A rabbit population in a fenced grassland rises rapidly, then growth slows and the population fluctuates near 600 as food becomes scarce. What pattern does this show?

A deer herd on an island rises to 2,000, strips much of its forage, falls to 400 after two severe winters, and later stabilizes near 900. Which sequence occurred?

A fish population is stable until a toxic spill kills individuals across all age groups. Which type of limiting factor most directly caused the sudden decline?

In a crowded colony, a respiratory infection spreads more rapidly as nesting density rises. What type of population regulation is shown?

After a dam removes a salmon run, a bear population declines over several years and then remains lower. Which limit most likely changed?

A bacterial culture doubles repeatedly while nutrients are abundant, producing a J-shaped population curve. Which condition best explains the record?

A city replaces wetlands with parking lots, increasing runoff and reducing breeding habitat for frogs. Which population response is most likely over time?

In a prairie, vole numbers rise, owl numbers rise a year later, and vole numbers then fall before the cycle repeats. What is the most likely explanation?

A forest insect population stays low for years, then surges after several mild winters and kills many trees before declining. Which statement best describes the surge?

A lake receives repeated nutrient runoff, causing algae to increase. After the algae die, the fish population declines. Which factor most directly limits the fish population?

A population of desert lizards falls sharply during a drought, even though the lizards were widely spaced. Why is drought classified as density independent?

A city adds reliable water supplies and sanitation, and its residents experience lower death rates while birth rates remain high. What population pattern is most likely next?

A country has 18 births and 10 deaths per 1,000 people in one year, with no net migration. What is its annual natural increase rate?

A population grows at 2% per year. Using the rule of 70, about how long will it take to double?

A town has 50,000 residents and grows by 1% in one year, assuming no migration. About how many residents will it have after that year?

A country has 24 births and 9 deaths per 1,000 people, plus net immigration of 3 people per 1,000. What is its total annual population growth rate?

A population of 800 elk grows at 5% per year. Assuming that rate for one year, how many elk are added?

A food web has 20,000 kJ of energy in grasses. Using the 10% rule, about how much energy is available to primary consumers?

A food web has 20,000 kJ of energy in grasses. Using the 10% rule, about how much energy is available to secondary consumers?

A population grows from 1,200 to 1,500 individuals in one year. What is the percent increase?

A species has 4,000 individuals. If 300 are born, 180 die, 90 immigrate, and 60 emigrate in a year, what is the net population change?

A county's population grows at 0.5% per year. Using the rule of 70, its doubling time is closest to which value?

A country has high birth rates and high death rates, so its population grows very slowly. Which demographic transition stage best fits?

A nation improves clean water and medical care; death rates fall quickly but birth rates remain high. Which stage has it entered?

In a country, birth rates are declining as education and employment opportunities for women expand, while death rates remain low. Which stage is most likely?

A country has low birth rates, low death rates, and near-zero population growth. Which stage best describes it?

A country records 8 births and 11 deaths per 1,000 people, with no migration. What does this indicate?

A country has a broad base on its age-structure diagram, meaning many people are younger than reproductive age. What does this most strongly suggest?

A country has a narrow base and a large proportion of older adults in its age-structure diagram. What demographic trend is most likely?

Why is the demographic transition model best described as a model of observed population patterns rather than a population-control policy?

A region's birth rate is 30 per 1,000 and its death rate is 8 per 1,000. Ignoring migration, what is its natural increase rate?

A forest is cleared for roads, farms, and housing, leaving isolated patches for native species. Which threat is most directly responsible for the decline?

A nonnative predatory fish is released into a lake and rapidly reduces native fish populations that lack defenses against it. What threat is dominant?

A commercial fleet removes breeding adults from a fish stock faster than the population replaces them. Which driver of biodiversity loss is involved?

Fertilizer runoff triggers algal blooms, and decomposition creates a hypoxic zone where many aquatic animals cannot survive. Which threat is acting directly on the ecosystem?

As ocean water warms, a coral species experiences repeated bleaching and reduced reproduction. Which driver is most directly causing this decline?

A developer drains a wetland to build warehouses. Besides eliminating wetland habitat, what ecosystem service is most directly reduced?

A small isolated population of mountain lions has little immigration and increasing inbreeding. Which consequence is most likely?

A pesticide biomagnifies in a lake food web. Which organisms are most likely to have the highest concentration?

A sea otter population declines, sea urchins increase, and kelp forests are heavily grazed. What role did sea otters most likely have?

A local population of a bird disappears from one state but survives in other states. What term describes this local loss?

Two protected forest blocks are separated by a highway. Which design most directly helps animals move between the blocks and maintain gene flow?

A reserve is planned for an interior-forest bird sensitive to roads and predators at forest edges. Which layout best minimizes edge effects?

A threatened plant survives only in a particular soil type on private land. Which Endangered Species Act action most directly identifies habitat essential to its conservation?

A rare frog's wetland habitat has been degraded by drainage ditches. Which restoration action most directly addresses the cause of its decline?

A crop disease threatens a region where nearly all farms grow one genetically similar variety. Which conservation approach would most improve resilience?

A park's invasive plant displaces native shrubs. Which management action is a direct form of biological control?

A fish species is nearly extinct in the wild, but habitat restoration will take years. Which strategy can preserve individuals and genetic material while recovery work proceeds?

A riparian forest beside a farm is restored with native vegetation. Which downstream benefit is most likely?

A conservation agency buys a buffer zone around a nesting area where recreation disturbs an endangered bird. What is the main purpose of the buffer?