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Section Outline
Section 3-1
3–1 What Is Ecology? Pages 63 - 65
A.
Interactions and Interdependence
B.
Levels of Organization
C.
Ecological Methods
1. Observing
2. Experimenting
3. Modeling
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3.1 What Is Ecology?
Interactions & Interdependence
*Ecology is the study of interactions among organisms and between
organisms and their environment
*Biosphere- contains the combined portions of the planet in which all of
life exists, including land, water and air, or atmosphere; extends 8
kilometers above Earth’s surface to as far as 11 km below the surface of
the ocean
*Interactions within the biosphere produce a web of interdependence
between organisms and the environment in which they live.
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Levels of Organization
*Some ecologists study interactions between a particular kind of organism
and its surroundings.
*Species- a group of organisms so similar to one another that they can
breed and produce fertile offspring.
*Populations- groups of individuals that belong to the same species and
live in the same area.
*Communities- assemblages of different populations that live together in a
defined area
*Ecologists may study a particular ecosystem- collection of all the
organisms that live in a particular place together with their nonliving
environment.
*Biomes are groups of ecosystems that have the same climate and similar
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dominant communities.
*Regardless of the tools they use, scientists conduct modern ecological
research using three basic approaches: observing, experimenting, and
modeling.
*Observing- 1st step in asking questions
*Experimenting- used to test hypotheses; some are conducted in labs,
some in natural ecosystems
*Modeling- gives insight into complex phenomena such as the effects of
global warming on ecosystems
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Figure 3-2 Ecological Levels of
Organization
Section 3-1
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Section Outline
Section 3-2
3–2 Energy Flow
A.Producers
1. Energy From the Sun
2. Life Without Light
B.Consumers
C.Feeding Relationships
1. Food Chains
2. Food Webs
3. Trophic Levels
D.Ecological Pyramids
1. Energy Pyramid
2. Biomass Pyramid
3. Pyramid of Numbers
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Section 2 Energy Flow
One of the most important factors that
determine whether an ecosystem can
sustain life.
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3-2A. Producers
Autotrophs – use energy from the
environment to make their own food.
Sunlight is the main energy source for life
on Earth.
Chemical energy – Mineral water flowing
underground can release energy needed
by some organisms.
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A-1 Energy from the sun
a. Photosynthesis – uses light energy
to power chemical reactions that
convert CO2 and H2O into oxygen
and energy rich carbohydrates such
as sugars and starches.
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A-1 Continued
2. Land – plants are the main autotrophs
Freshwater – algae
Wet ecosystems – cyanobacteria
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A-2 Life without Light
Chemosynthesizers – use chemical
energy to produce carbohydrates.
(Deep sea vents)
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3-2B. Consumers
1.Obtain energy from other organisms
because they cannot produce their own
energy.
2.Heterotrophs – organisms that must rely
on other organisms for their food and
energy supply
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Continued….
Types of Heterotrophs:
a.Herbivores – eat only plants; cow, deer
b.Carnivores – eat only animals; snakes,
owls, dogs
c.Omnivores – eat both plants and
animals; humans, bears, crows
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continued
d. Detritivores – eat plant and animal
remains and other dead matter (detritus);
mites, earthworms, snails
e. Decomposers – break down organic
matter; fungus & bacteria
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3-2C Feeding Relationships
Introduction:
Energy is a one way path from the sun to
autotrophs to heterotrophs
1. Food chains – a series of steps in
which organisms transfer energy by
eating and being eaten
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C-2 Food Webs
Show more complex feeding
relationships; more realistic
Links all food chains in an ecosystem
together
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Figure 3-8 A Food Web
Section 3-2
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C-3 Trophic Levels
a.Each step in a food chain or web
b.Producers always make up the first
trophic level
c.Consumers make up the second, third,
fourth, etc.
d.Each consumer depends on the trophic
level before it for energy
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3-2D Ecological Pyramids
Introduction:
A diagram that shows the relative
amount of energy or matter
contained within each trophic level in
a food chain or food web.
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D-1 Energy Pyramid
Only about 10% of the energy in the
previous tropic level is transferred to the
next level.
The energy is used for life processes
such as growth, reproduction, and
movement. (lost as heat)
Usually because the organisms are bigger
and harder to maintain.
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D-2 Biomass Pyramid
Biomass – the total amount of living tissue
within a given trophic level
It represents the amount of potential food
available for each trophic level in an
ecosystem.
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D-3 Pyramid of Numbers
Number of individual organisms at each
trophic level.
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Section Outline
Section 3-3
3–3
Cycles of Matter
A. Recycling in the Biosphere
B. The Water Cycle
C. Nutrient Cycles
1. The Carbon Cycle
2. The Nitrogen Cycle
3. The Phosphorus Cycle
D. Nutrient Limitation
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The Water Cycle
Section 3-3
Condensation
Precipitation
Evaporation
Transpiration
Runoff
Seepage
Root
Uptake
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Figure 3-13 The Carbon Cycle
Section 3-3
CO2 in
Atmosphere
CO2 in Ocean
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Figure 3-14 The Nitrogen Cycle
Section 3-3
N2 in Atmosphere
NH3
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NO3and NO2-
Video
Cycles in Nature
Click the image to play the video segment.
3.3 Cycles of Matter
1. More than 95% of an organism’s body is made up of oxygen, carbon,
hydrogen, and nitrogen
*RECYCLING IN THE BIOSPHERE
1. Unlike the one-way flow of energy, matter is recycled within and
between ecosystems.
2. Elements, chemical compounds, and other forms of matter are passed
from one organism to another and from one part of the biosphere to
another through biogeochemical cycles.
3. Matter can cycle through the biosphere because biological systems do
not use up matter, they transform it.
4. Biogeochemical cycles pass the same molecules around again and
again within the biosphere.
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The Water Cycle
1. All living things require water to survive.
2. Water molecules enter the atmosphere as water vapor when they
evaporate from the ocean or other bodies of water.
3. The process by which water changes from liquid form to an
atmospheric gas is called evaporation.
4. Water can also enter the atmosphere by evaporating from the leaves of
plants in the process of transpiration.
5. Sun heats atmosphere during the day.
6. As warm air rises, it cools.
7. Water vapor condenses into droplets that form clouds.
8. When droplets become large enough, they return to Earth’s surface in
the form of precipitation.
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9. On land, much of the precipitation runs along the surface of the ground
until it enters a river or stream that carries runoff back to an ocean or
lake.
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Nutrient Cycles
•
All the chemical substances that an organism needs to sustain life are
its nutrients.
• Nutrients are needed for: building tissues and carrying out essential life
functions
• Nutrients are passed between organisms and the environment through
biogeochemical cycles
• The Carbon Cycle- carbon is a key ingredient in living tissue- in the
form of calcium carbonate, carbon is an important component of animal
skeletons and is found in different rocks.
CO2 is taken in by plants during photosynthesis and is given off by both
plants and animals during respiration
• 4 main types of processes move carbon through its cycle:
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1. Biological processes, such as photosynthesis, respiration, and
decomposition take up and release carbon and oxygen
2. Geochemical processes, such as erosion and volcanic activity, release
carbon dioxide to the atmosphere and oceans.
3. Mixed biogeochemical processes such as the burial and decomposition
of dead organisms and their conversion under pressure into coal and
petroleum, store carbon underground.
4. Human activities such as mining, cutting and burning forests, and
burning fossil fuels, release carbon dioxide into the atmosphere.
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In the atmosphere, carbon is present as CO2.
*CO2 is released into the atmosphere by volcanic activity, by
respiration, by human activities and by decomposition.
Plants take in CO2 and use the carbon to build carbs during
photosynthesis.
Carbs passed along food webs to animals.
In the ocean, carbon is found in the form of calcium carbonate, which is
formed by marine organisms.
Accumulates as a chalky substance in the bones and shells of
organisms.
Compounds break down and the carbon returns to the atmosphere.
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The Nitrogen Cycle
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All organisms require nitrogen to make amino acids, which in turn are
useful to build proteins
N2 makes up 78% of Earth’s atmosphere.
NH3 (Ammonia), nitrate ions, and nitrite ions are found in wastes
produced by many organisms
Plant fertilizers add nitrogen to the biosphere
Nitrogen gas is the most abundant form of nitrogen on Earth
Only certain bacteria can use this form of nitrogen directly
Some bacteria convert nitrogen gas into ammonia by nitrogen fixation
When organisms die, decomposers return nitrogen to the soil as
ammonia
Other soil bacteria convert nitrates into nitrogen gas by
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dentrification.
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The Phosphorus Cycle
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Phosphorus- impt in the formation of DNA and RNA
Not common in the biosphere
Does not enter the biosphere
Remains mostly on land in rock and soil minerals
Exists as inorganic phosphate
As rock and sediment wear, phosphate is released
Washes into rivers and streams where it dissolves; some makes its
way to the oceans, where it is used by some marine organisms
8. Some phosphate stays on land and cycles between organisms and the
soil.
9. When plants absorb phosphate form the soil or from water, the plants
bind the phosphate into organic compounds.
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Nutrient Limitation
1. Primary Productivity- rate at which organic matter is created by
producers; controlled by the amount of available nutrients; limiting
nutrient- when an ecosystem is limited by scarce nutrients
2. Fertilizers containing nitrogen, phosphorus, and potassium are added
to crops to boost productivity.
3. When an aquatic ecosystem receives a large input of a limiting nutrient,
the result is often an immediate increase in the amount of algae and
other producers- algal bloom
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Interest Grabber Answers
1. What living things are found in and around your school?
Living things in the school are students, teachers, principal, assistant
principals, clerical staff, custodians, lunchroom staff. Students may also
include animals in science labs. Living things around the school include
grass, trees, shrubs, insects, birds, and so on.
2. What nonliving things are found in your school?
The building, furniture, desks, books, papers, and so on
3. Into what large groups are the students in your school divided?
9th, 10th, 11th, 12th grades, or years
4. Into what smaller groups are these large groups divided?
Classes
5. Are these groups ever divided into even smaller groups? If so, what are
these groups?
Students may say that science classes are divided into lab groups; other
classes may be divided into groups for projects.
Interest Grabber Answers
1. Make a list of five foods that you like to eat. Indicate whether the food comes
from a plant (producer) or an animal (consumer).
Student lists will be individualized. One possible example would be a
hamburger, which comes from a cow or steer.
2. Like many birds, chickens eat grains, which are seeds. Where do seeds come
from?
Seeds come from plants.
3. Meat comes from beef cattle. What do cattle eat?
Cattle eat grass or grains.
4. Construct a diagram showing how one of your favorite foods obtains its
energy. Include as many levels as you can.
Student diagrams will be individualized based on their food choice. Using the
hamburger example, the beef in the hamburger comes from cattle. The cattle
feed on grass or grain. Grass or grains are plants, which
use energy from the sun to make their own food.
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Interest Grabber Answers
1. When rain falls on the ground, it either soaks into the soil or runs across the
surface of the soil. When rainwater runs across the land, what body of water
might collect the rain?
Possible answers: a stream, river, pond, or lake
2. From here, where might the water flow?
Into a river, and eventually into the ocean
3. After the rain, the sun comes out and the land dries. Where does the water
that had been on the land go?
It evaporates and becomes a gas in the atmosphere.
4. Construct a diagram that would illustrate all the places a molecule of water
might go. Begin with a raindrop and end with a cloud.
Student diagrams may include the following: a raindrop —> lawn —>
a stream —> river —> large lake —> atmosphere —> cloud.