Chapter 3

The Biosphere

I. Ecology

A. scientific study of interactions among organisms

and between organisms and their environment, or

surroundings

B. Ecological Levels of Organization

1. Organism = One individual

2. Population = One group of species in same

place and time

3. Community = Two or more species

(populations) that interact

4. Ecosystem = Communities interacting with

abiotic factors

3-1

5. Biome = Group of “like” ecosystems

6. Biosphere = pertains to area where living organisms

occur (land, water, air)

a. extends from about 8 km (3.6 miles) up to as far as

11 km (5 miles) down

Individual Population

Community

Ecosystem

Biome

Biosphere

C. Ecological Methods

1. Observation

2. Experimenting

3. Modeling = Using math formulas based on

observation and experiments

3-2 I. Energy Flow

A. Producers = (autotrophs) produce their own food

B. Consumers = (heterotrophs) rely on other organisms

for their food

2. Chemoautotrophs – use inorganic chemicals to

make their food

1. Photoautotrophs = use sunlight to make their own

food

1. Herbivores, Carnivores, Omnivores,

Detritivores (feed on plant and animal remains),

Decomposers (break down dead organic matter)

II. Feeding Relationships

A. Food Chain =

Algae

Zooplankton Small Fish

Squid

Shark

One way flow of energy from

producers to consumers

1. Eventually end up with decomposers

Page 69

B. Food Web =

Shows complex

interactions

Page 71

1. All possible

feeding relationships

2. More realistic

C. Trophic Level =

Each step in a

food chain/web

1. Producers are 1st,

consumers 2nd, 3rd etc.

III. Ecological Pyramids

A. Energy Pyramid (Page 72)

0.1% Third-level

consumers

1% Second-level

consumers

10% First-level

consumers

100% Producers

1. Shows the relative amount of energy available at

each trophic level

2. Only 10% is

transferred to

the next level

because

organisms fail

to capture and

eat all of the

food available

B. Biomass Pyramid (page 72)

1. The total amount of living tissue within a given

trophic level

5000 grams

of grain

500 grams of

chicken

50 grams of

human tissue

2. expressed

in terms of

grams

3. represents

the amount

of potential

food

available for

each trophic

level

C. Pyramid of Numbers (Page 73)

1. shows the

relative number

of individual

organisms at

each trophic

level

2. Decreases at

each higher

trophic level

3. Not true for

trees

3-3 I. Cycles of Matter

A. Biogeochemical Cycles

1. Matter is passed from one organism to another

and from one part of the biosphere to another

B. Water Cycle

1. Rain, run-off, evaporation/transpiration,

condensation (clouds) rain

2. Transpiration = water evaporates from plants

leaves to atmosphere

The Water Cycle

Page 75

C. Carbon Cycle

1. Carbon moves in biosphere by: photosynthesis,

respiration, decomposition, volcanoes, coal/fossil

fuels, mining

2. Carbon is a key ingredient of living tissue

Carbon Cycle CO2 in

Atmosphere

Photosynthesis

feeding

feeding

Respiration

Deposition

Carbonate

Rocks

Deposition

Decomposition

Fossil fuel

Volcanic

activity

Uplift

Erosion

Respiration

Human

activity

CO2 in Ocean

Photosynthesis

Page 77

D. Nitrogen Cycle

2. Only bacteria can use Nitrogen gas as is must be

converted to another form for other organisms to use

3. Nitrogen Fixation = bacteria change N into useable

form (ammonia)

1. All organisms require nitrogen to make proteins

4. Such bacteria live in the soil and on the roots of

plants called legumes

5. Other soil bacteria convert nitrates into N gas in a

process called denitrification: releases nitrogen into

the atmosphere

Nitrogen Cycle

Bacterial

nitrogen fixation

N2 in

Atmosphere

NH3

Synthetic fertilizer

manufacturer

Uptake by

producers

Reuse by

consumers

Decomposition,

excretion

Atmospheric

nitrogen fixation

Uptake by

producers Reuse by

consumers

Denitrification

Decomposition,

excretion

NO3 and

NO2

Page 78

E. Phosphorus Cycle

1. Not common in atmosphere

2. Two Cycles:

a. Short-term plants get phosphorus from soil,

animals eat plants and die, phosphorus is back in

soil

b. Long-term rock exposed, phosphorus

washed into sea, gets back into rock

• Organic phosphate

moves through the

food web and to the

rest of the

ecosystem.

Phosphorus Cycle

Ocean

Land

Organisms

Sediments

F. Nutrient Limitation

1. primary productivity of an ecosystem is the rate at

which organic matter is created by producers

a. Controlled by the amount of available nutrients

2. When a a single nutrient is scarce or cycles very

slowly, this substance is called a limiting nutrient

a. When an aquatic ecosystem receives a large

input of a limiting nutrient—such as runoff from

heavily fertilized fields—the result is often an

immediate increase in the amount of algae and

other producers = Algal Bloom disrupts the

equilibrium of an ecosystem.

3-1

The combined portions of the planet in which life

exists, including land, water, and the

atmosphere, form the

A. biosphere.

B. community.

C. species.

D. ecosystem.

3-1

A group of organisms that can breed and produce

fertile offspring is known as a(an)

A. ecosystem.

B. species.

C. biome.

D. community.

3-1

Compared to a community, an ecosystem includes

A. the nonliving, physical environment as well as the community.

B. only the physical environment of an area without the organisms.

C. the entire biome but not the biosphere.

D. only one of the populations within the community.

3-1

An ecological method that uses mathematical

formulas based on data collected is

A. observing.

B. experimenting.

C. modeling.

D. hypothesizing.

3-1

An ecologist marks out an area in a specific

ecosystem and proceeds to identify the number

of insect species in the area. This is an example

of ecological

A. experimentation.

B. observation.

C. modeling.

D. inference.

3–2

The main source of energy for life on Earth is

A. organic chemical compounds.

B. inorganic chemical compounds.

C. sunlight.

D. producers.

3–2

Organisms that feed on plant and animal remains

and other dead matter are

A. detritivores.

B. carnivores.

C. herbivores.

D. autotrophs.

3–2

How does a food web differ from a food chain?

A. A food web contains a single series of energy

transfers.

B. A food web links many food chains toget

C. A food web has only one trophic level.

D. A food web shows how energy passes from

producer to consumer.

3–2

In a biomass pyramid, the base of the pyramid

represents the mass of

A. heterotrophs.

B. primary consumers.

C. producers.

D. top level carnivores.

3–2

The amount of energy represented in each trophic

level of consumers in an energy pyramid is

about

A. 10% of the level below it.

B. 90% of the level below it.

C. 10% more than the level below it.

D. 90% more than the level below it.