Chapter 4Ecosystems & Energy

EcologyThe branch of biology that

deals with the interactions between organisms and the

relationship between organisms and the

environment.

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.

Levels of Biological Organization

Levels of Organization Cellular

Organization– Cells– Tissues– Organs– Organ Systems– Organisms– SPECIES

Ecosystem Organization– Species– Population– Community– Ecosystem– Landscape– Biosphere

SpeciesA group of organisms capable of

producing more members of the same organism..

Homo sapiens with Homo sapiens

Not Homo sapiens with Homo habilus

Species

The Brown Trout Salmo trutta

Population

Includes all the members of a species found in a

given area.Ex: sunfish in a pond

Community Includes all the populations

in a given area.

Ex: all plants, animals, and microorganisms make up a

pond community

EcosystemIncludes all the members of the

community plus the physical environment in which they live

in.–Interaction of biotic and abiotic

factors

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

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

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:

1. There must be a constant supply of energy (sunlight for photosynthesis).

2. There must be living organisms that can incorporate the energy into organic compounds (food).

3. There must be a recycling of materials between organisms and the environment.

Limiting Factors Determines the types of organisms which

may exist in that environment. Examples are:

1. A low temperature common to northern latitudes determines in part what species of plants can exist in that area.

2. The amount of oxygen dissolved in a body of water will help determine which species of fish will exist there.

Landscape A spatially heterogeneous region that

includes several interacting ecosystems

Connections among ecosystems found in a particular area.

BiosphereThe portion of the earth in

which life exists.The biosphere is composed

of many complex ecosystems that include

water, soil, and air.

Ecological OrganizationPopulation ( or )

Community ( + + )

Ecosystem ( )

Biosphere ( )

Do Now: Compare and contrast potential energy

and kinetic energy using biological or ecological examples and references

Types of energy Energy: the capacity

or ability to do work.

Potential Energy: Stored energy.

Kinetic Energy: The energy of motion.

Do Now: Define energy and briefly describe

how the different forms contribute to the continual energy needs of organisms

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

Types of energy

Nuclear Energy: energy found within atomic nuclei.

Types of Energy

Electrical Energy: energy that flows as charged particles.

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)

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.

Closed and Open Systems

Earth is an open system because it receives Earth is an open system because it receives energy from the sun.energy from the sun.

Types of Energy

Potential EnergyPotential Energy Mechanical (Kinetic) EnergyMechanical (Kinetic) Energy

HeatHeat Energy Energy NuclearNuclear Energy Energy

ElectricalElectrical Energy Energy

ChemicalChemical Energy Energy

Radiant (Solar)Radiant (Solar)

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.

          

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

Energy Flow through a food Chain

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.

Energy Flow

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)

DDT in Food Webs

DDT

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)

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

Do Now: Discuss the contributions of

saprotrophs and detritivores to a balanced ecosystem.

Identify two representatives of each group in your discussion

(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.

Food Chain

(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

Food Web at the Edge of an Eastern Deciduous Forest

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.

(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.

B. ALL living organisms must carry

out ALL 8 life functions

Nutrition

Transport

Respiration

Excretion

Synthesis

Growth

Regulation

Reproduction

Autotroph

An organism capable of making their own food

–Photosynthetic

–Chemosynthetic

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

PhotosynthesisThe most common type of

autotrophic nutrition In this process, organisms

use energy from sunlight, carbon dioxide, and water to make food (usually glucose)

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)

Structure of Chloroplast

http://seawifs.gsfc.nasa.gov/SEAWIFS.html

Which Wavelengths are the best for photosynthetic plants?

Which Wavelength is the worst?

Absorption of Light byAbsorption of Light byChlorophyll Chlorophyll aa and Chlorophyll and Chlorophyll bb

V B G YO R

Chlorophyll b

Chlorophyll a

Wavelengths effects on Photosynthesis

ROY G BIV The maximum amount of The maximum amount of

photosynthesis will occur when photosynthesis will occur when exposed to exposed to redred and and blueblue light because light because it is these two colors that are easily it is these two colors that are easily absorbed in great quantity by the absorbed in great quantity by the chlorophyll chlorophyll

For green leaves, For green leaves, greengreen light is light is reflected and therefore has the least reflected and therefore has the least affect on photosynthesisaffect on photosynthesis

Formula for Photosynthesis

6CO6CO22 + 12H + 12H22O + radiant energy O + radiant energy C C66HH1212OO66 + 6H + 6H22O + 6OO + 6O22

CC66HH1212OO66 + 6O + 6O22 + 6H + 6H22O O 6CO 6CO22 + 12H + 12H22O + work energy O + work energy

Formula for Cellular RespirationFormula for Cellular Respiration

Photosynthesis and Cellular Respiration

Photosynthesis occurs in two stages:

1. Light Reaction

2. Dark Reaction

Structure of Chloroplast

Light reactionsLight reactions Dark reactionsDark reactions

Chloroplast

water

O2

Sugars

CO2

Light-Dependent Reactions

CalvinCycle

NADPH

ATP

ADP + PNADP+

Sunlight

Section 8-3

6CO6CO22 + 12H + 12H22O + radiant energy O + radiant energy C C66HH1212OO66 + 6H + 6H22O + 6OO + 6O22

Photosynthesis: An Overview

1. Light Reaction1. Occurs in the grana of the chloroplast.2. First stage of photosynthesis.3. Begins with the absorption of light energy

by chlorophyll.4. Photolysis occurs- a reaction in which H2O

molecules split into oxygen and hydrogen.5. All oxygen given off during photosynthesis

comes from the photolysis of water.6. ATP (Adenosine triphosphate), which is a

form of chemical energy, is produced.

Chloroplast

(H2O) (H2O)

Oxygen Oxygen (6O(6O22))

I am out of here!

Light ReactionLight Reaction

12 WATE12 WATER R moleculesmolecules

12 Hydrogen

(This all occursIn the Grana.)

12 Hydrogen

NADPHNADPH+ ATP+ ATP

AKA AKA PhotolysisPhotolysis

Dark Reaction“Calvin Cycle”“Light IndependentReaction”

12 Hydrogen12 Hydrogen

6(CO2)

NADPHNADPH+ATP+ATP

C6H1206 6(H20)

AKA Glucose

(This all occurs in the Stroma.)

Carbon Fixation

The Food Factory

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.

Factors Affecting the Rate of Photosynthesis

1. Light Intensity

2. Water

3. Carbon dioxide level

4. Temperature

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

Adaptations for Photosynthesis

B. Terrestrial Plants (land-dwelling)

1. Occurs in leaves that provide the maximum surface area for the absorption of light.

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)

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?

Glucose

(C6H12O6)

2 pyruvic acid

2 ATP

2 PGAL

(C3H5O3)

Glycolysis (splitting glucose)

+4 ATP

Net Gain:???

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

Glycolysis (splitting glucose)All three reactions with Glycolysis Glycolysis occurs in cytoplasm Reactions are catalyzed by enzymes

Glucose 2 Pyruvate

(six carbons) (three carbons)

Aerobic RespirationAerobic Respiration

Glucose + OGlucose + O22 H H22O + COO + CO22 + 36 ATP’s + 36 ATP’s Again, enzymes are used and a net of 36 Again, enzymes are used and a net of 36

ATP’s are producedATP’s are produced

Equations for Anaerobic RespirationEquations for Anaerobic Respiration1. Lactic Acid Fermentation1. Lactic Acid Fermentation

glucose glucose 2 lactic acids + 2 ATP’s 2 lactic acids + 2 ATP’s

2. Alcoholic Fermentation2. Alcoholic Fermentation

glucose glucose 2 alcohol + 2 CO 2 alcohol + 2 CO22 + 2 + 2 ATP’sATP’s

In each equation, enzymes are used and a net In each equation, enzymes are used and a net gain of 2 ATP’s are producedgain of 2 ATP’s are produced

Equations for Anaerobic

Respiration

glucose 2 lactic acids + 2 ATP’s

glucose 2 alcohol + 2 CO2 + 2 ATP’s

In each equation, enzymes are used and a net gain of 2 ATP’s are produced

Equation for Aerobic

Respiration

glucose + O2 H2O + CO2 + 36 ATP’s

•Again, enzymes are used and a net of 36 ATP’s are produced

Who am I?

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?

Net Primary Productivity (NPP)

=Gross Primary

Productivity (GPP) (total energy from

photosynthesis /unit area/time)

- Plant respiration (energy invested by

plants)

(NPP) = GPP (rate) – Plant Respiration

Humans Humans competecompete with other species with other species for for energyenergy. .

Our planet cannot handleOur planet cannot handlethe burden from human the burden from human overpopulationoverpopulation..

Total energy producedTotal energy producedEnergy costEnergy cost

Humans Humans competecompete with other species with other species for for energyenergy. Our planet cannot handle. Our planet cannot handlehuman human overpopulationoverpopulation..

Table 9l-1: Average annual Net Primary Productivity of the Earth's major biomes.

 Ecosystem Type Net Primary Productivity(kilocalories/meter 2 /year)

 Tropical Rain Forest  9000

 Estuary  9000

 Swamps and Marshes  9000

 Savanna  3000

 Deciduous Temperate Forest  6000

 Boreal Forest  3500

 Temperate Grassland  2000

 Polar Tundra  600

 Desert  < 200

http://www.physicalgeography.net/fundamentals/9l.html

There are 3 basic organisms in a food web:

1)Producers

2)Consumers 2a) Primary consumers

2b)Secondary consumers

3)Decomposers

There are 3 basic organisms in a food web:

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

Question Briefly discuss the role of autotrophs in

an ecosystem

http://www.dnr.state.wi.us/org/water/fhp/lakes/under/oxygen.htm

There are 3 basic organisms in a food web:

1. 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.

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.

Antarctic food web

Antarctic food web

Krill!Krill!

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?

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?

D-End