AP Biology Exam Review Flashcards

Conservation and Population Dynamics

Conservation of Diversity

• Conservation of habitat diversity directly leads to the conservation of both species diversity and genetic diversity.

Population-Limiting Factors

• Population growth is limited by several factors:
  • Food availability
  • Water availability
  • Breeding area
  • Hunting
  • Competition
  • Birth rate
  • Death rate

Logistic Growth Model

• Logistic growth models level off at the carrying capacity, which is the maximum population size an environment can sustain.

Density-Dependent and Independent Factors

Density-Dependent Factors

• Limiting factors that depend on the size of the population.
• These factors only become limiting when the population density reaches a certain level.
• They affect large, dense populations more significantly than small, scattered populations.
• Examples:
  • Disease
  • Parasites

Density-Independent Factors

• Factors that affect all populations in similar ways, regardless of population density.
• Examples:
  • Weather
  • Natural disasters
  • Human activities (deforestation, damming rivers, etc.)
  • Seasonal cycles
• These factors usually cause crashes in population size.

Species Interactions

Parasitism

• Parasites derive nourishment from their hosts, harming them in the process. (+/-)

Mutualism

• An interaction that benefits both species involved. (+/+)

Commensalism

• An interaction where one species benefits, and the other is not affected. (+/0)

Community Ecology

Disturbance

• A disturbance is an event that changes a community.

Succession

• Succession involves the regrowth of a community from small to large organisms.

Niche

• A niche is the position or function of an organism in a community.
• Competitive Exclusion Principle: No two species can occupy the same niche at the same place at the same time.

Biogeochemical Cycles

Carbon Cycle

• Key components include:
  • CO_2 in the atmosphere
  • Photosynthesis
  • Respiration
  • Decomposition
  • Detritivores
  • Burning of wood and fossil fuels

Nitrogen Cycle

• Processes involved in the nitrogen cycle:
  • Nitrogen Fixation: Conversion of nitrogen gas into ammonium.
  • Nitrification: Conversion of ammonium to nitrites and then to nitrates.
  • Assimilation: Uptake of nitrogen compounds by plants.
  • Movement through the food web.
  • Ammonification: Conversion of decomposed material back into ammonium.
  • Denitrification: Returning nitrogen back to the atmosphere.

Phosphorous Cycle

Animal Behavior

Innate Behavior

• Behaviors that are due to genetic programming.
• Examples: Kinesis and Taxis

Learned Behavior

• Modification of behavior resulting from specific experiences.

Organism Responses to Environmental Changes

Behavioral Mechanisms

• Organisms change behavior in response to environmental cues (temperature, light, food availability).
• Example: Migratory birds using the sun and stars for navigation.
• Example: Insects timing reproduction based on day length changes.

Physiological Mechanisms

• Changes in the activity of genes, enzymes, and hormones in response to environmental cues.
• Example: Plants changing leaf shape in response to light intensity.
• Example: Animals changing skin or fur color in response to temperature.

Photoperiodism

• Photoperiodism in plants is the ability of plants to sense changes in the length of daylight and to use this information to regulate growth and development.

Thermoregulation

Endotherms

• Endotherms maintain a constant internal body temperature.
• Humans maintain a body temperature between 97 and 99°F.
• Endotherms use a significant amount of energy to maintain their internal temperature.

Ectotherms

• Ectotherms do not maintain a constant internal body temperature.
• Examples: Snakes and fish
• They must change their behaviors to regulate internal temperature, such as hibernating or basking in the sun.

Metabolic Rate and Body Mass

• Generally, smaller organisms have a higher metabolic rate.
• Example: A mouse metabolizes things much more quickly than a human.

Disruptions to Ecosystems

Changes in Energy Availability

• Changes in available energy (e.g., sunlight) can affect the number and size of trophic levels in an ecosystem.
• A decrease in sunlight can reduce primary producer productivity, affecting herbivores and carnivores.
• An increase in sunlight can increase primary producer productivity, affecting herbivores and carnivores.

Producer Level Changes

• A change in the producer level can affect the number and size of other trophic levels.
• A reduction in primary producers can reduce the food supply for herbivores, reducing carnivore populations.
• An increase in primary producers can increase the food supply for herbivores, increasing carnivore populations.

Biodiversity and Species Distribution

• Changes in energy availability can affect the biodiversity and distribution of species.
• Changes in sunlight can cause shifts in species distribution.
• Changes in primary producer productivity can cause changes in the distribution of herbivores and carnivores.

K-Selected Strategy

• A reproductive strategy characterized by long life spans, fewer offspring, high parental care, and investment in offspring.
• These species are often larger and have longer developmental periods.

Metabolic Rate

• Metabolic rate is the speed at which an organism's body uses energy or burns calories.

Species Diversity

• Species Richness: The number of different species present in a community.
• Species Evenness: The relative abundance of each species within a community.
• Species Diversity: Accounts for both richness and evenness, providing a comprehensive measure of community composition.

Invasive Species

• Invasive species, introduced intentionally or accidentally by humans, can disrupt native ecosystems and outcompete native species.

AP Biology Exam Sample Question: Chi-Square Test

Scenario

• A study examining fruit-fly behavior using a covered choice chamber to determine if a substance influences spatial distribution. 60 flies are introduced at the center.
• Ripe banana at one end, unripe at the opposite end.
• Observations recorded after 1 minute and 10 minutes.

Chi-Square Test

Null Hypothesis

• The flies would be evenly distributed across the three chambers (ripe, middle, and unripe).

Chi-Square Calculation

Sum = 48.9

• Chi Square Value: 48.9

Degrees of Freedom

• Degrees of freedom = number of conditions - 1 = 3 - 1 = 2

Critical Value

• For a confidence level of 0.05 and 2 degrees of freedom, the critical value is 5.99.

Conclusion

• Since the calculated Chi-Square value (48.9) is much larger than the critical value (5.99), we reject the null hypothesis.
• This means the flies are not randomly assorting themselves, and the banana is influencing their behavior.

Additional Concepts

Agonistic Behavior

• Aggressive behavior that occurs due to competition for food or other resources.

Simpson’s Diversity Index

• Formula: Diversity Index = 1 − Σ(n/N)^2
  • n = the total number of organisms of a particular species
  • N = the total number of organisms of all species

Population Ecology

• Population growth rate: r = (births – deaths)/N
  • r = reproductive rate
  • N = population size

Carrying Capacity

• Carrying capacity is the maximum number of individuals of a species that a habitat can support.

Limiting Factors

• Factors that limit a population.
• These factors are either density-independent or density-dependent.

Exponential Growth

• Exponential growth occurs when a population is in an ideal environment.
• Results in a J-shaped curve.

Ecological Succession

• Predictable procession of plant communities over a relatively short period (decades or centuries).

Primary Succession

• Ecological succession in which no previous organisms have existed.

• Lichens are considered pioneer organisms.## Cooperative behavior

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

• There is a relationship between metabolic rate per unit body mass and the size of multicellular organisms. Typically, the smaller the organism, the higher the metabolic rate. This is because the ratio of surface area to volume decreases as the size of an organism increases, which means that smaller organisms have to work harder to maintain their body temperature and to obtain food.

• In addition to affecting trophic levels, changes in energy availability can also affect the biodiversity and distribution of species in an ecosystem. For example, a change in sunlight can cause a shift in the distribution of species, as some species may be better adapted to the new conditions than others. Similarly, a change in the productivity of primary producers can cause a change in the distribution of herbivores and carnivores, as some species may be better able to exploit the new food resources than others.