Topic 5 and Option G - Ecology. 5.1 Communities and Ecosystems 5.1.1 Define:(1) Ecology—the study of relationships between living organisms and between

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.


5.1.2autotroph (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????


heterotroph (consumer) – organisms that use the energy in organic matter, obtained from other organisms

Examples: ????


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???


5.1.4Describe 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.


5.1.5

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.


5.1.6

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


5.1.7

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


5.1.9

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


5.1.13

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.


Internal Assessment

Think about what will effect how plants are distributed in an ecosystem….

First IA pause and Statistics Pause.


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


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


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


G.1.6 Outline the following interactions between species: competition, herbivory, predation, parasitism, and mutualism (with examples).


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.


• 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


• 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.


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


• 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


• 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.


• 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.


- 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

http://en.wikipedia.org/wiki/Image:Neogobius_melanostomus2.jpg

Define biomagnification – At each trophic level, toxic substances (Hg, pesticides, TCDD, etc.)

become more concentrated


• 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.

Documents

Topic 5 and Option G - Ecology. 5.1 Communities and Ecosystems 5.1.1 Define:(1) Ecology—the study of relationships between living organisms and between