the process of photosynthesis. In return, plants release oxygen into the
atmosphere. Alternatively, plants are consumed by primary consumers and the
carbon they contain is passed along to them. Primary consumers then pass their
carbon along to secondary consumers when they are eaten. Consumers breathe out
carbon dioxide returning carbon to the atmosphere. When producers, primary
consumers and secondary consumers die, their bodies are broken down by
decomposers and the carbon contained in them returned to the soil.
2. Why is carbon important (1st paragraph)? Backbone of life on Earth – everything is
built on carbon.
3. How abundant is carbon? Fourth most abundant element in the Universe.
4. Where is most of Earth’s carbon stored? In rocks.
5. How does carbon move from the atmosphere to the lithosphere? Carbon in the
atmosphere combines with water to form a weak acid that falls to the surface as
rain. The acid in the rain dissolves the rocks and releases ions which are carried to
the sea by rivers.
6. What happens when coal and other fossil fuels are burned? The carbon that is stored in
them is released into the atmosphere which alters the balance of the carbon cycle
and is potentially changing Earth’s climate.
7. How do volcanoes release carbon into the atmosphere? When they erupt they release
carbon gas to the atmosphere.
8. How does the ocean help to remove carbon from the atmosphere? Carbon dioxide gas
dissolves into the water at its surface. Since carbon dioxide gas concentrations are
higher now than in previous years, the ocean absorbs more of the of the carbon
dioxide gas in the atmosphere. Because it is so larger, it has the ability to absorb a
lot of it.
9. What controls the rate at which the ocean removes carbon from the atmosphere? Winds,
currents and temperature.
10. How do green plants remove carbon from the atmosphere? Plants use carbon through a
process called photosynthesis. Plants absorb carbon dioxide and sunlight to create
glucose for building plant structures.
11. What is photosynthesis? The process that plants use to remove carbon dioxide from
the atmosphere to create glucose.
12. What is the chemical reaction for photosynthesis? CO2 + H20 + energy  CH2O +O2
13. What are four ways that carbon can move from a plant and be returned to the atmosphere?
Break down the sugar to get the energy they need to grow, animals eat plants and
break down sugar to get energy, plants die and decay, fire consumes plants.
14. What is cellular respiration? Opposite of photosynthesis. Process used by animals where
carbon dioxide is released as a by-product of glucose breaking down to get the
energy they need.
15. What is the chemical reaction for cellular respiration? CH2O +O2  CO2 + H2O + energy
16. Compare the two chemical reactions… photosynthesis and cellular respiration. They are
the opposite reactions to each other.
The Nitrogen Cycle
Diagram:
Rain deposits nitrogen
N2 (in the atmosphere)
onto the soil
Legumes convert
nitrogen into
plant-usable form
Denitrification
Plants uptake
nitrogen
Plant and
animal waste
Bacteria convert
Leaching
nitrogen to plant-
Factories produce
usable form
nitrogen fertilizers
Questions:
1. Trace the path of a molecule of nitrogen through the nitrogen cycle, explaining what
happens to it each step along the way. Nitrogen is removed from the atmosphere by
legumes (e.g. soya beans or clover). When a plant or animal dies the nitrogen that is
in their bodies is converted to a usable form for plants by bacteria found in the
soil. Plants use nitrogen for growth. Bacteria also convert nitrogen into the soil
into a form that is released back into the atmosphere. Nitrogen in the atmosphere
can be absorbed by rain and then deposited onto the soil. Factories produce
nitrogen fertilizers. Fertilizers enter the cycle when they are deposited on the soil.
Some nitrogen is removed from the cycle by leaching.
2. What is nitrogen needed for? For plants to grow, develop and produce seed.
3. What is the main source of nitrogen in soils? From organic matter. Where does it come
from? From plant and animal residue.
4. What is the largest single source of nitrogen? The atmosphere.
5. How else does nitrogen enter the cycle? Fertilizers, air, manure, decaying plant
material.
6. Why does nitrogen have to be converted from one form to another? Because it has to be
converted into a usable form – in one form it is nitrogen gas in the atmosphere, but
that form can’t be used by plants, so it has to be changed into a form that can be.
7. How is nitrogen removed from the cycle? Denitrification volatilization, runoff,
leaching.
8. Define the following terms.
a. Denitrification – bacteria in the soil change nitrates to atmospheric nitrogen
b. Runoff – carries nitrogen on the surface of the earth into rivers and streams
c. Leaching – removal of nitrogen from the soil by carrying it very deep into the
soil that it is no longer usable in the cycle