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Topic 5 and Option G - Ecology
5.1 Communities and Ecosystems
5.1.1Define: (1)
Ecology—the study of relationships between living organisms and between organisms and their environment.
Ecosystem—a community and its abiotic environment. Population—a group of organisms of the same species who live in the
same area at the same time. Community—a group of populations living and interacting with each
other in an area. Species—a group of organisms which can interbreed and produce
fertile offspring. Habitat—the environment in which a species normally lives or the
location of a living organism.
5.1 Communities and Ecosystems
5.1.2autotroph (producer) – organisms that use
an external energy source to produce organic matter from inorganic raw materials
Examples: trees, plants, algae, blue-green bacteria
What process are they doing????
5.1 Communities and Ecosystems
heterotroph (consumer) – organisms that use the energy in organic matter, obtained from other organisms
Examples: ????
5.1 Communities and Ecosystems
1. consumers – feed on other living things
2. detritivore – feed on dead organic matter by ingesting it
3. saprotroph (decomposer) – feed on dead organic material by secreting digestive enzymes into it and absorbing the products
So, what’s the difference here???
5.1 Communities and Ecosystems
5.1.4Describe what is meant by a food chain
giving three examples, each with at least three linkages (four organisms). (2)
A food chain is a sequence of relationships between trophic levels where each member feeds on the previous one.
Don’t include decomposers in your food chain in your notes.
5.1 Communities and Ecosystems
5.1.5
Describe what is meant by a food web.(2)
A food web is a a diagram that shows the feeding relationships in a community. The arrows indicate the direction of energy flow.
5.1 Communities and Ecosystems
5.1.6
Define trophic level. (1)
A trophic level is where an organism is positioned on a food web (it’s feeding relationship to other organisms).
Producer
Primary consumer
Secondary consumer
Tertiary consumer
5.1 Communities and Ecosystems
5.1.7
Deduce the trophic level of organisms in a food chain and a food web.
(3)
Quaternaryconsumers
Tertiaryconsumers
Carnivore
Carnivore
Secondaryconsumers
Carnivore
Primaryconsumers
Herbivore
Primaryproducers
Plant
A terrestrial food chain
5.1 Communities and Ecosystems
5.1.9
State that light is the initial energy source for almost all communities. (1)
What process???
5.1.10
Explain the energy flow in a food chain.(3)
Microorganismsand other
detritivores
Tertiaryconsumers
Secondaryconsumers
Detritus Primary consumers
Sun
Primary producers
Heat
Key
Chemical cyclingEnergy flow
Heat
Heat
Heat
5.1.11
State that energy transformations are 10–20% efficient. (1)
Growth (new biomass)
Cellularrespiration
Feces100 J
33 J
67 J
200 J
Plant materialeaten by caterpillar
5.1.12
Explain what is meant by a pyramid of energy and the reasons for its shape.(3)
Notice the loss of energy with each transfer in a food chain
5.1 Communities and Ecosystems
5.1.13
Explain that energy can enter and leave an ecosystem, but that nutrients must be recycled.
(3)
Energy enters as light and usually leaves as heat.
Nutrients do not usually enter an ecosystem and must be used again and again. Nutrients include: Carbon, Nitrogen, and Phosphorus
Assimilation
N2 in atmosphere
DecomposersNitrifyingbacteria
Nitrifyingbacteria
Nitrogen-fixingsoil bacteria
Denitrifyingbacteria
NitrificationAmmonification
Nitrogen-fixingbacteria in rootnodules of legumes
NO3–
NO2–NH4
+NH3
Nitrogen Cycle
G1 Community Ecology
• G.1.1 Outline the factors that affect the distribution of plant species, including temperature, water, light, soil pH, salinity, and mineral nutrients.
• G.1.2 Explain the factors that affect the distribution of animal species including temperature, water, breeding sites, food supply and territory.
G1 Community Ecology
Internal Assessment
Think about what will effect how plants are distributed in an ecosystem….
First IA pause and Statistics Pause.
G1 Community Ecology
G.1.5 Explain what is meant by the niche concept.
The total of a species’ use of biotic and abiotic resources is called the species’ ecological niche.
- Habitat- Feeding relationships- Symbiotic/other interactions with
organisms
G1 Community Ecology
G.1.7 Explain the principle of competitive exclusion.
• two species competing for the same limiting resources cannot coexist in the same place – one must leave or becomes extinct
G1 Community Ecology
G.1.8 Fundamental vs Realized Niches
Fundamental = where the species is designed to live the best
Realized = where the species actually resides because of competition
G1 Community Ecology
G.1.6 Outline the following interactions between species: competition, herbivory, predation, parasitism, and mutualism (with examples).
G1 Community Ecology
G.1.9 Define biomass - each tier represents the dry weight of all organisms in one trophic level
Trophic level Dry weight(g/m2)
Tertiary consumers
Secondary consumers
Primary consumers
Primary producers
1.5
11
37
809
G2 Ecosystems and biomesG.2.1 Define gross production and net
production.
Gross Production = the amount of light energy converted to chemical energy by autotrophs in an ecosystem
Net Production = Energy able to be passed on by producers to consumers
G.2.2 GP – R (Respiration) = NP
G2 Ecosystems and biomes
• G.2.5 Construct a pyramid of energy, given information.
G2 Ecosystems and biomes
• G.2.6 Distinguish between primary and secondary succession.
• Primary succession occurs where no soil exists when succession begins
• Secondary succession begins in an area where soil remains after a disturbance
G2 Ecosystems and Biomes
• G.2.7 Outline the changes in species diversity and production during primary succession.
• Not very diverse: Lichen pioneer species
• Very diverse: Forest climax community
G2 Ecosystems and Biomes• G.2.8 Explain the effects of living organisms on
the abiotic environment, with reference to the changes occurring during primary succession.
• Small amount of soil formed by the lichens is colonized by mosses, which do not have roots and require little soil
• As the seedless plants live and die decomposition increases the richness of the soil
• Grasses can successfully grow
G2 Ecosystems and biomes
• G.2.9 Distinguish between biome and biosphere.
• Biome = Communities on earth that contain similar plant and animal inhabitants
• Biosphere = part of Earth that can contain life
G2 Ecosystems and Biomes
• G.2.11 Outline the characteristics (temperature, moisture, vegetation) of six major biomes.
• Desert• Grassland• Shrubland• Temperate deciduous forest• Tropical rainforest• Tundra
• G.1.3 Describe one method of random sampling, based on quadrat methods, that is used to compare the population size of two plant or two animal species.
G1 Community Ecology
1) Mark off a large 10 x 10 meter grid area2) Toss a 1 x 1 meter square into the grid area randomly3) Identify and count all the larger plant species first4) Smaller plant species, like grass, divide your square into several smaller 10 x 10 cm squares. Count the number of individual plants in several of those smaller squares, average, and multiply by 100 to get an estimate. 5) Toss the 1 x 1 m square to obtain more data.
G3 Impacts of humans on ecosystems
• G.3.1 Calculate the Simpson diversity index for two communities.
• N – total number of individual organisms (all species combined)
• n – number of individuals of a particular species
G3 Impacts of humans on ecosystems
• G.3.2 Analyse the biodiversity of the two local communities using the Simpson index.
• High Index (closer to one) – Higher the biodiversity
• This index ranges from zero to one and is literally a measure of the probability that two organisms taken at random from the sample are different species. A number close to zero means low diversity and it is likely you will get the same species of organism and a number close to one means high diversity.
Internal Assessment
Quadrat Lab
5.3 Populations5.3.1Outline how population size can be affected by
natality, immigration, mortality and emigration. • Natality – offspring are produced and added to
the population• Mortality – individuals die and are lost from the
population• Immigration – individuals move into the area
from somewhere else and add to the population• Emigration – individuals move out of the area
and are lost from the population
5.3 Populations
5.3.2
Draw a graph showing the sigmoid (S-shaped) population growth curve.
5.3 Populations
Exponential Phase
Population increases exponentially because the natality rate is higher than the mortality rate. This is because there is an abundance of food, and disease and predators are rare.
5.3 Populations
Transitional Phase
Difference between natality and mortality rates are not as great, but natality is still higher so population continues to grow, but at a slower rate.
Food is no longer as abundant due to the increase in the population size. May also be increase predation and disease.
5.3 PopulationsPlateau PhaseNatality and mortality are equal so the population
size stays constant.
Limiting Factors:shortage of food or other resourcesincrease in predatorsmore diseases or parasites
If a population is limited, then it has reached its carrying capacity
5.3 Populations
Define carrying capacity.
The maximum population size that can be supported by the environment
5.3 Populations
In a random sample, every individual in a population has an equal chance of being selected.
Describe one technique used to estimate the population size of an animal species based on a capture-mark-release-recapture method.(2)
• Various mark and recapture methods exist. • Knowledge of the Lincoln index (which involves
one mark, release and recapture cycle) is required.
5.3 Populations
population size =
where . . .• n1= number of individuals initially caught, marked and released• n2 = total number of individuals caught in the second sample• n3 = number of marked individuals in the second sample
3
21
n
xnn
5.3 Populations
• IA – Mark and Recapture
5.2 Greenhouse effect
5.2.1Draw the carbon cycle to show the
processes involved. • The details of the carbon cycle should
include the interaction of living organisms and the biosphere through the processes of photosynthesis, respiration, fossilization and combustion. Recall of specific quantitative data is not required.
5.2 Greenhouse Effect
5.2.2
Analyze the changes in concentration of atmospheric carbon dioxide using historical records.
What’s happening to carbon dioxide levels?
5.2 Greenhouse effect
• Explain the relationship between rises in concentrations of atmospheric carbon dioxide, methane and oxides of nitrogen and the enhanced greenhouse effect.
Greenhouse Effect
CausesLight from the sun has short wavelengths
and can pass through most of the atmosphere.
This sunlight warms the earth which in turn emits long wave radiation.
This long wave radiation is bounced back by the greenhouse gases, such as carbon dioxide, methane, water vapour, and sulphur dioxide
5.2 The greenhouse effect
5.2.6 Outline the consequences of a global temperature rise on artic ecosystems.
- Loss of ice habitat - Increased success of
pests
G3 Impacts of humans of ecosystems
• Ozone layer absorbs UV radiation
• CFCs are causing a hole in the ozone layer
• Excessive UV radiation can cause: – Skin cancer– Vital bacteria would
die
G3 Impacts of humans on ecosystems
• G.3.4/5 List 3 examples of introduced/alien species and discuss the impact.
-Purple Loosestrife-spread alarmingly fast, - removed from their natural controlling agents. - dramatic disruption in water flow in rivers and canals, - Native food and cover plant species, notably the cattails, are crowded out.
G3 Impacts of humans on ecosystems
• Zebra mussels were first detected in the Great Lakes in 1988 and have caused widespread damage in the ecosystem.
• Zebra Mussels are edible, but most experts advise against eating any found in areas of pollution concern since zebra mussels accumulate contaminants and toxins from the water that they filter.
G3 Impacts of humans on ecosystems
- Round Goby- Survives well in degraded environmental conditions -Competitive advantage compared to native species. -Heavy feeding on invasive mussels(zebra and quagga) results in greater biomagnification- No predators due to defensive mechanism
Define biomagnification – At each trophic level, toxic substances (Hg, pesticides, TCDD, etc.)
become more concentrated
G3 Impacts of humans on ecosystems
• How can we keep invasive species in check via a biological mechanism? – Decide on a local area that is currently being
impacted negatively by an invasive species.– Find out what that negative impact is and which of
the invasive species is causing it. – Research a BIOLOGICAL means of controlling
that species in order to stop the negative impact. – Put together a proposal illustrating your method of
restoring the ecosystem.