Unit 2 – Lecture 2
Ecology
 Ecology  the relationship between an org and its
environment
 Includes relationships between
 biotic and other biotic factors
 biotic and abiotic factors
Important Concepts
 Habitat –
 where an org lives
[tree, lake,
burrow…etc]
 Niche –
 what an org does
 making dams, eating certain orgs,
etc.
 EVERYTHING
it does, basically.

Biotic  Biotic Relationships
 Symbiosis – a relationship between 2 orgs

three types that we will cover:
 mutualism – benefit-benefit
 often referred to as simply symbiosis,
but you must use the more specific term
 commensalism – benefit-unaffected
 parasitism – benefit-harm
Discuss
 Come up with 2 examples
of each of the symbiotic relationships:
mutualism [benefit-benefit]
commensalism [unaffected-benefit]
parasitism [harmed-benefit]
BioticBiotic cont’d
 Other – Non Symbiotic – Relationships
 Predator-Prey –
one org feeds off of the other
 Competition –
 organisms compete for the same resources

Food Chains & Food Webs
 Do Not list humans, decomposers, or scavengers.
 detritovore – feeds off of detritus [dead or decaying
organic matter] – decomposers/scavengers
 Food Chain – a linear representation of feeding
 chains are linear – a single line
 ex:
Food Chains & Webs – cont’d
 Food Web – a branched & often interconnected
representation of feeding
 webs have many branches and interconnections
 ex:
Descriptive Org Terms
 Autotroph – an organism which makes its own food
 “auto-” – self
 “troph” – nutrients / food / feeder
 aka producer
 examples?
Descriptive Org Terms – cont’d
 Heterotroph – cannot make its own food, feeds off of
other organisms
 “hetero” – different
 aka consumer
 “vore” terms – carnivore, omnivore, herbivore,
detritovore/decomposer
Discuss
 What do each of these “vore” terms mean?
carnivore
omnivore
herbivore
detritovore
Descriptive Org Terms – cont’d
 decomposer – obtains nutrients by breaking down
decaying organic matter
 organic – any substance containing the element
Carbon
Sequence Terms for Consumers
 Used in food chains or food pyramids for
CONSUMERS, NOT in food webs. You may use either
of the given terms.
 Primary aka First Order consumers
 eats the producer
 herbivore or omnivore
 Secondary aka Second Order consumers
 eats the primary/1st order consumer
 omnivore or carnivore
Sequence Terms – cont’d
 Tertiary aka Third Order consumer
 eats secondary / 2nd order consumer
 carnivore or omnivore
 Quaternary aka Fourth Order consumer
 eats tertiary / 3rd order consumer
 carnivore or omnivore
 etc…
Terms in Chains & Pyramids
 Top Predator –
 an animal with has no natural enemies
 will always be final step in food chain / pyramid

NOT all pyramids & chains have a top predator

HUMANS ARE NOT TOP PREDATORS…
Discuss / Complete
 Fill in #4 on your sheet using the
terms you just learned in #s 1-3.
[sequence terms, vore terms, and the rest]
Check Your Work!
Producer
Heterotroph
Heterotroph
Heterotroph
Autotroph
1st Order
Consumer
2nd Order
Consumer
3rd Order
Consumer
Primary
Consumer
Secondary
Consumer
Tertiary
Consumer
Omnivore
Carnivore
Carnivore
Top
Predator
Energy/Food Pyramids
 Energy Pyramid – a pyramid-shaped representation of
a food chain
 shows the transfer of energy btw organisms

only 10% of the energy taken in is passed
on to the next trophic level

90% of energy taken in is lost [used for fuel for the
body’s actions and for body’s reactions]
Energy/Food Pyramids
 Energy Pyramid – a pyramid-shaped representation of
a food chain
 trophic level – a nutrient/food level [“troph…”

each step in a food chain, web,
or energy pyramid is a new trophic level

a pyramid will have as many levels as the food
chain it represents
Energy/Food Pyramids
 the terms used to describe orgs on the food chain are
also used for each trophic level here.
 as available energy decreases, the number of
organisms [circle one: also decreases / increases].
Homework
 Complete the Food Chains,
Food Webs & Food Pyramids worksheet
found on pages 6-7 in your packet.