Energy Flow in Ecosystems - Middle School Life Science

Identify the correct arrow direction: grass and rabbit in a food chain model.

Grass rabbit. Arrow points from grass (eaten) to rabbit (eater).
What is a producer in an energy-flow model (food chain or food web)?

An organism that makes its own food, usually by photosynthesis. Creates energy-rich molecules from inorganic materials.
Which organisms are at the first trophic level in an energy pyramid?

Producers. They capture energy directly from sunlight.
Choose the correct sequence for energy flow in a simple ecosystem model.

Sun producers consumers decomposers. Energy flows one-way through all organism types.
What is the term for a consumer that eats secondary consumers?

Tertiary consumer. Third-level consumer, eats carnivores.
Which organisms return nutrients to the soil or water by breaking down matter?

Decomposers. This completes the nutrient cycle in ecosystems.
What happens to most energy at each trophic transfer in an ecosystem model?

It is lost as heat through life processes. Organisms use energy for metabolism and movement.
What is a producer in an ecosystem energy model?

An organism that makes its own food, usually by photosynthesis. They convert light energy into chemical energy in food.
Identify the role of algae in an energy-flow model: producer, consumer, or decomposer?

Producer. Photosynthetic organism that makes its own food.
What is a trophic level in an ecosystem model?

A feeding level in a food chain or food web. Each level represents organisms with similar energy sources.
What is the term for a consumer that eats only producers?

Primary consumer (herbivore). First-level consumers eat only plants.
What is the original source of energy for most food webs?

The Sun. Producers convert solar energy into food energy.
If producers store $1000$ energy units, about how many reach primary consumers using the $10\%$ rule?

$100$ energy units. $1000 \times 0.1 = 100$ energy units transfer.
Which term names a model that shows one pathway of energy transfer?

Food chain. It's a linear sequence of who eats whom.
What is the role of secondary consumers in energy flow models?

They eat primary consumers and transfer energy upward. They're carnivores at the third trophic level.
What is a consumer in an energy-flow model?

An organism that gets energy by eating other organisms. Cannot produce its own food, must consume others.
Which model shows many interconnected feeding relationships: food chain or food web?

Food web. Shows complex, realistic feeding relationships.
If primary consumers have $200$ energy units, about how many reach secondary consumers?

$20$ energy units. $200 \times 0.1 = 20$ following the 10% rule.
Identify the trophic level: a hawk that eats a snake that ate a mouse that ate plants.

Tertiary consumer. Count four levels: plant, mouse, snake, hawk.
Which direction does energy flow in a food chain arrow: from food to eater or eater to food?

From food to eater. Arrow shows energy transfer direction.
In a food web, what does it mean if one organism has many arrows pointing to it?

It eats many different organisms (many energy sources). Multiple arrows in = diverse diet.
Which model best shows that energy decreases at higher trophic levels?

Energy pyramid. Its triangular shape shows energy loss at each level.
Identify the role of mushrooms in an energy-flow model: producer, consumer, or decomposer?

Decomposer. Fungi break down dead organic matter.
What is the role of tertiary consumers in energy flow models?

They eat secondary consumers and are higher-level predators. They're at the fourth trophic level.
What is a decomposer in an ecosystem energy model?

An organism that breaks down dead matter and wastes for energy. They recycle nutrients back into the ecosystem.
What is a consumer in an ecosystem energy model?

An organism that gets energy by eating other organisms. They cannot make their own food like producers can.
What is the role of primary consumers in energy flow models?

They eat producers and transfer energy to higher levels. They're herbivores at the second trophic level.
What happens to most energy as it moves from one trophic level to the next?

It is lost as heat through life processes. Only about 10% transfers to the next level.
What do decomposers return to the environment that helps producers grow again?

Nutrients (recycled matter). Matter cycles while energy flows one-way.
Which statement best describes energy availability at higher trophic levels?

Less energy is available at higher trophic levels. Energy decreases as it moves up the chain.
What is a decomposer in an energy-flow model?

An organism that breaks down dead matter and wastes for energy. Recycles nutrients back to soil for producers.
What is a detritivore in an energy flow model?

An organism that eats dead organic matter (detritus). Examples include earthworms and millipedes.
What is the approximate fraction of energy transferred to the next trophic level?

About $10\%$ . The 10% rule shows energy loss between levels.
Which term names a model that shows many connected feeding relationships?

Food web. It's more realistic than a simple chain.
What is the correct order of energy flow in a simple food chain model?

Producer → consumer(s) → decomposer. Energy flows from those who make to those who take to those who break.
What is the term for a consumer that eats primary consumers?

Secondary consumer. Feeds on herbivores, second step from producers.
What does an arrow in a food chain model represent?

Direction of energy transfer (from food to eater). Energy flows from the organism being eaten to the eater.
What is a trophic level in an energy-flow model?

A feeding position in a food chain or food web. Each level represents who eats whom.
Which group is missing if a model shows only producers and consumers but no recycling?

Decomposers. Without them, nutrients wouldn't return to producers.
What is the primary energy source for most ecosystems on Earth?

Sunlight (solar energy). Powers photosynthesis, the foundation of most food chains.

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