BIO 156 Chapter 24 Power Point PP07

8/14/2019 BIO 156 Chapter 24 Power Point PP07

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BIO 156

Chapter 24


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Ecology and the Environment


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An Introduction to Ecosystems

Ecology is thestudy of theinteractions

betweenorganisms,including humans,

and theirenvironment.


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The biosphere is the zone in which all life exists on

Earth. The biosphere extends from the bottom of the

oceans to the top of the highest mountains. The biosphere is a closed system in which materials

are recycled over and over.

The only outside contribution is sunlight, whichpowers virtually all biological processes.


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The Biosphere


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The biosphere is divided into biomesand aquatic life zones.

Each biome and aquatic life zone hascharacteristic plant and animal life.

The biomes have characteristic climates.


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Ecosystems consist of organisms andtheir environment. Ecosystems consist of two basic

components:abiotic and biotic. Abiotic components are the physical and

chemical factors needed for life.

Biotic components are the organisms that livein an ecological system.

A group of organisms of the same speciesliving ina specific region constitutes a population.


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Habitat is the physical space where anorganism lives.

An organisms niche consists of all of anorganisms relationships in anecosystem.


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Ecosystem Function

Producers generate nutrients

consumed by all other organisms. Producers are organisms that synthesize

organic materials from sunlight, carbondioxide, and water.

The major producers are the plants,photosynthetic protists, and photosyntheticbacteria.

Consumers are organisms dependent on

producers and other organisms for food. Four t es of consumers are resent:


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Organisms are part offood webs.

A food chainrepresents afeeding relationshipin an ecosystem.

There are twogeneral types offood chains: razer


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Food Chains


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Food Web


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The organisms of afood chain exist ondifferent trophic levels.

In a grazer foodchain, plants(producers are on

the first trophiclevel; herbivoresare on the second;carnivores are onthe third.

An energy pyramid


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Nutrient cycles consist of two phases,

the organismic and the environmental. In the organismic phase, nutrients are

found in the biota.

In the environmental phase, a nutrient

exists in the air, water or soil, or in two ormore.

Three important nutrient cycles are the Water cycle

carbon cycle


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The water cycle, or hydrological cycle, collects,purifies, and distributes water throughout theplanet. Evaporation and precipitation run the water cycle.


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The carbon cycle recycles carbon throughout the planet.


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The nitrogen cycle recycles nitrogen throughout theplanet.

Nitrogen fixation is the conversion of atmospheric

nitrogen to ammonia.


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Succession is the progressive development ofbiological communities. Primary succession occurs where no community

previously existed. Secondary succession occurs where a community

was destroyed by natural or human events.


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Overshooting the Earths Carrying Capacity

Carrying capacity is the number oforganisms an ecosystem can sustainindefinitely.

It is determined by food production.

resource supplies.

the capacity of the environment toassimilate or destroy waste products of


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In many places, the human population

is exceeding food production. Many resources are in short supply and

will be depleted in the near future.

Nonrenewable resources are finite. Renewable resources can replenish

themselves naturally.

Pollution from human activities exceeds


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Overpopulation Problems and Solutions

Overpopulation is a conditionin which populations exceedthe ability of the environmentto supply resources and/orassimilate wastes.

Overpopulation is a problemin virtually all countries, richand poor.

The human population isgrowing exponentially.

Reducing population growth


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Resource DepletionEroding the Prospects of All Organisms

Humanity isdestroying the


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Soil erosion, like deforestation, is also aworldwide phenomenon. The destruction of productive soils threatens the

long-term prospects for food production. Soil conservation and population control

measures can help ensure an adequate supply ofsoil


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Many areas of the world are facing watershortages or will soon face them as thehuman population and demand for waterincrease.

Most students alive today will see theend of oil in their lifetimes.

P ll ti


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Pollution Our waste is overwhelming nutrient cycles, poisoning other

species (and ourselves.

Global warming results from the release of carbon dioxide andother air pollutants.

Carbon dioxide is a greenhouse gas affecting globalwarming.

The environmental impacts of global warming could be severe.

Solving global warming requires massive action, and soon.

L ti f th ld th t d b id


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Large portions of the world are threatened by acid

rain and snow. Power plants, factories, automobiles, and other

sources release sulfur dioxide and nitrogendioxide as gaseous pollutants.

In the atmosphere, they are converted to sulfuricand nitric acid, respectively.

Acids fall from the sky in wet and dry deposition.


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Acid Rain

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BIO 156 Chapter 24 Power Point PP07