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ecology

Coral Bleaching

In this analysis and discussion activity, students learn about basic coral biology.

Then, they find answers to their questions about coral bleaching.

This activity concludes with questions about how we can reduce coral bleaching and why we need to check sources for potential bias.

Food Webs – How did the elimination and return of wolves affect other populations in Yellowstone?

To begin this hands-on, minds-on activity, students view a video about ecosystem changes that resulted when wolves were eliminated from Yellowstone National Park and later returned to Yellowstone. Then, students learn about food chains and food webs, and they construct and analyze a food web for Yellowstone. Finally, students use what they have learned to understand a trophic cascade caused by the elimination of wolves from Yellowstone.

This learning activity provides an introduction to the learning activities, Carbon Cycles and Energy Flow through Ecosystems and the Biosphere and Trophic Pyramids. All three of these activities are included in Food Webs, Energy Flow, Carbon Cycle and Trophic Pyramids, which is intended for classroom instruction.

Carbon Cycles and Energy Flow through Ecosystems and the Biosphere

In this analysis and discussion activity, students learn that the biosphere requires a continuous inflow of energy, but does not need an inflow of carbon atoms.

To understand why, students apply fundamental principles of physics to photosynthesis, biosynthesis, and cellular respiration, the processes which are responsible for carbon cycles and energy flow through ecosystems.

Thus, students learn how ecological phenomena result from processes at the molecular, cellular and organismal levels.

Trophic Pyramids

In this analysis and discussion activity, students discover the reasons why (in many ecosystems) plants are more common than primary consumers, which in turn are more common than secondary consumers.

To begin, they learn about the factors that influence the net rate of biomass production. They figure out why the net rate of biomass production is lower for each higher trophic level in an ecosystem.

Then, students construct and analyze trophic pyramids. Finally, they apply what they have learned to understanding why more resources are needed to produce meat than to produce an equivalent amount of plant food.

Ecology Concepts and Learning Activities

This overview summarizes major ecological concepts and recommends learning activities on topics such as food webs, energy flow through ecosystems, the carbon cycle, trophic pyramids, exponential and logistic population growth, species interactions in biological communities, succession, and effects of human activities on ecosystems. This overview also recommends introductory ecology readings. 

Food Webs, Energy Flow, Carbon Cycle, and Trophic Pyramids

Food web with plants and animals

To begin this hands-on, minds-on activity, students view a video about ecosystem changes that resulted when wolves were eliminated from Yellowstone National Park and later returned to Yellowstone. Then, students learn about food chains and food webs, and they construct and analyze a food web for Yellowstone. Students use what they have learned to understand a trophic cascade caused by the elimination of wolves from Yellowstone.

Next, students learn that the biosphere requires a continuous inflow of energy, but does not need an inflow of carbon atoms. To understand why, students apply fundamental principles of physics to photosynthesis, biosynthesis, and cellular respiration, the processes which result in carbon cycles and energy flow through ecosystems.  

In the final section, students use the concepts they have learned to understand trophic pyramids and phenomena such as the relative population sizes for wolves vs. elk in Yellowstone. Thus, students learn how ecological phenomena result from processes at the molecular, cellular, and organismal levels.

Stability and Change in Biological Communities

This analysis and discussion activity engages students in understanding how biological communities remain stable and how they change during ecological succession.

Students analyze several types of research evidence, including (1) repeated observations of a biological community to assess stability or change over time, (2) analyses of dated fossils in a peat bog, and (3) analyses of how mutualism, competition and trophic relationships contribute to stability or change in biological communities.

Students use this evidence to understand the causes of stability and succession in a variety of habitats, including a tropical forest, a new volcanic island, abandoned farm fields, and ponds. Students also analyze the effects of climate and non-native invasive plants.

The Student Handout is available in the first two attached files and as a Google doc designed for use in online instruction. The Teacher Notes, available in the third and fourth attached files, provide background information and instructional suggestion and explain how this activity is aligned with the Next Generation Science Standards. A PowerPoint with illustrations of each habitat is available in the last attachment.

The Ecology of Lyme Disease

Tick anatomy diagramThis analysis and discussion activity engages students in understanding the lifecycle and adaptations of black-legged ticks and the relationships between these ticks, their vertebrate hosts, and the bacteria that cause Lyme disease.

Students use this background to analyze when and where human risk of Lyme disease is greatest, why rates of Lyme disease have increased in recent decades in the US, and ecological approaches to preventing Lyme disease.

Understanding and Predicting Changes in Population Size – Exponential and Logistic Population Growth Models vs. Complex Reality

Whooping crane

In this analysis and discussion activity, students develop their understanding of the exponential and logistic population growth models by analyzing the recovery of endangered species and growth of bacterial populations. Students learn about the processes that cause exponential or logistic population growth, interpret data from several investigations, and apply their understanding to policy questions.

Next, students analyze examples where the trends in population size do not match the predictions of the exponential or logistic population growth models. They learn that models are based on simplifying assumptions and a model’s predictions are only accurate when the simplifying assumptions are true for the population studied.
In the last section, students analyze trends in human population size and some of the factors that affect the earth’s carrying capacity for humans. 

One version of the Student Handout also includes mathematical equations for exponential and logistic population growth. Appendices to these Teacher Notes offer optional questions on food poisoning, exponential growth of a rabbit population, additional examples of exceptions to the logistic population growth model, and a research challenge (to develop proposals for sustainable use of two resources that may limit the earth’s carrying capacity for humans).

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