IB Environmental systems and societies Topic 2.2D Food Chain and Energy Loss Revision Notes (SL/HL)

IB Environmental systems and societies Topic 2.2D Food Chain and Energy Loss Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Food Chains: energy flows one way and most of it is lost at every step

Definition

Food chain

A food chain is a linear sequence that shows how organic matter and energy flow from one organism to another.

A food chain is a single linear feeding sequence that shows how energy flows from one organism to the next.
It begins with producers, which capture sunlight and build carbon compounds through photosynthesis.
Energy then passes to consumers, each of which eats producers or other consumers.
A food chain is linear, whereas a food web joins many chains into an interconnected network (see 2.2F).

Note

Producers are covered in detail in 2.2B and consumers in 2.2C, so this article only names them briefly.
The focus here is how energy moves along the chain and why so much of it is lost.

Trophic levels: each feeding step is one position in the chain

Definition

Trophic level

A trophic level is the feeding position of an organism within a food chain or web, based on how it obtains its energy and nutrients.

A trophic level is the feeding position an organism occupies, counted from the producer upward.
Producers form the first trophic level and make their own carbon compounds by photosynthesis.
Primary consumers (herbivores) form the second trophic level and eat producers.
Secondary consumers (carnivores or omnivores) form the third trophic level and eat primary consumers.
Tertiary consumers form the fourth trophic level and are often the top predators of the chain.

Exam technique

Number a trophic level by counting energy transfers from the producer, not by the order in which you name the organisms.
In grass then zebra then lion, the zebra is at the second trophic level because it takes energy directly from a producer.

Worked examples of consumers at each level

Definition

Consumer

Consumers are organisms that obtain energy by feeding on other organisms.

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Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Food Chains: energy flows one way and most of it is lost at every step

Definition

Food chain

A food chain is a linear sequence that shows how organic matter and energy flow from one organism to another.

A food chain is a single linear feeding sequence that shows how energy flows from one organism to the next.
It begins with producers, which capture sunlight and build carbon compounds through photosynthesis.
Energy then passes to consumers, each of which eats producers or other consumers.
A food chain is linear, whereas a food web joins many chains into an interconnected network (see 2.2F).

Note

Producers are covered in detail in 2.2B and consumers in 2.2C, so this article only names them briefly.
The focus here is how energy moves along the chain and why so much of it is lost.

Trophic levels: each feeding step is one position in the chain

Definition

Trophic level

A trophic level is the feeding position of an organism within a food chain or web, based on how it obtains its energy and nutrients.

A trophic level is the feeding position an organism occupies, counted from the producer upward.
Producers form the first trophic level and make their own carbon compounds by photosynthesis.
Primary consumers (herbivores) form the second trophic level and eat producers.
Secondary consumers (carnivores or omnivores) form the third trophic level and eat primary consumers.
Tertiary consumers form the fourth trophic level and are often the top predators of the chain.

Exam technique

Number a trophic level by counting energy transfers from the producer, not by the order in which you name the organisms.
In grass then zebra then lion, the zebra is at the second trophic level because it takes energy directly from a producer.

Worked examples of consumers at each level

Definition

Consumer

Consumers are organisms that obtain energy by feeding on other organisms.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 2.2D Food Chain and Energy Loss Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

Food Chains: energy flows one way and most of it is lost at every step

Trophic levels: each feeding step is one position in the chain

Worked examples of consumers at each level

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Food Chains: energy flows one way and most of it is lost at every step

Trophic levels: each feeding step is one position in the chain

Worked examples of consumers at each level

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account