Chapter 3: The Biosphere

What is ecology?

Ecology

• Ecology – the study of interactions among organisms and between organisms and their environment

• Interdependence – dependence of every form of life on other living things and natural resources (air, water, land) in its environment

Levels of Organization• Biosphere – largest, portions of planet

where life exists (land, H2O, air)– 8 km above to 11 km below

• Biome – group of ecosystems with same climate (temp. and rainfall)

• Ecosystem – collection of all organisms in a particular place together with the abiotic (physical) environment.

Levels of Organization• Community – groups of different

populations that live together in a defined area.

• Population – groups of individuals of same species in same area.

• Species – group of organisms so similar that they can mate and produce fertile offspring.

Levels of Organization

Biotic and Abiotic Factors• Biotic – living

– Plants, Animals ,Mold, Fungi, Bacteria, Protist

• Abiotic – Nonliving– Sunlight, soil, wind, water,

temperature

• Habitat – the area where an organism lives; includes both biotic and abiotic factors.

Ecological Methods1. Observation – 1st step to

designing an experiment

2. Experiment – test hypotheses; imitate & manipulate

3. Modeling – make models based on observation & experiment

• Helps make future predictions

3.2 ENERGY FLOW (Autotrophs and Heterotrophs)

• One of the most important factors to determine capacity to sustain life is Energy Flow

Autotrophs (producers)• Can trap light energy to produce food (organic

molecules)– Plants– Some protists– Some bacteria

• Photosynthesis – captures solar energy and converts it to chemical energy

6CO2 + 6H2O C6H12O6 + 6O2

• Chemosynthesis – Chemical energy used to produce carbohydrates

SUN

Heterotrophs (consumers)

• Can’t trap energy directly; must acquire it from other organisms– Herbivores – plants– Carnivores – animals– Omnivores – both– Detritivores – remains of

dead plants & animals– Decomposers – break down

organic matter

3.2 Energy Flow in Ecosystems

• Food Chains and Food Webs

Food Chains and Food WebsSUN Autotrophs Heterotroph

1. Food Chain – energy trapped by producers passed on when organisms eat and are eaten

2. Food Web – relationship more complex than a chain

Trophic Levels and Ecological Pyramids

• Trophic Levels – each step in a food chain/web

Ex: producers, then consumers• Ecological Pyramids – shows relative amount of energy

at each level (10% rule)• Biomass – total amount of living tissue within a trophic

level

Trophic Levels and Ecological Pyramids

3.4 Cycles of Matter

*Recycle Matter*

Carbon Cycle

• Photosynthesis – uses CO2 from atmosphere– Happens in the CHLOROPLAST

6CO2 + 6H2O C6H12O6 + 6O2

• Respiration – returns CO2 to atmosphere– Happens in the MITOCHONDRIA

C6H12O6 + O2 H2O + CO2

Carbon Cycle

The Carbon Cycle

1. Volcanoes, respiration, fossil fuels, and decomposition add CO2 to atmosphere.

2. Plants take CO2 and make carbohydrates3. Plants are eaten by animals and carbohydrates

are passed through the food chain.4. As the animal breathes and eventually dies and

decomposes CO2 is return to atmosphere.

Decomposing Fox

Water Cycle

Water Cycle1. Water enters the atmosphere by:

• Evaporation – water changes from a liquid to a gas

• Transpiration – Evaporation through leaves

2. As water rises it cools condenses into tiny droplets that form clouds.

3. Droplets return to Earth as precipitation.4. Water enters the rivers, ground water, ocean

or plant roots to restart cycle. Making Clouds

Nitrogen Cycle

Nitrogen Cycle

1. Nitrogen gas makes up 78% of atmosphere

2. Nitrogen Fixation: bacteria take nitrogen gases and turn it into ammonia, nitrite, and nitrate.

3. Plants and animals use nitrate to make amino acids.

4. Animal dies and decomposes returning nitrates to the soil.

5. Denitrification: other bacteria convert nitrates into nitrogen gas.

Fertilizer Runoff

Nutrient Limitation• Primary Productivity – the rate at which

organic molecules are created by producers

• If nutrients are in short supply, they are called LIMITING NUTRIENTS

Ex: Nitrogen is often limiting in water; if there is suddenly as input of N (fertilizer runoff), organisms can grow rapidly (Algal Bloom)

Human ImpactsLook at each of the cycles in your notes. In each cycle there is at least one to two ways that imbalance can occur.• Identify the sources of imbalance and in

particular how human activities upset the cycles.• Explain how this imbalance impacts the cycle

and potential ecological problems that could result.

• You should identify at least one imbalance for each cycle (water, nitrogen, and carbon)?

• Each table group will turn in one paper with your answers.