Pyramids of Biomass

This lesson covers:

  1. Biomass is just the mass of living organisms 
  2. How pyramids of biomass show the amount of biomass at each trophic level of a food chain
  3. Why the amount of biomass decreases as you go up the food chain
  4. How to calculate the efficiency of biomass transfer between levels in a food chain

What does each bar in a pyramid of biomass show?

The number of organisms in that trophic level

The energy within all of organisms in that trophic level

The biomass of all organisms in that trophic level

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Diagram showing a pyramid of biomass with arrows indicating energy transfer between trophic levels.

Roughly what proportion of energy biomass is transferred between trophic levels?

1%

10%

90%

100%

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Which of these is NOT true when drawing pyramids of biomass?

The primary consumer is at the bottom

Bars must be equally spaced around the midpoint

Bars must be touching

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Illustration of a lion representing an apex predator in a pyramid of biomass.

Where are apex predators on a pyramid of biomass?

At the bottom of the pyramid 

They are not shown on the pyramid 

At the top of the pyramid 

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What does the biomass of an organism refer to?

The mass of an organism

The mass of waste an organism excretes in its life

The mass of food an organism ingests in its life

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Illustration of a pyramid of biomass with a highlighted bar representing a trophic level.

The image above shows a pyramid of biomass. Which trophic level does the highlighted bar represent?

Apex predators

Primary consumers

Secondary consumers 

Producers

Decomposers

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Illustration of a pyramid of biomass with a highlighted bar representing a specific trophic level.

The image above shows a pyramid of biomass. Which trophic level does the highlighted bar represent?

Producers

Secondary consumers 

Decomposers

Apex predators

Primary consumers

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Image showing a pyramid of biomass with highlighted trophic level bar.

The image above shows a pyramid of biomass. Which trophic level does the highlighted bar represent?

Primary consumers

Producers

Secondary consumers 

Decomposers

Apex predators

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Which of the groups below is NOT shown on a pyramid of biomass?

Decomposers

Apex predators

Primary consumers

Secondary consumers 

Producers

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Give three reasons why only ~10% of the energy & biomass is passed on at each stage in a food chain? 

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Illustration showing biomass transfer between trophic levels with a flower, rabbit, snake, and owl with respective weights.

Calculate the efficiency of biomass transfer between trophic level 2, and trophic level 3. Round your answer to 1 decimal place.

10.5%

13.0%

11.1%

12.1%

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Diagram showing biomass transfer from a plant to a rabbit, then to a snake, and finally to an owl with respective weights of 3675 kg, 350 kg, 34 kg, and 4.2 kg.

Calculate the efficiency of biomass transfer between trophic level 3, and trophic level 4. Round your answer to 1 decimal place.

12.4

%

%

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Illustration showing biomass transfer between trophic levels with a flower, rabbit, snake, and owl, indicating weights of 5100 kg, 490 kg, 48 kg, and 5 kg respectively.

Calculate the efficiency of biomass transfer between trophic level 1, and trophic level 2. Round your answer to 1 decimal place.

9.6

%

%

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