1. 3-1 What is Ecology?
Ecology – the scientific study of interactions among organisms and their surroundings.
Ecologists – scientists who study the environment
Biosphere – the combined portions of the planet in which all of life exists, including land (lithosphere), water (hydrosphere), and air (atmosphere).
So as we start our trip through Ecology we first need to understand what Ecology is. Ecology is the study of the interactions of all organisms within their surroundings. Ecologists are scientists who study the environment, and a biosphere is the combination of all portions of the planet where life exits. The land is called the lithosphere, water is called the hydrosphere, and the air is called the atmosphere.

2. Levels of Organization (From least inclusive to most inclusive)
1) Species – the individual organism.
2) Populations – a group of organisms of one species that interbreed and live in the same place at the same time.
3) Communities – a collection of interacting populations.
4) Ecosystems – made up of the interactions among the populations in a community. This could include their habitat (the place where an organism lives out its life) or its niche (the role and position a species has in its environment)
5) Biome – a group of ecosystems that have the same climate and similar dominant communities.
We organize all this into levels. If we were to start at the smallest level we would be discussing the individual organism, which we call the “species”. From there we start discussing populations, or groups of species that can breed together and live in the same place at the same time. Increasing from there we start talking about communities, here we have a collection of populations all interacting with each other. Next we get larger and start discussing ecosystems, now you have many interactions among the populations. This includes the habitat (the place where the organism lives) or its niche (is the part of the environment into which a species fits, and to which it is adapted, how an organism makes a living in a place). Then you have the biome which is a group of ecosystems that have the same climate and similar dominate communities.

3. Figure 3-2 Ecological Levels of Organization
Section 3-1
This shows a pictorial explanation of what we just talked about. The species is the elk, then it lives with other elk in a population. The community shows other organisms which it lives with. The ecosystem shows a larger area showing how they interact and how other species may play a role. The biome shows the climate and similar geographic areas, finally the biosphere is the largest area showing the entire Earth, all of the land, water, and air. (lithosphere, the hydrosphere, and the atmosphere)

4. Energy Flow Energy flows in one direction through an ecosystem
Interest Grabber
Section 3-2
Energy Flow
Energy flows in one direction through an ecosystem
From the sun or inorganic compounds to
Producers (organisms that can make their own food)
Through various levels to consumers (organisms that rely on other organisms for food).
Your body gets the energy and materials it needs for growth and repair from the foods you eat.
We know we get energy from the sun. We also know we need that for plants to grow as they are the beginning of the food chain. Producers are any organism that can produce their own food, such as plants. Producers are also called “autotrophs”. Once the producer used the sun’s energy it get’s eaten by a heterotroph (or an organism that cannot make their own food) or a consumer. This consumer is not on that goes out shopping (that‘s economics and we are talking about ecology). There are many different types of consumers. You are a consumer and you get your energy, that began from the sun, through eating your veggies and meat. You need this energy to create muscles and growth.

5. 3-2 Energy Flow
Food Chains – a diagram that show the flow of energy from green plants to consumer organisms
Grass  rabbit  hawk
Food Webs – a diagram that shows the many possible food chains that exist in an ecosystem.
Trophic Levels
The first step in any food chain is always the producer. The second step is always the herbivore. Since the herbivore is the first consumer, it is sometimes referred to as the first order or (primary) consumer. The second consumer is the second order (secondary) consumer. Next is the third order (tertiary) and fourth (quaternary) consumer. Decomposers may be at any step except the first.
Food chains show a direct line of energy flow from the plant to higher level consumer. This example shows the grass, as the producer, is eaten by the rabbit (primary consumer), and then the rabbit get’s eaten by the hawk. The energy is flowing from plant to rabbit and ending with the hawk.
Food webs are different as there are many possible scenarios in an ecosystem. It may show the grass getting eaten by the rabbit which could get eaten by a coyote, or a wolf, or a hawk. So the webs show more complexities that are present in an ecosystem. Where as the food chains only show one possibility. Trophic levels show the different levels of the food chain. The first level is always the producer (autotroph/organism that can make it’s own food.) Next you see a primary consumer, these are the herbivores (animals that eat only plants), the second level or the secondary consumer would be omnivores as they can eat plants and animals. Third level (tertiary) and the fourth level (quaternary) consumers are both carnivores (eating only meat). Finally you have your detritivores (decomposers) they break down any dead or decaying material and can be found at any level except the producer level.

6. Trophic Levels
Fourth order consumers (Quaternary) Heterotrophs
Third order consumers (Tertiary) Heterotrophs
Second order consumers (Secondary) Heterotrophs
First order consumers (Primary) Heterotrophs
Producers Autotrophs Available Energy Decreases
Heterotrophs- rely on other organisms for their food; Herbivores, Carnivores, Omnivores, Detritivores (feed on dead matter)e.g. mites, earthworms, snails. Decomposers (break down organic matter) e.g. bacteria and fungi.
Autotrophs- plants, some algae, and certain bacteria capture energy from the sun and use that energy to make their own food. Autotrophs make food automatically!
Fact: Sunlight is the main energy source for life on earth.
This is a diagram showing exactly what we just talked about. Starting at the bottom we have our sun, as without it the rest cannot live. Next you see the autotrophs (the producers) these organisms can make their own food. Everything else is a heterotroph as they rely on other organisms to obtain their energy in the form of food. Heterotrophs consist of herbivores, omnivores, carnivores, detritivores and decomposers. Primary consumers (herbivores) rely on the autotrophs (producers) exclusively in order to obtain their energy, secondary consumers (omnivores) rely on both plants and animals to get their energy, tertiary and quaternary rely on meat only as they are carnivores.

7. Food Chain vs. Food Web
A food web contains many overlapping food chains so it is much more complex than a single food chain.
Here you see the differences between a food web and a food chain. On the left you can see many options for animals to obtain their energy from other organisms, on the right you only see one chain from the sun to the tertiary consumer.

8. Ecological Pyramids Section 3-2 Energy Pyramid
Shows the relative amount of
energy available at each trophic
level. Organisms use about 10
percent of this
energy for
life processes.
The rest is lost
as heat.
Pyramid of Numbers
Shows the relative
number of individual
organisms at each
trophic level.
These diagrams show the relationships between energy, biomass, and populations. You can see from the Energy Pyramid that the amount of energy significantly drops as you move up from the pyramid. Producers get 100% of the energy from the sun, but the transfer of energy is greatly decreased as the consumers are added. Primary consumers percentages drop from 100% in producers down to 10% for primary, the decrease continues as secondary consumers only obtain 1%, and the tertiary consumers obtain 0.1%. Where does the rest of this heat go? It’s lost to heat. A pyramid of biomass (living organic matter) is a more accurate indication of how much energy is passed on at each trophic level. The biomass in each trophic level is always less than the trophic level below. This is because biomass is a measure of the amount of food available. They pyramid of numbers shows the feeding relationship and the number of organisms at each trophic level. The pyramidal shape indicates that the number of organisms or species is largest at the bottom, and is narrowing towards top. This helps to determine how much food an organism might need by calculating the energy lost due to it’s trophic level.
Biomass Pyramid
Represents the amount of
living organic matter at each
trophic level. Typically, the
greatest biomass is at the
base of the pyramid.

9. Matter is constantly recycled within and between ecosystems.
3-3 Cycles of Matter
Biogeochemical Cycles – the flow of chemicals between the environment and the organisms
Matter is constantly recycled within and between ecosystems.
Biogeochemical cycles, whew big word, but it’s really just the flow of chemicals between the organisms the environment. We know that matter cannot be created nor destroyed so it has to be constantly recycled throughout the Earth.

10. THE WATER CYCLE Heat evaporates water from oceans, lakes, and streams.
Water is then carried into the atmosphere where it condenses and returns to the Earth in the form of precipitation.
Plants release water from their leaves through transpiration.
This is a continuous cycle.
You have all learned about the water cycle, here is a quick overview. Heat makes the water phase change into a gas. The gas rises into our atmosphere and cools. As it cools it condenses into water droplets which form clouds and then fall to the earth in different forms. Plants can also release water through their leaves, this is called transpiration.

11. The Water Cycle Section 3-3 Condensation Precipitation Evaporation
Transpiration
Evaporation
Runoff
Seepage
This diagram shows a more detailed explanation. We can start again with the oceans/rivers/lakes/and plants with transpiration sending water out into the atmosphere. There it will condense and precipitate (fall to earth). Once it falls to earth it can either runoff (to lakes/ocean) or it can seep through the dirt into underground water reservoir where plants can take water there or the water underground may create large reservoir or eventually seek out the ocean.
Root
Uptake

12. THE CARBON CYCLE
The Carbon Cycle is driven by photosynthesis and respiration.
In photosynthesis plants take in carbon dioxide and water to produce glucose and oxygen.
The plant’s role is to produce an organic carbon compound called glucose.
During respiration, organisms use oxygen and glucose to produce carbon dioxide and water.
Carbon dioxide is released into the atmosphere by respiration as well as many other activities. This is a continuous cycle that occurs between plants and animals.
We know that carbon dioxide is in the atmosphere as we are constantly exhaling it throughout the day. Where did we obtain that carbon? Well from eating food, all of our food contains carbon. The carbon cycle starts in the atmosphere where plants take in carbon dioxide to survive. They then use photosynthesis to create glucose (which as luck would have it contains carbon). You then eat the plant and you now have the carbon in your body. You body uses what it needs and then you exhale again giving the plants the carbon they need to survive. This happens with all heterotrophs (consumers).

13. Figure 3-13 The Carbon Cycle
Section 3-3
CO2 in
Atmosphere
CO2 in Ocean
Here again is a more detailed approach. You see that carbon is in everything, including the ocean. You can see all the different relationships between producers (autotrophs) and consumers (heterotrophs). You see decomposition leading to fossils, which leads to fossil fuels we use that sends the carbon back again into the atmosphere. You can see how carbon actually enters the rock cycle and even a volcano (yay!) that is expelling carbon back into the atmosphere, all for it to start again and again.

14. CO2 in
atmosphere
Diffusion
Respiration
Photosynthesis
Plants and algae
Plants
Animals
Industry and home
Combustion of fuels
Carbonates in sediment
Bicarbonates
Deposition of
dead material
Deposition
of dead
material
Fossil fuels
(oil, gas, coal)
Dissolved CO2

15. THE NITROGEN CYCLE
Over 78% of the air is nitrogen gas, but in this form it is useless to organisms.
Most living organisms use nitrogen only in the form of nitrates and ammonia.
The conversion of nitrogen gas to ammonia is called nitrogen fixation.
This process is carried out by bacteria located in the roots of legumes (peas and beans).
Other bacteria convert ammonia into nitrates and nitrites. Plants then take in the nitrates.
Animals eat the plants, and we obtain nitrogen. Other bacteria in the soil convert nitrates back into nitrogen.
This process is called denitrification. Then the nitrogen gas is returned to the atmosphere for the cycle to begin again.
Here is a general representation of the nitrogen cycle. Most of the nitrogen is in our atmosphere and in a form we cannot use. So we have bacteria as our friends as they can change around and convert nitrogen compounds into useable forms for us. Once it’s useable for plants than nitrogen works its way through the food chain as it is necessary for all animals (including you). When plants/animals die and decompose they reenter the soil or left over nitrogen that wasn’t needed reenters the atmosphere and we start again.

16. Figure 3-14 The Nitrogen Cycle
Section 3-3
N2 in Atmosphere
The nitrogen cycle describes how nitrogen moves between everything from plants, to animals, the atmosphere, the dirt or soil, and even bacteria. Nitrogen is extremely important to all life on Earth. For Nitrogen to be used by different life forms on Earth, it must change into different states. Nitrogen in the atmosphere, or air, is N2. But we must be able to convert N2 into nitrates, nitrites, and ammonium throughout the cycle. Without the use of bacteria in the cycle the nitrogen cannot change into the necessary states needed, so it is by far the most important aspect of the cycle. Bacteria change the nitrogen in the soil to a useable form for the plants (autotrophs/producers) which then get eaten by animals (heterotrophs/consumers). Fixation, where the bacteria take the first step in fixing the nitrogen to be useable for plants they do this by changing the nitrogen to ammonium. Nitrification is the process by which ammonium gets changed into nitrates by bacteria, nitrates are what the plants absorb. The plants then use Assimilation to get the nitrogen by absorbing the nitrates in the soil using their roots. The nitrogen gets used in creating amino acids, nucleic acids, and chlorophyll. Then the plant dies and ammonification is the part of the cycle that includes the decaying process. When it dies the decomposers turn the nitrogen back into ammonium and we start the process again. The last term we haven’t discussed is denitrification, this is were any extra nitrogen left over enters the atmosphere, bacteria is not needed for this to occur.
NO3-
and NO2-
NH3

17. Atmospheric nitrogen Carnivores Herbivores Birds Plants Fish excretion
amino acids
Carnivores
Atmospheric
nitrogen
loss to deep sediments
Fish
Plankton with
nitrogen-fixing
bacteria
Nitrogen-fixing
(plant roots)
(soil)
Denitrifying
Death, excretion, feces
Nitrifying bacteria
soil nitrates
excretion
Decomposing bacteria
Ammonifying bacteria

18. All organisms require phosphorus.
THE PHOSPHORUS CYCLE
All organisms require phosphorus.
Plants obtain phosphorus from the soil, and animals obtain phosphorus from plants.
When animals and plants die, they return phosphorus to the soil.
Phosphorus moves through the cycle through rocks, soil, water, sediments, plants and animals. It is essential for cell development and plays a key role in creating molecules that store energy, such as ATP (adenosine triphosphate), DNA and lipids (fats and oils).

19. Over time, rain weakens rocks and causes them to break down (we call this weathering) the rocks that are broken down then release phosphates and other minerals. This is not useable and is considered inorganic phosphate and is then absorbed into the soil or washed down into the water.
Our amazing plants come to our rescue again and take up the inorganic phosphate from the soil and turn it into something we can use. The plants may then be consumed by animals. Once in the plant or animal, the phosphate is incorporated into organic molecules such as DNA. When the plant or animal dies, it decays, and the organic phosphate is returned to the soil. Once it has returned to the soil, organic forms of phosphate can be made available to plants by bacteria again saving the day that break down organic matter to inorganic forms of phosphorus. This process is known as mineralisation. Phosphorus in soil can end up in waterways and eventually oceans. Once there, it can be incorporated into sediments over time and go into the creation of rocks.
Video

20. Loss to deep sediment
Rocks and
minerals
Soluble soil
phosphate
Plants and
algae
Plants
Urine
Land
animals
Precipitates
Aquatic
Animal tissue
and feces
Decomposers
(bacteria and
fungi)
(bacteria & fungi)
Phosphates
in solution
Loss in
drainage

21. Interest Grabber Answers
1. What living things are found in and around your school?
Living things in the school are students, teachers, principal, assistant principals, clerical staff, custodians, lunchroom staff. Students may also include animals in science labs. Living things around the school include grass, trees, shrubs, insects, birds, and so on.
2. What nonliving things are found in your school?
The building, furniture, desks, books, papers, and so on
3. Into what large groups are the students in your school divided?
9th, 10th, 11th, 12th grades, or years
4. Into what smaller groups are these large groups divided?
Classes
5. Are these groups ever divided into even smaller groups? If so, what are these groups?
Students may say that science classes are divided into lab groups; other classes may be divided into groups for projects.
Section 1 Answers

22. Interest Grabber Answers
1. Make a list of five foods that you like to eat. Indicate whether the food comes from a plant (producer) or an animal (consumer).
Student lists will be individualized. One possible example would be a hamburger, which comes from a cow or steer.
2. Like many birds, chickens eat grains, which are seeds. Where do seeds come from?
Seeds come from plants.
3. Meat comes from beef cattle. What do cattle eat?
Cattle eat grass or grains.
4. Construct a diagram showing how one of your favorite foods obtains its energy. Include as many levels as you can.
Student diagrams will be individualized based on their food choice. Using the hamburger example, the beef in the hamburger comes from cattle. The cattle feed on grass or grain. Grass or grains are plants, which use energy from the sun to make their own food.
Section 2 Answers

23. Interest Grabber Answers
1. When rain falls on the ground, it either soaks into the soil or runs across the surface of the soil. When rainwater runs across the land, what body of water might collect the rain?
Possible answers: a stream, river, pond, or lake
2. From here, where might the water flow?
Into a river, and eventually into the ocean
3. After the rain, the sun comes out and the land dries. Where does the water that had been on the land go?
It evaporates and becomes a gas in the atmosphere.
4. Construct a diagram that would illustrate all the places a molecule of water might go. Begin with a raindrop and end with a cloud.
Student diagrams may include the following: a raindrop —> lawn —> a stream —> river —> large lake —> atmosphere —> cloud.
Section 3 Answers