4.A.6 Portfolio

Describe how ecosystems provide organisms with their energetic and matter requirements.

It starts off with the producers. This group is composed of plants and other organisms that are “photosynthetic,” meaning that they make their food and molecules necessary for life from the energy of the sun. This process is also known as photosynthesis. Then, the energy from the producers is transferred to organisms that eat the producers or primary consumers (herbivores), which break down the producer’s molecules. Then energy is transferred to secondary and tertiary consumers. When these animals die, the ecosystem’s decomposers will eat the dead animals for sustenance, transferring the dead animal's energy to both the ecosystem, in the form of heat energy, and the decomposer.

Explain how changes in climate can influence primary productivity in an ecosystem.

Climate change has forever been linked to changes in the ecosystem. Many animal species go extinct as they are unable to adapt to the changes presented in their environment. However, primary productivity is affected because the first ones to be affected by climate change are the producers. Due to this and the way energy is transferred within the ecosystem, humans will eventually these effects. 

If a certain species of plant died in the ocean because the water was too cold or hot, then all the fish eating that plant would eventually die off. Then the fish eating that fish would die off and so on. Eventually humans would notice this change in climate as the fish that they ate also died off to due a lack of prey caused by climate change.

Compare food chains and food webs.

Food chains differ from food webs in that food chains main focus is on how each organism in an ecosystem obtains its food. Food chains follow only one path and  contain arrows pointing from one organism to another to point out which organisms are eaten by which. Food webs aim more to demonstrating the flow of energy and nutrients in an ecosystem. They show more of how several animals and plants are connected.

Source: http://aisdvs.aldine.k12.tx.us/mod/book/view.php?id=169242&chapterid=32229

Describe the major interactions among organisms in a food web.

Each trophic level will contain less energy than the last as only a typical 5% to 10% of energy is passed down each organism. Therefore there are usually no more than four or five levels within a food chain. At first trophic level are the primary producers, plants and organisms that use the sun's energy to produce food. Then there are primary consumers, or herbivores. Then,  secondary consumers are carnivores that eat herbivores. On the top are tertiary consumers, carnivores that eat other carnivores.


Explain how modeling of the trophic structure of an ecosystem can be used to make predictions about the effects of changes in biotic and abiotic factors on that ecosystem.  

With the modeling of the trophic structure of an ecosystem, we are able to see how organisms and abiotic factors interact with each other and how the flow of energy and nutrients occurs. Having access to this, therefore, also allows us to predict how changes of biotic or abiotic factors will affect all others. In order to affect organisms, something in the ecosystem, whether abiotic or biotic, will increase or decrease the transfer of energy from each trophic level more or less than the typical 10% that is passed. Modeling the trophic structure would allow us to make predictions on which organisms would stop receiving energy due to changes in biotic or abiotic factors or receive an increase in energy instead.


Describe the strengths and limitations of this approach

This approach is helpful in the fact that it does help ecologist predict what might happen in ecosystems did undergo any major changes. However, this approach only allows ecologists to view one ecosystem at a time. This is limiting especially since there are a variety of ecosystems.

Provide examples to demonstrate how human activities have impacted ecosystems on local, regional, and global scales.  Describe the causes, and effects of these impacts, and discuss possible avenues of mitigating these impacts.

Deforestation is human activity that has had a serious impact on the ecosystem. Before we began to cut down habitats, forest used to account for 30% of the Earth’s land area. TOday, areas the size of Panama are being lost. This has caused several consequences. Millions of species have lost their homes, the soil of the forests becomes dry since trees no longer provide shade, and global warming has increased since trees that absorb the harmful greenhouse gases are being cut down. The most evident and quickest way to stop the effects of deforestation is to simply stop cutting down trees. However, given the power and motivation of large companies, a reasonable solution may be to end the practice of clear cutting. Instead, a balance of trees cut and new ones planted should be established.

Source: http://environment.nationalgeographic.com/environment/global-warming/deforestation-overview/

Provide examples of species that have been driven to extinction by human activities.

- Pyrenean Ibex: Went extinct in 2000 due to too much hunting

Source: WikiMedia

-Tasmanian Tiger: Lived in Australia; were often shot and trapped as people believed they killed livestock

Source: WikiMedia

- Javan Tiger: Became extinct around the mid-1970’s due to loss of their forest habitat and excess hunting  

Source: WikiMedia

Source: http://www.huffingtonpost.com/2013/10/22/11-extinct-animals_n_4078988.html

Predict the effect of a change in one of the components on the interactions within the community and matter and energy flow.

If one of the components were to change, this may allow the ecosystem for a greater variety of ways to react to the change in environment. A change in the molecule may possibly give cells the ability to have many different functions, since even the smallest change has an effect. Therefore with this genetic alteration, species may move up or down in the food chain due to their remarkable ability to adapt to the changes in the environment.