5.1 communities and ecosystems. what do these words mean? give examples of organisms from each...
TRANSCRIPT
TOPIC 5: ECOLOGY AND
EVOLUTION5.1 Communities and ecosystems
AUTOTROPHS VS HETERTROPHS What do these words mean? Give examples of organisms from each
group.
DETRITIVORES Ingests and then digest dead organic
matter Eg. Earthworms, woodlouse
SAPROTROPH An organism that lives in or on non-
living organic matter They secrete digestive enzymes into it
and absorb the products of digestion Digest first, then absorb Nature’s recylers – recycle nutrients Heterotrophs
Eg. Fungi, bacteria
CONSUMER An organism that ingests other organic
matter that is living or recently killed Heterotrophs
FOOD CHAINS Show the flow of energy
through the trophic levels of a feeding relationship
Trophic level: feeding position of an organism in food chain
Each organism feeds on the organism before it
Arrows point towards the consumer Indicate the direction of
energy and nutrient flow
WHAT IS WRONG WITH THIS?
CHALLENGE Group A: Create a food chain with three
linkages (four organisms) from a desert ecosystem
Group B: Create a food chain with three linkages (four organisms) from a grassland ecosystem
Draw on the whiteboard. Now lets label it together as a class.
FOOD CHAIN EXAMPLES
Tertiary consumers
Secondary consumers
Primary consumers
Producers
CHALLENGE
Can you pick out a 3 step food chain and a 4 step food chain?
Can you find two organisms that fit into more than one trophic level?
FOOD WEB Shows complex feeding relationships
showing interacting food chains
CHALLENGE ANSWERS
ENERGY
Light is the initial source of energy for almost all communities
This comes from the SUN
ENERGY FLOW Energy flows through food chains, but
some (90%) is lost between each trophic level
Loss is due to:Material not consumedMaterial not assimilatedHeat loss through cellular respiration
Nutrients are recycled
ENERGY PYRAMIDS Show the flow of energy between trophic
levels Never 100% efficient, around 90% loss The width of the bars is proportional to the
energy in that tropic levelOnly approx. 10% of energy is passed on to the next trophic level.
Unit = kJ m-2 y-1
HOMEWORK DBQ pg. 169 Working with data pg. 170