Correct answer: A

The correct answer is The variety of life in an area, including genes, species, and ecosystems..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: Biodiversity includes genetic diversity within species, species diversity, and ecosystem diversity.
3. Check the answer: The correct answer is The variety of life in an area, including genes, species, and ecosystems..

Correct answer: B

The correct answer is The variety of alleles and traits within a species or population..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: Genetic diversity gives a population different inherited traits that may support adaptation and resilience.
3. Check the answer: The correct answer is The variety of alleles and traits within a species or population..

Correct answer: C

The correct answer is The number and relative abundance of different species in a community..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: Species diversity considers both how many species are present and how evenly individuals are distributed among them.
3. Check the answer: The correct answer is The number and relative abundance of different species in a community..

Correct answer: D

The correct answer is The variety of ecosystems and habitats in a region..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: Ecosystem diversity describes variation among habitats, communities, and ecological processes across a landscape.
3. Check the answer: The correct answer is The variety of ecosystems and habitats in a region..

Correct answer: A

The correct answer is A species with an unusually large effect on ecosystem structure compared with its abundance..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: Removing a keystone species can cause major changes because many ecological relationships depend on it.
3. Check the answer: The correct answer is A species with an unusually large effect on ecosystem structure compared with its abundance..

Correct answer: B

The correct answer is A species whose presence, absence, or condition provides information about environmental conditions..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: Indicator species can be sensitive to specific conditions and help scientists monitor ecosystem health.
3. Check the answer: The correct answer is A species whose presence, absence, or condition provides information about environmental conditions..

Correct answer: C

The correct answer is The ability of an ecosystem to recover after disturbance..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: A resilient ecosystem can absorb or recover from disturbances while maintaining important functions.
3. Check the answer: The correct answer is The ability of an ecosystem to recover after disturbance..

Correct answer: D

The correct answer is The ability of an ecosystem to remain relatively unchanged when disturbed..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: Resistance describes how well an ecosystem withstands disturbance without major changes.
3. Check the answer: The correct answer is The ability of an ecosystem to remain relatively unchanged when disturbed..

Correct answer: A

The correct answer is Different species may perform overlapping roles and respond differently to change..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: Functional diversity can help an ecosystem continue operating when one species declines or conditions change.
3. Check the answer: The correct answer is Different species may perform overlapping roles and respond differently to change..

Correct answer: B

The correct answer is A region with many unique species that faces significant habitat loss or threat..

1. Identify the ecosystem concept: Determine whether the question focuses on biodiversity, ecosystem structure, environmental change, or conservation.
2. Apply the ecological principle: Hotspots combine high levels of endemism with substantial threats, making conservation especially important.
3. Check the answer: The correct answer is A region with many unique species that faces significant habitat loss or threat..