Ecosystems & Energy

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Chapter 4

• Ecosystems Energy

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Ecology

• The branch of biology that deals with the
  interactions between organisms and the
  relationship between organisms and the
  environment.

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Do Now

• Draw a flow chart to represent the organizational
  relationships between the following terms from
  the most inclusive to the least inclusive
  ecosystem, population, species, community, and
  biosphere.

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Levels of Biological Organization
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Levels of Organization

• Ecosystem Organization
• Species
• Population
• Community
• Ecosystem
• Landscape
• Biosphere

• Cellular Organization
• Cells
• Tissues
• Organs
• Organ Systems
• Organisms
• SPECIES

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Species

• A group of organisms capable of producing more
  members of the same organism..
• Homo sapiens with Homo sapiens
• Not Homo sapiens with Homo habilus

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Species

• The Brown Trout Salmo trutta

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Population

• Includes all the members of a species found in a
  given area.
• Ex sunfish in a pond

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Community

• Includes all the populations in a given area.
• Ex all plants, animals, and microorganisms make
  up a pond community

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Ecosystem

• Includes all the members of the community plus
  the physical environment in which they live in.
• Interaction of biotic and abiotic factors

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Abiotic Factors

• Nonliving factors.
• The abiotic factors of an ecosystem include the
  physical and chemical factors that affect the
  capacity of an organism to live and reproduce.
  These factors are
• 1. Intensity and duration of light
• 2. Temperature range
• 3. Amount of moisture
• 4. Type of substrate
• 5. Availability of inorganic substances and
  gases
• 6. pH

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Biotic Factors

• Living factors
• These factors directly or indirectly affect the
  environment.
• Thus, the organisms, their presence, parts,
  interaction, and wastes all act as biotic
  factors.
• These interactions include
• 1. Nutritional relationships
• 2. Symbiotic relationships

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Requirements for a Stable Ecosystem

• The ecosystem involves interactions between
  living and nonliving things. Certain
  requirements must be met for a stable ecosystem
  to exist
• There must be a constant supply of energy
  (sunlight for photosynthesis).
• There must be living organisms that can
  incorporate the energy into organic compounds
  (food).
• There must be a recycling of materials between
  organisms and the environment.

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Limiting Factors

• Determines the types of organisms which may exist
  in that environment.
• Examples are
• A low temperature common to northern latitudes
  determines in part what species of plants can
  exist in that area.
• The amount of oxygen dissolved in a body of water
  will help determine which species of fish will
  exist there.

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Landscape

• A spatially heterogeneous region that includes
  several interacting ecosystems
• Connections among ecosystems found in a
  particular area.

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Biosphere

• The portion of the earth in which life exists.
• The biosphere is composed of many complex
  ecosystems that include water, soil, and air.

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Ecological Organization
Population ( or
) Community (
) Ecosystem (
) Biosphere ( )
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Do Now

• Compare and contrast potential energy and kinetic
  energy using biological or ecological examples
  and references

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Types of energy

• Energy the capacity or ability to do work.
• Potential Energy Stored energy.
• Kinetic Energy The energy of motion.

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Do Now

• Define energy and briefly describe how the
  different forms contribute to the continual
  energy needs of organisms

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Types of energy

• Heat Energy thermal energy that flows from an
  object with a high temp. (heat source) to an
  object with a lower temp. (heat sink).

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• Nuclear Energy energy found within atomic nuclei.

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Types of Energy

• Electrical Energy energy that flows as charged
  particles.

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• Thermodynamics The study of energy its
  transformations.
• 1st Law of Thermodynamics energy cannot be
  created nor destroyed, but it can be transformed.
• 2nd Law of Thermodynamics when energy is
  converted some usable energy is degraded into a
  less usable form. (Entropy)

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Do Now

• Cellular respiration occurs in both plant and
  animal cells while photosynthesis only occur in
  plant cells. How are plant and animals connected
  via these two processes? Be sure to include
  balanced chemical equations as part of your
  answer.

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Closed and Open Systems
Earth is an open system because it receives
energy from the sun.
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Types of Energy
Chemical Energy
Potential Energy
Mechanical (Kinetic) Energy
Radiant (Solar)
Nuclear Energy
Heat Energy
Electrical Energy
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Energy Flow Relationships

• For an ecosystem to be self-sustaining, there
  must be a flow of energy between organisms.
• The pathway of energy flow through the living
  components of an ecosystem are represented by
  food chains and food webs.

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Nutritional Relationships

• Involves the transfer of nutrients from one
  organism to another within an ecosystem.
• In terms of nutrition, organisms are either
  autotrophs or heterotrophs
• SEE OWL LAB

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Energy Flow through a food Chain
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Energy Losses

• The mouse receives energy from the food it eats.
• Cells extract the food's energy for growth,
  acquiring food, escaping enemies lost as heat.
  Some lost in the mouse's waste (feces).
• The remaining energy is stored in the mouse's
  body and is available to the organism that preys
  on it.
• About 90 of the energy is used or lost, only 10
  is available to predators.

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Energy Flow
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Biological Magnification

• A nondegradable or slowly degradable substance
• That becomes more and more concentrated in the
  tissues of organisms at higher trophic levels of
  a food web.
• Dichloro-Diphenyl-Trichloroethane (DDT)
• Polychlorinated biphenyls (PCBs)

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DDT in Food Webs
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DDT
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PCBs in Food Webs

• PCB concentrations in animal tissue can be
  magnified up to 25 million times.
• Microscopic organisms pick up chemicals from
  sediments
• Consumed in large numbers by filter feeding
  zooplankton.
• Mysid shrimp then consume zooplankton
• fish eat the mysid
• and so on up the food web to the herring gull.
• (Figure and caption from Our Stolen Future, p.
  27)

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DDT Detection

• In 1962, Rachel Carson, a former U.S. Fish and
  Wildlife Service (USFWS) scientist and writer,
  published Silent Spring, outlining the dangers of
  DDT

Fig. 41-8, p.736
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Do Now

• Discuss the contributions of saprotrophs and
  detritivores to a balanced ecosystem.
• Identify two representatives of each group in
  your discussion

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(A) Food Chains

• Green plants and other photosynthetic organisms
  are the organisms in an ecosystem that can
  convert radiant energy from sunlight into food.
• A food chain involves the transfer of energy from
  green plants through a series of organisms with
  repeated stages of eating and being eaten.

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Food Chain
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(B) Food Webs

• In a natural community, most organisms eat more
  than one species and may be eaten, in turn, by
  more than one species.
• Thus, the various food chains in a community are
  interconnected forming a food web.
• SEE OWL LAB

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Food Web at the Edge of an Eastern Deciduous
Forest
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Do Now

• Define and discuss three applications of the
  term ecological pyramid.
• What accounts for the shape of the pyramid?
• Use sketches of each type of pyramid with
  associated quantitative units to support your
  comparison.

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(C) Pyramid of Energy

• The greatest amount of energy in a community is
  present in the organisms that make up the
  producer level.
• Only a small portion of this energy (10) is
  passed on to primary consumers, and only a
  smaller portion (10 of the original 10) is
  passed on to secondary consumers.
• A pyramid of energy can be used to illustrate the
  loss of usable energy at each feeding level.

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B. ALL living organisms must carry out ALL 8 life
functions
Nutrition
Synthesis
Transport
Growth
Respiration
Regulation
Reproduction
Excretion
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Autotroph

• An organism capable of making their own food
• Photosynthetic
• Chemosynthetic

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Chemosynthesis

• A type of autotrophic nutrition
• Does not require light as an energy source
• Energy is obtained by chemical reactions within
  the cell
• Example Hydrothermal vent bacteria

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Photosynthesis

• The most common type of autotrophic nutrition
• In this process, organisms use energy from
  sunlight, carbon dioxide, and water to make food
  (usually glucose)

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Chloroplast

• Contains pigments called
• chlorophylls (a b greens)
• Xanthophylls (yellow)
• Carotenes (orange)
• It is in the chloroplast that light energy is
  trapped by chlorophylls and glucose is formed as
  the product. (food)

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Structure of Chloroplast
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Wavelengths effects on Photosynthesis
Absorption of Light by Chlorophyll a and
Chlorophyll b

• Which Wavelengths are the best for photosynthetic
  plants?
• Which Wavelength is the worst?

Chlorophyll b
Chlorophyll a
V
B
G
Y
O
R
http//seawifs.gsfc.nasa.gov/SEAWIFS.html
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ROY G BIV

• The maximum amount of photosynthesis will occur
  when exposed to red and blue light because it is
  these two colors that are easily absorbed in
  great quantity by the chlorophyll
• For green leaves, green light is reflected and
  therefore has the least affect on photosynthesis

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Formula for Photosynthesis
6CO2 12H2O radiant energy ? C6H12O6 6H2O
6O2
Formula for Cellular Respiration
C6H12O6 6O2 6H2O ? 6CO2 12H2O work energy
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Photosynthesis and Cellular Respiration
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Photosynthesis occurs in two stages

• Light Reaction
• Dark Reaction

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Structure of Chloroplast
Light reactions
Dark reactions
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Photosynthesis An Overview
Section 8-3
6CO2 12H2O radiant energy ? C6H12O6 6H2O
6O2
Sunlight
Chloroplast
NADP
ADP P
Light- Dependent Reactions
Calvin Cycle
ATP
NADPH
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1. Light Reaction

• Occurs in the grana of the chloroplast.
• First stage of photosynthesis.
• Begins with the absorption of light energy by
  chlorophyll.
• Photolysis occurs- a reaction in which H2O
  molecules split into oxygen and hydrogen.
• All oxygen given off during photosynthesis comes
  from the photolysis of water.
• ATP (Adenosine triphosphate), which is a form of
  chemical energy, is produced.

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Light Reaction
Oxygen (6O2)
Chloroplast
I am out of here!
12 WATER molecules
(H2O)
12 Hydrogen
12 Hydrogen
AKA Photolysis
(This all occurs In the Grana.)
NADPH ATP
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(This all occurs in the Stroma.)
Dark Reaction Calvin Cycle Light
Independent Reaction
NADPH ATP
12 Hydrogen
12 Hydrogen
Carbon Fixation
6(CO2)
C6H1206
6(H20)
AKA Glucose
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The Food Factory
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6
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2. Dark Reaction

• Occurs in the stroma of the chloroplast.
• The second stage of photosynthesis.
• It is here that CO2 is converted to carbohydrates
  by a process called carbon fixation.
• CO2 ? PGAL ? C6H12O6
• Light is not required.
• The dark reaction requires ATP from the light
  reaction for it to take place.

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Factors Affecting the Rate of Photosynthesis

• Light Intensity
• Water
• Carbon dioxide level
• Temperature

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Adaptations for Photosynthesis

• A. Unicellular Organisms
• 1. Almost all chlorophyll-containing
  unicellular organisms are aquatic. (live in
  water)
• 2. The raw materials for photosynthesis
  are absorbed directly from the water and into the
  cell
• Ex algae
• cyanobacteria

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Adaptations for Photosynthesis

• B. Terrestrial Plants (land-dwelling)
• 1. Occurs in leaves that provide the
  maximum surface area for the absorption of light.

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Plants

• Leaves- have stomates for gas exchange
• Stems- have lenticels for gas exchange
• Roots- gas exchange occurs across a moist
  membrane
• of root hairs (diffusion)

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Do Now

• Briefly explain the process of cellular
  respiration and uses of the energy obtained from
  the process. Your answer should include the
  following terms glucose, water, carbon dioxide,
  chemical energy, and oxygen. What organisms
  carry on this process?

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Glycolysis (splitting glucose)
2 ATP
2 pyruvic acid
2 PGAL (C3H5O3)
Glucose (C6H12O6)
4 ATP
Net Gain???
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Glycolysis (splitting glucose)

• Net Energy Yield from Glycolysis
• Energy requiring steps
• 2 ATP invested
• Energy releasing steps
• 2 NADH formed
• 4 ATP formed
• Net yield is 2 ATP and 2 NADH

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Glycolysis (splitting glucose)
All three reactions with Glycolysis

• Glycolysis occurs in cytoplasm
• Reactions are catalyzed by enzymes
• Glucose 2 Pyruvate
• (six carbons) (three carbons)

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• Equations for Anaerobic Respiration
• 1. Lactic Acid Fermentation
• glucose ? 2 lactic acids 2 ATPs
• 2. Alcoholic Fermentation
• glucose ? 2 alcohol 2 CO2 2 ATPs
• In each equation, enzymes are used and a net gain
  of 2 ATPs are produced

• Aerobic Respiration
• Glucose O2 ? H2O CO2 36 ATPs
• Again, enzymes are used and a net of 36 ATPs are
  produced

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Equations for Anaerobic Respiration

• glucose ? 2 lactic acids 2 ATPs
• glucose ? 2 alcohol 2 CO2 2 ATPs
• In each equation, enzymes are used and a net gain
  of 2 ATPs are produced

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Equation for Aerobic Respiration

• glucose O2 ? H2O CO2 36 ATPs

• Again, enzymes are used and a net of 36 ATPs are
  produced

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Who am I?
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Do Now

• What is the human impact on net primary
  productivity? What are the potential
  environmental problems associated with this
  impact and what changes would be required to
  minimize human impact?

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Net Primary Productivity (NPP)Gross Primary
Productivity (GPP) (total energy from
photosynthesis /unit area/time) - Plant
respiration (energy invested by plants)
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(NPP) GPP (rate) Plant Respiration
Total energy produced
Energy cost
Humans compete with other species for energy.
Our planet cannot handle the burden from human
overpopulation.

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Table 9l-1 Average annual Net Primary
Productivity of the Earth's major biomes.
Humans compete with other species for energy.
Our planet cannot handle human overpopulation.

http//www.physicalgeography.net/fundamentals/9l.h
tml
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There are 3 basic organisms in a food web

• 1)Producers
• 2)Consumers
• 2a) Primary
  consumers
• 2b)Secondary consumers
• 3)Decomposers

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There are 3 basic organisms in a food web

• Producers- include green plants and other
  photosynthetic organisms that synthesize the
  organic nutrients that supply energy to other
  members in the community.

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Question

• Briefly discuss the role of autotrophs in an
  ecosystem

http//www.dnr.state.wi.us/org/water/fhp/lakes/und
er/oxygen.htm
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There are 3 basic organisms in a food web

• Consumers- include all heterotrophic organisms.
  Organisms that feed on green plants are primary
  consumers, or herbivores. Secondary consumers,
  or carnivores, feed on other consumers. Omnivores
  eat producers and consumers.

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There are three basic classes of organisms in a
food web

• Decomposers are the organisms (saprotrophs)
  that break down wastes and dead organisms so that
  chemical materials are returned to the
  environment for use by other living organisms.

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Antarctic food web
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Antarctic food web
Krill!
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Do Now

• What are krill? Using appropriate terminology,
  discuss the role of krill in the Antarctic food
  web, and describe what has been happening to the
  population of these animals over that past 150
  years and why. What has been the impact on this
  Antarctic ecosystem of human related change in
  the global environment?

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Do Now

• Today, commercial fishermen are fishing down the
  food web. This is unsustainable. WHY? How can
  this movement down the marine food web be
  reversed?

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D-End