Transcript Communities and Ecosystems 5.1

5.1 Communities and Ecosystems
Assessment Statements
•Define species, habitat, population, community, ecosystem, and ecology
•Distinguish between autotroph and heterotroph
•Ditinguish between consumer, detritivores and saprotrophs
•Describe what is meant by a food chain, giving three examples, each with at
least 3 linkages (4 organisms)
•Describe what is meant by food web
•Define trophic level
•Deduce the trophic level or organisms in a food chain and a food web
•Construct a food web containing up to 10 organisms, using appropriate
information
•State that light is the initial energy source for almost all communities
•Explain the energy flow in a food chain
•State that energy transformations are never100% efficient
•Explain reasons for the shape of pyramids of energy
•Explain that energy enters and leaves ecosystems, but nutrients must be
recycled.
•State that saprotrophic bacteria and fungi (decomposers) recycle nutrients.
Create a food chain with at least 5 organisms
1. Ocean
2. Freshwater Lake
3. Desert
4. Temperate Forrest
5. Rain Forrest
6. Antarctic Ocean
7. Tundra
8. Savanna
9. Temperate Grassland
10.Coral Reef
Label Autotrophs/ Producers, and Heterotrophs/Consumers
Show energy flow of food chain with arrows
Label the Trophic Levels
Include decomposers at the end of the chain
What are detritivores and saprotrophs?
Species: a group of organism that can
interbreed and produce fertile offspring
Habitat: the environment in which a species
normally lives or the location of a living
organism
Population: a group of organisms of the same
species who live in the same area
Community: a group of populations living and
interacting with each other
Ecology: the study of relationships between living
organisms and between organisms and their
environment
Ecosystem: a community and its abiotic (nonliving; temperature, humidity, wind, rainfall
etc.) environment
Autotroph/Heterotroph
Autotroph: an organism that synthesizes its organic
molecules from simple inorganic substances
Heterotroph: an organism that obtains organic
molecules from other organisms
Consumers, Detritivores, Saprotrophs
Consumers: an organism that ingests other organic
matter that is living or recently killed.
Detritivore: an organism that ingests non-living
organic matter.
Saprotrophs: an organism that lives on or in nonliving organic matter, secreting digestive enzymes
into it and absorbing the products of digestion,
examples; bacteria and fungi
Define the terms species, population and community.
Species: Population:. Community: [3]
Food Chain
Producer
Oak tree
Quercus
Sea
lettuce
Ulva
Saguaro
cactus
Carnegiea
→
Primary
consumer
→
Caterpillar
Archips
→
Finger limpet
Collisella
→
Jackrabbit
Lepus
→
Secondary
consumer
→
Spotted towhee
Pipilo
→
Rock crab
Cancer
→
Rattlesnake
Crotalus
→
Tertiary
consumer
→
Cooper’s
Hawk
Accipitor
→
Giant
Octopus
Octopus
→
Red-tailed
Hawk
Beauteo
Trophic level
Trophic level is the position of an organism in a food
chain
5th trophic level
4th trophic level
3rd trophic level
2nd trophic level
1st trophic level
Describe what is meant by a food chain using an
example with four named organisms. [4]
food chains describe the feeding relationships between
species;
arrows show (one) path of energy flow in an ecosystem /
energy flow described;
food chain with arrows pointing in the correct direction;
producer first step in chain;
three other named organisms making a realistic food
chain; [4 max]
Accept explicit common names exact enough to identify
the food source e.g. Oak not
tree, sparrow not bird, rye grass not just grass, etc.
Food Web
Few consumers feed on only one source of food. A food
web shows a much more realistic picture of the feeding
relationships of the organisms in a habitat.
Organisms can change trophic levels depending on
what they are eating at any particular time.
Describe what is meant by a food
chain and a food web. [6]
The diagram below shows a simplified food web for a lake
State the initial energy source for the above food web. [1]
Define the term trophic level. [1]
Deduce the trophic level of the immature game fish.[1]
In the food web shown, identify one heterotroph and one autotroph. [1]
Explain, using an example of a food chain, how trophic levels
can be deduced. [4]
Energy and Food Chains
State that light is the initial energy source for almost
all communities.
Energy and Food Chains
Arrows in a food chain show the direction of flow of both the energy and
nutrients that keep organisms alive.
Energy flow through an ecosystem can be quantified and analyzed.
At each step in the food chain, energy is lost from the chain in various ways.
Some is not consumed, some leave the food chain as waste or when an
animal dies, and some is used by living organisms as they respire.
The lost energy cannot be passed to the next trophic level.
STATE: Energy transformations are never 100% efficient
An area of the African savannah where grass, antelopes and
cheetahs form a simple food chain
Energy loss 1 –not consumed. The grass stores energy from photosynthesis but
antelopes only eat some parts of the grass, so they don’t consume all the energy stored.
Energy loss 2- not assimilated. The grass that is eaten passes through the digestive
system of the antelope but not all of it is digested and absorbed, some passes out in the
feces.
Energy loss 3- cell respiration. The antelope uses energy to move and keep its body
temperature constant. As a result, some energy is lost to the environment as heat.
The energy remaining after respiration goes into building the antelope’s body, and this
energy becomes available to the cheetah when it eats the antelope.
Transfer of energy between trophic levels is represented by
energy pyramids.
The width of each of the levels in the pyramid is proportional
to the amount of energy it represents
Energy losses occur at every step in a food chain.
Every link in the chain results in losses, so that eventually there
will be insufficient energy to support any further trophic levels.
That’s why most food chains contain between 3 and 5 organisms.
Energy enters an ecosystem is light, converted to stored chemical
energy and finally is lost as heat.
The diagram below represents an energy pyramid and
four trophic levels.
Identify the trophic level of the organisms indicated below.
I: IV
[2]
(ii) Calculate the approximate amount of energy in kilojoules
transferred in m–2 yr–1
from trophic level I to trophic level II.
______________________kJ
Explain the reason for the shape of a
pyramid of energy. [3]
Energy Flow and Nutrient Recycling
All organic matter from organisms, including everything from
living or dead material or waste, is eventually consumed by
other organisms.
All these organisms respire and release energy as heat.
All the energy that enters an ecosystem as light energy is
trapped by photosynthesis, will eventually be converted to heat
and become unavailable to be used again by living things.
Nutrients are continually recycled.
A nitrogen atom may be absorbed as nitrate by a plant root, and used
to make an amino acid.
The amino acid may pass into an
Animal when the plant is eaten,
And then pass out of the animal’s
Body during excretion.
Soil bacteria may convert urea
In the excreted material back
Into nitrate and the cycle begins.
STATE: Saprotrophic bacteria and fungi (decomposers)
recycle nutrients