Unit 1: Ecosystems - Merit Science

Unit 1: Ecosystems Students will understand that living organisms interact with one another and their environment Terms to Know Predator-prey Consumers Symbiosis

Producers Competition Limiting Factor Ecosystem Competition

Carbon Cycle Decomposers Nitrogen Cycle Food Chain

Oxygen Cycle Biotic Population Abiotic Diversity

Community Energy Pyramid Variable Quantitative Evidence

Qualitative Inference Objective 1: How does energy flow through an ecosystem? Section 1: Ecosystems: Am I all alone? Objective 1: Energy Flows Through an Ecosystem Do organisms live in isolation?

No, organisms are not separated from their environment or from other organisms. They interact in many ways with their surroundings. Ecology is the study of biotic (living) and abiotic (nonliving) interactions in an environment. Energy Flows Through an Ecosystem

All organisms have the ability to grow and reproduce. To grow and reproduce, organisms must get materials and energy from the environment. Plants obtain their energy from the sun through photosynthesis. Animals obtain their energy from other organisms.

These plants and animals, as well as bacteria and fungi, are constantly interacting with other species as well as the non-living parts of their ecosystem. Energy Flows Through an Ecosystem Abiotic Factors the parts of the environment that are not living, such as sunlight, climate, soil, water and air. Biotic Factors are the parts of the environment that are

alive, or were alive and then died, such as plants, animals, and their remains. Biotic factors also include bacteria, fungi and protists. Ecosystems can be studied at small levels or at large levels. The levels of organization are described below from the smallest to the largest. A population is a group of organisms belonging to the same species that live in the same area and interact with one another. Individuals are members of the same species (a group of individuals who are genetically related and can breed to produce

fertile offspring), if their members cannot produce offspring that can also have children. The second word in the two-word specific epithet name given to every organism is the species name. For example, in Homo sapiens, sapiens is the species name and Homo is the genus. A community is all of the populations of different species that live in the same area and interact with one another. Ecosystems can be studied at small levels or at large levels. The levels of organization are described below from the smallest to the largest.

An ecosystem includes the living (biotic) organisms (all the populations) in an area and the non-living (abiotic) aspects of the environment and their interactions. A niche is the role an organism plays in its ecosystem. Essentially what services it provides and does in an ecosystem. For example, a sardines niche would be to eat algae and phytoplankton and serve as a food source for many different fish species. The biosphere (the highest level of ecological organization, it is the part of the earth, including the air, land, surface, rocks and water, where life is found) includes almost all of the Earth. Parts of the lithosphere, hydrosphere and atmosphere make up the biosphere.

Ecosystems can be studied at small levels or at large levels. The levels of organization are described below from the smallest to the largest. Ecosystem Levels Ecologists study ecosystems at every level, from the individual organism to the whole ecosystem and biosphere. They can ask different types of questions at each level. Think Like an Ecologist 1. What are the levels of ecological organizations? Describe from largest to smallest. 2.

What are some of the abiotic factors that scientists monitor when dealing with stream ecosystems? 3. What are some of the biotic factors that scientists monitor when dealing with stream ecosystems? 4. Remembering what youve learned about the scientific process, why is it valuable for scientists to use the same procedures and gather the same information across different streams and a wide ranging geography? What does this allow them to do? How does this affect the strength and applicability of their research? 5. Pick your favorite cartoon or comic book story. Write a descriptive essay

that illustrates the ecosystem they live in and what makes it unique. Be sure to describe the abiotic and biotic components, species, communities and interactions that would occur there. Section 2: Food Chains and Food Webs: Whos eating Whom? Objective: Summarize how energy flows through an ecosystem through food chains and food webs. Food Chains and Food Webs: Whos eating whom? Food chains always begin with producers, organisms that use a primary energy source (most commonly the sun) and photosynthesis, to make their own food energy.

Consumers (organisms that cannot make their own food and must get energy from the other living organisms) can be herbivores, carnivores, or omnivores. Food chains might also include decomposers (organisms that get nutrients and energy by breaking down the remains of dead organisms or animal waste) such as bacteria and fungi. Through the process of decomposition, they recycle nutrients like carbon and nitrogen back into the environment so producers can use them. Food Chains and Food Webs: Whos eating whom? A food chain represents a single pathway by which energy and matter flow through an ecosystem.

Food chains are generally simpler than what really happens in nature. Most organisms consumeand are consumed bymore than one species. Food Chains and Food Webs: Whos eating whom? A food web represents multiple pathways through which energy and matter flow through an ecosystem. It includes many

intersecting food chains. It demonstrates that most organisms eat, and are eaten, by more than one species. Activity: Ecosystem Analysis Planet Earth Episode Think Like an Ecologist 1. What type of relationships do food webs and food chains depict? 2. What is the role of decomposers in an ecosystem? What is the source of the matter that is decomposed?

3. How do the actions of earthworms improve soil quality? How does this impact the amount of biomass an ecosystem can support? 4. How are food chains and food webs the same? How are they different? 5. There is going to be a zombie apocalypse. Only one producer can survive. It is your job to choose which producer survives. Explain, in full sentences, which producer you would choose and why? Section 3: Energy Pyramids: Why do we have more warthogs than cheetahs?

Objective: Explain how energy enters, is used, transferred and lost as it moves through organisms in an ecosystem. How much energy can be gained from the warthog? If the cheetah is successful in capturing the warthog, he would gain some energy by eating it. But would the cheetah gain as much energy as the warthog has ever consumed? No, the warthog has used up some of that energy for its own needs. The cheetah will only

gain a fraction of the energy that the warthog has consumed throughout its lifetime. Plants When an herbivore eats a plant, the energy in the plant tissues is used by the herbivore. But how much of that energy is transferred to the herbivore? Plants are producers, bringing the energy into the ecosystem by converting

sunlight into glucose. The plant needs and uses much of that energy. After the plant uses the energy from glucose for its own needs, the excess energy is available to the organism that eats the plant. Herbivores The herbivore uses the energy from the plant to power its own life processes and to build more body

tissues. Only about 10% of the total energy from the plant gets stored in the herbivores body as extra body tissue. The rest of the energy is used by the herbivore and released as heat. Predators The next consumer on the food

chain that eats the herbivore will only store about 10% of the total energy from the herbivore in its own body. This means the carnivore will store only about 1% of the total energy that was originally in the plant. Only about 10% of energy of one step in a food chain is stored in the next step in the food chain.

The majority of the energy is used by the organism or released to the environment. Energy Flow through a Food Chain Energy Loss Every time energy is transferred from one organism to another, there is a loss of energy. Energy is typically lost in the form of heat and respiration.

This loss of energy can be show in an energy pyramid. Since there is energy loss at each step in a food chain, it takes many producers to support just a few carnivores in a community. Energy Pyramids Each step of the food chain in the energy pyramid is called a trophic level.

Plants or other photosynthetic organisms (autotrophs) are found on the first trophic level, at the bottom of the pyramid. The next level will be the herbivores, and then the carnivores that eat the herbivores. Energy Pyramids This energy pyramid shows four levels of a food chain, from producers to carnivores.

Because of the high rate of energy loss in food chains, there are usually only 4 or 5 trophic levels in the food chain or energy pyramid. There just is not enough energy to support any additional trophic levels. Heterotrophs, organisms that cannot produce their

own food, are found in all levels of an energy pyramid other than the first level. Activity: Energy Pyramid Venn Diagram Starburst Energy Pyramid Lab Think Like an Ecologist 1. A warthog weighs 100 lbs. If a cheetah eats the warthog, approximately how many pounds will be used for energy by the cheetah? 2. What happens to the energy in the food that you eat when it gets into your body?

3. If the producers in an ecosystem were able to produce 10,000 kcal of energy through photosynthesis, about how much energy would be transferred to the first consumers in the food chain? How much energy would transfer from producers to secondary consumers? How much would transfer from producers to tertiary consumers? 4. You are a general in the civil war and come upon a farm. If you can only commandeer one of the following: cows, pigs, corn or chickens. Which one will you take to support your large army and why? Which will supply your army with the most energy? Use full sentences. Section 4: Energy: Is it worth it? Objectives:

Describe how organisms balance the energy used to get food and the energy from food. Provides examples of how food production varies worldwide. Describe strategies used by organisms to balance the energy expended to obtain food to the energy gained from food. Energy: Is it worth it? Why do animals behave the way they do?

A cat chases a mouse to catch it. A mother dog nurses her puppies to feed them. All of these behaviors have the same purpose: getting or providing food. All animals need food for energy. They need energy to move around. They need energy just to stay alive. Energy allows all the processes inside cells to occur. Why do organisms do the things that they do? Organisms must balance the

amount of energy they use to get food with the amount of energy they gain from the food. They have to decide if the prize is worth the effort. The spider shown had to use a lot of energy to build his web, but hopefully he will be able to catch many insects before he builds a new one. Food for Thought

If the spider uses 100 kcal to build his web, and each insect caught gives him an average of 20 kcal, how many insects does he need to catch before its worth it to build the web? 5 insects Imagine if you had to run for an hour in order to get a candy bar. Would you do it? Probably not, because you would use more energy running than you would get from the candy bar. On the other hand, if you just had to walk around the block, it might be worth it.

Hummingbirds have to use energy hovering at a flower in order to drink the nectar. They will only do it if they get more energy from the nectar than it takes to hover. A coyote will chase a rabbit to catch it, but only for so long. At some point, its not worth it anymore because he has to use too much energy in the chase. Carrots vs. Snickers Lab This is a unit hook activity in which students will be introduced to the idea of using and obtaining energy in an ecosystem. They will also begin to understand that organisms expend different amounts of energy to obtain more energy. Students will understand strategies organisms use to balance energy

intake with energy expenditure. Balancing Energy Animals have come up with many creative strategies to balance the energy used to obtain food with the energy gained from the food. Bird migration is an example of this. Even though it is very difficult to fly so far, they are rewarded with plenty of available food, so the prize is worth the effort. Hibernation is another example. During hibernation, animals may carefully regulate their metabolism to slow it down and may also lower their core body temperature. Prior to hibernation, when food is

plentiful, they eat in excess in order to store energy for the long period of inactivity during hibernation. Lab: Energy & Calories In this lab students will learn to correlate calories with obtaining and using energy. They will do this by analyzing several meals, calculating caloric value and calculating their own calorie expenditure. Think like an Ecologist 1. If it took the same amount of energy to chase a mouse as it did to chase a rat, which do you think a cat would choose to chase? Why? 2. What is an example of a strategy used to balance energy used to obtain food with energy gained from the food (other than migration and hibernation)?

3. If you have a gas station a few miles from your house where the gas is $3.20 a gallon and one 15 miles away at $3.00 a gallon, which one do you go to? Write in paragraph format using complete sentences. Section 5: Humans and Food: Where does my food come from? Objective: Investigate food production in various parts of the country and world. Where does my food come from? Food production varies dramatically in different parts of the world. In many places, people can only eat the foods that are grown or caught locally. In other places, like the United States, we have access

to food from all over the world. How does this access to food affect us? How does it affect the world around us? One major concern is the use of processed food, which has been changed from its original form, frequently stripping it of its nutritional value and adding in extra sugars and fats. Processed foods are very common in the United States and include things like pop-tarts, cheese whiz, and hot dogs. These foods have many calories but little nutrient content, so they contribute to the obesity epidemic in America.

Another concern related to food processing is the amount of fossil fuels that must be used in order to transport food from its source to the processing plants and eventually stores. Activity: My Favorite Food Students will chose a favorite food and create a poster or brochure to describe the source of this food, it's health benefits and it's cost to the environment.

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