Link back to the Teacher’s Guide Table of Contents

Week 28: Response to the Environment (Animal Behavior): Topic 8.1

Teaching objectives for Topic 8.1, Responses to the Environment

Topic 8.1 is a big, sprawling topic. If you’re like me, then examining the College Board’s objectives in their Course and Exam Description won’t give you the clearest guidance about what to teach. What’s below are these objectives, pretty much verbatim.
  1. LO ENE-3.D: Explain how the behavioral and/or physiological response of an organism is related to changes in internal or external environment.
    1. ENE-3.D.1: Organisms respond to changes in their environment through behavioral and physiological mechanisms.
      1. Exclusion: no specific physiological mechanism is required
        1. Photoperiodism and phototropism in plants
        2. Taxis and kinesis in animals
        3. Nocturnal and diurnal activity
    2. ENE-3.D.2: Organisms exchange information with one another in response to internal changes and external cues, which can change behavior.
        1. Fight-or-flight response
        2. Predator warnings
        3. Plant responses to herbivory
  2. LO IST-5.A: Explain how the behavioral responses of organisms affect their overall fitness and may contribute to the success of the population.
    1. IST-5.A.1: Individuals can act on information and communicate it to others.
    2. IST-5.A.2: Communication occurs through various mechanisms—
      1. a. Organisms have a variety of signaling behaviors that produce changes in the behavior of other organisms and can result in differential reproductive success.
          1. Territorial marking in mammals
          2. Coloration in flowers
      2. b. Animals use visual, audible, tactile, electrical, and chemical signals to indicate dominance, find food, establish territory, and ensure reproductive success.
          1. Bird songs
          2. Pack behavior in animals
          3. Predator warnings
          4. Coloration
    3. IST-5.A.3: Responses to information and communication of information are vital to natural selection and evolution—
      1. a. Natural selection favors innate and learned behaviors that increase survival and reproductive fitness.
      2. b. Cooperative behavior tends to increase the fitness of the individual and the survival of the population.
          1. Parent and offspring interactions
          2. Courtship and mating behaviors
          3. Foraging in bees and other animals
          1. Pack behavior in animals
          2. Herd, flock, and schooling behavior in animals
          3. Predator warnings
          4. Colony and swarming behavior in insects
          5. Kin selection
    4. EXCLUSION STATEMENT: The details of the various communications and behavioral systems are outside the scope of the exam and course

While these objectives might be hard to convert into specific teaching moves, there are some important biological literacy goals. We want our students to be able to explain 1) how animal behavior can be elicited in response to environmental cues, 2) how animals communicate with one another, and  3) how animal behavior is optimized by natural selection. And, on top of that, being able to analyze sets of data and diagrams related to animal behavior is something that shows up pretty frequently on the AP Bio exam.

Holding all that in mind, here’s what I came up with. There’s a strong emphasis on case study analysis.

Teaching about Responses to the Environment on s

Our module on animal behavior covers this material in four tutorials. You can find the main menu on this page.

Fixed Action Patterns and Behavior Genes

Fixed action patterns are “hard-wired” behaviors found in many animals (including humans). These patterns were first discovered by the Dutch Ethologist Niko Tinbergen. Once your students learn about these, we move onto the evidence that certain behaviors can be genetically encoded. This takes us into foraging behaviors in Drosophila larvae, nest building behavior in mice, and parental care in voles. In these rodents, the concentration of a certain hormone seems to determine whether fathers are monogamous or promiscuous. In the case study, there’s a discussion of a Partner Preference test which is fascinating in its own right, but also linked to the AP Bio choice chamber lab (discussed below).

Learning and Orienting

In this tutorial we move from hard-wired behaviors to ones that involve learning. The first of these is imprinting, first discovered (and hilariously manipulated) by Austrian zoologist Konrad Lorenz. This is followed by analysis of much more complex learned behaviors: learning songs in songbirds, and navigation in wasps. The tutorial ends with an unbelievably cool study of how ants know how to make their way back to the nest after foraging. This is known as the ant odometer, and you don’t want to miss it.


This tutorial examines the internal and external cues that animals use during migrations. In the first case study, we focus on how Indigo buntings navigate by learning how to follow the stars. In the second, we look at how sea turtle hatchlings are able to first find their way to the sea. Once the turtles make it out to sea, they face the challenge of long distance migrations (that often span thousands of miles). To do that, they use magnetoreception and perception of geomagnetic signatures to find their way back to the beaches where they originally hatched. I found this to be mind-blowing when I first learned about it. My guess is that your students (and you) will feel the same.

Living in Groups

The module ends with a tutorial about group behavior and its biological basis. The first case study looks at alarm calls in Belding’s ground squirrels. Who do you think gives alarm calls first: males or females? Why would that be? What you’ll see this that this study is a great way to get into the concept of kin selection and inclusive fitness. This leads to a look at haplodiploidy in bees, and how that can explain the social structure of a bee hive. We end with a discussion of honey bee dances, and how bees use their dances to communicate about the direction and distance to food sources to other members of the hive.

Additional Resources

In the AP Biology Lab Manual, you can find the “Fruit Fly Behavior Lab” (investigation 12). I use a much simpler (and less expensive) version of this lab. My version involves pill bugs (Armadillium vulgare), which you or your students can probably find in any park (or backyard). If students collect 10 each, you’ll have more than enough. I have a set of choice chambers that I bought from Carolina biological supply, but you can have your students construct their own by cutting out the bottom of two milk cartons, cutting out a notch to make a pathway between them, and then scotch taping them together. Then just lay a paper towel that’s cut to size on the bottom of each carton and you’ll be set.

Here’s a link to my version of the lab. I’m sure it can be improved. And just to prove to myself that it could be done, I just spent about 10 minutes putting together a milk-carton choice chamber. Here’s a photo.

Week 32: Ecosystems (Topic 8.2)

Learning objectives for Topic 8.2, Energy Flow through Ecosystems

Here are the College Board’s objectives for Topic 82,  pretty much verbatim.

TOPIC 8.2: Energy Flow Through Ecosystem

  1. LO ENE-1.M: Describe the strategies organisms use to acquire and use energy.
    1. ENE-1.M.1: Organisms use energy to maintain organization, grow, and reproduce—
      1. a. Organisms use different strategies to regulate body temperature and metabolism.
        1. i. Endotherms use thermal energy generated by metabolism to maintain homeostatic body temperatures.
        2. ii. Ectotherms lack efficient internal mechanisms for maintaining body temperature, though they may regulate their temperature behaviorally by moving into the sun or shade or by aggregating with other individuals.
      2. b. Different organisms use various reproductive strategies in response to energy availability.
      3. c. There is a relationship between metabolic rate per unit body mass and the size of multicellular organisms—generally, the smaller the organism, the higher the metabolic rate.
      4. d. A net gain in energy results in energy storage or the growth of an organism.
      5. e. A net loss of energy results in loss of mass and, ultimately, the death of an organism.
  2. LO ENE-1.N: Explain how changes in energy availability affect populations and ecosystems.
    1. ENE-1.N.1: Changes in energy availability can result in changes in population size.
    2. ENE.1.N.2: Changes in energy availability can result in disruptions to an ecosystem—
      1. a. A change in energy resources such as sunlight can affect the number and size of the trophic levels.
      2. b. A change in the producer level can affect the number and size of other trophic levels.
  3. LO ENE-1.O: Explain how the activities of autotrophs and heterotrophs enable the flow of energy within an ecosystem.
    1. ENE-1.O.1: Autotrophs capture energy from physical or chemical sources in the environment—
      1. a. Photosynthetic organisms capture energy present in sunlight.
      2. b. Chemosynthetic organisms capture energy from small inorganic molecules present in their environment, and this process can occur in the absence of oxygen.
    2. ENE-1. O.2: Heterotrophs capture energy present in carbon compounds produced by other organisms.
      1. a. Heterotrophs may metabolize carbohydrates, lipids, and proteins as sources of energy by hydrolysis.
    1. Seasonal reproduction in animals and plants
    2. Life-history strategy (biennial plants, reproductive diapause)
    3. Food chains/webs
    4. Trophic pyramids/Diagrams

Teaching about Ecosystems on

It was surprising to see endothermy and ectothermy tucked into this unit on Ecosystems. My tutorial on thermoregulation is back in unit 4, so if you’ve been following my sequence, you would have covered that with your students back in November. If you haven’t, you can send your students to the preceding link.

Carbon Cycle

It’s had to imagine teaching about ecosystems at the AP/Introductory college level without teaching about biogeochemical cycles. But the term “biogeochemical cycle” doesn’t appear anywhere in the 2019 Course and Exam Description. Nor does the term “carbon cycle.” Oversight? Hard to know. My first tutorial focuses on … the Carbon Cycle. It’s pretty easy, and I can’t imagine sending my students out into a world where the number 1 issue is climate change caused by disruption of the carbon cycle without them understanding the carbon cycle. I hope you feel the same way.

Nitrogen Cycle

The nitrogen cycle is similarly missing from the Course and Exam description. Again it’s hard to know if that was deliberate or an oversight. If you’re running out of time and have to skip something, then this would be the tutorial to skip.

Food Chains and Food Webs 

This tutorial will teach your students about autotrophs, heterotrophs, food chains, food webs, and the basics of trophic levels.

Trophic Levels

This tutorial goes into depth about trophic levels, and will take your students through energy pyramids and the 10% rule. Pyramids of numbers and biomass are also covered, along with biomagnification.

ALERT: What our tutorials don’t cover.

I want to alert you to two topics that I don’t cover in my tutorials (they’re now on my list for adding over the summer).

Additional Resources

As I said above, I’m not sure if the Carbon Cycle is part of the curriculum anymore. But if you teach it, I have a music video for you. I also have one about food chains. My Food Chains Song is one of the only songs I’ve written to someone else’s melody. It’s based on the Ballad of Jed Clampett, also known as the “Beverly Hillbillies Song.” Both songs are immensely singable (and playable on guitar). Here are the links.

  1. Carbon Cycle
  2. Food Chains Song

I can’t share the links for the next two items directly (because they’re copyrighted material) but the high school biology POGILS on “Energy Transfer in Living Organisms,” and “Ecological Pyramids are both excellent and highly recommended.

Week 30: Population Ecology, Community Ecology

Learning objectives for Topics 8.3-4 (Population Ecology) and 8.5 – 6 (Community Ecology and Biodiversity)

If you want to look at the College Board’s objectives for these topics, you can do so on my condensed outline (this link takes you to the Ecology unit: just scroll down). Of you can do the same at the College Board’s original pdf.

Here’s an outline of how I cover this material on

TOPICS 8.3 and 8.4, Population Ecology.

  1. What is a population?
    1. Defining and describing populations
    2. How individuals in a population interact with each other and with their environment
  2. Explain the general factors explaining population growth, and the general equation for this growth  (dN/dt = B – D)
  3. Explain how exponential growth works (and its relevant equation: dN/dt = rmaxN
  4. Explain how density can affect population growth by imposing limiting factors
    1. Density Dependent Limiting Factors
    2. Density Independent Limiting Factors
    3. Logistic Growth equation (dN/dt = rmaxN (K-N/K))

Topics 8.5 and 8.6: Community Ecology and Biodiversity

  1. Species Interactions
    1. Mutualism
    2. Parasitism
    3. Commensalism, amensalism
    4. Competition (leading to niche partitioning and character displacement)
    5. Predator/Prey interactions (leading to evolutionary arms races)
  2. Trophic Cascades and keystone species
  3. Biodiversity

Teaching about Population Ecology, Community Ecology, and Biodiversity on

Here’s how I cover the objectives listed above (and more). Depending on where you are in the in the curriculum, “more” might or might not be equivalent to “better,” so read below.

Population Ecology 1: Key Attributes of Populations

This tutorial describes some of the dimensions by which population biologists describe populations. These include size, density, range, and dispersion patterns. I follow this by looking at age structure and survivorship curves. While this is important biology, it’s hard to know if this is what the College Board means in their objective about “How individuals in a population interact with each other and with their environment.” If you’re pressed for time, you can skip this tutorial.

Population Ecology 2: Understanding Population Growth

This tutorial teaches exponential growth and logistic growth. This includes limiting factors, carrying capacity, predator/prey-related population oscillations,  and r v. K selection.

The tutorial ends with a discussion of what I think is one of the most important issues facing our species: human population growth. Because that topic is definitely not on the AP exam, you can skip it if you’re pressed for time (but I hope you don’t).

Community Ecology 1: Species Interactions

This first community ecology tutorial starts with a discussion about niche and habitat. It then runs your students through the gamut of species interactions (mutualism, parasitism, commensalism, amensalism, predation, herbivory, and parasitoidism).

Two of these interactions receive special attention. The section on competition is expanded to include competitive exclusion, niche partitioning, character displacement, and realized v. fundamental niches. A section on evolutionary arms races gets students to take a closer look at the consequences of predator/prey and parasite/host interactions.

Community Ecology 2: Keystone Species and Trophic Cascades

This second community ecology tutorial looks at keystone species and trophic cascades. I built this tutorial around the HHMI video “Some Species are More Equal than Others.”

Community Ecology 3: Ecological Succession

The term “ecological succession” doesn’t appear in the College Board’s Course and Exam Description. I can’t imagine teaching a unit on ecology without teaching this concept. But if you have to skip a tutorial because you’re running out of time, then this would be the one to skip.

Community Ecology 4: Biodiversity

This tutorial looks at the three dimensions of biodiversity (genetic, species, and ecological). As a preview of the last topic of the course (ecosystem disruption) I provide an overview of biodiversity’s importance. The tutorial ends by looking at how biodiversity can be measured, and walks students through how to understand and use the Simpson Biodiversity Index.

Additional Resources

Flinn’s High School level POGIL on Population gives great reinforcement of exponential and logistic growth.

Week 31: Ecosystem Disruption

Learning objectives for Topic 8.7 (Disruptions to Ecosystems)

If you want to look at the College Board’s objectives for these topics, you can do so on my condensed outline (this link takes you to the Ecology unit: just scroll down). Of you can do the same at the College Board’s original pdf.
Here’s how I’ve rendered these objectives into a form that’s easier for you and for your students
  1. List and describe the traits that predispose a species to become an invasive species.
    • High reproductive rates, tolerance of a wide range of conditions, generalist ecological niche.
  2. Explain how invasive species affect ecosystem dynamics and biodiversity.
    • When invasive species enter a new habitat, they tend to grow exponentially.
    • As invasive species are freed from control by their former predators or competitors, they can outcompete or overexploit the species in their new environment, or overrun their new habitat.
    • The overall effect is a decrease in biodiversity.
  3. Describe the human activities that lead to changes in ecosystem structure and/ or dynamics.
    • Destruction or degradation of habitat, habitat fragmentation, introduction of invasive species,
    • Introduction of new diseases that can devastate native species.
    • Climate disruption that is altering habitats worldwide.
  4. Explain how geological and climatic changes can change ecosystem structure and/or dynamics.
    • Changes in geology and climate can alter habitats and change ecosystem distribution.
Basically, if your students understand
  1. how invasive species can disrupt ecosystems, and
  2. how habitat disruption affects species,

then you’re pretty much set. The last topic (geological and meteorological events…) is something that I covered in my tutorial about extinction.

Teaching about Ecosystem Disruption on

This topic fits into one tutorial, which you can access here on

The tutorial starts by setting the stage. We’re in what’s widely regarded as the Anthropocene Age: humans have become the dominant biological and geological force on the planet. One of the main consequences of our preeminence is the Sixth Extinction (the fifth was when the dinosaurs were wiped out 65 million years ago). If you haven’t read Elizabeth Kolbert’s book The Sixth Extinction, then you should put it on your summer reading list. If you can’t make that happen, then you can read Kolbert’s 2009 article about the sixth extinction in the New Yorker.

I follow this introduction with an excerpt about the unique biological role of humanity from what might be a surprising source: one of my favorite movies, The Matrix. I’m curious about what you think about this section. Is it useful? Something students can relate to? If you have an opinion, use the “Contact” menu to send me an email and let me know.

After setting the stage, the rest of the tutorial runs through the major ways that humans have disrupted ecosystems. These include

  1. habitat destruction
  2. habitat fragmentation
  3. overharvesting/overhunting
  4. spreading invasive species

The tutorial ends with measures that we can take as a species to protect other species. This includes some large scale moves (controlling human population growth, moving from fossil fuels to renewable energy), but also some smaller scale things such as

  1. strategies for bringing endangered species back from the edge,
  2. principles for design of nature reserves (it’s all about maximizing quality habitat and avoiding population bottlenecks for the species within the reserves),
  3. Focusing on biodiversity hotspots.

HOLY COW. That’s the end of the course! Congratulations.

Additional Resources

  • Flinn’s POGIL on Eutrophication gives a nice window into ecosystem disruption through changing nutrient cycling. This tutorial fits well with one of the objectives in Community Ecology (ENE-4.B.2: Interactions among populations determine how they access energy and matter within a community).
  • HHMI’s Lionfish Invasion is a great way to tie together invasive species with a review of population growth models.

Summative Activities for Unit 8

To pull together Unit 8

  1. Use the AP Bio review materials on Your students can access these same materials on the Biomania AP Bio app, and results from both are recorded in your teacher dashboard. These review materials include
    1. Unit 8 AP Bio Review Flashcards
    2. Unit 8 AP Bio Review Multiple Choice Questions
    3. Unit 8 AP Bio Review Free Response Questions
  2. The progress check questions for Unit 8 on AP Classroom.