AP®︎ Biology: Unit 8 Practice Test

Essential Knowledge: 8.1.A.1

Organisms respond to changes in their environment through behavioral and physiological mechanisms. Exclusion: Knowledge of specific behavioral or physiological mechanisms is beyond the scope of the AP Exam. Illustrative examples: Photoperiodism and phototropism in plants; Taxis and kinesis in animals; Nocturnal and diurnal activity.

Essential Knowledge: 8.1.A.2

Organisms exchange information with one another in response to internal changes and external cues, which can change behavior. Illustrative examples: Fight-or-flight response; Predator warnings; Plant responses to herbivory.

Essential Knowledge: 8.1.B.1

Organisms communicate through various mechanisms (visual, audible, tactile, electrical, and/or chemical signals). i. Organisms have a variety of signaling behaviors that produce changes in the behavior of other organisms and can result in differential reproductive success. ii. Animals use signals to indicate dominance, find food, establish territory, and ensure reproductive success. Exclusion: Knowledge of specific mechanisms of communication is beyond the scope of the AP Exam. Illustrative examples: Parent and offspring interactions; Courtship and mating behaviors; Foraging by bees and other animals.

Essential Knowledge: 8.1.B.2

Responses to information and communication of information are vital to natural selection and evolution. i. Fitness favors innate and learned behaviors that increase survival and reproductive success. ii. Cooperative behavior tends to increase the fitness of the individual and the survival of the population. Exclusion: The details of the various communication and community behavioral systems are beyond the scope of the AP Exam. Illustrative examples: Pack behavior in animals; Herd, flock, and schooling behavior in animals; Predator warnings; Colony and swarming behavior in insects; Kin selection.

Essential Knowledge: 8.2.A.1

Organisms use energy to organize, grow, reproduce, and maintain homeostasis. i. Organisms use different strategies to regulate body temperature and metabolism. Endotherms use thermal energy generated by metabolism to maintain homeostatic body temperatures. Ectotherms lack efficient internal mechanisms for maintaining body temperature, although they may regulate their temperature behaviorally by moving into the sun or shade or by aggregating with other individuals. ii. A net gain in energy results in energy storage, the growth of an organism, and increased reproductive output. iii. A net loss of energy results in loss of mass, a decrease in reproductive output, and, eventually, the death of an organism. Illustrative examples: Seasonal reproduction in animals and plants; Life-history strategy (biennial plants, reproductive diapause).

Essential Knowledge: 8.2.A.2

Different organisms use various reproductive strategies in response to energy availability. Some organisms alternate between asexual and sexual reproduction in response to energy availability.

Essential Knowledge: 8.2.B.1

Ecological levels of organization include populations, communities, ecosystems, and biomes.

Essential Knowledge: 8.2.B.2

Energy flows through ecosystems, while matter and nutrients cycle between the environment and organisms via biogeochemical cycles. The cycles are essential for life, and each cycle demonstrates the conservation of matter. The cycles are interdependent.

Essential Knowledge: 8.2.B.3

Biogeochemical cycles include abiotic and biotic reservoirs, as well as processes that cycle matter between reservoirs.

Essential Knowledge: 8.2.B.4

The hydrologic (water) cycle involves water movement and storage within the hydrosphere. Reservoirs include oceans, surface water, the atmosphere, and living organisms. Processes include evaporation, condensation, precipitation, and transpiration.

Essential Knowledge: 8.2.B.5

The carbon cycle involves recycling carbon atoms through Earth’s biosphere into organisms as carbohydrates and back into the atmosphere as carbon dioxide (CO₂). At the highest levels of organization, the carbon cycle can be simplified into four parts: photosynthesis, cellular respiration, decomposition, and combustion.

Essential Knowledge: 8.2.B.6

The nitrogen cycle involves several steps, including nitrogen fixation, assimilation, ammonification, nitrification, and denitrification. These steps are performed by microorganisms in the soil. The largest reservoir of nitrogen is the atmosphere. In nitrogen fixation, nitrogen gas (N₂) is fixed into ammonia (NH₃), which ionizes to ammonium (NH₄⁺) by acquiring hydrogen ions from the soil solution.

Essential Knowledge: 8.2.B.7

The phosphorus cycle involves weathering rocks releasing phosphate (PO₄³⁻) into soil and groundwater. Producers take in phosphate, which is incorporated into biological molecules; consumers eat producers, transferring phosphate to animals. Phosphorus returns to the soil via decomposition of biomass, or excretion. Phosphate can also be incorporated back into the environment via decomposition of decaying organic matter.

Essential Knowledge: 8.2.C.1

Changes in energy availability can result in changes in population size. Illustrative examples: Food chains/webs; Trophic pyramids/diagrams.

Essential Knowledge: 8.2.C.2

Changes in energy availability can result in disruptions to an ecosystem. i. A change in energy resources such as sunlight can affect the number and size of the trophic levels. Trophic levels include producers; primary, secondary, tertiary, and quaternary consumers; and decomposers. ii. A change in the biomass or number of producers in a given geographic area can affect the number and size of other trophic levels.

Essential Knowledge: 8.2.D.1

Autotrophs capture energy from physical or chemical sources in the environment. i. Photosynthetic organisms capture energy present in sunlight contributing to primary productivity. ii. Chemosynthetic organisms capture energy from small inorganic molecules present in their environment, which can occur in the absence of oxygen.

Essential Knowledge: 8.2.D.2

Heterotrophs, which include carnivores, herbivores, omnivores, decomposers, and scavengers, metabolize carbohydrates, lipids, and proteins as sources of energy. Heterotrophs capture the energy present in carbon compounds by consuming organic matter derived from autotrophs incorporating matter into their tissues.

Essential Knowledge: 8.3.A.1

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

Essential Knowledge: 8.3.A.2

Many adaptations in organisms are related to obtaining and using energy and matter in a particular environment. i. Population growth dynamics depend on birth rate, death rate, and population size. RELEVANT EQUATION Population Growth— dN/dt = B - D where dt = change in time B = birth rate D = death rate N = population size dN = change in population size ii. Reproduction without constraints results in the exponential growth of a population. RELEVANT EQUATION Exponential Growth— dN/dt = r_max N where dt = change in time N = population size dN = change in population size r_max = maximum per capita growth rate of population

Essential Knowledge: 8.4.A.1

Carrying capacity is the sustainable abundance of a species that can be supported by the ecosystem’s total available resources.

Essential Knowledge: 8.4.A.2

As limits to growth attributable to density-dependent and density-independent factors are imposed, a logistic growth model typically ensues. Relevant Equation: Logistic Growth— dN/dt = r_max N (1 − N/K) where dt = change in time N = population size dN = change in population size r_max = maximum per capita growth rate of population K = carrying capacity

Essential Knowledge: 8.5.A.1

The structure of a community is measured and described in terms of species composition and species diversity. RELEVANT EQUATION Simpson’s Diversity Index— Diversity Index = -∑ (n/N)^2 where n = total number of organisms of a particular species N = total number of organisms of all species

Essential Knowledge: 8.5.B.1

Communities are groups of interacting populations of different species that change over time based on the interactions between those populations.

Essential Knowledge: 8.5.B.2

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

Essential Knowledge: 8.5.B.3

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

Essential Knowledge: 8.5.B.4

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

Essential Knowledge: 8.6.A.1

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

Essential Knowledge: 8.6.A.2

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

Essential Knowledge: 8.6.B.1

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

Essential Knowledge: 8.7.A.1

An adaptation is a genetic variation that is favored by selection and manifests as a trait that provides an advantage to an organism in a particular environment.

Essential Knowledge: 8.7.A.2

Heterozygote advantage is when the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype.

Essential Knowledge: 8.7.A.3

Mutations are not directed by specific environmental pressures.

Essential Knowledge: 8.7.B.1

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 native species for resources. Illustrative examples: Kudzu; Zebra mussels.

Essential Knowledge: 8.7.C.1

Human impact accelerates changes at local and global levels. These activities can drive changes in ecosystems, such as the following, that cause extinctions to occur: i. Biomagnification ii. Eutrophication. Illustrative examples: Dutch elm disease; Potato blight.

Essential Knowledge: 8.7.D.1

Geological and meteorological events affect habitat change and ecosystem distribution. Biogeographical studies illustrate these changes. Illustrative examples: Global climate change; Logging; Urbanization; Monocropping; El Niño; Continental drift; Meteor impact on dinosaurs.