Ecology. Basic Concepts Species : a group of organism that can interbreed & produce fertile...

Ecology

Basic Concepts• Species : a group of organism that can interbreed &

produce fertile offspring.(have a common gene pool).•Habitat: the environment in which species normally

lives (location).• Population: a group of the organism of the same

species ,living in the same area at the same time.• Community: a group of populations living &

interacting with each other in an area.• Ecology: the study of relationships between living

organisms & their environment.

2Amit Mishra - NES International School Mumbai

Environment

• Its everything which surrounds an organism.• It has 4 main components• Hydrosphere (water)• Atmosphere (gases)• Lithosphere (rocks)• Biosphere (all living beings)• The first 3 are abiotic components while the

4th is the Biotic component


Autotrophs & heterotrophs


• Autotrophs are the organisms with the capacity to make their own food.• Eg.:cynobacteria, Algae,Grass, Trees.

• Hetrotrophs are the organisms which do not have the capacity to produce their own food.• Eg.:animals,fish,zooplanktons.

• Three types :• consumers • detritivore • saprotroph


Detrivores & saprotrophs

• Detrivores are the organism that consumes dead organic matter.

• Eg.: earthworm, woodlice.• Saprotrophs are the organisms that live on, or

in, dead organic matter. (digesting the food by secreting enzymes).


Food chain & food web


• A food chain is a sequence of relationships between trophic levels where each member feeds on the previous one.

• A food web is a diagram that shows the feeding relationships in a community. The arrows indicate the direction of energy flow.

• It’s the interlinking of the food chains.


• Define trophic level. (1) • A trophic level is where an organism is

positioned on a food web.• Producer• Primary consumer• Secondary consumer• Tertiary consumer


• Sun is the principal source of energy in biological systems.

• Green plants absorb only a very small fraction of (about 10%) of the light energy.

• Light energy converts into chemical energy by plants.


10 % Law of energy flow

• Of the total energy entering a particular trophic level, only 10% is available for the next higher trophic level.

• Grass → Goat → Tiger• 200 Kg → 20Kg → 2Kg• Hence short food chains provide more energy to

higher trophic level.• That’s the reason why vegetarians get more energy

than meat eating people.


Ecological pyramids

• Pyramid of biomass• Biomass is the total dry mass of all organism in an unit area.• Total biomass = biomass of producers + biomass of consumers

+ biomass of decomposers.• The mass of all the organisms at each step of the

food chain is measured.• On the basis of the measurement of the dry mass

(at each trophic level) a diagram can be drawn.• This is known as pyramid of Biomass.


Pyramid of Number

• This is drawn according to the number of organisms at each trophic level of the food chain.


Pyramid Of Energy

• Energy pyramids are formed by measuring the amount of energy available at each trophic level in the food chain.

• The energy is measured over a fixed period of time.


Pyramid of Energy


Explain that energy can enter and leave an ecosystem, but that nutrients must be recycled.

Energy enters as light and usually leaves as heat. Nutrients do not usually enter an ecosystem and must

be used again and again. Nutrients such as Carbon dioxide, Nitrogen, and Phosphorus


Greenhouse EffectPhenomenon• The mean global temperature has

risen about 1 degree Celsius since 1856. • We saw an increase between 1910

and 1940, and from 1970 onwards.


Greenhouse Effect

Human Activities

• Increased burning of fossil fuels releasing Greenhouse gases

• Deforestation – less trees to convert CO2 back to O2

• Other industrial activities that release other Greenhouse gases


Greenhouse Effect

Causes

• Light 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 19Amit Mishra - NES International School

Mumbai

Greenhouse Effect

• Flooding of low –lying land • Melting of glaciers and polar ice• More frequent storms and

hurricanes• Changes in weather patterns


Greenhouse Effect

Measures

• Increase photosynthesis and reduce emissions by:

•restoring ecosystems where there has been deforestation or desertification

•spreading nutrients such as iron in nutrient-deficient oceans to encourage algal growth


Greenhouse Effect

• Reducing energy consumption; insulation, smaller vehicles, local grown food instead of transported• Changing from fossil fuels to solar,

wind, or nuclear


Carbon cycle

• The carbon cycle includes the interaction of living organisms and the biosphere through the processes of photosynthesis, respiration, fossilization and combustion.


Populations

Outline how population size can be affected by natality, immigration, mortality and emigration.


Populations

• 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 – indivuals move out of the area and are lost from the population


Populations

Draw a graph showing the sigmoid (S-shaped) population growth curve. (1)


Populations

• Lag phase: population just begins to grow

• Exponential PhasePopulation 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.


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.


Populations• Plateau Phase

Natality and mortality are equal so the population size stays constant.

• Limiting Factors:• shortage of food or other resources• increase in predators• more diseases or parasites

• If a population is limited, then it has reached its carrying capacity


Populations

Define carrying capacity.

The maximum population size that can be supported by the environment


Populations

List three factors which set limits to population increase.

Limiting Factors:• shortage of food or other resources• increase in predators• more diseases or parasites


Ecology. Basic Concepts Species : a group of organism that can interbreed & produce fertile...

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