AP Biology : Understanding Food Webs

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #11 : Understanding Food Webs

The energetic hypothesis states that __________.

Possible Answers:

Several food chains linked together create food webs

The lower trophic levels provide sufficient energy for higher trophic levels

The length of a food chain is limited by insufficient energy transfer through the food chain 

Biomass increases with energy and trophic level

The abundance of organisms at higher trophic levels are supported by lower trophic energy  

Correct answer:

The length of a food chain is limited by insufficient energy transfer through the food chain 

Explanation:

The energetic hypothesis states that the length of a food chain is limited by the inefficiency of energy transfer along the chain. Only ten percent of energy stored in organic matter at each trophic level is actually converted to organic matter at the next trophic level. This keeps trophic structures in check and limits the abundance of predatory organisms at the top of the trophic structure.  

Example Question #12 : Understanding Food Webs

Which of the following are commonly referred to as the producers of the biosphere?

Possible Answers:

Autotrophs

Detritivores

None of these

Heterotrophs

Correct answer:

Autotrophs

Explanation:

Autotrophs are the producers of the biosphere in that they turn inorganic materials into organic material. Plants are an example of autotrophs. Heterotrophs feed on autotrophs and other heterotrophs. Animals are an example of heterotrophs.

Example Question #13 : Understanding Food Webs

Which of the following best describes the consumers within the biosphere?

Possible Answers:

None of these

Detritivores

Heterotrophs

Autotrophs

Correct answer:

Heterotrophs

Explanation:

Heterotrophs are the consumers of the biosphere in that they do not produce organic material but rather consume other organisms. Animals are an example of heterotrophs. Autotrophs produce their own organic material from inorganic materials. Plants are an example of autotrophs.

Example Question #14 : Understanding Food Webs

Animals are an example of which of the following categories of organisms?

Possible Answers:

Biosphere producers

Heterotrophs

Autotrophs

Photoautotrophs

Correct answer:

Heterotrophs

Explanation:

Animals are a type of heterotrophs. Heterotrophs are unable to make their own organic materials and so they must consume other organic materials in the form of autotrophs and other heterotrophs.

Example Question #15 : Understanding Food Webs

Which of the following describes a property of a heterotroph?

Possible Answers:

It makes organic molecules from 

It obtains energy from the plants it consumes

It uses sunlight filtered through pigment to get energy

It oxidizes organic molecules to get its energy

It emits 

Correct answer:

It oxidizes organic molecules to get its energy

Explanation:

Heterotrophs get energy from organic molecules. They are unable to fix carbon dioxide from the atmosphere into organic molecules, nor do they make oxygen as a byproduct of metabolism. They can consume autotrophs and heterotrophs (organic molecules) to get energy and carbon.  

Example Question #16 : Understanding Food Webs

Which of the following processes is an example of primary production?

Possible Answers:

Carnivorous consumption

All of these

Decomposition

Photosynthesis

Correct answer:

Photosynthesis

Explanation:

Primary production is defined as the synthesis of organic compounds from atmospheric carbon. The main process through which this synthesis occurs is photosynthesis. Primary production is characterized as the generation of biomass in autotrophs. On the other hand, secondary production is described as the generation of biomass in heterotrophs.

Example Question #17 : Understanding Food Webs

Which of the following would be considered as a secondary producer?

Possible Answers:

Flowering plant

Antelope

Cacti

Kelp

Correct answer:

Antelope

Explanation:

Secondary production is defined as the generation of biomass by heterotrophs, mainly through the transfer of organic compounds among trophic levels. Organisms that are primarily responsible for secondary production include animals, protists, and fungi.

Example Question #18 : Understanding Food Webs

Which of the following statements best describes the place of primary consumers on the food chain?

Possible Answers:

None of these

Primary consumers are herbivores and consume primary producers

Primary consumers are carnivores

Primary consumers are carnivores and consume primary producers

Correct answer:

Primary consumers are herbivores and consume primary producers

Explanation:

In the food chain of most ecosystems, primary consumers are the organisms that consume primary producers, making them herbivores.

Example Question #19 : Understanding Food Webs

In the food chain, which of the following is consumed by secondary consumers?

Possible Answers:

Autotrophs

Primary consumers

Tertiary consumers

Primary producers

Correct answer:

Primary consumers

Explanation:

Secondary consumers consume primary consumers in the food chain (i.e. a snake eating grasshoppers).

Example Question #20 : Understanding Food Webs

Which of the following is true regarding herbivores?

Possible Answers:

Herbivores are primary consumers

Herbivores eat plant material and are primary consumers

Herbivores eat plant material and are secondary consumers

Herbivores are secondary consumers

Correct answer:

Herbivores eat plant material and are primary consumers

Explanation:

Herbivores are organisms that eat plant material. They are considered as the primary consumers in an ecosystem. An example of an herbivore is a deer, which feeds on flowers and grass.

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