AP Biology Unit 8 Trivia

In a population of meerkats, individuals often engage in sentinel behavior, where one meerkat stands guard to alert others of predators while the rest forage. How does this behavior exemplify kin selection, and what is the evolutionary advantage of such behavior?

A.Increases survival of related individuals

B.Promotes genetic diversity in the population

C.Ensures personal survival over others

D. Decreases individual fitness for group benefit

A - Kin selection explains how behaviors that increase the survival of relatives can be favored by natural selection, as they enhance the propagation of shared genes. Sentinel behavior increases the survival chances of related individuals, thus promoting the individual's genetic contribution to future generations.

In a controlled experiment, researchers manipulated energy availability for a population of Daphnia (water fleas). Based on general biological principles, what is the expected relationship between energy availability and reproductive output in Daphnia?

A. Reproductive output remains constant regardless of energy availability

B. Linear increase in both sexual and asexual reproduction

C. Asexual reproduction increases with energy availability, but sexual reproduction occurs mainly when conditions worsen or energy is limited

D. Sexual reproduction dominates at all energy levels

C - In Daphnia, asexual reproduction (parthenogenesis) is favored under high energy availability and favorable environmental conditions, as it allows rapid population growth. When energy availability declines or environmental conditions become stressful, Daphnia switch to sexual reproduction, which produces resistant eggs for survival in harsh conditions rather than for immediate population growth. Therefore, as energy availability increases, asexual reproduction rates rise. Sexual reproduction is not triggered by very high energy but rather by environmental cues such as crowding, low energy, or stress.

A population of deer in a forest ecosystem exhibits logistic growth. Which factor would most directly cause the population to shift from exponential growth to a reduced growth rate?

A. Increased immigration from neighboring populations

B. Reduced predation pressure from wolves

C. Approaching carrying capacity as resources become limited

D. Increased genetic diversity within the population

C - As a population approaches carrying capacity, density-dependent factors like resource competition intensify, causing growth rates to decline from exponential to reduced rates in the logistic growth model.

Two populations of the same species are observed in different environments. Population X reaches a larger size than Population Y. What is the most likely explanation for the difference in population sizes?

A. Population Y experiences only density-independent factors

B. Environment X has more interspecific competition

C. Population X has a higher intrinsic growth rate

D. Environment Y has more severe density-dependent limiting factors

D - If Population Y reaches a smaller size than Population X, this suggests that stronger density-dependent limiting factors are present in Environment Y, which restricts the growth of Population Y.

In a three-level trophic cascade, wolves were reintroduced to an ecosystem where they had been extirpated. Which pattern would most likely be observed as a direct result of this reintroduction?

A. Decreased plant diversity due to competitive exclusion

B. Increased herbivore population due to apparent competition

C. Increased plant biomass due to reduced herbivory

D. Decreased primary productivity due to nutrient limitation

C - In a three-level trophic cascade, top predators (wolves) reduce herbivore populations, which decreases herbivory pressure and allows plant biomass to increase - a classic indirect positive effect across trophic levels.

A researcher is studying two forest ecosystems of equal size. Forest A has 15 tree species while Forest B has only 3 tree species. Which of the following is most likely to be observed in Forest A compared to Forest B?

A. Greater resistance to pathogen outbreaks

B. Higher primary productivity per individual tree

C. Decreased niche partitioning

D. Simplified food web structure

A - Greater species diversity typically provides ecosystem resilience against disturbances like pathogen outbreaks, as pathogens are often species-specific and less likely to devastate all species simultaneously.

Which scenario represents secondary succession altering ecosystem distribution after a disruption?

A. Coral polyps establishing on submerged shipwreck

B. Forest regrowth on abandoned farmland with soil intact

C. Pioneer species colonizing newly formed volcanic island

D. Lichen growth on exposed rock after glacier retreat

B - Secondary succession occurs when an ecosystem recovers after disturbance where soil remains intact, as in abandoned farmland, while the other options describe primary succession on newly created or exposed substrates.

A study of vervet monkeys revealed they use different alarm calls for different predators (snakes, eagles, leopards). When researchers played recordings of these calls, monkeys responded with appropriate predator-specific behaviors without seeing the actual predator. This demonstrates:

A. Operant conditioning through repeated exposure

B. Fixed action patterns triggered by environmental cues

C. Semantic communication in predator warning systems

D. Phenotypic plasticity in response to climate change

C - Vervet monkeys' predator-specific alarm calls represent semantic communication, where distinct vocalizations convey specific information about predator type, allowing appropriate defensive responses without direct predator observation.

A scientist measures the energy budget of a mammal in a metabolic chamber. Which data would provide the strongest evidence that the organism is experiencing a net energy deficit?

A. Decreasing body mass despite constant activity levels

B. Fluctuating body temperature throughout the day

C. Increased respiratory rate during exercise periods

D. Higher water consumption during daylight hours

A - Decreasing body mass with constant activity directly indicates that the organism is catabolizing its own tissues for energy, providing clear evidence of a net energy deficit.

A population of deer shows the following age distribution: 15% pre-reproductive, 45% reproductive, and 40% post-reproductive. What can be inferred about this population's current status?

A. The population has high genetic diversity

B. The population is experiencing exponential growth

C. The population is likely declining

D. The population has reached carrying capacity

C - The high proportion of post-reproductive individuals (40%) combined with a low percentage of pre-reproductive individuals (15%) indicates a declining population with insufficient young to replace the aging members.

In a population of voles, researchers observe the following changes as population density increases: decreased body size, delayed sexual maturity, and increased aggression. These changes represent:

A.Genetic drift in isolated populations

B.Founder effects from recent colonization

C.Directional selection for smaller body size

D.Density-dependent physiological responses

D - These changes are physiological responses to increased population density and resource competition, not evolutionary changes from genetic drift, founder effects, or directional selection.

In a field experiment, researchers introduced a non-native plant species to several isolated meadow plots. After 10 years, they observed different community outcomes in different plots. Which factor most likely explains the variable community responses?

A. Presence of different ecological engineers

B. Differential network effects of species interactions

C. Variation in soil nutrient availability

D. Differences in initial species richness among plots

B - Variable community responses to invasion likely result from complex network effects where the same species has different impacts depending on the web of direct and indirect interactions specific to each community.

A keystone predator is removed from a coastal marine ecosystem. Which of the following best describes the likely short-term ecological consequence?

A. Reduced nutrient cycling with no effect on biodiversity

B. Decreased species diversity due to competitive exclusion

C. Stabilization of prey population densities

D. Immediate increase in primary productivity

B - Removal of a keystone predator typically leads to population explosions of their prey, which can outcompete other species and reduce overall diversity through competitive exclusion in the short term.

Which human activity would most directly contribute to ecosystem fragmentation while potentially leaving the total habitat area relatively unchanged?

A. Construction of highways through wilderness areas

B. Increasing atmospheric carbon dioxide levels

C. Clear-cutting large sections of forest

D. Introducing non-native predator species

A - Highway construction creates barriers that fragment habitats without necessarily reducing total area significantly, disrupting gene flow and migration while isolating populations on either side of the barrier.