The BiosphereChapter 3

3.1Levels Within LevelsAn ecosystem is a collection of all

the organisms that live in a particular place, together with their nonliving, or physical, environment.

Within an ecosystem, there are several levels of organization. Your school and its grounds are similar to an ecosystem.

In Your Notebook1. What living things are found

in and around your school?2. What nonliving things are

found in your school?3. Into what large groups are

the students in your school divided?

4. Into what smaller groups are these large groups divided?

What Is Ecology?The scientific study of

interactions among organisms and between organisms and their physical environment.◦How do cats live with dogs?◦Why are some species protected?◦How have humans changed the

landscape and atmosphere here on earth?

Levels of OrganizationLook on pages 64 & 65 in your

bookIn Your Notebook

◦Draw a circle and label it “Me”◦Draw five concentric circles and label

each of them with the appropriate level of organization.

◦Describe your population, community, etc.

Biotic and Abiotic FactorsEnvironment

◦All conditions surrounding an organism

Biotic Factors◦Any living part of the environment

Abiotic Factors◦Any nonliving part of the

environment◦Sunlight, heat, precipitation,

humidity, wind or water currents, soil type

Biotic and Abiotic Factors

In Your NotebookRead Page 67In your own words, explain the

difference between biotic and abiotic factors.

Give three examples of each.

Ecological MethodsObservation

◦What lives here?◦How does an animal protect its

young?Experimentation

◦Artificial environment◦Greenhouse

Modeling◦Global warming◦Solar system

In Your NotebookGive an example of two objects

or activities in your life that are interdependent. Explain your choice.

Suppose you want to know if the water in a certain stream is safe to drink. Which ecological method(s) would you use in your investigation? Explain your reasoning.

3.2 Producers and ConsumersAll living things need energy. Some

organisms can make their own energy from inorganic (nonliving) things in their environment, but other organisms need to consume other living things in order to get energy.

The ways in which an organism obtains energy define its role in its ecosystem—some organisms rely on others for energy, while others compete with each to obtain energy.

Indeed, the need for energy drives many of the interactions that occur within ecosystems.

In Your Notebook1. List five activities that you do

every day that require energy.2. How do you get the energy

that your body needs to carry out its normal functions?

3. What might happen if you didn’t get enough energy for your body to carry out its normal functions? What might happen if you were not using all the energy that you were taking in?

Primary ProducersThe first producers of energy-rich

compounds that are later used by other organisms.

AKA – Autotrophs◦Make their own food◦Plants, Algae and

some bacteria

Primary ProducersPhotosynthesis

◦Using light energy from the sun to convert carbon dioxide and water into carbohydrates

Chemosynthesis◦Use chemical energy to produce

carbohydrates◦Usually found in deepest part of

ocean

In Your NotebookIn your own words, explain two

differences and two similarities between photosynthetic and chemosynthetic producers.

ConsumersOrganisms that rely on other

organisms for energy and nutrients.AKA-Heterotrophs

◦Must get energy from other organisms◦Classified by the way they get their

food Carnivores Scavengers Decomposers Herbivores Omnivores Detritivores

In Your NotebookHow do producers make energy-

rich compounds?

How do consumers get the energy they need for life processes?

What are some different categories of consumers?

3.3 Pass It AlongEnergy flows in one direction

through an ecosystem, from the sun or inorganic compounds to producers (organisms that can make their own food) through various levels to consumers (organisms that rely on other organisms for food).

Your body gets the energy and materials it needs for growth and repair from the foods you eat.

In Your Notebook1. Make a list of five foods that you

like to eat. Indicate whether the food comes from a plant (producer) or an animal (consumer).

2. Like many birds, chickens eat grains, which are seeds. Where do seeds come from?

3. Meat comes from beef cattle. What do cattle eat?

4. Construct a diagram showing how one of your favorite foods obtains its energy. Include as many levels as you can.

Food Chains and Food WebsWhat happens to energy stored

in body tissues when one organism eats another?◦Eaten Eater

How does energy flow through ecosystems?◦Energy flows in a one way stream,

from primary producers to various consumers.

Food Chains and Food WebsFood Chain

◦A series of steps in which organisms transfer energy by eating and being eaten. Vary in length Always start with primary producer

Food Chains and Food WebsMost ecosystems more complicated and don’t have single simple chainFood Web

◦Network of feeding interactions

Food Chains and Food WebDecomposers and DetritivoresMost producers die without being

eaten◦Decomposers convert the dead

material to detritus◦This detritus is then eaten by

detritivores◦Decomposition process also releases

nutrients that get used by primary producers

In Your NotebookExplain how food chains and food

webs are related

Food Webs and DisturbanceWhat happens in this food web if

the population of krill declines?

Trophic Levels and Ecological PyramidsTrophic Level

◦A step in the food chain◦Primary producers are always the

first stepEcological Pyramid

◦Shows the relative amount of energy or matter contained in each level

◦Three types Pyramids of energy Pyramids of biomass Pyramids of numbers

Pyramids of EnergyShows the relative amount of

energy available at each trophic level of the food chain or food web

How does the amount of energyat each level limitthe number oforganisms thatcan live there?

Pyramids of Biomass and NumbersBiomass◦Shows the relative amount of living

organic matterNumbers

◦Shows the relative number of individual organisms at each trophic level

In Your NotebookWrite a creative story about the

organisms that live and interact in a fictitious ecosystem.

Another student is going to read your story and will have to construct a food web for this ecosystem from the details that you include.

3.4 Cycles of MatterLiving organisms are composed

of mostly oxygen, carbon, hydrogen and nitrogen.

Throw in sulfur and phosphorus and you have all nutrients necessary to live.

But organisms can’t make these elements, so where do they come from?

Recycling in the BiosphereEnergy flows in one directionMatter is recycled within and

between organismsBiogeochemical cycle

◦Matter is never created or destroyed◦It just changes forms

Biogeochemical CyclesBiological Processes

◦All activities performed by living things

Geological Processes◦Volcanoes, breakdown of rock,

earthquakesChemical and Physical Processes

◦Clouds, precipitation, lightning, running water

Human Activity◦Mining, burning of fossil fuels,

deforestation

The Water Cycle

In Your NotebookDescribe how each of the

following terms relates to the water cycle.◦Evaporation◦Transpiration◦Precipitation◦Runoff

The Carbon Cycle

In Your NotebookRead page 82Describe one biological, one

geological, one chemical and one human activity that is involved in the carbon cycle.◦Hint: Look at the color coded key

that goes with Figure 3-17

The Nitrogen CycleNitrogen Fixation

◦Bacteria convert nitrogen gas into ammonia

Denitrification◦Conversion of nitrates into nitrogen

gas which is then released into the atmosphere

The Phosphorus CycleVital part of DNA and RNANot found in atmosphere

Nutrient LimitationIf ample sunlight and water are

available, the primary productivity of an ecosystem may be limited by the availability of nutrients.◦If your recipe calls for 2 eggs to make

24 cookies, and you have plenty of flour, sugar, etc., how many cookies can you make if you have 1 egg?, 4 eggs?, 5 eggs?

Limiting Nutrient◦The nutrient that runs out first

Nutrient LimitationSoil

◦Farmers use fertilizers with large amounts of nitrogen, phosphorus and potassium

◦Carbon not necessary, plants get it from the atmosphere

Aquatic Ecosystems◦Ocean usually limited by nitrogen◦Freshwater usually limited by

phosphorus Gets out of balance when runoff from farm

fields gets into water supply

In Your NotebookHow does the matter that flows

through an ecosystem differ from the way that energy flows?

Explain how a nutrient can be a limiting factor in an ecosystem.