Ecosystem Disruptions and Biodiversity Review

What is the primary source of energy for most ecosystems?

• The Moon

• The Sun

• The Ocean

• The Wind

Answer explanation

The primary source of energy for most ecosystems is the Sun. It provides the light energy that plants use for photosynthesis, forming the base of the food chain and supporting all life forms in the ecosystem.

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DOK Level 1: Recall

Which of the following best describes a food web?

• A linear sequence of organisms through which nutrients and energy pass

• A complex network of interconnected food chains

• A single path of energy flow in an ecosystem

• A diagram showing the number of organisms at each trophic level

Answer explanation

A food web is best described as a complex network of interconnected food chains, illustrating how various organisms interact and transfer energy within an ecosystem, unlike a linear sequence or single path.

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DOK Level 1: Recall

How might a natural disaster, such as a forest fire, impact the energy transfer in a food web?

• It increases the number of predators

• It disrupts the availability of food sources

• It has no effect on the food web

• It increases the number of herbivores

Answer explanation

A forest fire disrupts the availability of food sources by destroying plants and habitats, which affects herbivores and subsequently the predators that rely on them, thus impacting the entire food web.

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DOK Level 2: Skill/Concept

What is primary ecological succession?

• The gradual replacement of one community by another

• The establishment of a community in an area of bare rock

• The rapid growth of a population

• The extinction of a species

Answer explanation

Primary ecological succession refers to the establishment of a community in an area of bare rock, where life begins to develop from scratch, unlike secondary succession which occurs in previously inhabited areas.

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DOK Level 1: Recall

Which of the following is an example of secondary succession?

• Lichen growing on a new lava flow

• Grass growing in a field after a fire

• Moss growing on a rock

• Algae growing in a pond

Answer explanation

Secondary succession occurs in areas where a disturbance has cleared an ecosystem but left the soil intact. Grass growing in a field after a fire exemplifies this, as it regrows after the fire, unlike primary succession which starts from bare rock.

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DOK Level 1: Recall

What role does biodiversity play in the stability of an ecosystem?

• It decreases the stability of an ecosystem

• It has no effect on the stability of an ecosystem

• It contributes to the stability and sustainability of an ecosystem

• It causes instability in an ecosystem

Answer explanation

Biodiversity enhances ecosystem stability by providing a variety of species that can adapt to changes, ensuring resilience against disturbances. This contributes to the overall sustainability of the ecosystem.

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DOK Level 1: Recall

Why is biodiversity important for the health of organisms within an ecosystem?

• It provides a variety of food sources and habitats

• It limits the number of species in an ecosystem

• It reduces competition among species

• It increases the likelihood of disease

Answer explanation

Biodiversity is crucial as it provides a variety of food sources and habitats, which supports the health and survival of different organisms within an ecosystem, ensuring stability and resilience.

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DOK Level 2: Skill/Concept

Which of the following is a consequence of reduced biodiversity in an ecosystem?

• Increased resilience to environmental changes

• Decreased stability and sustainability

• Enhanced food web complexity

• Improved ecosystem health

Answer explanation

Reduced biodiversity leads to decreased stability and sustainability in an ecosystem, as fewer species can result in less resilience to changes and disruptions, making the ecosystem more vulnerable.

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DOK Level 2: Skill/Concept

What is the effect of human intervention on the transfer of energy in food webs?

• It always increases energy transfer efficiency

• It can disrupt the natural flow of energy

• It has no impact on energy transfer

• It stabilizes the food web

Answer explanation

Human intervention can disrupt the natural flow of energy in food webs by altering habitats, introducing invasive species, or changing resource availability, which affects the interactions between organisms.

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DOK Level 2: Skill/Concept

Which of the following is a characteristic of primary succession?

• Occurs in areas with existing soil

• Begins in a lifeless area with no soil

• Happens rapidly over a few days

• Involves only animal species

Answer explanation

Primary succession begins in lifeless areas without soil, such as after a volcanic eruption or glacier retreat. This distinguishes it from secondary succession, which occurs in areas with existing soil.

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DOK Level 1: Recall