esc 301.02 ii ecology c short

7/29/2019 Esc 301.02 II Ecology c Short

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ESC 301

ECOLOGY-Part C

Ferhan een


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Climate and Major Biomes


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Abiotic Effects of Latitude andAltitude

Abiotic Effects of Latitude and

Altitude


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Succession and Disturbance Ecological succession: transition between

biotic communities Primary: no previous biotic community

Secondary: previously occupied by a

community Aquatic: transition from pond or lake to

terrestrial community


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Material Cycles


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Hydrological Cycle (Water Cycle)

Most of earths water is stored in the oceans,

but solar energy continually evaporates this

water, and winds distribute water vapor

around the globe.

Water that condenses over land surfaces, inthe form of rain, snow or fog supports all

terrestrial ecosystems.


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Water Cycle

Living organisms emit the moisture to the

atmosphere through respiration andperspiration.

Eventually, this moisture re-enters the

atmosphere or enters lakes and streams and

ultimately the oceans.


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WATER CYCLE


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Carbon Cycle Carbon serves a dual purpose for organisms:

Carbon is a structural component of organicmolecules (C6H12O6, sugar)

Chemical bonds provide metabolic energy.

The carbon cycle begins with photosynthetic

organisms that take up (CO2, carbon dioxide) to formstarch.

Starch is taken up by several organisms, digested instomach and simple sugars get broken down to

simpler ones (CO2 , H20 & energy).


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Carbon cycle (contd.)

Sugar molecules either undergo

respiration and release carbon in the formof C02.

From simple sugar also large organicmolecules can be formed.

When organisms decay carbon returns to

nature.


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Combustion of fossil fuel (e.g coal and oil)

releases carbon atoms into the atmosphere. Aquatic biomass leads to formation of limestone

deposits.

Carbon cycle (contd.)


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Carbon Cycle


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Carbon Cycle


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Carbon Cycle


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Nitrogen cycle Several organic molecules contain nitrogen

Amino acids, peptides and proteins are largeorganic molecules that living organisms need for

their existence.

Nitrogen is a very important nutrient for livingthings.

Nitrogen is a primary component of many

household products (Ammonia and others) andagriculture fertilizers.


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Nitrogen Cycle (cont.)

Nitrogen makes up about 78% of the air, but plants

cannot use N2, the stable diatomic molecule in air.

Plants acquire nitrogen through the nitrogen cycle.

Nitrogen-fixing bacteria (live in roots of legumes) and

blue-green algae) are highly organised to fix nitrogen

of the atmosphere to ammonia ( N2

to NH3)

They combine hydrogen of atmosphere with nitrogen

and form ammonia (NH3)


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Nitrogen cycle (contd.) Ammonia in plants is used to make amino acids which is

used as building blocks to form protein (a polypeptidechain made up of several amino acids).Thus, inorganicnitrogen is converted into an organic form.

After plants cells absorb nitrates, these nitrates arereduced to ammonia (NH

3) and then used by the plant.

There are aerobic bacteria oxidizing ammonia to nitrite(NO2

-).

There are aerobic bacteria oxidizing nitrite further to

nitrate (NO3-

),which green plants can absorb and use. This conversion of ammonia to nitrate is called

nitrification.


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Nitrogen cycle (cont.) Fungi and bacteria decay dead organisms, converting

organically bound nitrogen into ammonia. Thisprocess is known as ammonification. Animals

produce urine which contains nitrogenous

compounds such as urea, which is also converted toammonia by ammonification.

Denitrifying bacteria reduce nitrates in soil or water

to nitrogen gas (N2), which is released into theatmosphere. This is called denitrification.


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Nitrogen cycle


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Modified from D. T. Krohne, General Ecology

Nitrogen cycle


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Nitrogen Cycle


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Nitrogen Cycle


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Critical Thinking Issue

How are Human ActivitiesAffecting the Nitrogen

Cycle?

Eutrophication of water

bodies

Nitrates in drinking water

Effects of increased use of

nitrogen fertilizers:

Nitrogen cycle

esc 301.02 ii ecology c short

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