Unit 2 Lesson 3 Energy and Matter in the

Ecosystem: Food Chains, Food Webs and

Biogeochemical cyclesSpringfield Central High School

Questions to Ponder from Lesson 2 What is a population in biology?

What is population dynamics?

What are the three phases that we can find a population in?

What is exponential growth?

What is logistic growth?

What restriction can there be on population growth?

What are immigration and emigration?

What does an age structure diagram show??

What is carrying capacity (K)?

What is extinction? 

How do humans impact other populations? 

Answer two of these questions.

Food Chains Vs Food WebsThis lesson is about how energy and matter move through an ecosystem.

How are food chains and food webs different?

Energy in the EcosystemAvailable energy in the ecosystems is captured by autotrophs and turned into organic molecules that store energy.  That energy can be passed from organism to organism and eventually back to the ecosystem. Scientists make models to show this movement of energy in an ecosystem.  Life is Powered by the Sun. Essentially all life on earth is powered by the energy released from the sun. There are exceptions to the sun being the energy source for life on earth.There are ecosystems at the ocean floor that rely on the energy in certain molecules for energy

How does the sun’s energy

animate life on earth?

What are exceptions to

life requiring the sun’s energy?

AutotrophsAutotrophs are often called the producers. The autotrophs produce the organic molecules, (sugars) that living organisms rely on for energy.

There are two types of autotrophs:Phototroph (photosynthetic autotroph)Chemotroph  (chemosyntheric

autotroph)

Here we have examples of two hypothetical food chains. One powered by the sun the other by molecules that store energy.

What are autotroph

s?

Why are autotrophs called

the producers

?

Photosynthetic Autotrophs Organisms that use energy from the sun to manufacture their own nutrients, (which can then be passed on to other organisms) are called photosynthetic autotrophs (aka. phototroph or  Photoautotroph) 

Examples of phototrophs: Cyanobacteria: A member of the eubacteria domain and kingdom that uses photosynthesis to produce chemical energy from the sun’s light.Green algae:  A Green algae is a protist that uses photosynthesis to produce sugar. Plants: Most plants use photosynthesis to transform light energy to carbohydrates, (chemical energy).  

Photosynthetic autotrophs capture sunlight and transform it into chemical energy. 

What is photosynthesis? What are the three types of

photosynthetic organisms?

Explain what a chloroplast is and

what its function is.

Chloroplast Found in plant cells, animal cells do not contain

chloroplasts. Contains chlorophyll pigments which gives plants their

green color. Thylakoids and stroma are found in the chloroplasts.

Thylakoids are the site of light reaction. Stroma is where the light independent reaction occurs.

Site of photosynthesis. Function:

◦ To produce glucose from carbon dioxide, water, and light.

Evolution of Photosynthetic Autotrophs (Chloroplasts Find Homes)Plants evolved from green algae which evolved from cyanobacteria.Cyanobacteria: Cyanobacteria uses photosynthesis to produce chemical energy from the sun’s light.Cyanobacteria is a member of the kingdom eubacteria, and is found living as individual cells or in colonies.  Cyanobacteria-like organisms' fossils have been discovered aging back 3.5 billion years ago.

Cyanobacteria are like free living chloroplasts.   

What are cyanobacteria,

and why are they important to

biology?

Evolution of Photosynthetic Autotrophs (cont.)

Cyanobacteria and EndosymbiosisCyanobacteria are known to live together with, and in close association with, other organisms in a mutualistic relationship. 

Example: Lichens are organisms made from a mutualistic/symbiotic relationship between fungus and photosynthetic autotrophs like cyanobacteria.  

Learn why cyanobacteria’s ability to

form mutualistic relationships has led

scientists to recognize the origin of chloroplasts

Evolution of Photosynthetic Autotrophs:

Cyanobacteria and Endosymbiosis (cont)Endosymbiotic Evolution Many scientists have concluded that some of the specialized cell structures, (organelles) found in eukaryote cells are ancestrally related to free living bacteria that formed mutualistic relationships with ancient eukaryote cells.Two examples are: mitochondria and Chloroplasts. 

Chloroplasts turn light energy into chemical energy, (sugars) Mitochondria turn sugars into another form of chemical energy that cells actually use (ATP).

Chloroplasts are believed to have evolved from cyanobacteria.

Evidence: Chloroplasts have their own cell membranes, their own DNA, which is bacterial DNA, one of cyanobateria strategies for survival is forming endosymbiotic relationships

Once cyanobacteria had been established in eukaryotic cells we have the evolution of photosynthetic protists such as phytoplankton and green algae. Explain endosymbiotic evolution.

Green Algae and PlantsGreen Algae and plants are both eukaryotic organisms which, (usually) contain chloroplasts in their cells

Plants have a more complex reproductive system than do algae.  

The photosynthetic capability of algae and plants is due to the chloroplasts. 

Discuss the evolution of

plants.

The Transfer of the Sun's Energy From Autotrophs to Heterotrophs

Organisms that cannot produce their own nutrients and must feed on other organisms are called heterotrophs. Herbivores are heterotrophs that feed on autotrophs:

Plant eaters.Carnivores are heterotrophs that feed on other heterotrophs: 

Meat eaters Omnivores are heterotrophs that eat both autotrophs and heterotrophs:  Meat and Plant eatersDetritivores (decomposers) are heterotrophic organisms that break down and absorb nutrients from dead organisms.  Many fungi and bacteria as well as some protozoans fill this niche

Heterotrophs are called the consumers.Heterotrophs consume the organic molecules that autotrophs make.Heterotrophs consume the organic molecules that are in other heterotrophs.Heterotrophs consume the organic molecules that store energy for food.

How Organisms Make Chemical Energy Usable, (Respiration)The chemical energy consumed by heterotrophs was energy transferred from light energy into chemical energy by autotrophs.We now know that photosynthesis is the process of turning light energy into carbohydrates, (sugars)RespirationRespiration is how organisms turn carbohydrates into ATP, the chemical energy that is used in the cells of organisms.Respiration happens in, (the other endosymbiont organelle) the mitochondriaLet’s look at the interaction Between Chloroplasts and Mitochondria. This is One of the key things to know in high school biology.Discuss the interaction and

interdependence of chloroplasts and mitochondria.

Watch the O2

Chloroplasts and Mitochondria

•Chloroplasts are the site of photosynthesis.•Photosynthesis is the production of sugar•Chloroplasts evolved from cyanobacteria

•Mitochondria are the site of cellular respiration.•Respiration is the release of energy stored in sugar•Mitochondria evolved via endosymbiosis

Note that the products of photosynthesis are used in respiration, and that the products of respiration are used

in photosynthesis.

Matter and Energy Flow in Ecosystems.Based on the symbiotic relationships and feeding relationships, biologists have made models to explain the flow of energy and matter through ecosystems.Food Chains Food chains are the simplest model for energy and matter flow through an ecosystem.

Nutrients and energy proceed from autotrophs to heterotrophs and eventually decomposers.Food chains are limited to only 3 to 5 links. At each link, energy is lost as heat. Each arrow represents the transfer and loss of energy .Explain the

significance of food chains.

The energy available at each trophic level can be represented  in a pyramid shape as can the  number of  organisms at each trophic level. 

The ecological pyramid model give more information than the classic food chain model.

Explain how each trophic level on a food chain or food pyramid

indicates available energy.

Matter and Energy Flow in Ecosystems. (cont.)

Each organism in a food chain represents a feeding level known as a trophic level.A Food Chain can also be represented as an ecological pyramid. 

Examples of food chains.

Matter and Energy Flow in Ecosystems. (cont.)

Trophic Dynamics

Scientists will often represent changes happening at each trophic level.

Compare the

available energy at

each trophic level to

the number of organisms

at each level.

Matter and Energy Flow in Ecosystems. (cont.)

Food WebsA food web is a more complex model showing the multiple food chains that exist in ecosystems.

A food web is a model to express the multiple relationships at each trophic level in a community.

Biogeochemical CyclesWe have seen energy and matter travel through the ecosystems using the food chain, ecological pyramid and food web models. Elements and molecules  also move through ecosystems and the biosphere and can be traced using another type of model, the biogeochemical cycles model."Bio", of course, refers to the living part of these cycles, while "geo" refers to the earth.  In the word, biogeochemical, "chemical" refers to what is cycling between the biotic and abiotic.  A chemical is anything with a chemical symbol or chemical formula. 

•Why do elements need to cycle through the biosphere; as opposed to energy that can flow through the ecosystems?•Does energy arrive on earth every day?•Does matter arrive on earth everyday?

This part of the lesson is about how elements cycle through the earth’s environment.

Where do living things

get the nutrients that

they need? Where are

these nutrients stored in the biosphere?

The Essential Elements of Life: CHONPS

What elements are CHONPS?Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous, Sulfur

We all know that hydrogen and oxygen are found in water; these elements are also the key components of sugars, (carbohydrates) and fats, (lipids). Where in living organisms do we find these other elements, and where?

Where in the lithosphere do we find these elements?

Carbon is the key element for life. Where does the carbon in living things come from? Carbon dioxide or other living things

ElementNutrient

BiologicalForm

Primary AbioticReservoir

Primary AbioticReservoirvoirs

Carbon C Carboydrates (CH2O)n

proteins, lipids, amino acids.

AtmosphericCO2

HydrologicCO3

= and HCO3-

GeologicCaCO3, Coal, Petroleum

Nitrogen N Proteins and other Nitrogencontaining organic molecules

Atmosphericnitrogen gas N2

Hydrologicammonium NH4

+

nitrate NO3-

nitrite NO2-

Phosphorus P DNA, ATP, Phospholipids

Geologicphospate rocks PO4

3-

Hydrologicdissolved phospate PO4

3-

Sulfur S Certain Amino Acids and Vitamins

Geologicsulfate rocks SO4

2-

AtmosphericH2S, SO2, SO3, H2SO4

HydrologicSO4

2- and H2SO4

Elements and Molecules Cycle Through Nature: There are many cycles in nature that model the movement of elements or chemicals.

Examples of non-biogeochemical cycles that effect the biogeochemical cycles:

Rock cycle: Silicone (Si)Essentially the entire periodic table of elements cycle in the rock cycle.

Explain how the rock cycle effects the biogeochemical

cycles.

Describe the water cycle and

this cycle’s impact on life.

Life depends on H2O

H2O cycles through the environment:

Water is pulled from the ground by plants’ roots.

Water is lost from plant leaves by transpiration, which causes negative pressure in the roots.  Water evaporates from bodies of water. Water as a gas, collects as clouds. Water condenses in clouds as

precipitation and falls to the ground.

Water Cycle

Carbon CycleThe carbon cycle is a true biogeochemical cycle.All living things are made with the element carbon.More than any other element, carbon is the element of life.Atoms of carbon form the framework for proteins, carbohydrates, lipids, and nucleic acids. (The 4 key molecules of living things).

The carbon cycle starts with photosynthetic autotrophs. Photosynthesis converts water and carbon dioxide into energy rich carbon molecules: glucose. Autotrophs use the energy stored in this molecule for energy.  

Notice the roles of O2 and CO2 in this cycle. Heterotrophs directly or indirectly feed on autotrophs and also use there carbon molecules for growth and energy. Carbon dioxide is released as organisms use the energy in carbon molecules.  Carbon is stored in the organic matter found in soil. This organic matter is called detritus. Carbon is also stored out of the cycle in coal and petroleum reserves. Fossil fuel burning frees this carbon as carbon dioxide.

Tell the story of the carbon cycle.

Tutorial

Carbon Cycle (cont) Animation

Oxygen CycleThe O cycle follows the movement of oxygen from the atmosphere to the biosphere and into the lithosphere. 

Oxygen is taken out of the atmosphere by photosynthesis.  Photosynthesis produces the organic molecules that contain oxygen and support the living things in the biosphere.

Through respiration and from the decay of living organisms oxygen enters the rock cycle (ie the lithosphere).

Compare the

oxygen cycle

and the carbon cycle.

Why are they so similar?

Animation

Nitrogen Cycle78% of the atmosphere is nitrogen in the form N2.Photosynthetic autotrophs, (like plants) can not use the N2 form of nitrogenNitrogen is a key component of proteins.Proteins are one of the key molecules that make living things.Nitrogen CycleAtmospheric nitrogen (N2) is transformed into a form of nitrogen that can be used by photosynthetic autotrophs in 3 ways: 

Lightning, certain bacteria that live in a mutualistic relationship with legume plants, human nitrogen fertilizer factories.

Plants need nitrogen as nitrates (NO3) or ammonium (NH4). Plants and other autotrophs use nitrogen to produce proteins. dfPlant protein is broken down for its nitrogen by animal heterotrophs to build animal proteins. 

Urine; animal waster, contains excess nitrogen. Other forms of bacteria break down organ matter and nitrates back into atmospheric nitrogen. 

Volatilization which is substances turning into gas, returns nitrogen to the atmosphere. This is the bad smell near farms and open toilets. 

Tell the story of the nitrogen

cycle.

Animation

Nitrogen Cycle (cont)ANIMATION

Phosphorus CycleAll organisms require phosphorus for growth and development. Phosphorus is an essential element in all cell membranes.

The phosphorus cycle is actually two cycles, a short term cycle and a long term cycle.The short term cycle phosphorus cycle begins when plants obtain phosphorus from the soil. Animals obtain phosphorus by eating plants. Animals and plants die and the phosphors in their bodies is returned to the soil.The long term phosphorus cycle begins when phosphorus is leached out of soil and into streams. Phosphorus washes into the oceans. Phosphorus in the oceans is incorporated into rocks and insoluble compounds.  Millions of years later as the environment changes, the rocks containing phosphorus is exposed and begins to erode into sediments. the phosphorus again becomes part of the soil and can enter the short term or long term P cycle.

Tell the story of the two phosphorus

cycles.

Animation

Phosphorus Cycle (cont) Animation

Central Concept: Ecology is the interaction among organisms and between organisms and their environment. 

6.1   Explain how birth, death, immigration, and emigration influence population size.

6.2   Analyze changes in population size and biodiversity (speciation and extinction) that result from the following: natural causes, changes in climate, human activity, and the introduction of invasive, non-native species.

6.3   Use a food web to identify and distinguish producers, consumers, and decomposers, and explain the transfer of energy through trophic levels. Describe how relationships among organisms (predation, parasitism, competition, commensalism, mutualism) add to the complexity of biological communities.

6.4  Explain how water, carbon, and nitrogen cycle between abiotic resources and organic matter in an ecosystem, and how oxygen cycles through photosynthesis and respiration.

What you need to know about Ecology

What are biotic and abiotic factors in an ecosystem? Give examples of

abiotic factors that effect living

things.

Questions to Ponder from Lesson 3 Part 1 What is the source of energy that animates life on earth?

What are autotrophs?

What are the two types of autotrophs, and how are they different?

What is photosynthesis? What is cyanobacteria?

What is endosymbiotic evolution?

What is a chloroplast?

What herbivores, carnivores, omnivores and detritivores?

What is repriration?

What is ATP? 

What is the relationship between chloroplasts and mitochondria? What is a food chain?What is a trophic level?What is a food web?

Questions to Ponder from Lesson 3 Part 2 What are biogeochemical cycles??

Where are carbon, nitrogen, phosphorus, oxygen and hydrogen found in living organisms?

Where are carbon, nitrogen, phosphorus, oxygen and hydrogen found in abiotic sinks in the earth or atmosphere? 

What is the rock cycle?

What is the water cycle?

What is the carbon cycle?

What is the nitrogen cycle?

What is the oxygen cycle? 

What is the phosphorus cycle?