Unit 10: Energy, Cyles in Nature and Human Impact

Where does most of the energy in an ecosystem originate from?

The sun is the main energy source for life on earth!

How do organisms get their energy?

There are 2 ways:

1. Autotrophs: Organism that captures energy from sunlight or inorganic substances to produce its own food; also called producers.

How do organisms get their energy?

There are 2 ways:

2. Heterotrophs: Organism that cannot make its own food and gets its nutrients and energy requirements by feeding on other organisms; also called consumers.

What are 6 different types of consumers?

Herbivores: Eat Plants

What are 6 different types of consumers?

Carnivores: Eat Meat

What are 6 different types of consumers?

Omnivores: Eat plants & meat

What are 6 different types of consumers?

Detritivore: Eat organic matter/poop – detritus

What are 6 different types of consumers?

Scavenger: Eats animals that are already dead.

What are 6 different types of consumers?

Decomposers: Breaks down all the rest (bones, feathers, dead trees…)

What is the difference between a food chain & food web?

Food Chain: A simple model that shows how energy flows through an ecosystem.

Parts of a Food Chain• Producer

• Consumer– 1st

– 2nd

– 3rd

– 4th

• Decomposer

• Any level in a Food Chain or Food Web is called a Trophic Level

Food Chain• Producer

• Primary Consumer (1st)

• Secondary Consumer (2nd)

• Tertiary Consumer (3rd)

• Important – the arrows always point in the direction of what is doing the consuming.

What are trophic levels?

Each step in a food chain/web is called a

trophic level.

BIOMASS: Total amount of living

tissue within a given trophic level

Food Chain

What is the difference between a food chain & food web?

Food Web: A model representing the MANY interconnected food chains and pathways in which energy flows through a group of organisms.

Food Web

Food Web

What are ecological pyramids?

Ecological Pyramid: Another model used to show how energy flows through ecosystems.

Can show:

* Amount of Energy

* Amount of Biomass

* Number of organisms

What are ecological pyramids?

What is this one showing?

* Amount of Energy

* Amount of Biomass

* Number of organisms

Biomass: The total mass of living matter at

each trophic level.

What are ecological pyramids?

What is this one showing?

* Amount of Energy

* Amount of Biomass

* Number of organisms

What is the 1/10th Rule?

* The reason that each trophic level can support only 1/10 of the amount of living tissue as the level below it is because each trophic level harvests only about one tenth of the energy from the level below.

* Only 10% of energy moves up to the next trophic level

The rest of the energy (90%) is LOST as HEAT• Running ● Hunting for food• Breathing ● Sleeping• Reproducing ● Maintaining body heat

What is the 1/10th Rule?

100,000 J

10,000 J

1,000 J

100 J

10 J

1 J90% Lost

Energy Pyramid

Energy Pyramid

Energy Pyramid

Cycles in Nature

• Law of Conservation of Matter– Matter cannot be created or destroyed

– What does that mean?

Please Watch

Cycles in Nature

• Nutrient – chemical substance that an organism obtains from the environment to sustain life.

• Biogeochemical Cycle – cycle that involves organisms, geological processes and chemical processes– Water Cycle, Carbon Cycle, Nitrogen Cycle,

Phosphorus Cycle

Water Cycle – continuous movement of water on the Earth

• Evaporation– Liquid water to gas from water source

• Condensation– Gas to liquid

• Transpiration– Evaporation on land – people, plants

• Precipitation– Falling products of condensation

• Melting– Runoff, Filtration

Please Watch

Carbon Cycle* All living things have carbon in them.

* Carbon is in proteins, carbohydrates, lipids, nucleic acids.

* Carbon dioxide is used by plants to make energy (carbohydrates)

* Carbon is released into the atmosphere when we burn fossil fuels.

* Carbon can be trapped in the ground as coal, oil, and gas deposits

What is the Nitrogen Cycle?• Most of the atmosphere has Nitrogen in it (78%)• Organisms CAN’T use Nitrogen GAS!!...so it needs to be “fixed”• “Fixing” nitrogen, is turning it from a gas into NITRATES

(usable)Nitrogen Fixation: Process in which nitrogen gas is captured and converted into a form plants can use (nitrates)

How is Nitrogen “fixed”?There are 2 main ways to “Fix” nitrogen

1.Lightning changes nitrogen gas into nitrates

How is Nitrogen “fixed”?There are 2 main ways to “Fix” nitrogen

2. Nitrogen Fixing Bacteria changes gas into nitrates

Found on roots of Legums only!

* Peanuts * Peas * Clover * Beans * and many more…

What is the Phosphorus Cycle?• Phosphorus is essential for growth & development• When organisms poop or die, they return phosphorus back to the cycle.

Why is it important for matter to be cycled through the

atmosphere, rather than just eliminated once it is used?

Answer this question in your notes.

Human Impact on Earth

Eutrophication, Bioaccumulation, Global Warming, Habitat Loss,

Resource Exploitation

Can there be too much of a good thing?

• YES!Eutrophication: Occurs when fertilizers, animal waste, sewage, or other substances rich in Nitrogen & Phosphorous flows into waterways, causing algae growth.

What is biomagnification?Biological Magnification or Bioaccumulation

Is the increasing concentration of toxic substances in organisms as trophic levels

increase in a food chain or food web.

Bioaccumulation = Biomagnification

What is an example of the use of a toxin that caused biomagnification?

• DDT: A pesticide used between the 1940s - 1970s

We sprayed DDT EVERYWHERE!

What is an example of the use of a toxin that caused biomagnification?

DDT causes bird eggs to be brittle, and break when parents try to sit on them to incubate them

What is an example of the use of a toxin that caused biomagnification?

Biomagnification or Bioaccumulation

Vocabulary• Renewable Resource

– Sun, water, air

• Non-renewable resource– Fossil fuels

• Global Warming• Soil Degredation• Habitat Destruction• Sustainable Use

– Using resources at a rate in which they can be replaced or recycled

What have people done to help?

• National Parks and Protected Forrests

• Creating Corridors between Habitat Fragments

• Sustainable Use Farming

• Wetland Restoration

• Wildlife Repopulation Projects

• Reusing and recycling

Habitat Corridor

What can you do?

• Recycle• Use other forms of energy besides

fossil fuels– Walk, bike, public transportation

• Don’t be wasteful– Turn off the water when you’re not using it,

turn off lights or any type of plug in device that does not need electricity all of the time, use what you buy – or give the rest to someone who could use it

Community Development in Nature

Succession

• Definition – how ecosystems are formed

• Two Types of Succession– Primary Succession– Secondary Succession

Pioneer Species• Definition - first organisms to start the

chain of events leading to a livable biosphere or ecosystem – Arrive first in primary succession– Ex lichens, algae, moss, bacteria

Pioneer Species

• First organisms to arrive in an area are called Pioneer Species

• Appear in Primary and Secondary Succession

• Ex Moss, Lichens, Fungi, Bacteria

Primary Succession

• Development of an ecosystem in an area where there was no previous life and no soil– Ex Weeds growing in the cracks of pavement– Ex Moss growing on a rock– Ex Hawaiian Islands – were formed from huge

volcano eruptions

Primary Succession

Secondary Succession

• Development of an ecosystem in an area where the previous ecosystem was destroyed– Ex 5 years after a forest fire destroyed the

trees, small plants are starting to grow in that area again

Goal of Succession

• Goal of Succession is to reach the CLIMAX Community– Climax Community – plants and animals and

the interactions between them has reached a steady state

• The ecosystem will change very little once the Climax Community is reached

• Ex Tropical Rain Forest