7.12AB Energy Flow in Ecosystems Quiz

Diagram the flow of energy in a simple food chain consisting of grass, rabbits, and foxes. Which organism receives the least amount of energy?

• Grass

• Rabbits

• Foxes

• All receive the same amount of energy

Answer explanation

In a food chain, energy decreases as it moves up trophic levels. Grass (producer) provides energy to rabbits (primary consumers), which in turn provide energy to foxes (secondary consumers). Thus, foxes receive the least energy.

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TEKS.SCI.7.12A

In an energy pyramid, if the producers have 10,000 Joules of energy, how much energy is typically available to the primary consumers?

• 10,000 Joules

• 1,000 Joules

• 100 Joules

• 10 Joules

Answer explanation

In an energy pyramid, only about 10% of the energy from producers is transferred to primary consumers. Therefore, if producers have 10,000 Joules, primary consumers receive approximately 1,000 Joules.

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TEKS.SCI.7.12A

Which of the following best describes how energy flows through an ecosystem?

• Energy is recycled within the ecosystem.

• Energy flows in a one-way stream, from primary producers to various consumers.

• Energy is created and destroyed within the ecosystem.

• Energy flows from consumers to producers.

Answer explanation

Energy flows in a one-way stream, starting with primary producers like plants, which convert sunlight into energy, and then passes to various consumers. This flow is not recycled or reversed, making the correct choice clear.

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TEKS.SCI.7.12B

What happens to the amount of available energy as it moves up trophic levels in an energy pyramid?

• It increases.

• It remains the same.

• It decreases.

• It fluctuates randomly.

Answer explanation

As energy moves up trophic levels in an energy pyramid, it decreases due to energy loss through metabolic processes and heat. Only about 10% of energy is transferred to the next level, leading to less available energy.

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TEKS.SCI.7.12A

Which process is primarily responsible for recycling matter and nutrients within the biosphere?

• Photosynthesis

• Decomposition

• Respiration

• Evaporation

Answer explanation

Decomposition is the process that breaks down dead organic matter, recycling nutrients back into the ecosystem. This is essential for maintaining soil health and supporting new plant growth, making it the primary process for recycling matter in the biosphere.

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TEKS.SCI.7.12B

In a food web, which of the following organisms would be considered a primary consumer?

• Grass

• Rabbit

• Fox

• Hawk

Answer explanation

In a food web, primary consumers are herbivores that eat producers. Grass is a producer, while the rabbit is a primary consumer that feeds on grass. The fox and hawk are secondary consumers, preying on primary consumers.

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TEKS.SCI.7.12A

How does the recycling of nutrients benefit an ecosystem?

• It allows for the continuous flow of energy.

• It prevents the accumulation of waste.

• It ensures that nutrients are available for producers.

• It increases the energy available at each trophic level.

Answer explanation

The recycling of nutrients ensures that essential elements are available for producers, which are the foundation of the ecosystem. This availability supports plant growth and sustains the entire food web.

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TEKS.SCI.7.12B

If a secondary consumer in an ecosystem receives 100 Joules of energy, how much energy did the primary consumer likely receive?

• 1,000 Joules

• 10,000 Joules

• 100 Joules

• 10 Joules

Answer explanation

In an ecosystem, energy transfer follows the 10% rule. If a secondary consumer receives 100 Joules, the primary consumer likely received 1,000 Joules, as they would have converted only a fraction of the energy from the primary producer.

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TEKS.SCI.7.12A

Which of the following is a key component of sustaining ecosystems?

• The continuous flow of energy

• The destruction of habitats

• The extinction of species

• The isolation of ecosystems

Answer explanation

The continuous flow of energy is essential for sustaining ecosystems as it supports all life forms and drives ecological processes. In contrast, habitat destruction, species extinction, and ecosystem isolation harm ecosystem stability.

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TEKS.SCI.7.12B

What is the primary source of energy for most ecosystems on Earth?

• The Moon

• The Sun

• The Earth's core

• Ocean currents

Answer explanation

The primary source of energy for most ecosystems on Earth is the Sun. It provides the light and heat necessary for photosynthesis, which is the foundation of food chains in various ecosystems.

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TEKS.SCI.7.12B