BIOLOGY: ECOLOGY Study Guide
**This study guide is meant as a GUIDE. It is not a substitute to studying the notes; learning the vocabulary or completing the review sheet(s). **
ECOLOGY: The study of the interactions between organisms and the living (biotic) and non-living (abiotic) components of their environment.
Everything’s connected! - Interdependence and Interconnectedness of everything in the environment:
Hierarchy: Species -> *Population (all members of one species living in the same area) -> community (all biotic factors in an ecosystem) ->
*Ecosystem (particular area in a biosphere, including biotic and abiotic) ->
Environment -> Biosphere (all living organisms and what supports them soil, water, air) *Remember a habitat is the PHYSICAL area is which an organisms lives.
Population Growth: Human population growth has grown the most over the past century (1900 – 2000) - Results in an increasing need for: Food, energy, space, waste disposal
Review Ozone & Global Warming:
 Ozone (O
3
) found in the earth’s upper atmosphere protects our planet from suns rays (UV light)
 *This UV light is a major contributor to skin CANCER
 *CFC’s (chlorofluorocarbons) are industrial chemicals that are depleting the ozone layer
THE GREENHOUSE EFFECT → A good thing really!
 Greenhouse gases (CO
2
, H
2
0 vapor) take some of the light reflecting off of the earth and direct it back towards the earth (like a mirror)
 This helps insulate earth and make it suitable for life
 HOWEVER,* human activities (burning of fossil fuels) have added to the amount of greenhouse gases, causing this insulating effect to be a bit too much …Global warming…BAD! Too much greenhouse effect -* Not everyone agrees that global warming is happening…
Review ECOLOGY of ORGANISMS
RESOURCES:
 Energy and materials a species needs to survive o (FOOD, NESTING SITES, WATER, SUNLIGHT)
*NICHE:
 The role a species plays in its environment o FUNDAMENTAL NICHE:
 The range of conditions a species can physically tolerate o REALIZED NICHE: (usually smaller than the fundamental niche)

 The range of resources a species actually uses
 *GENERALIST: species with broad niches (Humans,
Raccoons)
 *SPECIALIST: species with narrow niches (Koala, Panda)
Pay special attention to the SPECIES INTERACTIONS below:
SYMBIOSES or SYMBIOTIC RELATIONSHIPS – Lichen is in a symbiotic mutualistic relationship between an autotroph and a fungus
1) PREDATION: A relationship in which one organism, the PREDATOR (i.e. Great
White Shark), captures, kills, and consumes another – the PREY (i.e. seals)
 Predators adapt to become better at capturing prey; prey adapt to become better at avoiding predators = *causes coevolution
 OFFENSES: o For instance: *Spider webs that trap insects; stripes on tigers coat to blend in; rattlesnakes heat sensitive pits that detect warm bodied prey; flesh-tearing teeth; Snake venom
 DEFENSES: o For instance - *Mimicry: when a harmless species resembles a poisonous or distasteful species; when two or more dangerous or distasteful species look alike (like *bright colorations on a nonpoisonous frog) and irritating chemicals (*secondary compounds - poison ivy)
2) PARASITISM: Relationship in which one organism is harmed while the other benefits – *Host is not immediately killed o Ectoparasites : Live on host but do not enter the body (deer ticks, fleas, lice) o Endoparasites : Live inside host (disease-causing bacteria, tapeworms)
3) COMPETITION: Due to niche overlap - *Most intense between closely related species because they use the same resources.
4) MUTUALISM: Relationship in which both species derive some benefit:
 EXAMPLE: Pollinators, Lichens
*
5) COMMENSALISM: Relationship in which one species benefits and the other is unaffected
 EXAMPLES: Epiphytes –
Review your Biomes Chart! Biomes are distinguished by the presence of characteristic plants and animals, as well as typical weather and climate
Know some basic information about each BIOME:
 7 major biomes exist in the world: For example:

1.
Tundra –trees are unusual in the tundra because permafrost prevents root growth
2.
Taiga – trees are adapted to the cold weather
3.
Temperate Deciduous Forest - presence of trees that lose their leaves during winter
4.
Temperate Grassland
5.
Desert
6.
Savanna
7.
Tropical Rain Forest – For instance: they are found near the equator, high in species richness, they are rapidly disappearing
Be familiar with Ecological Succession: Gradual, sequential re-growth of species in an area **Organisms come and go and change the environment so that they can support the growth of other species.
PRIMARY SUCCESSION – Development of a community in an area that has not
previously supported life - For instance, on bare rock, sand dunes, islands formed by volcanic eruption, glacier retreating
 Slower (because soil layer must be established)
SECONDARY SUCCESSION: Re-establishment of life following the disruption of an existing community…Forest fire, farming, logging, etc.
 More rapid (because soil is intact)
 Pioneer species – Predominate early in succession - small, fastgrowing, fast-reproducing and can disperse their seeds over a large area - Crabgrass, ragweed, lichen
Review the Ecosystem Cycles
Water, minerals, and nutrients are always reused/recycled in an ecosystem
They travel through BIOCHEMICAL CYCLES (i.e the Water, Carbon and Nitrogen
Cycles) For example: Remember that carbon can be followed through the processes of PHOTOSYNTHESIS and RESPIRATION
And that nitrogen fixing bacteria “fix” nitrogen gas and covert it into ammonia
(NH3) that plants can then use.
Review ENERGY TRANSFER IN AN ECOSYSTEM
PRODUCERS – make their own food - plants, some bacteria, protists
CONSUMERS – cannot make their own food
 CONSUMERS:
 HERBIVORES – eat producers (caterpillar, antelope, deer)
 CARNIVORES – eat other consumers (lions, cobras, praying mantises)
 OMNIVORES – eat producers and consumers (humans, grizzly bears)
 DETRITIVORES – feed on ecological “garbage” (recently dead, fallen leaves; animal waste, etc.) For example - Decomposers – break down complex molecules in dead organic matter into smaller ones (fungi, bacteria) and return those nutrients to the soil

Review TROPHIC LEVELS
 An organism’s position in the sequence of energy transfer -> energy flows from producers to consumers o Energy transfer is never 100% efficient o Some biomass cannot be consumed
 Therefore, higher levels access less energy and support fewer organisms
 **For example: Producers are found on the lowest tier of the trophic pyramid)
FOOD CHAIN – a single pathway of feeding relationships among the organisms in an ecosystem
FOOD WEB - Depicts all the interrelated food chains within an ecosystem