Energy and Food Webs


Energy and Food Webs

Part 1:

  • Provide an example of a food chain in the area where you live.
  • Humans are parts of food chains and food webs, too. Where on a food web would you typically find humans (near the bottom with the producers, at the top with carnivores, or somewhere in between)? Explain.
  • What are some advantages of being part of a food web rather than a food chain?

Part 2:

Here is a food web for Lake Michigan:

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  • In the Lake Michigan food web, is it possible to identify the most important producer? Why or why not?
  • What would happen if there was a change in the population size for any one of the producers (either an increase or a decrease)? How could these changes impact other producers and organisms on other trophic levels?
  • Provide at least two types of impacts that humans could have on this food web.
  • Read the description of the sea lamprey on page 2 of the food web. This species is described as non-native.
    • Propose a mechanism for how this fish was introduced to Lake Michigan.
    • What challenges could occur within a food web when a new predator like this is introduced into an ecosystem?
    • What natural population controls are missing for this species within this food web?
    • Do you think steps should be taken to eradicate this species from the food web? Explain why or why not? If so, what steps can be implemented?

Topic 3: Costs and Economies of Scale

  • You have learned a good deal about production costs and profit in this unit. You have also learned that accountants and economists calculate profit differently. Moreover, many suppliers experience economies of scale as output expands, which implies that long-run average total costs are falling. At very high levels of production, however, many firms are likely to experience diseconomies of scale.
  • Discussion Checklist:
  • Discuss the difference between how accountants and economists calculate profit giving example of costs each might use in this calculation.
    B. Why do firms experience diseconomies of scale as they increase production volume?
    C. How might firms “avoid” experiencing diseconomies of scale?

Sample paper

Energy and Food Webs

Part one

  1. Many individuals tend to confuse between a food chain and a food web. A food web usually consists of many food chains and a food chain commonly follows a single path as animals attempt to find food. Below is a good example of a food chain

Leaf –  ant – spider – frog – bird – snake – big bird of prey

  1. It is likely to find humans at the top with the carnivorous in most food chains and food webs basically because he is one of the final consumers of producers. Nevertheless, the human is known to consume both greens and fresh making him one of the carnivorous and he is likely to be found at the top with other fresh eaters.
  2. Some of the possible advantages of a food web include:
  3. A food web is more accurate and nutritious than food chains considering that animals eat different things and are eaten by different things.
  4. Food web helps to demonstrate the correlation between organisms besides showing just the flow of energy like in the case of a food chain(Polis, 2013).

Food web for Lake Michigan

Part two

  1. No.

It is not possible to identify the most important producer in this scenario basically because the food web is so complex that all the producers seem to be equally important for the continuation of the life cycle.

  1. A decrease in the size of one of the producers will lead to a decrease in other sea life considering there will be no enough food to feed others groups of animals. Reduction in one producer means the other producer will be consumed to an extent it is no more and the population will start decreasing. On the other hand, an increase in one producer will lead to an increase in the whole population as there will be enough food to feed the population.
  2. Contamination of sea water, which supports the lives of some of the producers which can lead to their extinction.

Consumption of some of the producer in the form of food, thus leading to their population, which in turn affects the food web

  1. Sea lamprey fish are native to the Northern Atlantic Ocean and are likely to have invaded Lake Michigan through shipping canals and shipping lines from other regions(Madenjian, 2015).
  2. The introduction of a new predator in a food chain increases the relationship between the animals as well as reducing the population of some.
  3. No

Steps should not be taken to eradicate such spices because they help to bring balance in animal life, ensuring that there are no too much of a certain population to sustain.

Costs and Economies of Scale

Part 3

  1. Accounting profit is comprised of the monetary costs an enterprise incurs and the revenue the enterprise receives. Accounting profit is obtained after total costs are subtracted from the total revenue. However, on the other hand, economic profit is the monetary cost and opportunity cost incurred by a firm and the revenue realized. It is obtained after explicit and implicit costs are subtracted from the total revenue of a firm.
  2. The diseconomies of scale are likely to occur due to diminishing returns. The law of diminishing return states that as more and more is increased to a fixed amount of variable for example capital or land, it is likely to get to a point where it cannot stretch anymore and thus, regardless of the increase in labor the production will not increase(Carlino, 2012).
  3. The only way to stop diseconomies of scale at such point is to avoid hiring more labor, especially when the marginal production starts to decline or gets to zero.


Carlino, G. A. (2012). Economies of scale in manufacturing location: theory and measure                        (Vol. 12). . Springer Science & Business Media.

Madenjian, C. P. (2015). Changes in the Lake Michigan food web following dreissenid mussel                 invasions: A synthesis. Journal of Great Lakes Research, 41, , 217-231.

Polis, G. A. (2013). Food webs: integration of patterns & dynamics. . Springer Science &                        Business Media.