Chapter 3

The Biosphere

Section 3-1: What is Ecology?

Ecology - Study of interactions among organisms, between organisms, and their surroundings.

The environment contains two factors:

1. Biotic Factors: all of the living things

2. Abiotic Factors: all of the nonliving items

Section 3-1: What is Ecology?

What is the biosphere?

1. Part of earth where all life exists

2. It’s range is 11 km(6.83 mi) below the surface ocean to 8 km(4.97 mi) above the surface of the ocean.

Section 3-1: What is Ecology?What are the levels of organization?

1. Species- group of organisms that can breed & produce fertile offspring

2. Population - groups of organisms of same species living in same area

3. Community - groups of different populations living in same area

4. Ecosystem - all organisms that live in same area along with environment

5. Biome - group of ecosystems with same climate & similar dominant communities

6. Biosphere - highest level of organization; where all life exists

Section 3-1: What is Ecology?

What are the methods used to study ecology?1. Observing2. Experimenting

A. Setting up an artificial environment in the lab

B. Conducted within the natural environment

3. Modeling A. Often based on mathematical

formulas based on data collection. B. Models are used to make predictions

Section 3-2: Producers & ConsumersWhat are primary producers/autotrophs?

Organisms that make their own food from sun/inorganic chemicals

They produce their food in two possible ways:1. Photosynthesis: Use energy from the sun to make

organic chemicals for energy; (i.e. plants; photosynthetic bacteria; plantlike protists; cyanobacteria)

6CO2 + 6H2O → C6H12O6 + 6O2

2. Chemosynthesis: Capture energy from source other than sunlight; use energy within chemical bonds of inorganic compounds like CO2 & H2S from volcanic vents to make organic molecules ; (example: sulfur bacteria)

Section 3-2: Producers & Consumers

What are consumers/heterotrophs?Organisms that can’t make their own food; they have to eat other organism for food/energy.

There are five types of consumers:1. Herbivores – only eat plants2. Carnivores – eat animals/meat3. Omnivores – eat both plants & animals4. Decomposers – break down dead/organic matter; recycle nutrients (bacteria, fungus)

5. Detritivores - eat decaying stuff (worms)

Section 3-3: Energy Flow

How does energy flow in an ecosystem?

It flows in one direction, from the sun to producers, and then to the consumers and decomposers.

What is a food chain?

A simple series of who eats who.

Section 3-3: Energy Flow

What is a food web?

A complex interaction of all of the food chains in an ecosystem.

Section 3-3: Energy Flow

What is a trophic level?1. One step in the food chain or the food web.2. Producers always occupy the first trophic level.3. Consumers occupy every level after the first.4. Primary consumers are always herbivores.

Section 3-3: Energy Flow

What is an ecological pyramid?

It is a model to show the amount of energy or matter in each trophic level.

There are three types of ecological pyramids:• Energy Pyramid• Biomass Pyramid• Pyramid of Numbers

The pyramid shape implies that there is less at each successive level.

Section 3-3: Energy FlowWhat is an energy pyramid?1. Shows how much energy is available at each trophic

level.2. 90% of the energy is used by the metabolism of the

organisms in that trophic level.3. 10% is passed on to the next trophic level.4. Each level has less and less energy available.

Section 3-3: Energy FlowWhat is a biomass pyramid?

1. Shows how much food is available at each trophic level.

2. There is less food available at each higher level.

3. Measured in g/m2

Section 3-3: Energy FlowWhat is a pyramid of

numbers?

1. Shows the number of individuals at each trophic level.

2. Because there is less energy at each level, there will be less individuals able to survive.

Section 3-4: Cycles of MatterKey idea: Matter is recycled within an ecosystem &

between different ecosystems.

Recycling in the biosphere is done through the biogeochemical cycles.

Types of biogeochemical cycles:1. Water cycle2. Nutrient Cycles:

A. Carbon CycleB. Nitrogen CycleC. Phosphorus Cycle

Condensation

Seepage

Runoff

Precipitation

TranspirationEvaporation

RootUptake

Section 3-4: Cycles of Matter

Water Cycle

Section 3-4: Cycles of Matter

Carbon Cycle

CO2 in the air

CO2 in ocean

Section 3-4: Cycles of Matter

Nitrogen Cycle

N2 in air

NO3- & NO2-NH3

Nitrogen Fixation – some bacteria turn N2 into the useable forms of NO3

- & NO2-. Denitrification – some bacteria convert nitrates into N2.

Section 3-4: Cycles of Matter

Phosphorus Cycle:

1. Phosphorus is needed by living things to form DNA/RNA.

2. Phosphorus DOES NOT enter the atmosphere like C, O, & N.

Section 3-4: Cycles of MatterWhat is primary productivity?

The rate at which producers create organic matter.

What controls primary productivity?Availability of nutrients. This is why fertilizer is added by farmers to their fields.

What is a limiting nutrient?A single nutrient that is scarce or slowly cycled through the ecosystem. For most land ecosystems, the limiting nutrient is nitrogen (N is required for protein production).

Section 3-4: Cycles of MatterWhat is an algal bloom?1. Occurs when an

aquatic ecosystem receives a large input of its limiting nutrient (phosphorus).

2. The rapid growth of algae can disrupt the balance of the ecosystem. Excess phosphorus from lawn fertilizer can cause this.