Content Knowledge

From the AP® Biology Course and Exam Description

UNDERSTANDINGS

8.1 Response to the Environment

-          Organisms respond to changes in their environment through behavioral and physiological mechanisms.
  EXCLUSION STATEMENT—No specific behavioral or physiological mechanism is required for teaching this concept.

o    Organisms exchange information with one another in response to internal changes and external cues, which can change behavior.

o    Individuals can act on information and  communicate it to others.

-          Communication occurs through various mechanisms—

-          Organisms have a variety of signaling behaviors that produce changes in the behavior of other organisms and can result  in differential reproductive success.

-          Animals use visual, audible, tactile, electrical, and chemical signals to indicate dominance,

-          find food, establish territory, and ensure reproductive success.

-          Responses to information and communication of information are vital to natural selection and evolution

o    Natural selection favors innate and learned behaviors that increases survival and reproductive fitness

o    Cooperative behavior tends to increase the fitness of the individual and the survival of the population.

EXCLUSION STATEMENT—The details of the

various communications and community behavioral

systems are beyond the scope of the course and the

AP Exam.

8.2 Energy Flow Through Ecosystems

-          Changes in energy availability can result in changes in population size.

-          Changes in energy availability can result in disruptions to an ecosystem

o    A change in energy resources such as sunlight can affect the number and size of the trophic levels.

o    A change in the producer level can affect the number and size of other trophic levels.

o    Autotrophs capture energy from physical or chemical sources in the environment

§  Photosynthetic organisms capture energy present in sunlight.

o    Chemosynthetic organisms capture energy from small inorganic molecules present in their environment, and this process can occur in the absence of oxygen.

-          Heterotrophs capture energy present in carbon compounds produced by other organisms.

o    Heterotrophs may metabolize carbohydrates, lipids, and proteins as sources of energy by hydrolysis.

8.3 Population Ecology

-          Populations comprise individual organisms that interact with one another and with the environment in complex ways.

-          Many adaptations in organisms are related to obtaining and using energy and matter in a

-          particular environment

o    Population growth dynamics depend on a number of factors.

§  Reproduction without constraints results in the exponential growth of a population.

8.4 Effect of Density of Populations

-          A population can produce a density of individuals that exceeds the system’s resource availability.

-          As limits to growth due to density-dependent and density-independent factors are imposed, a logistic growth model generally ensues.

8.5 Community Ecology

-          The structure of a community is measured and described in terms of species composition and species diversity.

-          Communities change over time depending on interactions between populations.

-          Interactions among populations determine how they access energy and matter within a community.

-          Relationships among interacting populations can be characterized by positive and negative effects and can be modeled. Examples include predator/prey interactions, trophic cascades, and niche partitioning.

-          Competition, predation, and symbioses, including parasitism, mutualism, and commensalism, can drive population dynamics.

-          Cooperation or coordination between organisms, populations, and species can result in enhanced movement of, or access to, matter and energy.

8.6 Biodiversity

-          Natural and artificial ecosystems with fewer component parts and with little diversity among the parts are often less resilient to changes in the environment.

-          Keystone species, producers, and essential abiotic and biotic factors contribute to maintaining the diversity of an ecosystem.

-          The diversity of species within an ecosystem may influence the organization of the ecosystem.

-          The effects of keystone species on the ecosystem are disproportionate relative to their abundance in the ecosystem, and when they are removed from the ecosystem, the ecosystem often collapses.

8.7 Disruptions to Ecosystems

-          An adaptation is a genetic variation that is favored by selection and is manifested as a trait

that provides an advantage to an organism in a particular environment

-          Mutations are random and are not directed by specific environmental pressures.

-          The intentional or unintentional introduction of an invasive species can allow the species

to exploit a new niche free of predators or competitors or to outcompete other organisms

for resources.

-          The availability of resources can result in uncontrolled population growth and ecological changes.

-          The distribution of local and global ecosystems changes over time.

-          Human impact accelerates change at local and global levels

o    The introduction of new diseases can devastate native species.

o    Habitat change can occur because of human activity

-          Geological and meteorological events affect habitat change and ecosystem distribution. Biogeographical studies illustrate these changes.