Download Ecology Unit Study Guide Levels of organization Organism

Ecology Unit Study Guide
Levels of organization
Organism 
(individual)
population
organisms of one species ex. all elk, all oaks)

community
(all biotic organisms in ecosystem)

ecosystem
(all biotic and abiotic components in environment)
 biosphere
all ecosystems
Places in an ecosystem:
Habitat: the address or place in an ecosystem that provides an organism with its needs
Niche: the job or role of an organism in an ecosystem. This describes what it eats, how it lives/eats, and where it lives. This is a very specific
description. Two different species of organisms do not occupy the same niche. If they do, there is competition and one organism does not survive.
Roles in an ecosystem:
Producers
plants, green bacteria, algae. They go through photosynthesis which creates food for all other organisms. They are the basis of all food chains.
Producers make their own food and use it for energy. Producers also go through respiration.
Consumers
Must “eat” or ingest other organisms for energy. They use this food in the process of respiration, which releases energy from their food. There are three
classes of consumers: herbivores eat plants, carnivores eat other animals, omnivores eat everything.
Decomposers
These organisms (bacteria, fungus) digest their food outside the organisms and absorb the nutrients. After absorbing their food, they also go through the
process of respiration
These roles cycle matter through an ecosystem and move energy through an ecosystem.
Trophic Levels
These are feeding or food levels. The first level is always a producer, the next level is a primary (1 st) consumer, the next level is a secondary consumer,
etc.
Food Chains
Show one way matter and energy can move. The arrows always point in the direction of energy movement. Food chains always start with a producer
Food Webs
Show the energy relationships in an ecosystem. The arrows show which way energy is moving. Organisms in a food web may have more than one
source of food, they may also be prey to several organisms.
Ecological Pyramids
At each level, only 10% of the energy is available from the lower level. The remaining 90% is used by the organism or released as heat.
Decomposers are found at every trophic level
Types of pyramids:
Energy Pyramid: show available energy at each trophic level, only 10% of energy on one level is available to the level above it. The 1 st trophic level is
always a producer. You can convert a food chain to an energy pyramid.
Numbers Pyramid: show the number of organisms at each trophic level, again, the lowest level is the producers
Biomass Pyramid: shows the mass of organic material available for energy at each trophic level.
Relationships in an Ecosystem:
Cooperation: organisms of the same species working toward a common goal. Organisms that hunt together or live some sort of colony demonstrate
cooperation
Competition: organisms of the same or different species that both need a limited resource (food, shelter, mates)
Symbiosis: organisms of DIFFERENT species that live in a very close relationship. At least one member benefits from the relationship
Mutualism: both species receive a benefit
Parasitism: one benefits (parasite) the other is harmed (host)
Predator/Prey: one organisms uses another for food. The predator hunts and eats the prey
Matter and Energy:
Matter recycles through a food web, energy moves in one direction. Energy is changed to different forms as it moves through a food web.
Carbon Cycle: processes that move carbon between the biotic and abiotic (physical) parts of an ecosystem.
Photosynthesis (ab), respiration (ba), consuming (bb), decomposition (ba), combustion (b/aa), diffusion (aa)
Carbon is also stored in fossil fuels, sea shells and limestone. The largest reservoir of carbon is the oceans
Humans affect the carbon cycle by burning fossil fuels & deforestation which increases the amount of CO 2 in the atmosphere, increase global warming
and increase the amount of acid rain.
Nitrogen Cycle: processes that move nitrogen between the biotic and abiotic (physical) parts of an ecosystem. 78% of the air is N 2 gas, only a few
bacteria can use it in this form so it has to be changed. Fixing: Bacteria and lightning chemically change nitrogen so that organisms use it. Nitrification:
bacteria bond nitrogen so that it can be absorbed by plants. Denitrification: bacteria convert nitrogen compounds back into N2 gas. Consuming moves
nitrogen from one living organism to another. Living things need nitrogen in order to make proteins and DNA.
Humans affect the nitrogen cycle by releasing fertilizer into surfaces, this increases algae growth and can “kill” a stream or lake