Chapter 3 The Basic Needs of Living Things. THE NATURE OF ECOLOGY Ecology is a study of connections in nature. How organisms interact with one another.

Chapter 3Chapter 3

The Basic Needs of The Basic Needs of Living ThingsLiving Things

THE NATURE OF ECOLOGYTHE NATURE OF ECOLOGY

Ecology is a study Ecology is a study of connections in of connections in nature.nature. How organisms How organisms

interact with one interact with one another and with another and with their nonliving their nonliving environment.environment.

Figure 3-2Figure 3-2

Organisms and SpeciesOrganisms and Species Organisms, the different forms of life on earth, Organisms, the different forms of life on earth,

can be classified into different species (similar can be classified into different species (similar organisms that can interbreed and produce organisms that can interbreed and produce fertile offspring) based on certain characteristics.fertile offspring) based on certain characteristics.

Populations, CommunitiesPopulations, Communities

Members of a species interact in groups called Members of a species interact in groups called populations (organisms of the same species in populations (organisms of the same species in the same place at the same time)the same place at the same time) There is genetic diversity within every populationThere is genetic diversity within every population

Populations of different species living and Populations of different species living and interacting in an area form a community.interacting in an area form a community.

EcosystemsEcosystems

A community interacting with its physical A community interacting with its physical environment of matter and energy is an environment of matter and energy is an ecosystem (biotic and abiotic parts)ecosystem (biotic and abiotic parts)

Ecosystems lack distinct boundaries and are Ecosystems lack distinct boundaries and are not isolatednot isolated Species can occupy multiple ecosystems and Species can occupy multiple ecosystems and

migrate between themmigrate between them

Ecotone: a transitional region between Ecotone: a transitional region between ecosystemsecosystems

Shares species and characteristics of bothShares species and characteristics of both May have more or fewer species than the May have more or fewer species than the

ecosystemsecosystems

Groups of ecosystems with similar climax Groups of ecosystems with similar climax communities are called biomescommunities are called biomes

Biomes describe terrestrial systems Biomes describe terrestrial systems Aquatic and wetland ecosystems are determined Aquatic and wetland ecosystems are determined

by depth, salinity, and permanence of waterby depth, salinity, and permanence of water LandscapeLandscape: a cluster of interacting : a cluster of interacting

ecosystems ecosystems BiosphereBiosphere: one huge system formed by all : one huge system formed by all

living things living things

Nonliving and Living Components of Nonliving and Living Components of EcosystemsEcosystems

Ecosystems consist of nonliving (abiotic) and Ecosystems consist of nonliving (abiotic) and living (biotic) components.living (biotic) components.

Figure 3-10Figure 3-10

Environmental factors Environmental factors

Organisms live in the environment with physical, Organisms live in the environment with physical, chemical, and biological biotic or abiotic factors chemical, and biological biotic or abiotic factors

ConditionCondition: any factor that varies in space and time : any factor that varies in space and time but is not used up (temperature, wind, pH, salinity)but is not used up (temperature, wind, pH, salinity)

ResourceResource: any factor consumed by organisms: any factor consumed by organisms Water, nutrients, light, oxygen, food, spaceWater, nutrients, light, oxygen, food, space

A factor can be both a condition and resourceA factor can be both a condition and resource Plants use water as a resource, but pond water is Plants use water as a resource, but pond water is

a condition a condition Factors determine whether a species occupies an Factors determine whether a species occupies an

areaarea

• Limiting factor: any factor that limits growth• Law of limiting factors: any factor outside the optimal

range will cause stress and limit growth, reproduction, and survival of a population

• Limiting factors may be a problem of too much or too little

• They can change over time (e.g., temperature vs. nutrients)

• The ultimate limiting factor: an organism’s genetic potential

• Synergistic effects (synergisms): factors (e.g., pollution) that interact to cause a greater effect than expected

Habitat and niche • Habitat: the place—defined by the plant community

and physical environment—where a species is adapted to live• A deciduous forest, swamp, etc. • Microhabitat: puddles, rocks, holes in tree trunks

• Niche: the sum of all conditions and resources under which a species can live • What the animal eats, where it feeds and lives, how it

responds to abiotic factors

• Species coexist in an area but have separate niches • Reducing competition by using different resources

Matter in living and nonliving systems

• Organisms take in matter and energy from the environment to grow and function

• Matter: anything that occupy space and has mass • All solids, liquids, and gases• All living and nonliving things • Is composed of atoms

• Atoms: the building blocks of all matter • Elements: 94 naturally occurring kinds of atoms • Made of protons, neutrons, electrons

• Chemical reactions rearrange atoms to form different kinds of matter

• Law of Conservation of Matter: atoms do not change and are not created or destroyed

• Compound: two or more different kinds of atoms• Water: H2O (it is also a molecule)

• The cycle of growth, reproduction, death, and decay is a continuous process• compounds are used, assembled, and disassembled

repeatedly

Atoms Compounds

The four spheres of Earth’s environment

• Atmosphere: the thin layer of gases separating Earth from outer space

• Oxygen (O2), nitrogen (N2), carbon dioxide (CO2)• Plus water vapor and other gases

• Hydrosphere • Water is an important molecule for living things

• Needs to be in liquid form

• Below freezing, water is a solid crystal form (ice or snow)

• Above freezing but below vaporization, water is a liquid

• Water undergoes melting and evaporation• Sublimation: water goes from solid directly into the

air

The lithosphereThe lithosphere• All elements required by organisms are in minerals• Mineral: a naturally occurring solid made by

geologic processes• A hard, crystalline structure of a given chemical

composition

• Rocks: made of small crystals of two or more minerals• Soil: particles of many different minerals

• Each mineral is made of two or more kinds of atoms• Bonded by an attraction between positive and

negative charges

Organic compounds• An organism’s body is composed of large

compounds• Proteins, carbohydrates (sugars, starches), lipids

(fats), nucleic acids (DNA, RNA)

• These compounds contain six key elements• Carbon (C), hydrogen (H), oxygen (O), nitrogen (N),

phosphorus (P), and sulfur (S)

• Organic compounds: chemical compounds making up tissues of living organisms• Very large, complex molecules• Mainly carbon, hydrogen, and oxygen

Energy affects matterEnergy affects matter Common forms of energy: light, heat, Common forms of energy: light, heat,

movement, electricitymovement, electricity Energy changes the Energy changes the positionposition or or statestate of of

mattermatter An explosion releases energy that causes An explosion releases energy that causes

matter to movematter to move Heating water causes it to boil and change Heating water causes it to boil and change

statestate Energy can move matterEnergy can move matter

Heat energy in a substance measures the Heat energy in a substance measures the movement of atoms and molecules in mattermovement of atoms and molecules in matter

Energy basicsEnergy basics Kinetic energyKinetic energy: energy in action or motion: energy in action or motion

Light, heat, physical motion, electrical currentLight, heat, physical motion, electrical current Potential energyPotential energy: energy in storage (e.g., : energy in storage (e.g.,

gasoline)gasoline) Chemical energyChemical energy: potential energy contained : potential energy contained

in chemicals and fuelsin chemicals and fuels Energy can be changed from one form to Energy can be changed from one form to

another another Potential to kinetic energyPotential to kinetic energy Kinetic to potential energy (e.g., charging a battery)Kinetic to potential energy (e.g., charging a battery)

Units of energyUnits of energy Energy cannot be measured in units of weight or Energy cannot be measured in units of weight or

volumevolume CalorieCalorie: the amount of heat required to raise the : the amount of heat required to raise the

temperature of 1 gram of water 1 degree Celsiustemperature of 1 gram of water 1 degree Celsius 1 kilocalorie = 1,000 calories1 kilocalorie = 1,000 calories

TemperatureTemperature: measures the molecular motion in : measures the molecular motion in a substancea substance Caused by kinetic energyCaused by kinetic energy

Movement of matter requires energy absorption Movement of matter requires energy absorption or releaseor release Change in matter cannot be separated from its Change in matter cannot be separated from its

change in energychange in energy

Laws of thermodynamicsLaws of thermodynamics First Law of Thermodynamics (Law of Conservation First Law of Thermodynamics (Law of Conservation

of Energy)of Energy): energy is neither created nor destroyed : energy is neither created nor destroyed But it may be converted from one form to anotherBut it may be converted from one form to another

Second Law of ThermodynamicsSecond Law of Thermodynamics: usable energy is : usable energy is lost in any energy conversionlost in any energy conversion

EntropyEntropy: a measure of the degree of disorder in a : a measure of the degree of disorder in a systemsystem Without energy input, everything goes toward increasing Without energy input, everything goes toward increasing

entropyentropy Increasing disorder releases heat from the systemIncreasing disorder releases heat from the system

To gain potential energy, energy must come from To gain potential energy, energy must come from somewheresomewhere Energy lost is greater than the energy gainedEnergy lost is greater than the energy gained

EntropyEntropy

Energy changes in organismsEnergy changes in organisms Breaking bonds in molecules releases energy Breaking bonds in molecules releases energy

to do workto do work OxidationOxidation: a loss of electrons: a loss of electrons

Usually accomplished by the addition of oxygen Usually accomplished by the addition of oxygen (which causes (which causes burningburning))

Inorganic compounds are nonflammable Inorganic compounds are nonflammable They have low potential energyThey have low potential energy

Production of organic material from inorganic Production of organic material from inorganic material represents a gain in potential energymaterial represents a gain in potential energy Breakdown of organic material Breakdown of organic material releasesreleases energy energy

Energy flows through an ecosystem in a linear Energy flows through an ecosystem in a linear fashion (from high quality to low quality forms fashion (from high quality to low quality forms – heat is the main low quality form that is lost – heat is the main low quality form that is lost to the “environment”)to the “environment”) Sun Sun autotrophs autotrophs heterotrophs heterotrophs

with decomposers all along the waywith decomposers all along the way

-only about 10% of the energy is passed on -only about 10% of the energy is passed on

to the next level in the chainto the next level in the chain

Matter is cycled through an ecosystemMatter is cycled through an ecosystem the 5 main geochemical cyclesthe 5 main geochemical cycles

• Carbon, nitrogen, water, phosphorus, sulfurCarbon, nitrogen, water, phosphorus, sulfur

What Sustains Life on Earth?What Sustains Life on Earth?

Producers: Basic Source of All FoodProducers: Basic Source of All Food ProducersProducers: make high-potential-energy organic molecules from low-: make high-potential-energy organic molecules from low-

potential-energy raw materials (COpotential-energy raw materials (CO22, H, H22O, N, P)O, N, P)

Most producers capture sunlight to produce carbohydrates by Most producers capture sunlight to produce carbohydrates by photosynthesis:photosynthesis:

Chemosynthesis:Chemosynthesis: Some organisms such as deep ocean bacteria draw energy from hydrothermal Some organisms such as deep ocean bacteria draw energy from hydrothermal

vents and produce carbohydrates from hydrogen sulfide (Hvents and produce carbohydrates from hydrogen sulfide (H22S) gas .S) gas .

Photosynthesis: Photosynthesis: A Closer LookA Closer Look

Chlorophyll molecules in the Chlorophyll molecules in the chloroplasts of plant cells chloroplasts of plant cells absorb solar energy.absorb solar energy.

This initiates a complex This initiates a complex series of chemical reactions series of chemical reactions in which carbon dioxide and in which carbon dioxide and water are converted to water are converted to sugars and oxygen.sugars and oxygen.

Figure 3-AFigure 3-A

Within the plantWithin the plant Glucose serves three purposesGlucose serves three purposes

It is the backbone for all other organic moleculesIt is the backbone for all other organic molecules It provides energy to run cell activities (e.g., It provides energy to run cell activities (e.g.,

growth)growth) It is stored for future use (as starch in potatoes, It is stored for future use (as starch in potatoes,

grains, seeds) grains, seeds) Each stage of the process uses Each stage of the process uses enzymesenzymes: :

proteins that promote the synthesis or proteins that promote the synthesis or breaking of chemical bondsbreaking of chemical bonds

Cell respirationCell respiration Consumers: Consumers: organisms that live on the organisms that live on the

production of othersproduction of others Obtain energy from feeding on and breaking down Obtain energy from feeding on and breaking down

organic matter made by producersorganic matter made by producers RespirationRespiration: organic molecules are broken : organic molecules are broken

down inside each cell down inside each cell Produces energy for the cell to useProduces energy for the cell to use The reverse of photosynthesisThe reverse of photosynthesis Oxygen is consumedOxygen is consumed Occurs in plants and animalsOccurs in plants and animals

C6H12O6 + 6 O2 6 CO2 + 6 H2O

Consumers: Eating and Recycling to Consumers: Eating and Recycling to SurviveSurvive

Consumers (heterotrophs) get their food by Consumers (heterotrophs) get their food by eating or breaking down all or parts of other eating or breaking down all or parts of other organisms or their remains.organisms or their remains. HerbivoresHerbivores

• Primary consumers that eat producersPrimary consumers that eat producers CarnivoresCarnivores

• secondary consumers that eat primary consumerssecondary consumers that eat primary consumers• Third and higher level consumers: carnivores that eat Third and higher level consumers: carnivores that eat

carnivores.carnivores. OmnivoresOmnivores

• Feed on both plant and animals.Feed on both plant and animals.

Cellular respiration is not 100% Cellular respiration is not 100% efficientefficient

Animals have respiratory organs to obtain oxygenAnimals have respiratory organs to obtain oxygen Carbon dioxide is eliminated through the lungsCarbon dioxide is eliminated through the lungs Many aquatic places are severely oxygen limitedMany aquatic places are severely oxygen limited

In keeping with the Second Law of ThermodynamicsIn keeping with the Second Law of Thermodynamics Cell respiration is only 40Cell respiration is only 40––60% efficient60% efficient The rest of the energy is released as waste (body) heatThe rest of the energy is released as waste (body) heat

Consuming more calories than your body needs Consuming more calories than your body needs converts calories to fat and results in weight gainconverts calories to fat and results in weight gain

Stored energy can be released from food without Stored energy can be released from food without oxygenoxygen Anaerobic respiration (fermentation) is less efficientAnaerobic respiration (fermentation) is less efficient

Aerobic and Anaerobic Respiration: Aerobic and Anaerobic Respiration: Getting Energy for SurvivalGetting Energy for Survival

Organisms break down carbohydrates and other Organisms break down carbohydrates and other organic compounds in their cells to obtain the organic compounds in their cells to obtain the energy they need.energy they need.

This is usually done through This is usually done through aerobic respirationaerobic respiration.. The opposite of photosynthesisThe opposite of photosynthesis

Aerobic and Anaerobic Respiration: Aerobic and Anaerobic Respiration: Getting Energy for SurvivalGetting Energy for Survival

Anaerobic respiration or fermentation:Anaerobic respiration or fermentation: Some decomposers get energy by breaking Some decomposers get energy by breaking

down glucose (or other organic compounds) in down glucose (or other organic compounds) in the absence of oxygen.the absence of oxygen.

The end products vary based on the chemical The end products vary based on the chemical reaction:reaction:• Methane gasMethane gas• Ethyl alcoholEthyl alcohol• Acetic acidAcetic acid• Hydrogen sulfideHydrogen sulfide• Lactic AcidLactic Acid

One-way flow of energyOne-way flow of energy Most solar energy entering ecosystems is absorbedMost solar energy entering ecosystems is absorbed

Heats the atmosphere, oceans, and landHeats the atmosphere, oceans, and land 22––5% is passed through plants to consumers5% is passed through plants to consumers

All energy eventually escapes as heat All energy eventually escapes as heat Entropy is increasedEntropy is increased Re-radiated into spaceRe-radiated into space

Energy flows in a one-way direction through ecosystemsEnergy flows in a one-way direction through ecosystems Light from the Sun is nonpolluting and nondepletableLight from the Sun is nonpolluting and nondepletable In contrast, nutrients are recycled and continually reusedIn contrast, nutrients are recycled and continually reused

Productivity of Producers: Productivity of Producers: The Rate Is CrucialThe Rate Is Crucial

Gross primary Gross primary production production (GPP) (GPP) Rate at which an Rate at which an

ecosystem’s ecosystem’s producers producers convert solar convert solar energy into energy into chemical energy chemical energy as biomass.as biomass.

Figure 3-20Figure 3-20

Net Primary Production (NPP)Net Primary Production (NPP)

NPP = GPP – RNPP = GPP – R Rate at which Rate at which

producers use producers use photosynthesis to photosynthesis to store energy minus store energy minus the rate at which they the rate at which they use some of this use some of this energy through energy through respiration (R).respiration (R).

Figure 3-21Figure 3-21

Food chains and webs show how eaters, the Food chains and webs show how eaters, the eaten, and the decomposed are connected to eaten, and the decomposed are connected to one another in an ecosystem.one another in an ecosystem.

Figure 3-17Figure 3-17

Food WebsFood Webs

Trophic levels are Trophic levels are interconnected interconnected within a more within a more complicated food complicated food web.web.

Figure 3-18Figure 3-18

Decomposers and DetrivoresDecomposers and Detrivores

Decomposers: Recycle nutrients in ecosystems.Decomposers: Recycle nutrients in ecosystems. Detrivores: Insects or other scavengers that feed Detrivores: Insects or other scavengers that feed

on wastes or dead bodies.on wastes or dead bodies.Figure 3-13Figure 3-13

Energy Flow in an Ecosystem: Losing Energy Flow in an Ecosystem: Losing Energy in Food Chains and WebsEnergy in Food Chains and Webs

In accordance with the 2In accordance with the 2ndnd law of law of thermodynamics, there is a decrease in the thermodynamics, there is a decrease in the amount of energy available to each amount of energy available to each succeeding organism in a food chain or web.succeeding organism in a food chain or web.

Energy Flow in an Ecosystem: Losing Energy Flow in an Ecosystem: Losing Energy in Food Chains and WebsEnergy in Food Chains and Webs

Ecological Ecological efficiencyefficiency: : percentage of percentage of useable energy useable energy transferred as transferred as biomass from biomass from one trophic level one trophic level to the next.to the next.

Figure 3-19Figure 3-19