Unit 8 Learning Objectives

Topic 8.1: Responses to the Environment

Note from Mr. W about Topic 8.1

The College Board’s objectives for Topic 8.1 are fairly vague. You can see these objectives in my Condensed CED, or just read the summary below.

  1. Based on cues in the environment, organisms change their behavior and physiology.
  2. Communication between organisms in response to internal or external changes can change behavior.
  3. Signaling changes the behavior of other organisms and is subject to natural selection.
  4. A variety of signals (visual, auditory, tactile, chemical, and electrical) are used to indicate social dominance, find food, and induce or solicit mating.
  5. Learned and innate behaviors are subject to natural selection.
  6. Cooperation between members of the same population can increase fitness.

To enable you to reach these objectives, I designed this topic around a series of case studies that will lead you to achieve the following objectives:

  1. Explain fixed action patterns
  2. Describe the evidence for the idea that behavior can be genetically controlled and transmitted.
  3. Describe key experiments illustrating the role of learning in behavior.
  4. Explain how animals use environmental cues to orient themselves and navigate.
  5. Explain the biological basis of migration in birds and sea turtles.
  6. Explain the role of inclusive fitness in animal behavior.

Topic 8.2: Energy Flow Through Ecosystems

  1. Compare and contrast endotherms and endotherms.
    • Endotherms use thermal energy generated by metabolism to maintain homeostatic body temperatures.
    • Ectotherms lack efficient internal mechanisms for maintaining body temperature. Their temperature can fluctuate widely, though they may regulate their temperature behaviorally by moving into the sun or shade or by aggregating with other individuals.
  2. Describe the relationship between metabolic rate and size.
    • Generally, the smaller the organism, the higher the metabolic rate.
  3. Describe the relationship between energy gain or loss and growth/survival/reproduction
    • Net energy gain results in energy storage or the growth of organisms or populations.
    • Net energy loss results in loss of mass, death, and population decline.
  4. Describe how energy flow through ecosystems can be graphically represented.
    • Through food chains, food webs, and energy pyramids.
  5. *Define biogeochemical cycle, and (as a representative example) explain the carbon cycle.
  6. Explain the effects of changes in energy availability on trophic levels and ecosystem structure.
    • Changes in energy availability can affect the number and size of the trophic levels. Specifically, a change in the producer level can affect the number and size of other trophic levels.
  7. Compare autotrophs and heterotrophs
    • Autotrophs capture energy from physical or chemical sources in the environment;
    • Heterotrophs capture energy by eating or absorbing chemical energy in organic compounds.
  8. Compare photoautotrophs with chemoautotrophs
    • Photoautotrophs use light to synthesize organic compounds. Plants, algae, and cyanobacteria are photoautotrophs.
    • Chemoautotrophs power the creation of organic compounds by oxidizing small inorganic molecules (such as iron). This process can occur in the absence of oxygen. All chemoautotrophs are bacteria or archaea.

Topics 8.3 and 8.4: Population Ecology

  1. Explain the general factors behind population growth, and the general equation for this growth  (dN/dt = B – D)
  2. Explain what exponential growth is and when it occurs, and be able to use its relevant equation (dN/dt = rmaxN)
  3. Define limiting factors.
  4. Compare and contrast Density Dependent and Density Independent Limiting Factors
  5. Define carrying capacity.
  6. Be able to use the Logistic Growth equation (dN/dt = rmaxN (K-N/K))
  7. Explain how population growth can be influenced by resource availability and predator-prey interactions.

Topics 8.5: Community Ecology

  1. Explain how communities change over time during the process of ecological succession.
  2. Describe the key Interactions that occur between the species in a community. This includes the following interactions and being able to describe the positive and negative effects on each species.
    • Mutualism
    • Parasitism
    • Commensalism, amensalism
    • Competition (leading to niche partitioning and character displacement)
    • Predator/Prey interactions (leading to evolutionary arms races)
  3. Explain what keystone species are, and what happens when keystone species are removed from their ecosystems.
    • An organism whose activity defines the structure of the entire ecosystem.
    • Often these are carnivores that control herbivores, increasing productivity and overall biodiversity.
    • When keystone species are removed, ecosystems can collapse.

Topic 8.6: Biodiversity

  1. Define Biodiversity, and describe its key components.
    • Species composition and richness.
  2. Know how to use the Simpson’s Biodiversity index.
  3. Explain the connection between biodiversity and ecosystem resilience.
    • Less biodiversity and less ecosystem complexity often equate to less resilience to environmental change.

Topic 8.7: Disruptions to Ecosystems

  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, the introduction of invasive species,
    • Introduction of new diseases that can devastate native species.
    • Climate disruption 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.