Energy Flow and Matter Cycling in Ecosystems

Biology Grades High School 10:25 Video
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Lesson Description

Explore how energy flows and matter cycles through ecosystems, starting with the sun and moving through producers, consumers, and decomposers.

Video Resource

Flow of energy and matter through ecosystems | High school biology | Khan Academy

Khan Academy

Duration: 10:25
Watch on YouTube

Key Concepts

  • Energy Flow
  • Matter Cycling
  • Trophic Levels
  • Photosynthesis and Respiration
  • Decomposition

Learning Objectives

  • Students will be able to describe how energy flows through an ecosystem.
  • Students will be able to explain how matter is recycled within an ecosystem.
  • Students will be able to identify different trophic levels (producers, consumers, decomposers) and their roles.
  • Students will be able to explain the roles of photosynthesis and respiration in the cycling of carbon.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students what they already know about food chains and food webs. Briefly discuss the importance of the sun as the primary energy source for most ecosystems.
  • Video Viewing (15 mins)
    Show the Khan Academy video "Flow of energy and matter through ecosystems". Instruct students to take notes on key terms and concepts presented in the video.
  • Discussion (15 mins)
    Lead a class discussion based on the discussion questions. Encourage students to share their observations and insights from the video.
  • Interactive Exercise (15 mins)
    Have students participate in the food web construction activity.
  • Wrap-up and Assessment (10 mins)
    Review the key concepts covered in the lesson. Administer the multiple choice quiz and fill in the blank quiz to assess student understanding.

Interactive Exercises

  • Food Web Construction
    Provide students with a list of organisms found in a specific ecosystem (e.g., a forest, a pond). Have them work individually or in small groups to create a food web diagram, illustrating the flow of energy and matter between the organisms. Alternatively, create a digital version of this as a drag and drop exercise.

Discussion Questions

  • What is the original source of energy for most ecosystems?
  • What is the difference between a producer, a consumer, and a decomposer?
  • Why is energy transfer between trophic levels only about 10% efficient?
  • How is matter recycled in an ecosystem?
  • What role do photosynthesis and respiration play in the cycling of carbon?

Skills Developed

  • Critical Thinking
  • Scientific Explanation
  • Data Interpretation
  • Model Construction

Multiple Choice Questions

Question 1:

What is the primary source of energy for most ecosystems?

Correct Answer: The Sun

Question 2:

Organisms that create their own food through photosynthesis are called:

Correct Answer: Producers

Question 3:

What gas is used by plants during photosynthesis to create biomolecules?

Correct Answer: Carbon Dioxide

Question 4:

Approximately what percentage of energy is transferred from one trophic level to the next?

Correct Answer: 10%

Question 5:

An organism that eats primary consumers is called a:

Correct Answer: Secondary Consumer

Question 6:

Organisms that break down dead organic matter are called:

Correct Answer: Decomposers

Question 7:

The process by which carbon is converted from a gaseous form to a solid form in plants is called:

Correct Answer: Carbon Fixation

Question 8:

What happens to the energy that is not transferred to the next trophic level?

Correct Answer: It is released as heat

Question 9:

An organism at the top of the food chain with no natural predators is called a(n):

Correct Answer: Apex Predator

Question 10:

What process releases carbon dioxide back into the atmosphere?

Correct Answer: Decomposition

Fill in the Blank Questions

Question 1:

The flow of ______ and the recycling of _______ are key processes in an ecosystem.

Correct Answer: energy

Question 2:

_______ are organisms that obtain energy by consuming other organisms.

Correct Answer: Consumers

Question 3:

Plants use the energy from the sun to convert carbon dioxide and water into glucose through a process called ________.

Correct Answer: photosynthesis

Question 4:

The different feeding levels in an ecosystem are called _______ levels.

Correct Answer: trophic

Question 5:

The process of breaking down dead organisms and waste products is called ________.

Correct Answer: decomposition

Question 6:

Energy is often lost as ______ during energy transfers in an ecosystem.

Correct Answer: heat

Question 7:

_______ consumers eat primary consumers.

Correct Answer: Secondary

Question 8:

Carbon is 'fixed' from a _______ form into a solid form during photosynthesis.

Correct Answer: gaseous

Question 9:

The most efficient way to get energy from the sun is to be a _________.

Correct Answer: producer

Question 10:

Unlike energy, matter is constantly _______ within an ecosystem.

Correct Answer: recycled

Educational Standards

B.LS2.3:Construct and revise an explanation based on evidence for the cycling of matter and the flow of energy in aerobic and anaerobic conditions. B.LS2.4:Use a mathematical representation to support claims for the cycling of matter and the flow of energy among organisms in an ecosystem. B.LS2.5:Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of carbon among the biosphere, atmosphere, hydrosphere, and geosphere.

Teaching Materials

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