BiologyChapter

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3.1 – What is Ecology?

Interactions and Interdependence• Ecology – the study of interactions among organisms and

their environment

• Oikos (ec) – Greek word meaning house

• Ology – means study of

Levels of Organization• The levels of organization that ecologists study include:

• Individuals

• Species – group of similar organisms that can breed and produce fertile offspring

• Populations – group of individuals of the same species that live in the same area and interbreed

• Communities – several populations that live together in an area

• Ecosystem – The interaction of all the organisms and the environment in a given area

• Biome – a group of ecosystems that have the same climate

• Biosphere – part of Earth in which life exists including land, water and atmosphere

• It extends about 8km above the Earth’s surface to about 11km below

• If you could shrink earth to the size of an apple, the biosphere would be thinner than the apple’s peel

Biotic and Abiotic Factors• Biotic Factors – all the living organisms in an ecosystem

• Example: tree, bird, bacteria, fungi

• Abiotic Factors – nonliving factors in an ecosystems

• Example: temperature, precipitation, wind, soil, sunlight, humidity

• Habitat – area where an organism lives including biotic and abiotic factors

• Niche – the role and position a species has in its environment

• No two species can share the same niche in the same habitat

3.2 – Energy Flow

• Sunlight is the main energy source for life

• Autotrophs

• Make their own energy

• Convert sun energy into chemical energy

• Also called a producer

• Plants are the main autotrophs on land

• Algae are the main autotrophs in water

• Some autotrophs can produce food in the absence of light

• Chemoautotrophs – organisms use chemical energy to produce carbohydrates

• Live in…

• Volcanic vents

• Deep ocean

• Hot springs

• Marshes

• Heterotrophs

• Get energy from other organisms

• Unable to make its own energy

• Also called consumers

• Types of Heterotrophs

• Herbivores

• Eats only plants

• Example: cows, deer, rabbits, bees, elephants, squirrels

• Carnivores

• Eats only animals

• Example: snakes, dogs, lions, crocodiles

• Omnivores

• Eats plants and animals

• Example: humans, bears, crows

• Detrivores

• Eat decomposing bits of organic matter

• Example: mites, earthworms, snails, crabs

• Decomposers

• Break down organic matter

• Example: bacteria and fungi

• Scavenger

• Ingest nonliving plants and animals

• Example: vulture, termite, beetle

Feeding Relationships• Food Chain – a straight line series of steps by which

energy is stored and passed on to higher trophic levels

• Food Web – a network of crossing interlinked food chains that shows all the possible feeding relationships at each trophic level

• Trophic Levels – the different feeding relationships in an ecosystem.

• Plants and other producers are 1st trophic level

• Consumers make up the 2nd, 3rd, or higher trophic levels

• Each consumer depends on the trophic level below it for energy

• Energy is transferred from one trophic level to another and is never 100%

• At each trophic level only 10% of the energy taken in by the organism is stored.

• Energy is passed through no more than four or five trophic levels

Ecological Pyramids• Ecological Pyramid – a diagram that shows the relative

amounts of energy or matter contained within each trophic level in a food chain or food web

3-3 Cycles of MatterProperties of Water• Water is perhaps the most important compound in living

organisms

• Water serves as a means of material transportation in organisms.

• Ex. Blood (is mostly water)

• Hydrogen bond – attraction between opposite charged molecules (H+ O-)

• Are important because they help hold many large molecules such as proteins together.

• Water resists changes in temperature

• Water requires more heat to increase its temperature.

• Water is like an insulator

• maintains homeostasis

• Water is one of the few substances that expands when it freezes.

• Ice is less dense than liquid

• Cohesion – attraction between like molecules

• Cohesion creates tension

• Tension – inward pulling on water molecules at the surface

• Adhesion – attraction between different molecules

• Biogeochemical Cycles – chemicals and nutrients are transferred from environment into organisms then back to the environment

The Water Cycle• Evaporation – process by which water changes from a

liquid to a gas

• Transpiration – loss of water from plants by the process of evaporation

• How does water move up a plant?

• Xylem – tubes in plants that transport water from roots to leaves.

• On sunny days, water evaporates from leaves

• Adhesion & Cohesion pulls up more water molecules into leaf cells

• Condensation – water vapor changes to a liquid

• Precipitation – water returns to the earth (rain, snow, hail)

Click to view animation.

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CO2

Organism eats plants

C6H12O6

Respiration

Burning Trees

Burning Fossil Fuels

Volcanic Activity

Oil Coal

Decomposition

Root Uptake

Photosynthesis

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Gaseous Nitrogen

N2

Ammonification

Bacteria convert wastes and decomposing organics to

NH3 → NH4

Nitrogen Fixation

Bacteria in the soil convert

N2 → NH3 → NH4

Denitrification

Bacteria convert

NO3 → N2

Nitrification

Bacteria convert

NH4 → NO2 → NO3

Autotrophs can take up NH4 and NO3

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• Humans are harming the nitrogen cycle by:

• Deforestation

• Conversion of grasslands for agriculture

• Sewage enters waterways

• Fossil fuel burning

• Vehicles having combustion engines releases NO2