chapter 3: the biosphere

Chapter 3: The Biosphere

ECOLOGY-the study of interactions among organisms & between organisms and their environment or surroundings.

LEVELS OF ORGANIZATION:BIOSPHERE-the largest level…to include all living things 8 km above the Earth’s surface & 11 km below the surface of the ocean.

BIOMEGroup of ecosystems that have the same climate and dominant

communities.

ECOSYSTEM*A collection of all the organisms

that live in a particular place, together with their non-living,

physical environment.*Lowest level of environmental

complexity that includes living & non-living factors.

COMMUNITY*The simplest group of more than one kind of organism in the biosphere.*Different populations that live together in a defined area.

POPULATIONAll members of the same

species that live in one area.

SPECIES (Individual)*Group of organisms so similar to one another that they can breed and produce fertile offspring.

•Species make up _________.•Populations make up _____.•Communities make up _____.•Ecosystems make up _____.•Biomes make up the ________.

ECOLOGICAL METHODS*Basic methods used by ecologists to study the living world are:

*Observing*Experimenting*Modeling

OBSERVING**Simply making observations of what the scientist is studying.

EX: Counting populations of a certain species.

EXPERIMENTING*Experiments are used to test hypotheses…these can take place outside in the field OR in a laboratory.

MODELING*Models are used when studies involve long periods of time or when the study involves large complex systems.*Ecological models may consist of mathematical formulas based on data collected through observation & experimentation.

EX: Predicting a population fluctuations in a community…

3-2 Energy Flow*Sunlight is the original source of almost all the energy in most ecosystems…it is the main energy source for life on Earth.

In FEW ecosystems organisms get their energy from another source.*Some types of organisms rely on the energy stored in inorganic chemical compounds.(Inorganic = without carbon)EX: Chemo synthetic bacteria

AUTOTROPHS*defined…An organism that uses energy to produce its own food supply from inorganic compounds.*Autotrophs capture energy from sunlight or chemicals to produce food.

EXAMPLES OF AUTOTROPHS:*Plants, some algae, & certain bacteria;*Autotrophs are also called producers.

PRODUCERDefined…organism that can capture energy from sunlight or chemicals & use it to produce food from inorganic compounds.

PRODUCERS = AUTOTROPHS

PRODUCERS ARE ESSENTIAL TO THE FLOW OF ENERGY IN THE

BIOSPHERE.Autotrophs use the sun’s energy to make food through a process called PHOTOSYNTHESIS.

PHOTOSYNTHESIS(Photo = light)

Process by which plants & some other organisms use light energy to power chemical reactions that convert water & carbon dioxide into oxygen & food/energy molecules.

Photosynthesis- Page 68…Figure 3-5

6 CO2 + 6 H2O --- C6H12O6 + 6 O2

Which element does each letter in the formula stand for?

CONSUMERSDefined…organism that relies on other organisms for its energy & food supply…also called a HETEROTROPH.

HETEROTROPHDefined…An organism that CANNOT MAKE its own food.

Types of Heterotrophs:•HERBIVORE- organisms that obtain energy by eating only PLANTS.•CARNIVORE- organisms that obtain energy by eating animals.•OMNIVORE-organisms that obtain energy by eating plants & animals.

DETRIVORES-

Organisms that obtain their energy by feeding on the remains of plants, animals, & other dead matter.DETRIUS- dead plant & animal remains (& other dead matter).

DECOMPOSER-Heterotrophic organism that breaks down & obtains energy from dead matter.

*****KNOW EXAMPLES OF ALL TYPES OF CONSUMERS!!

FEEDING RELATIONSHIPSEnergy flows through an ecosystem in ONE direction…from the sun or inorganic compounds to PRODUCERS (autotrophs) and to various CONSUMERS (heterotrophs).

FOOD CHAINSFigure 3-7 Page 69

FOOD CHAIN- a series of steps in an ecosystem in which organisms transfer energy by eating or by being eaten!**Food chains show a ONE WAY ONLY energy flow in an ecosystem.

FOOD WEBS•FOOD WEB- a network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem.•A food web links all the food chains in an ecosystem…See Figure 3-8 page 71;

Each step in a food web is called a TROPHIC LEVEL.A TROPHIC LEVEL…is a “feeding level” one step in a food chain or food web.**Producers make up the FIRST trophic level.

CONSUMERS MAKE UP:*2nd Trophic Level (primary consumers)*3rd Trophic Level (secondary consumers)*4th Trophic Level (tertiary consumers)*5th Trophic Level (quaternary consumers)

ECOLOGICAL PYRAMIDSPAGE 72

Defined…A diagram that shows relative amounts of energy or matter contained within each trophic level in a food chain or food web.

3 Types of Ecological Pyramids:•ENERGY PYRAMIDS•BIOMASS PYRAMIDS•PYRAMIDS OF NUMBERS

ENERGY PYRAMID*shows the relative amount of energy available at each trophic level.*Only 10% of the energy is passed from one trophic level to the next. The rest is ‘lost’ as heat.

BIOMASS PYRAMID*Represents the amount of living organic matter at each trophic level.*The greatest biomass is usually at the bottom of the pyramid!!

BIOMASS- the total amount of living tissue within a given trophic level. Biomass is usually expressed in terms of grams of organic matter/unit area.

A biomass pyramid represents the amount of potential food available at each trophic level in the pyramid.

PYRAMID OF NUMBERS…shows the relative numbers of individual organisms at each trophic level.

Because each trophic level harvests only about 1/10 of the energy from the level below, it can only support about 1/10 the amount of living tissue.

3-3 CYCLES OF MATTERUNLIKE the one way flow of

energy, MATTER is RECYCLED within and between ecosystems.

BIOGEOCHEMICAL CYCLESDefined…process in which elements, chemical compounds, & other forms of matter are passed from one organism to another AND from one part of the biosphere to another.

THE WATER CYCLEEVAPORATION- process by which water changes from a liquid to a gas.TRANSPIRATION-evaporation of water from the leaves of plants.

Precipitation- rain, snow, sleet, or hail.RUN OFF-water that runs along the surface of the Earth;

GROUNDWATER- water that seeps into soil;

NUTRIENT CYCLE*Nutrients-chemical substances required to keep an organism alive.

CARBON CYCLE*Carbon is a key ingredient in all living organisms.*Be sure to study the carbon cycle on page 77 for your test!!!

CARBON CYCLE *Carbon cycles between various components of the biosphere….BIOLOGICAL-Photosynthesis, respiration, decomposition;GEOCHEMICAL-release of CO2 by volcanoes.

(Carbon Cycle)*Human Activity-mining, industry, burning fossil fuels;*MIXED BIOGEOCHEMICAL PROCESSES-burial of organisms that turn into fossil fuels such as coal.

NITROGEN CYCLE*All organisms require nitrogen to make amino acids which in return make PROTEINS.*There are many different forms of nitrogen: Nitrogen Gas (N2); Ammonia (NH3); Nitrate Ions (NO3

-); Nitrite Ions (NO2

-);

(Nitrogen Cycle)*Nitrogen gas in the atmosphere is very abundant but cannot be used DIRECTLY by most organisms.Only certain types of bacteria can use the “free nitrogen”.

NITROGEN FIXATION

Defined…the process of converting nitrogen gas into ammonia…this is carried out by bacteria that live in “nodules” on the roots of certain types of plants.

Other bacteria convert ammonia into nitrates & nitrites.*Once the nitrates & nitrites are available…PRODUCERS can use them to make proteins.CONSUMERS eat the producers & reuse the nitrogen to make their OWN proteins.

(Nitrogen Cycle)*When organisms die, decomposers return nitrogen to the soil as ammonia. Plants are able to use ammonia (fertilizer!!);

DENITRIFICATIONDefined…the conversion of nitrates into nitrogen gas (with the help of certain bacteria!)

*This process releases nitrogen into the atmosphere.

PHOSPHORUS CYCLE*Phosphorus is important to living things because it forms important life sustaining molecules such as DNA & RNA.

(phosphorus cycle)*Phosphorus does not enter the atmosphere like carbon, water, & nitrogen.

It remains mostly on land and in oceans.

NUTRIENT LIMITATIONPRIMARY PRODUCTIVITY-the rate at which organic matter is created by producers.

LIMITING NUTRIENT-Defined…a substance that is scarce or cycles very slowly and therefore limits the ecosystem…in terms of an organism’s growth.