NGS - Principles of Ecology - Sec. 2: Energy Flow in Ecosystems

How does energy flow in an ecosystem?

• From the sun to autotrophs to heterotrophs

• From chemical compounds to consumers to producers

• From consumers to producers

• From the owl to the gecko to the grasshopper

Answer explanation

Energy flows in an ecosystem starting from the sun, which is captured by autotrophs (producers) through photosynthesis. Heterotrophs (consumers) then obtain energy by consuming autotrophs, making the correct flow: sun to autotrophs to heterotrophs.

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What is a primary producer in a food chain?

• An organism that is at the top of the food chain

• An organism that eats other organisms

• An organism that uses the sun to produce food

• An organism that decomposes dead matter

Answer explanation

A primary producer is an organism that uses the sun to produce food, typically through photosynthesis. This distinguishes it from other roles in the food chain, such as consumers and decomposers.

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Which of the following is a primary consumer?

• Grass

• Gecko

• Grasshopper

• Owl

Answer explanation

The grasshopper is a primary consumer as it feeds on plants like grass. In contrast, the gecko is a secondary consumer that eats insects, and the owl is a tertiary consumer that preys on small mammals and birds.

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What does a food web illustrate?

• A single path of energy flow

• All possible feeding relationships in a community

• The number of organisms at each trophic level

• The amount of energy at each trophic level

Answer explanation

A food web illustrates all possible feeding relationships in a community, showing how different organisms are interconnected through various food chains, rather than just a single path of energy flow.

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What is a trophic level?

• The total number of organisms in an ecosystem

• The top predator in a food chain

• The amount of energy lost between levels

• A step in the transfer of energy and matter in a food chain

Answer explanation

A trophic level refers to a step in the transfer of energy and matter in a food chain, indicating the position of organisms in the ecosystem, such as producers, primary consumers, and higher-level consumers.

What does an energy pyramid show?

• The flow of energy from one trophic level to the next

• The total number of organisms at each level

• The biomass of each organism

• The complexity of a food web

Answer explanation

An energy pyramid illustrates the flow of energy from one trophic level to the next, showing how energy decreases as it moves up the pyramid. This highlights the efficiency of energy transfer in ecosystems.

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What is a biomass pyramid?

• A diagram showing the flow of energy

• A diagram illustrating feeding relationships

• A diagram comparing the biomass at each trophic level

• A diagram showing the number of organisms

Answer explanation

A biomass pyramid specifically compares the total biomass at each trophic level in an ecosystem, illustrating how energy and matter are distributed among producers, consumers, and decomposers.

What does a pyramid of numbers illustrate?

• The energy used by each organism

• The total number of organisms at each trophic level

• The complexity of feeding relationships

• The biomass available at each level

Answer explanation

A pyramid of numbers illustrates the total number of organisms at each trophic level, showing how many individuals exist at each stage in the food chain.

Which organism is a tertiary consumer in the example food chain?

• Grass

• Grasshopper

• Gecko

• Owl

Answer explanation

In the food chain, grass is a producer, grasshoppers are primary consumers, and geckos are secondary consumers. The owl, being a predator of the gecko, is the tertiary consumer, making it the correct answer.

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Why is a food web more complex than a food chain?

• It shows the number of organisms at each level

• It shows only one path of energy flow

• It compares the biomass of organisms

• It includes all possible feeding relationships

Answer explanation

A food web is more complex than a food chain because it includes all possible feeding relationships among organisms, showing how they interact in an ecosystem, unlike a food chain which depicts a single path of energy flow.

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