Lesson 4 - Pyramids of Numbers and Biomass

Pyramid, Biomass, Number, Energy, Trophic Level

• Start
• Re-cap questions from previous lessons
• Main
• Discuss what is meant by biomass
• Discuss the difference between pyramids of biomass and number with examples
• Students draw pyramids of number and biomass to scale on graph paper and evaluate which is best
• Plenary
• Exam Question

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Pyramid, Biomass, Number, Energy, Trophic Level

Lesson 4 - Pyramids of Numbers and Biomass

Starter:

1. Draw a food chain of the following organisms - Toad, grass, snake, slug.

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• Name the -

a) producer

b) primary consumer

c) secondary consumer

d) tertiary consumer

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If you are finished:

Which organism is a herbivore and a carnivore?

Which one do you think is an omnivore?

Pyramid, Biomass, Number, Energy, Trophic Level

Lesson 4 - Pyramids of Numbers and Biomass

Starter:

1. Draw a food chain of the following organisms -

Grass Slug Toad Snake

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• Name the:

a) producer - Grass

b) primary consumer - Slug (Herbivore)

c) secondary consumer - Toad (Omnivore...)

d) tertiary consumer - Snake (Carnivore)

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Pyramid, Biomass, Number, Energy, Trophic Level

Lesson 4 - Pyramids of Numbers and Biomass

Lesson Objectives:

State what Biomass is

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Evaluate two types of pyramids

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Construct pyramids of biomass and numbers

Pyramid, Biomass, Number, Energy, Trophic Level

What is Biomass?

The source of all our energy on Earth is the Sun. This energy is used by plants to grow

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Biomass is the total dry mass of living material in a food chain or food web.

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How do we represent the flow of energy and matter in a food chain?

Pyramid, Biomass, Number, Energy, Trophic Level

Representing Food Chains

We can show the total biomass for each level within a food chain using a Pyramid of Biomass.

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We can also show the population of organisms for each level within a food chain using a Pyramid of Numbers.

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Pyramid, Biomass, Number, Energy, Trophic Level

Pyramid of Biomass

The width represents the mass of each organism at each level

Pyramid, Biomass, Number, Energy, Trophic Level

Pyramids of Numbers

The width represents the number of each organism at each level

Pyramid, Biomass, Number, Energy, Trophic Level

Task:

1. Describe in your own words what Biomass is.

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• Describe the difference between the pyramid of Biomass and Pyramid of Numbers.

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Pyramid, Biomass, Number, Energy, Trophic Level

Task:

• Describe in your own words what Biomass is - Biomass is the total dry mass of living material in a food chain or food web.

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• Describe the difference between the pyramid of Biomass and Pyramid of Numbers - Pyramid of Biomass shows the total dry mass for each feeding level within a food chain, whereas the Pyramid of Numbers shows the total population of organisms at each feeding level.

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Pyramid, Biomass, Number, Energy, Trophic Level

Numbers vs Biomass��Which one do you think is best?

Pyramid, Biomass, Number, Energy, Trophic Level

Learning Check

Using graph paper and the data in the tables:

1. Draw a pyramid of biomass
2. Draw a pyramid of numbers
3. Decide which pyramid is the best representation. Explain why.

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Maths

Pyramid, Biomass, Number, Energy, Trophic Level

Pyramid, Biomass, Number, Energy, Trophic Level

Whiteboards

Pyramids of numbers and biomass quiz

Pyramid, Biomass, Number, Energy, Trophic Level

Final Task

Complete the exam question.

Make sure you read every �question carefully!

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5 Marks = 5 Minutes

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Pyramid, Biomass, Number, Energy, Trophic Level

Answers:

1a. (88/88000)x100 = 0.1 2 marks

1 mark for correct working, 1 mark for correct answer

b. Shape: pyramid with 4 tiers 1 mark

Labels: Plants, Herbivores, Carnivores, Top�carnivores 1 mark

c. More energy / biomass / materials / matter available or less energy lost or energy used up 1 mark

Give a total out of 5

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Pyramid, Biomass, Number, Energy, Trophic Level

Logos / symbols

Pyramid, Biomass, Number, Energy, Trophic Level