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ECOLOGY The study of the interactions between organisms and their environment. 5.1.1

ECOLOGY The study of the interactions between organisms and their environment. 5.1.1

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ECOLOGY

The study of the interactions

between organisms and their

environment.5.1.1

ENVIRONMENT = all the factors that affect an organism. 5.1.1

ABIOTIC FACTOR = non-living factors in an environment.

BIOTIC FACTORS = living factors in an

environment.

ABIOTIC and BIOTIC FACTORS 5.1.1

ECOSYSTEM includes all the biotic & abiotic factors in an environment. 5.1.1

5.1.9 – 5.1.19

ECOSYSTEM 5.1.1

A stable, settled unit of nature consisting of community of organisms, interacting with each other and with their surrounding physical and chemical environment.

Biosphere

Ecosystems

Communities

Populations

Organisms

5.1.1

SOME IMPORTANT ECOLOGICAL TERMS 5.1.1

Population: All living things of the same species in a habitat at any one time. Ex. Panda population in China in 1989

Community: All the living things in a habitat or ecosystem, the total of all populations.

Species: A group of individuals of common ancestry that closely resemble each other and that are normally capable of interbreeding to produce fertile offspring.

Biosphere: The inhabited part of the Earth. All ecosystems on Earth.

NICHE = both the habitat of an organism occupies and the mode of

nutrition employed

G.1.5

HABITAT = place where an organism or population of organisms

live.

FOOD CHAIN = used to show how matter & energy move through an ecosystem. It shows feeding relationship between organisms.

5.1.4

LIVING THINGS CAN BE CLASSIFIED ACCORDING TO THEIR ROLE IN AN ECOSYSTEM

5.1.3 and 5.1.14

• PRODUCERS: are the organisms which produce their own food by using inorganic molecules. Photosynthetic organisms or chemosynthetic.

• CONSUMERS: organisms which feed on other organisms.

a. Herbivores: they eat plants.

b. Carnivores: they eat meat.

c. Omnivores: they eat both meat and plants

• DECOMPOSERS: they feed on dead animals or plants, causing matter to be recycled by other living things

FOOD WEB = shows all the possible food chains in an ecosystem 5.1.5

Each organism in food chain represents a “feeding” or TROPHIC LEVEL 5.1.6

5.1.7

1st Trophic Level

2nd Trophic Level

3rd Trophic Level

producers

1o or 2o consumer

2o or 3o consumer

decomposers

5.1.8

Discuss the difficulties of classifying organisms into trophic levels. G.2.3

Sometimes it is hard to determine the trophic

level of organisms on the secondary or tertiary

consumers which feed on different organisms.

• What is the trophic level of omnivores?• What is the trophic level of sea star in

marine ecosystem

ECOLOGICAL PYRAMIDS

• Are graphical models of the quantitative differences that exist between the trophic levels of a single ecosystem.

• In accordance to the 2nd Law of Thermodynamics, there is a tendency for numbers and quantities to biomass and energy to decrease along food chains, therefore the pyramids become narrower toward the top.

PYRAMID OF NUMBERS represents storages found at each trophic level.

Units vary

PYRAMID OF BIOMASS represent the standing stock at each trophic level. G.1.8

Units:

J m-2

or

g m-2

• Compare the biomass of the organisms in higher trophic levels and lower trophic levels.

• Compare the number of the organisms in higher trophic levels and lower trophic levels.

PYRAMID OF PRODUCTIVITY represents the flow of energy through each trophic

level. 5.1.11

Units:

J m-2 yr-1

or

g m-2 yr-1

• As you move up each trophic level, only 10% of the energy is transferred.

• The other 90% is used for everyday life functions, metabolism. 5.1.9

1o consumers

3o consumers

2o consumers

producers

10 J m-2 yr-1

100 J m-2 yr-1

1,000 J m-2 yr-1

10,000 J m-2 yr-1

5.1.10 -5.1.11 -

Construct a pyramid of energy, given appropriate information. G.2.5

Trophic level Energy (kJm-2yr-1

1 87 0702 35 2623 1 6024 87

Pyramid structure affectsthe functioning of an ecosystem.

Bioaccumulation (biomagnifications)

Bioaccumulation:. If a chemical is not biodegradable, it accumulates in the body and causes disease, it is called bioaccumulation

Biomagnification: the process by which chemical substances become more concentrated at each trophic level. While the concentration of the chemical may not affect organisms lower in the food chain, it causes death in top trophic level because of high concentration.

.

The Cycling of Matter in Ecosystems 5.2.1

Chemicals in ecosystems are used again and again. In other words chemicals are recycled. This kind of recycling is fundamental to sustainability for two reasons.

1- It prevents accumulation of wastes.

2- It guarentees that the ecosystem will not run out of essential elements.

LIVING THINGS THAT HAVE ROLE IN RECYCLING OF CHEMICALS 5.1.14

• Scavengers: are the animals that eat dead animals. Ex. Carrion crow, fox, vulture

• Detritivores: are the animals that feed on dead plants. Ex. Slug, snails, earthworms

• Saprotrophs: are the microorganisms that convert organic molecules of dead living things into inorganic. Ex. Fungi, bacteria

CARBON CYCLE 5.2.1

Carbon Cycle

There are five processes that affect C cycle.

a- Photosynthesis:

b- Cellular respiration:

c-Chemosynthesis:

d- Fossilization

e- Combustion:

Photosynthesis

• Light energy is converted into chemical energy.

Cellular RespirationCellular respiration is a series of reaction in which organic molecules are oxidized and broken down into CO2 and water.Oxygen is used.

• Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and on oxidant accompained by the production of heat or both heat and light in the form of either glow or flames.

• What is the relationship between carbon cycle and green house affect?

• How does human being affect carbon cycle?

• What are the green house gases?

Water vapour, Carbondioxide, Methane, CFC (chlorofluorocarbons), Ozone,

5.2. GREEN HOUSE EFFECT

GLOBAL WARMING AND THE PRECAUTIONARY PRINCIPLE

“Better safe than sorry”

Read page 151.

Discuss consequences of global warming.

Evaluate the precautionary actions.

Causes of global warming

Combustion of fossil fuels. Industrial revolution

Volcanic eruption

Reducing size of forests

Precautionary actions1- Raising sea level

2- Warming up sea water, volume of sea increases

3- flooding on sea level land (agriculture land)

4- Raising of the sea water temp. prevents mixing surface water with deep water, so algal population decreases. More CO2 in the atm.

5- Destruction of forest is faster than natural growth of forest.

6. Interruption of ocean current causes climate changes.

1- Conserve fossil fuel stock

2- develop nuclear power to supply electricity.

3. Develop renewable sources of power.

4. Develop biofuel sources.

5. Reduce use of fuels (insulation of buildings )

6. Reduce use of fossil fuel for transportation

7. Terminate destruction of forests.

THE ARCTIC and THE CONSEQUENCES OF GLOBAL WARMING

Read page 153.

Outline the consequences of global warming

for arctic ecosystem.

Consequences of global warmingfor arctic ecosystem

1-Loss of ice habitats.

2- Decaying detritus releases huge amount of methane and CO2 . More global warming

3- Expansion in the range of habitats soil rich humus are formed.

4- Growth of taiga forest absorb sun light causing further warming.

5- Increase in insect populations and insect eating animals population.

6- Wider flora

7- Small mammals will expand their habitat

8- Predators will increase.

9- Increase in pathogen number.

Chemosynthesis - HL• Chemosynthesis is

the production of organic molecules by using energy from inorganic molecules. Bacteria make chemosynthesis.

5.3. Population Dynamics

Changes in Population Size

New individuals are added to the population by natality (b) and immigration (i)

Individuals are lost from the population due to mortality (m) and emigration (e)

The overall change can be determined by:

Population change = (b + i) – (m + e)

What is a population?• Individuals of one species

simultaneously occupying the same general area, utilizing the same resources and influenced by similar environmental factors

• Population ecology is concerned with fluctuations in population size and the factors that regulate populations

Logistic Population Growth

Exponential growth: population increases, enough nutrients space, high mortality

Transitional phase: Natality rate start to fall, mortality increases.

Slow growth: period of adaptation to conditions

Plateau phase: natality and mortality rates are equal

Time

Time (months)

Po

pu

lati

on

siz

e (N

)

0 1 2 3 4 5 6 7 8 9 10 11 120

50

100

150

200

250

300

350

400

450

500

• Factors that limit population growth

• Four factors interact to limit population size:– Availability of raw materials– Availability of energy– Accumulation of wastes – Interactions among organisms

Time

Nu

mb

er o

f in

div

idu

als

(N)

0

K

G = rN

G = rN(K – N)

K