What is a cycle? A cycle is a series of repeating events.
Examples? The most important cycles for living things involve
water, carbon and nitrogen. In all of these cycles, matter moves
continuously through the atmosphere, the land, and living things.
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The Water Cycle Movement of water through the atmosphere, the
ground, and bodies of water, and living things is called the water
cycle. 3
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Evaporation Evaporation is the change from a liquid (such as
water) to a gas. In the water cycle, evaporation occurs when the
suns energy warms the water in oceans, lakes and soil. Question:
Where does the water vapor go when it is formed? 4
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Transpiration Transpiration is the process by which living
things release water vapor into the atmosphere. Plants and algae
release most of the water vapor. 5
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Quick Check What are two processes that allow water to move
into the atmosphere? 6
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Condensation Who has seen a sweating glass of ice water before?
Condensation is the process by which water vapor changes from a gas
to a liquid. This change occurs when the water vapor cools, which
creates the liquid again. When have we seen this happen? 7
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Precipitation Precipitation includes rain, snow, sleet, &
hail. -water moves from the atmosphere to the land and the ocean as
precipitation - this precipitation seeps into the ground, where it
is stored in underground caverns or in porous rock -groundwater
supplies water to soil, streams, rivers, and oceans 8
Slide 9
Water Cycle 9 Condensation
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Quick Check Once the vapor goes up into the atmos- phere, how
does it come back down? 10
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Carbon Cycle Another cycle that is very important to all
organisms on Earth is the carbon cycle. Since all living things are
made up of molecules that contain carbon, this cycle is very
important. Carbon cycle is the movement of carbon from the
nonliving environment into living things and back. 11
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Photosynthesis Photosynthesis is the process by which plants
use carbon dioxide from the air to make sugars. Most animals get
the carbon they need by eating plants. (Carbon bonds store energy
allowing living organisms to move, eat, sleep, breath and repair so
important!) 12
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Photosynthesis Equation H 2 O + CO 2 + O 2 + C 6 H 12 O 6 H 2 O
- water CO 2 - carbon dioxide - from the sun - with green
chlorophyll O 2 - oxygen C 6 H 12 O 6 - glucose sugar LIGHT ENERGY
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Photosynthesis Photosynthesis usually occurs in the leaves of
plants, specifically in the chloroplasts of each cell. Do root
cells have chloroplasts? Only plants, algae, some protists, and
some bacteria are photosynthetic producers. Animals, fungi, and
other protists and bacteria are consumers. They are not
photosynthetic.
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Cell Respiration Respiration Respiration returns the carbon
from plants and animals to the atmosphere. 15
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Cell Respiration Equation O 2 + C 6 H 12 O 6 H 2 O + CO 2 ATP
ENERGY + Cell respiration occurs in the cells of all living
organisms. This process keeps it alive by creating energy in a form
that the cells can use. Without this ATP energy, the cell cannot
perform any of its vital functions (make/acquire food, break it
down, make DNA, reproduce, etc.).
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Decomposition Decomposition is the breakdown of dead organisms
and organic wastes, which releases carbon dioxide. Ex. When fungi
and certain bacteria decompose organic matter, they return carbon
to the soil and air. 17
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Combustion Carbon in coal, oil, and natural gas is returned to
the atmosphere as carbon dioxide when these fuels are burned.
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The Carbon Cycle 19
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21 Natural Sources of Carbon: Death of plants and animals
Animal waste Atmospheric CO2 Weathering Methane gas from cows (and
other ruminants) Aerobic respiration from terrestrial and aquatic
life Sources of Carbon from Human Activity: Burning wood or forests
Cars, trucks, planes Burning fossil fuels such as coal, oil and
natural gas to produce heat and energy for our homes and
businesses
Slide 22
Nitrogen Cycle - movement of nitrogen from the nonliving
environment into living things and back again 22
Slide 23
Nitrogen Cycle About 78% of the Earths atmosphere is made up of
nitrogen gas (N 2 ). All organisms need nitrogen to build protein
and DNA, but cannot use N 2 as it is. Nitrogen fixation- nitrogen
is changed into a usable form by certain bacteria in plant roots
and soil (usable forms = ammonia, nitrates, nitrites) Then, as
animals eat plants they get the usable nitrogen. 23
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Nitrogen Cycle - key points Some bacteria help get usable
nitrogen ready for animals. Other types of bacteria help return the
nitrogen to the atmosphere. These bacteria break down dead
organisms and animal wastes. 24
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Nitrogen cycle 25
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Pollution Pollution is the presence of dangerous levels of
substance in the environment. The pollutants might be a solid,
chemical, gas, or even energy. When they enter the cycles, they
disrupt the normal cycles. 26
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Pollution Over time human activities have altered the cycles.
How? Pollution from our busy lives has affected our soil, water,
and air quality. We are using resources faster than they can be
replaced. 27
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Resource Depletion Humans cause environmental problems by using
up or depleting natural resources. renewable resources can be used
over and over again or has an unlimited supply nonrenewable
resources cannot be replaced (or can be replaced, but over
thousands or millions of years) 28
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Check for Understanding What would happen to the water cycle,
carbon cycle, and nitrogen cycle if most of the land on Earth were
paved? Predict what would happen if scientists would develop a crop
with more nitrogen fixing bacteria in their roots. 29
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Modifications of Earth Cycles What are some things that alter
the cycles? Do these changes alter just one cycle or can they
affect all of the cycles? 30
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Quick Check What is the major reason that the cycles are
altered? Give some examples on how humans have changed specifically
the nitrogen cycle? 31
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Why is resource depletion bad for the Earths cycles? If soil
erosion continues, then the cycles will not continue the same.
-water washes away soil, what are the causes? If air continues to
be polluted, the cycles will not convert the air as before and C
and N levels released will not be the same. 32
Slide 33
Why is resource depletion bad for the Earths cycles? Habitat
destruction is another way humans have modified air quality, soil,
and water on Earth. Our pollution is affecting where organisms
live. Forests and wetlands have been altered and affected by our
pollution. These changes have really affected the cycles of the
Earth and will continue to alter the cycles. 33
Slide 34
Human Modification of Cycles can affect the balance of:
Producer-a photosynthetic organism Primary Consumer -an animal that
eats grass and other producers in a food chain; an herbivore
Secondary Consumer -an animal that feeds on smaller herbivores
Tertiary Consumer -an animal that feeds on secondary consumers
Decomposer -an organism, often a bacterium or fungus, that feeds on
and breaks down dead plant or animal matter, thus making organic
nutrients available to the ecosystem 34
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Thought Questions -relate all answers to cycles- What will
happen if trees are not being replaced when used? What will happen
if soil erosion occurs? What will happen to the nitrogen cycle if
there are fewer healthy plants? What will happen if nitrogen fixing
bacteria are not present? 35
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Questions for Assessment Describe how human activities have
modified soil and water. 36
Slide 37
Describe how human activities have modified soil and water 37
Predict results of modifying the Earths cycles; water, carbon &
nitrogen and show that modification may disrupt the delicate
balance of producers, consumers, and decomposers. Modifications:
Volcanic eruption Power plant (burning fossil fuels) Fertilizer
run-off
Slide 38
What if: a volcano erupted causing events of catastrophic
proportions; draw and explain how this would affect the Earths
cycles 38