Module 1 Intro

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1. Module 1 Intro

Introduction

Module 1—Energy Flow and the Cycling of Matter

Module Introduction

In Module 1 you will examine the use of energy and the cycles of matter within the biosphere. You will learn that capturing energy is done through organisms called producers. You will investigate how producers are able to convert the energy they capture into chemical energy that can be used by other organisms called consumers. You will also gather evidence about and describe how consumers allow energy to flow through the biosphere. Then you will look at how finite resources are cycled through the biosphere.

By the end of this module, you will be able to explain how the relationships between producers and consumers—abiotic and biotic components of the biosphere—maintain a constant cycling of matter and energy flow.

The essential questions that you will be looking at in this module are the following:

How does energy enter the biosphere, and how is it distributed?
Once energy is in the biosphere, how does energy become useful?
What properties of water contribute to water’s role in the biosphere?
Why is the cycling of matter within the biosphere important to life on Earth?
How are biodiversity and biomagnification related to energy flow and the cycling of matter?

Once you have completed Module 1, you will work on a module project that requires you to answer the essential questions for this module. These questions will be answered through an analysis of a photograph, a sketch, or an image from a magazine. When you are ready to begin the module project, go to the Module Summary and Assessment to read the instructions and learn how you will be graded.

1.1. Big Picture

Big Picture

Module 1—Energy Flow and the Cycling of Matter

Big Picture

For almost half of the year, your outdoor view might look like a winter landscape.

This photo shows snow-covered trees in the sunshine.

This photo shows a sunny day in a backyard with a garden in the foreground and flowers on a deck in the background.

This is a photograph of a sunny day on an Edmonton street during the autumn. There are yellow and brown leaves on the ground.

And then you know the weather cycle is continuing when you see falling leaves.

These photographs are familiar scenes to most people in Alberta. For many people, their favourite season is summer. Everything seems alive! It also seems like many people are more interactive with the surroundings (e.g., animals, people, and plants).

In reality, people are constantly exchanging energy and matter with the environment every day—365 days a year. This means that there must be something happening even in the spring, fall, and winter. Energy must be constantly flowing, and nutrients must be cycling somehow in order for life cycles to continue. After all, you eat and go outside whether it is winter or summer.

This module will guide your discovery of exactly how energy flows in the biosphere and how matter cycles. As you work through Module 1, return to these photographs. Each time you finish a lesson, look at these pictures or view the scenery outside and ask yourself this Big Picture question: “How does energy flow and matter cycle?” As you progress in the module, your answer will become more complex and complete.

Each lesson will focus on answering one of the following questions:

How does energy enter the biosphere, and how is it distributed?
Once energy is in the biosphere, how does it become useful?
What properties of water contribute to water’s role in the biosphere?
Why is the cycling of matter within the biosphere important to life on Earth?
How do biodiversity and biomagnification relate to energy flow and the cycling of matter?

When you finish Module 1, you will have completed several lesson assignments and a module project. When you are ready to work on your Module Project, go to the Module Summary and Assessment for instructions.

1.2. In this Module

In This Module

Module 1—Energy Flow and the Cycling of Matter

In This Module

Lesson 1—Energy for Life

You already know that every organism in the biosphere requires energy. This lesson will build on what you already know about photosynthesis. You will also explore how some organisms capture and store chemical energy rather than light energy. In order to better understand the capture and storage of energy, as well as its release, you will explore the relationship between the processes of photosynthesis, chemosynthesis, and cellular respiration.

What processes do producers use to harness energy?
How is energy distributed through the biosphere?

Lesson 2—Energy Flow Through Trophic Levels and the Cycling of Matter

This lesson will examine how energy is transferred from one organism to another within an ecosystem. To do this, you will study the flow of energy between producers and consumers. You will see that the flow of energy can be compared to the links in a chain. You will also find out how much energy is actually available from one trophic level to another within a food chain.

How can you model the transfer of energy and matter between organisms?
How can you use math to explain the differences in energy flow in various ecosystem food chains?

Lesson 3—Two Hydrogens and an Oxygen: One Small Molecule, One BIG Role

Water is a key player in the dynamic balance of the biosphere. This lesson looks at the importance of water to the biosphere, especially to biogeochemical cycles (that’s just a big word for “chemicals of the living Earth”).

What chemical and physical properties of water make water an important part of biogeochemical cycles?

Lesson 4—Cycling of Matter

What matter matters? Carbon, oxygen, nitrogen, and phosphorus are substances that matter. Since there is a finite supply of these chemicals, they must be cycled or the supply will run out. This lesson looks at the cycling of these substances and provides you with the opportunity to discover exactly how important these molecules are to you.

How do carbon, oxygen, nitrogen, and phosphorus cycle through the biosphere?

Lesson 5—Biodiversity and Biomagnification

Once you look at how energy flows and matter cycles, it would be a good idea to relate that to biodiversity and biomagnification. Both are affected by the distribution of energy and matter. By looking at these two concepts you will be better able to explain the equilibrium that can exist in the biosphere.

How do biodiversity and biomagnification relate to energy flow and the cycling of matter?

Once you have completed these lessons you will complete a module project. Once the project is complete you will move on to Module 2, which looks at the fine balance of energy and matter and how human actions can create imbalances that can eventually reach global proportions.

Module Assessment

You will be graded according to the work you complete for the lesson assignments and the module project. The module project is the final assignment for Module 1.

1.3. Lesson 1 Intro

Lesson 1

Module 1—Energy Flow and the Cycling of Matter

Lesson 1—Energy for Life

Get Focused

Two hands frame the Sun in a combined blue and cloudy sky.

How does energy enter the biosphere? If you walk out your front door, part of the answer is right there in front of you. Look carefully, and notice all the producers around us. What is the importance of autotrophs (producers) and how do they contribute to our society?

biosphere: all areas on Earth that can sustain life and are inhabited by organisms (atmospher, hydrosphere, lithosphere)

equilibrium: balance in a system; the overall fluctuations in the system balance out and there is no net change over time

producers: organisms that are able to produce their own energy by harnessing chemical or solar energy; also called autotrophs

consumers: organisms that must obtain energy by eating other organisms; also called heterotrophs

In order to better understand how energy begins to flow through the biosphere and helps to maintain equilibrium, you will look at the role of autotrophs and heterotrophs.

Consider the following essential questions as you complete Lesson 1:

What process is used for autotrophs to harness their own energy?
How is energy distributed through the biosphere?

Module 1: Lesson 1 Assignment

Your teacher-marked Module 1: Lesson 1 Assignment requires you to submit a response to the following:

Lesson 1 Lab: Photosynthesis: Part A
your choice of two "Try This" questions

You can access your Module 1: Lesson 1 Assignment. Complete the assignment electronically and submit your completed assignments in the Assignment 1 Hand-in. Your answers can be saved on this document to your course folder.

The other questions in this lesson are not marked by the teacher; however, you should still answer these questions to assess your learning. The "Self-Check" and "Try This" questions are placed in this lesson to help you review important information and build key concepts that may be applied in future lessons.

After a discussion with your teacher, you must decide what to do with the questions that are not part of your assignment. For example, you may decide to submit to your teacher the responses to "Try This" questions that are not marked. You should record the answers to all questions in this lesson and place those answers in your course folder.

The choices you make about responding to the "Self-Check" and "Try This" questions will depend upon your learning style, your abilities in this subject, and your goals for the course.

There are several types of questions in this lesson. For the "Self-Check" questions you can respond mentally, write out your response, or record your answer in any other way that works for you. There are "Try This" questions that will often be a part of your lesson assessment. These may require more attention and detail.

You will also be asked to complete labs virtually, on your own, or in a science lab. Lab reports will usually be used as a lesson assessment as well. At times, you will be asked to engage in discussion topics with other students. All hand-in assignments will be clearly indicated at the end of Get Focused and throughout the lesson. Not all questions/activities will be submitted as Assessments, but they do reinforce the key concepts you must learn to be successful.

Think of these questions/activities as little bits of Lego. You need to have many pieces of Lego before you can build a useful object. By the end of each module, you should have collected and stored enough Lego bits of knowledge to feel comfortable building ideas with them. If you are a few pieces short, you need to revisit a lesson.

As you work through Lesson 1, you need to decide if you will make your own notes, bookmark web pages for reference, draw diagrams/charts, or use other means to remember. You are in charge of how you learn. You can save everything in your course folder or, if you prefer paper, then attach your assignments, notes, and musings in a real binder. Don’t forget that some items MUST be put in the course folder.

1.4. Page 2

Lesson 1: Page 2

Module 1—Energy Flow and the Cycling of Matter

Explore

Read

Begin this lesson by reading from pages 8 and 9 in your textbook. Don’t read “Investigation 1A,” but read the remainder of page 11 and to the bottom of the first column on page 12. Pay special attention to “Figure 1.2” on page 9, which shows the relationship between photosynthesis and cellular respiration. Also note “Figure 1.4” on page 11, which shows the distribution of solar energy in the biosphere.

Self-Check

SC 1. Answer questions 3 and 4 on page 9 of the textbook.

SC 2. What conclusion can you make about the energy transfer from the solar system to organisms on Earth?

Check your work.

Self-Check Answers

SC 1.

The energy in photosynthesis is solar energy converted to chemical energy. The energy in cellular respiration is from the stored chemical energy that originated from photosynthesis; chemical energy is converted to other kinds of energy like heat and motion (energy required for cellular processes to occur.) Celllular respiration energy will never be involved in photosynthesis.
Consumers require the products of producers (e.g., oxygen, carbohydrates) and contribute the chemical elements of carbon dioxide and water, which are required for photosynthesis by producers.

SC 2. The energy transfer from the solar system to organisms on Earth is not efficient because only 2% of this energy transfer actually makes it to living things (producers). However, the producers that capture this energy are capable of sustaining life on Earth with only 2% of this energy by producing from 150- to 200-billion tonnes of biomass.

Producers: Energy Harvesters

photosynthesis: the process by which plants, algae, and some kinds of bacteria use solar energy to chemically convert carbon (inorganic) into carbohydrates (organic) such as sugars and starches

chemosynthesis: the process by which certain fungi and bacteria use the energy from chemical nutrients to chemically convert carbon (inorganic) into carbohydrates (organic)

In this part of Lesson 1 you will examine the various mechanisms involved in collecting and storing energy. Biology is full of diversity, so it may not come as a surprise to you that there are two methods used by producers or autotrophs to store energy. These methods are photosynthesis and chemosynthesis. Photosynthesis is used by terrestrial producers with access to a light source. Chemosynthesis is used by deep-sea producers with no access to solar energy.

The flow of energy begins with producers. Terrestrial producers are capable of completing the conversion process (photosynthesis) by absorbing water from the ground and carbon dioxide from the air. Chloroplasts, containing the green pigment chlorophyll, that are inside the cells of a producer capture the solar energy generated by the Sun.

A photo of a green birch leaf is shown against a black background.

Solar energy is converted to chemical energy. This is an important event, since your body requires chemical energy to keep functioning.

Photosynthetic Equation

6 CO2(g) + 6 H2O(l) + solar energy → C6H12O6(aq) + 6 O2(g)

This equation shows the first law of thermodynamics—energy has changed forms.

first law of thermodynamics: energy in a system cannot be created nor destroyed; it changes forms

photoautotrophs: the process by which plants, algae, and some kinds of bacteria use solar energy to chemically convert carbon (inorganic) into carbohydrates (organic) such as sugars and starches

This photograph is a microscopic view of cyanobacteria. The cyanobacteria look like flattened, green, transparent worms.

Some photoautotrophs are not plants, but are special bacteria capable of performing photosynthesis. These bacteria are called cyanobacteria and are usually found in fresh water environments, but they can also be found in such areas as oceans; damp, rocky areas; and damp soil. Some even live in the fur of sloths!

Photosynthesis is an important mechanism for capturing and storing energy. It is not surprising, therefore, to find out that approximately 98% of all producers use photosynthesis to produce food! Those are the organisms capturing a fraction of the Sun’s energy. What about the other 2% of producers? What mechanism do they use? Why don’t they use photosynthesis?

The other 2% of producers don’t use photosynthesis for the simple reason that they do not have access to the 2% of solar energy available to photoautotrophs. These organisms can be found in extreme environments, such as the ocean floor. These environments usually share a common characteristic—they are in complete darkness! These organisms resort to a mechanism called chemosynthesis to convert inorganic molecules into an organic molecule that will serve as a food source.

It is time to more closely explore the processes of photosynthesis and chemosynthesis.

1.5. Page 3

Lesson 1: Page 3

Module 1—Energy Flow and the Cycling of Matter

Watch and Listen

A Closer Look at Producers and Photosynthesis

A photo is shown of a cereal crop with a blue sky and clouds above the field.

Photosynthesis provides organisms with the energy they need to stay alive. What happens if limiting factors such as low light intensity, low carbon dioxide levels, or extreme temperatures inhibit the rate at which photosynthesis can occur? Do plants start dying? What happens to oxygen levels, a by-product of photosynthesis? How would inhibited photosynthesis affect consumers that depend on plants for energy and for the oxygen needed for the process of cellular respiration?

Watch a video to better understand how the various limiting factors of photosynthesis were discovered. The limiting factors mentioned in this lesson and in the video will be examined further in the photosynthesis lab that you’ll complete later in Lesson 1.

Try This

TR 1. Scientific Inquiry

What series of hypotheses and observations and discoveries led scientists to the conclusion that carbon dioxide and oxygen were involved in what is now know as photosynthesis?

Assignment

Please note that you will complete two Try This questions in the Assignment.

1.6. Lab

Lesson 1: Lab

Module 1—Energy Flow and the Cycling of Matter

Lesson 1 Lab: Photosynthesis

You will find the necessary questions needed to complete this lab in the Module 1: Lesson 1 Assignment. The link to this assignment is found at the beginning of Lesson 1 in the Get Focused section.

Purpose

In this lab you will study photosynthesis in a variety of conditions. You will vary light intensity, carbon-dioxide levels, temperature, and the colour (wavelength) of light in order to find out how each factor affects oxygen production. Oxygen production is used to measure the rate of photosynthesis. See the instructions that follow about accessing the Photosynthesis Lab Gizmo to simulate photosynthesis.

limiting factor: any biotic or abiotic factor that controls or limits the functioning of an organism

Problem

Which conditions produce the best rate of photosynthesis?
How do limiting factors affect the rate of photosynthesis?

Part A: Lab Report

To assist with this lab go to the Lesson 1 Assignment document. Your lab report should be set up in the same format as this template. You will save your lab report in your course folder and later submit it to your teacher for assessment. You may want to access the Photosynthesis Laboratory Evaluation Rubric to see how the quality of your report is assessed.
Consider the problem and prepare a hypothesis before you open the Photosynthesis Lab Gizmo.
Open the Photosynthesis Lab Gizmo. You may need a LearnAlberta password to access this lab. Contact your teacher for this information.
Click on the “Exploration Guide” button just above the gizmo. Print and follow the procedure provided.
Answer the Observation questions in your lab report as you complete the lab simulation.
When you write your conclusion, make sure to answer the questions that were asked from the “Problem” section of the lab. Also state whether or not your hypothesis was correct. Support your answer with specific examples from the lab.
If you choose to work with a partner, make sure to indicate both names on your lab report.

Part B: Gizmo Questions

Once you have completed the lab and your lab report, answer the self-scoring assessment questions found in the gizmo. Check your results. You will receive an individual report of your self-scoring assessment results and an explanation of the science behind each answer. Select and copy the text from the self-scoring assessment. Paste the text into a word-processing document, and save these results to your online course folder. This is not to be marked by your teacher.

This document may be useful when you complete the unit essay question at the end of Unit A. It will also be revisited in Unit C, so be sure to save this assignment.

1.7. Page 4

Lesson 1: Page 5

Module 1—Energy Flow and the Cycling of Matter

Try This

TR 2. About 2% of solar energy is used for photosynthesis. Where’s the other 98%?

Explain where the other 98% of solar energy goes. Predict what would happen if there were fluctuations (an increase or a decrease) in these percentages. Also predict what might cause these changes. “Figure 1.4” on page 11 in your textbook may be helpful.

Read

Read “Energy for Life in the Deep Ocean” on pages 12 and 13 of your textbook.

Self-Check

SC 3. Answer question 7 on page 13 of the textbook.

Check your work.

Self-Check Answers

SC 3. Chemosynthesis is similar to photosynthesis because they both use one form of energy to create the organic molecules required for life. This is the beginning of energy flow in a system lacking light.

A difference is that chemosynthetic organisms use the energy from splitting hydrogen sulfide bonds instead of energy from the Sun. Chemosynthetic organisms produce sulfuric acid instead of oxygen. Chemosynthetic organisms are mainly bacteria.

Watch and Listen

A Closer Look at Producers and Chemosynthesis

Discovery: Arctic Hydrothermal Vents

The northernmost hydrothermal vent fields in the world were discovered in late July 2005 on a research expedition northwest of Norway.

Adam Schultz, COAS geophysicist who has studied hydrothermal systems since the 1980s, was part of the collaborative expedition with the University of Bergen, Norway. An instrument he created, called the Medusa Isosampler, played a key role in documenting the characteristics of the new vent fields.

Hydrothermal vents—also called “smokers” or “chimneys”—form along the Mid-Ocean Ridge, an area along the ocean floor where the Earth’s crust splits apart and new crust bubbles up in the form of lava from the mantle. The ridge is the Earth’s largest geologic feature; it zips up and down the middle of the world’s ocean basins like seams on a baseball, and is considered one of the most extreme environments on Earth.

“I’ve seen a lot of hydrothermal systems all over the world’s oceans,” Schultz said, “and these Arctic fields are spectacular.

“There is also a vast low-temperature field that supports a diverse community of life, including large sea-lilies that sit atop mineral-bacterial chimney-like structures that look like pineapples. That is a particularly strange form of vent, because the fluids come out at temperatures only a fraction of a degree above the temperature of the background seawater, and that is very cold—below zero Celsius—which is only possible in the Arctic.”

Much of the Arctic Ridge system is unexplored, and prior to this discovery, a vent field on the shelf of Iceland was the only one scientists had ever laid eyes upon. In marked contrast to that Icelandic field, the new fields are replete with animal life.1

1“Discovery: Arctic Hypothermal Vents,” Ocean & Air–A Magazine of Innovation in Earth Systems Science
<http://oceanandair.coas.oregonstate.edu/index.cfm?fuseaction=content.display&pageID=91>;, 4 September 2007. Reproduced by permission.

Discoveries like those discussed in the article explain how organisms are able to live in extreme environments where light is not available for producers to capture solar energy.

Listen to a past episode of “Quirks and Quarks,” where scientists talk about the process of chemosynthesis as it occurs in the most extreme conditions of deep-sea volcanic vents. To get to this site, enter the key words “Quirks and Quarks CBC” into a search engine. This should get you to the main Quirks and Quarks CBC website of the CBC radio science program. Once there, type in “Extreme Living: Deep Sea Vents” into the CBC search bar in the top-right corner of the page. Listen to this podcast with the following Try This questions in mind.

Try This

Scientific Inquiry

TR 3. The discovery of deep-sea organisms using chemosynthesis is listed by the scientists in the “Quirks and Quarks” episode as one of the top three discoveries in science. What is significant about chemosynthesis that allows it to open other avenues of theory?

TR 4. How did the discovery of microbes in geothermal vents lead to the possibility of new technology?

TR 5. What other hypotheses have been formed due to the discovery of these chemosynthetic organisms?

1.8. Page 5

Lesson 1: Page 6

Module 1—Energy Flow and the Cycling of Matter

How Energy Flows Through Consumers

Read

Now you will be taking a close look at consumers. Read pages 13 to 15 in your textbook, starting at “A Closer Look at Consumers.” Continue reading to “Section 1.1 Summary” on page 14. Make note of the different ways to classify consumers.

Self-Check

SC 4. Do questions 6, 7, and 8 on page 15 of your textbook.

Check your work.

Self-Check Answers

SC 4.

The first law of thermodynamics states that energy cannot be created or destroyed, but it can be transformed from one form to another, or passed from one object to another. The second law of thermodynamics states that with each energy conversion, there is less energy to do useful work, because some energy is converted into a form that organisms cannot use, such as heat.
The albedo of fresh snow is 80 to 90 percent, while the albedo of water is 25 percent or less. (See page 11 of the textbook.) Forests and grasses have even lower albedo values (7 to 18 percent and 18 to 25 percent, respectively). With the loss of snow and ice cover, which both have high albedos, more of Earth’s surface will have a low albedo. As the albedo of Earth’s surface decreases, less incoming radiant energy from the Sun is reflected by the Earth’s surface. More radiant energy is absorbed, further warming the planet and reducing snow and ice cover.
As the skunk cabbage carries out cellular respiration and other reactions, it transfers energy to the environment as dissipated heat, which melts the snow.

SC 5. What do the yellow and green arrows represent in the diagram that follows? How would you label each of the pictures (e.g., producer, consumer)? How is the second law of thermodynamics represented in this diagram?

Check your work.

Self-Check Answers

SC 5. The second law of thermodynamics is represented by the loss of heat at every level. There is less and less energy available after each conversion.

Reflect and Connect

Draw a diagram (by hand or by computer) or write a paragraph describing what you know about the flow of energy through the biosphere. Make sure that your diagram or paragraph represents each of the summary points from pages 14 and 15 of your textbook. Your diagram or paragraph is a work in progress and will be modified once you complete Lesson 2. Complete your work and save it in your course folder so that you can access it again in Lesson 2.

Module 1: Lesson 1 Assignment

Remember to submit the Assignment answers to your teacher as part of your Module 1: Lesson 1 Assignment.

1.9. Page 6

Lesson 1: Page 7

Module 1—Energy Flow and the Cycling of Matter

Lesson Summary

In this lesson you explored the following essential questions:

What processes do producers use to harness energy?
How is energy distributed through the biosphere?

In this lesson you learned that approximately 98% of all producers use photosynthesis to capture and store solar energy. You also learned that the other 2% of producers that use chemosynthesis live in extreme conditions, such as the ocean floor, and do not have access to solar energy. Part of understanding photosynthesis is to explore factors that can get in the way of it running smoothly.

Since the vast majority of photoautotrophs capture and store solar energy, it is safe to say that solar energy maintains life in the biosphere. It is necessary for the right conditions to be present so that this vital process of capturing and storing energy can continue. You also looked at how solar energy is distributed outside of photosynthesis. Like everything in biology, there is a need for homeostasis—balance, equilibrium, and maintaining a steady state. If any part of the big picture were to go missing, there would be a big problem. Where would people be if suddenly there were no Sun or no producers?

Lesson 2 will look at how people and other organisms survive because of the continuous flow of energy.

Lesson Glossary

biosphere: all areas on Earth that can sustain life and are inhabited by organisms (air, water, land)

chemosynthesis: the process by which certain fungi and bacteria use the energy from chemical nutrients to chemically convert carbon (inorganic) into carbohydrates (organic)

consumers: organisms that must obtain their food (energy) by eating other organisms (producers or consumers); also called heterotrophs

equilibrium: all living components of the biosphere (e.g., humans, bacteria, plants) balance in a system; the overall fluctuations in the system balance out and there is no net change over time

first law of thermodynamics: energy in a system cannot be created nor destroyed; it changes forms

limiting factor: any biotic or abiotic factor that controls or limits the functioning of an organism

photoautotrophs: photosynthetic producers

photosynthesis: the process by which plants, algae, and some kinds of bacteria use solar energy to chemically convert carbon (inorganic) into carbohydrates (organic) such as sugars and starches

producers: organisms that are able to produce their own food (energy) by harnessing chemical or solar energy; also called autotrophs

1.10. Lesson 2 Intro

Lesson 2

Module 1—Energy Flow and the Cycling of Matter

Lesson 2—Energy Flow Through Trophic Levels and the Cycling of Matter

Get Focused

This graphic shows a cartoon version of an aquatic food chain. A large fish with big teeth chases a medium-sized fish which, in turn, appears ready to eat a small fish.

Do you ever get the feeling that you are outnumbered? There are more plants, four-legged animals, and insects than there are of you. You get the picture. If you want to be philosophical about your presence in your own backyard, you are just one in a sea of thousands. But why are you outnumbered? Think about the complexity of your diet and what you know about energy flow. Hypothesize where you fit in terms of energy flow in the biosphere.

In Lesson 1 you learned that producers can use photosynthesis or chemosynthesis to fuel their life processes. Producers are the initial energy supplier for you, the consumer. You also reviewed cellular respiration and determined how it is used to access energy.

Of all the energy that Earth receives, Lesson 2 will focus on the small fraction of the Sun’s energy that is transferred from one organism to another within an ecosystem. You will study the flow of energy between producers and the various types of consumers. You will also find out how much energy is actually available from one trophic level to another within a food chain.

trophic level: describes the feeding level through which matter and energy are transferred; indicates an organism’s position in the food chain (e.g., producer, primary consumer, secondary consumer)

food chain: a diagram or model that uses a straight line to show how food (energy) transfers from producers to primary consumers to higher trophic levels

food web: a diagram or model that shows the connections among food chains (food/energy transfer) in an ecosystem

Consider the following essential questions as you complete this lesson:

How can you model the transfer of energy and matter between organisms?
How can you use math to explain the differences in energy flow in various ecosystem food chains?

Module 1: Lesson 2 Assignments

Your teacher-marked Module 1: Lesson 2 Assignment requires you to submit a response to the following:

“Investigation 1.B: Weave Your Own Food Web”
Choose ONE of the two Try This Thought Labs
TR 4
Discussion (if this is the discussion piece you decided would be for assessment)

You can access your Module 1: Lesson 2 Assignment. You can print off the assignment or save the download to your computer. Your answers can be saved on this document to your course folder.

You must decide what to do with the questions that are not marked by your teacher.

Remember that these questions provide you with the practice and feedback that you need to successfully complete this course. You may decide to respond to all the questions and place those answers in your course folder.

1.11. Page 2

Lesson 2: Page 2

Module 1—Energy Flow and the Cycling of Matter

Explore

Read

Begin this lesson by reading page 16 of your textbook up to and including the left side of page 18. This information reviews what you have previously learned about feeding relationships in ecosystems. Organisms can be identified in many ways, such as through feeding relationships, and organisms can be organized into trophic levels. These levels also indicate the amount of energy available to organisms.

Self-Check

SC 1. Answer question 14 on page 16 of the textbook.

SC 2. Answer questions 15 and 16 on page 18 of the textbook.

Check your work.

Self-Check Answers

SC 1.

The first trophic level contains producers. The secondary trophic level contains primary consumers, while the third level is made up of secondary consumers. Tertiary consumers are in the fourth level, and the fifth trophic level is composed of quaternary consumers.

SC 2.

Less energy is transferred from one trophic level to the next trophic level because from 80 to 95 percent of chemical energy is transferred to waste products and to the environment as heat during cellular respiration. This is summarized as the “rule of 10,” which means that approximately 10 percent of the initial energy at one trophic level will transfer to the next, a different trophic level.
Food chains are limited in length because eventually the available transferable energy dwindles to nothing. An example is that 100 kJ energy −> 10 kJ energy −> 1 kJ energy −> 0.1 kJ energy, and so on.

Read

Continue reading from pages 18 to 24 in your textbook. Be sure to take note of the many different diagrams. These diagrams are a visual way of organizing and presenting the transfer of energy from one trophic level to another trophic level by showing biomass, the available energy, or the numbers of organisms. After these readings you will be asked to compare and contrast these diagrams and to use math to show energy flow through trophic levels.

Self-Check

Feeding Relationships

SC 3. How would you label this diagram? Scroll over each picture to see if you chose the correct terminology.

Virtual Ecosystem

SC 4. If you understand food chains, trophic levels, and the classification of producers and consumers, then you can skip this activity. If you are having difficulty, you should check this virtual laboratory.

Carefully read the questions and the procedure for the laboratory.

SC 5. Answer question 18 from page 24 of the textbook.

Check your work.

Self-Check Answers

SC 5.

An energy pyramid cannot be inverted. An energy pyramid shows the reduction in energy amounts at each trophic level rather than numbers of organisms or biomass. Energy is interpreted the same way by scientists, whereas biomass is not. There are no exceptions as to how energy is interpreted. Energy will ALWAYS be less as you move up through the trophic levels

Try This

TR 1. In this activity you will construct, test, and compare two food chains. The first will be a northern food chain and the other will be a forest food chain. To access this activity you will need to do a web search. In your Internet search engine, type in the keyword “ecokids.” Choose the “.ca” website. Using the Ecokids website search bar, type in the keywords “chain reaction.” Choose the first activity that appears in your search, or access “Chain Reaction—Build a Food Chain.”

To support this comparison, access this interactive activity. While it provides a simple explanation of food chains, it does model the effect of losing trophic levels in a food chain. This is valuable in identifying the differences between the arctic and the forest food chains.

Record your answer and save it to your course folder.

1.12. Page 3

Lesson 2: Page 3

Module 1—Energy Flow and the Cycling of Matter

Thought Lab 1.1: Analyzing Energy Transfers

Assignment

TR 2. Complete Analysis questions 2, 3, and 4 on page 20 of the textbook. Save them in your course folder. You will be choosing one of the “Thought Labs” to hand in to your instructor as part of your Lesson 2 Assignment.

This is a photo of a field of wheat at sunset. Superimposed in the right corner is a chicken. In the left corner is a superimposed dinner plate, along with a set of hands clutching a fork in the left hand and a knife in the right.

wheat field: © hougaard malan/iStockphoto

dinner plate: © Marc Dietrich/iStockphoto

rooster: © emmanuelle bonzami/iStockphoto

Thought Lab 1.2: Energy Fluctuation in an Ecosystem

Assignment

TR 3. Complete Analysis questions 1 to 4 on page 25 of your textbook. There is space available for you to write your answers for this activity in your Module 1: Lesson 2 Assignment. Be sure to save your responses to your course folder.

This is a photo of a seal on an ice floe.

1.13. Page 4

Lesson 2: Page 4

Module 1—Energy Flow and the Cycling of Matter

Read

As a summary of Chapter 1 of your textbook, read page 29 from the book.

Try This

TR 4. Answer question 10 on page 27 of your textbook. Be sure to answer all parts of the question, and clearly show your calculations. Be sure to use significant digits when possible. Check the following box to see metric conversions.

Metric conversions.

TR 4.

1000 g = 1 kg
1 t = 1000 kg
1000 J = 1 kJ

Reflect and Connect

This is a photo of a cow.

Remember the diagram from Lesson 1 that you completed and stored in your course folder? Now that you know more about energy flow through trophic levels, how could you modify the diagram? Complete your additions and save the diagram to your course folder. The diagram will be revisited. This should help you with the following assignment (Investigation 1.B).

Complete the following investigation. Save it to your course folder.

Lesson 2: Assignment

Refer to Lesson 2: Assignment and complete Investigation 1.B.

Investigation 1.B: Weave Your Own Food Web

Complete “Investigation 1.B” on pages 22 and 23 of your textbook. Post your Investigation answers to the discussion area. See below to get a tutorial on how to perform the calculations.

Self-Check

SC 6. Answer questions 7 and 8 on page 27 of the textbook.

SC 7. Answer questions 1, 5, 9, 12, 16, and 19 on pages 30 and 31.

Check your work.

Self-Check Answers

SC 6.

7. The unit area in a measure of biomass provides a basis of comparison and can be considered a controlled variable. Without including the unit area, comparisons of dry weight would be meaningless.

8. a) less producers = less energy for higher trophic levels (limits food supplies) = less organisms at each trophic level

b) more secondary consumers = less primary consumers = more producers → there would be more energy available for primary consumers

SC 7.

1. Decomposers feed on once living or organic matter to survive; they are not creating their own energy.

5. The spring melt is starting earlier, the sea ice is thin, and the weather is unusual. These observations coincide with scientific data.

9. a) Species have varied diets. For example, people eat vegetables (primary consumer) but also eat fish (tertiary consumer).

b) When an organism is not dependent on only one food source, the chances of it surviving a year where that food source was scarce is increased. When organisms can ensure survival through hardship (fluctuations in energy flow), an ecosystem has greater stability (greater biodiversity = greater stability).

12. Seasons (winter—snow covered and leaves are gone), drought, and the amount and intensity of sunlight can limit growth.

16. The relative number of producers that can support consumers is greater in a grassland due to the size of the producer; an aspen tree can support many primary consumers due to its size.

19. a) producer to primary consumer—rule of 10—1 kg X 10 = 10 kg of strawberries would have to be eaten for you to gain 1 kg of mass.

b) producer to primary consumer to secondary consumer to tertiary consumer—rule of 10—1 kg x 10 x 10 x 10 = 1000 kg of plant material would be consumed through this food chain so that you could gain 1 kg of mass.

Discuss

Assignment

Use information from the activity in Reflect and Connect, and from any other activity that you completed, to respond to the following question: Should vegetarianism be encouraged in Canada? Identify the benefits/risks of the Canadian population adopting total vegetarianism.

These discussions are a place where you can share ideas and opinions, so put some thought into your posting! Respond to at least one other classmate's posting.

Discussion Guide

Expectations	Excellent (3)	Fair (2)	Poor (1)	Incomplete (0)
Completeness (X6)	The student clearly states a position and provides relevant support (facts, figures, uses specific vocabulary in context).	The student states a position and provides support (facts, figures, uses specific vocabulary).	The student does not take a position. The information has some validity but lacks focus.	The student did not answer the question.
Insight	The student demonstrates an excellent understanding of the question. The student has done research for the “Extension” question and states sources.	The student demonstrates a good understanding of the question, but seems a bit confused with some of the answers. The student has done some research for the “Extension” question, but does not state sources.	The student gives confusing answers and does not seem to understand.	The student did not complete the investigation.
Total	21 marks

Expectations

Excellent

(3)

Fair

(2)

Poor

(1)

Incomplete

(0)

Completeness (X6)

The student clearly states a position and provides relevant support (facts, figures, uses specific vocabulary in context).

The student states a position and provides support (facts, figures, uses specific vocabulary).

The student does not take a position. The information has some validity but lacks focus.

The student did not answer the question.

Insight

The student demonstrates an excellent understanding of the question.

The student has done research for the “Extension” question and states sources.

The student demonstrates a good understanding of the question, but seems a bit confused with some of the answers.

The student has done some research for the “Extension” question, but does not state sources.

The student gives confusing answers and does not seem to understand.

The student did not complete the investigation.

Total

21 marks

Reflect on the Big Picture

What is energy? For most organisms, it comes from what they eat. As you stand outside, possibly in your backyard, you should have a better appreciation for the importance of plants. You should also have an understanding of why people are outnumbered, and you should possess the ability to compare the transfer of energy in your ecosystem with that of an aquatic or extreme (deep sea or arctic) ecosystem. You have now mastered how energy flows and are now heading to the realm of cycling matter.

Module 1: Lesson 2 Assignment

Remember to submit the Assignment answers to your teacher as part of your Module 1: Lesson 2 Assignment.

1.14. Page 5

Lesson 2: Page 5

Module 1—Energy Flow and the Cycling of Matter

Lesson Summary

In this lesson you explored the following essential questions:

How can you model the transfer of energy and matter between organisms?
How can you use math to explain the differences in energy flow in different ecosystem food chains?

conservationist: someone who advocates saving and/or conserving natural resources

During this lesson you should have learned that energy transfer through food chains is very inefficient. You may have considered becoming a vegetarian if you are a conservationist. And you should be able to model and calculate energy transfer in a variety of ways. If you don’t think that you have this mastered, you should talk to your teacher.

You also looked at a variety of different ecosystems and the biodiversity within these systems. Remember that stable ecosystems have a greater biodiversity than unstable ecosystems. Stable ecosystems, such as a tropical rainforest, are less affected by changes at any given trophic level or changes to the environment.

This is because organisms at higher trophic levels have a more varied diet and can feed on a variety of food sources, as opposed to an unstable ecosystem, such as the Arctic, where organisms at higher trophic levels have a very specific food source. In an ecosystem like the Arctic, slight changes to global temperature may more easily affect organisms at the lower trophic levels of a food chain.

As you move to Lesson 3, you will begin to explore the importance of water in cycling matter.

Lesson Glossary

conservationist: someone who advocates saving and/ or conserving natural resources

food chain: a diagram or model that uses a straight line to show how food (energy) transfers from producers to primary consumers to higher trophic levels

food web: a diagram or model that shows the connections among food chains (food/energy transfer) in an ecosystem

1.15. Lesson 3 Intro

Lesson 3

Module 1—Energy Flow and the Cycling of Matter

Lesson 3—Two Hydrogens and an Oxygen: One Small Molecule, One BIG Role

Get Focused

So you’ve looked out your back door and contemplated the role of producers and consumers in making sure energy continuously flows and supports life on Earth. But what about how stuff like matter gets around? And what “matter” really matters? Biologists tend to favour the elements of carbon, oxygen, nitrogen, and phosphorus because THESE are essential building blocks for all life on Earth. But these chemicals don’t have legs to get from one place to another. Like people can use waterways to move themselves around, molecules interact with water to cycle themselves from point A to point B and back to point A.

You know that water is important to sustain life processes—living things die without it. But to better understand what role water plays in your back yard, you need to determine what properties of water are important when it comes to cycling the matter that matters.

Consider the following question as you complete this lesson:

What chemical and physical properties of water make water an important part of biogeochemical cycles?

Module 1: Lesson 3 Assignments

Your teacher-marked Module 1: Lesson 3 Assignment requires you to submit a response to the following:

Lesson 3 Lab: Assessing Water Quality
Lesson 3 Lab: Societal Uses of Water

You must decide what to do with the questions that are not marked by the teacher.

Remember that these questions provide you with the practice and feedback that you need to successfully complete this course. You should respond to all the questions and place those answers in your course folder.

1.16. Page 2

Lesson 3: Page 2

Module 1—Energy Flow and the Cycling of Matter

This is a black and white artistic poster about water.

Explore

Read

Begin your introduction to this lesson by reading pages 34 to 36 of your textbook. Water has many unique properties that make it an important part of cycling matter. This part of the textbook revisits what you have learned about water in Science 10, such as heat capacity, adhesion, cohesion, and the ability to dissolve many substances. Water, through the hydrologic cycle, cycles substances important to biosphere equilibrium.

Self-Check

SC 1. Do you know your water cycle? Do a review by looking at the diagram in the "Check your work" box. See if you know how to correctly label the hydrologic cycle.

SC 2. Why is water considered to be the “universal solvent”? How is this useful?

Check your work.

Self-Check Answers

SC 1.

SC 2. Because water is a polar molecule, the positively charged hydrogen atoms easily form bonds with negatively charged ionic molecules. The negatively charged oxygen atom will also form an ionic bond with positively charged ionic molecules. Therefore, water will dissolve almost any ionic compound. Since it dissolves so many compounds, water then has the ability to transport ionic compounds where they are needed. For example, phosphorus in the soil dissolves in water in order to get to the roots of plants

Read

Continue reading from pages 36 to 37 in your textbook. Start reading at “Hydrogen Bonding Affects Water in Different Phases.”

Self-Check

SC 3. Look at this photo.

This is a photo of water beading on a leaf.

What property of water causes water to bead on surfaces? Explain.

SC 4. Answer question 2 on page 37 of the textbook.

SC 5. Why does ice float? Why is this important?

Check your work.

Self-Check Answers

SC 3. Hydrogen bonding or cohesion, which is the attraction of water molecules to each other (polarity), causes surface tension.

SC 4.

Water has a 100°C temperature range before it will change state (ice or vapor). Therefore, water has the ability to transport nutrients in varying conditions (e.g., Arctic versus tropical conditions). Water must be liquid (aqueous) to dissolve substances.
Water changes density as it cools, which will cause it to sink and rise and cycle oxygen and nutrients. Water is most dense at 4°C.
Adhesion provides an upward force on water and counteracts the pull of gravity. Cohesion happens because water molecules are more attracted to themselves than other molecules (to a point), and as one molecule moves out of the plant (transpiration), another will take its place.

SC 5. Ice floats because it is less dense than water. If ice was denser, life in aquatic systems would die every winter if a body of water froze from the bottom up.

1.17. Page 3

Lesson 3: Page 3

Module 1—Energy Flow and the Cycling of Matter

Characteristics of Water

Water is a finite resource in the biosphere, and it can be found in three different states: liquid, solid, and gas. Since water is a finite resource, it must be cycled. There is a lot of water in the biosphere, and it is mostly (97%) found in liquid form. A molecule of water will undergo many phase changes in order to complete a full turn of the hydrologic cycle.

Dissolving substances allow water to carry nutrients to other parts of an ecosystem where they may be used as needed. Keep in mind that water does not discriminate between dissolvable matter! Polar wastes and toxic substances can also be dissolved and transported in water.

Benefits of Hydrogen Bonding

Properties of water that are influenced by hydrogen bonding between water molecules include cohesion, adhesion, and heat capacity.

cohesion: inter-molecular attraction between like-molecules of a substance

Water is strongly cohesive due to the polarity of its molecules.

adhesion: the tendency of unlike molecules to cling together because of attractive forces

Water is adhesive also due to polarity—the negative and positively charged molecules in water attract other ionic molecules.

heat capacity: the amount of heat energy (J) required to change the temperature of one gram of substance by 1°C

Water has a high heat capacity of 4.19 J/g°C.

Water Strider

The description of hydrogen bonding you just read, which describes the attraction between neighbouring water molecules, is often referred to as cohesion within water. The strength of cohesion between water molecules results in water’s high surface tension. As shown in the photograph, the cohesive forces between water molecules support the spider’s weight. Surface tension allows the surface of a body of water to become a habitat for many insects. This increases the biodiversity within aquatic ecosystems.

Adhesion is the attraction of water molecules to other substances. This allows water to be drawn upwards within plant tissues, against the force of gravity, from the roots to the leaves. Once water reaches the leaves, it becomes involved in the process of photosynthesis.

As you may recall from previous science courses, photosynthesis is the primary energy-producing process for ecosystems. Adhesion permits water to be drawn to the leaves of large plants, increasing the proportion of solar energy captured by producers. Capturing solar energy, in turn, greatly increases the energy available for consumers.

Finally, the attractive forces between water molecules have the ability to store thermal energy. Water’s high heat capacity allows large quantities of heat to be absorbed and slowly released back into the surroundings. Having a high heat capacity allows water to moderate the temperature within systems—this helps maintain a relatively constant body temperature or reduce large fluctuations in climate.

Watch and Listen

Water quality affects both producers and consumers within an ecosystem. As you have learned, water is a universal solvent. This makes water an excellent medium in which to carry particles within the biosphere. As mentioned earlier, water is not able to discriminate against particles as either good or bad. Human activities can influence what becomes dissolved in water, affecting water quality.

The Canadian Broadcasting Corporation (CBC) has posted archived audio and television clips from the 1950s to 2000 on its website that chronicle the ongoing effects of human activity to the water quality of the Great Lakes. To access this series of sound bites, search for "CBC" in your search engine. Once you are at the home CBC site, locate the search box in the top-right corner and enter the keyword search "Troubled Waters." The first link should take you to "Troubled Waters: Trouble in the Great Lakes." Pick several clips to view and listen to. What are your thoughts after listening to some of these clips?

The pollution of a lake might be understandable, but what about the quality of the water you drink? Water treatment involves altering the concentration of substances dissolved in water to meet national standards. In some areas of Canada, work is still required to ensure that people have safe drinking water. Return to the CBC home page and enter the keyword search term “slow boil.” Select the first URL. Read the introductory material describing water-quality issues confronting many people who live on First Nations reserves.

Once you have read through the introduction, choose the “Audio” clip about a reserve in Nova Scotia.

Try This

TR 1. Canada is a developed country. Is it surprising that some Canadians do not have access to a clean water source? Why do these people not have access to clean water? What should be done about this? Save your response to your course folder.

Read

Finish reading this section in the textbook from pages 38 to 40. Be sure to read through “Thought Lab 2.1: Water Gains and Losses” on page 38.

Self-Check

SC 6. What are the similarities between the water budget of a person and a kangaroo rat?

SC 7. Answer questions 4 and 5 on page 39 of the textbook.

Check your work.

Self-Check Answers

SC 6. In both organisms, water gained = water lost and the most water is lost through urine and evaporation.

SC 7.

Organisms gain water through eating, metabolism, and drinking.
Organisms lose water through urine, feces, and evaporation (breathing and sweating).

1.18. Lab 1

Lesson 3: Lab 1

Module 1—Energy Flow and the Cycling of Matter

Lesson 3 Lab: Assessing Water Quality

You have previously seen that water quality can seriously affect human health and the health of other organisms within an ecosystem. Water pollution caused by human activities can decrease the quality of fresh water.

Access the Virtual Lab Assessing Water Quality to explore how pollution can affect organisms in the biosphere. Make sure you read the information about acid rain and pH levels included with the lab.

Follow the instructions given in the simulation in order to complete the lab. Print the table located as a link in the bottom of the virtual lab, and record the changes you observe as you conduct the experiment. Once you have completed and repeated the experiment, you will generate a laboratory report by following the template in the Lesson 3 Assignment. Follow the instructions included in the template, save a copy in your course folder, and then submit a copy to your instructor for assessment. In your report, make sure you explain the role carbonic acid had in the experiment. Identify the process in the hydrologic cycle that could expose freshwater ecosystems to an acid.

1.19. Page 5

Lesson 3: Page 5

Module 1—Energy Flow and the Cycling of Matter

Try This

TR 2. In the virtual experiment you just completed, carbonic acid was used to simulate the effect of acid deposition originating from natural and human-made sources. Consider the many routes water can take while cycling through the hydrologic cycle. You will control the path of a drop of water as it travels through the hydrologic cycle, and you will learn about the interconnectedness of various ecosystems and global water use.

Go to this site.

Step 1:	Print the “Exploration Guide” included with the “Water Cycle Gizmo.”
Step 2:	Follow the procedure outlined in the “Exploration Guide.”
Step 3:	Answer the questions in the “Exploration Guide” as you complete the Gizmo.
Step 4:	When you get to question 2 in the section titled “Follow Your Own Water Cycle,” try to create the shortest possible cycle that passes through “Industry” and “Agriculture.” Also, try to create the longest cycle that passes through “Industry” and “Agriculture.” Export both cycles into a word-processing document, which you will keep in your online portfolio and later use in a discussion.
Step 5:	Write a journal entry for the following “Exploration Guide” questions: Due to greenhouse gas emissions, many scientists agree that Earth is gradually warming up. If global warming continues, what do you think will happen to the glaciers and icecaps of Earth? What consequences will this have for people and other living things? Consider your own household water usage. Besides drinking and cooking, in what other ways do you use water? Which activity do you think accounts for the greatest percentage of your own personal water usage? In what ways could you reduce your water usage if there was a water shortage? Feel free to discuss these questions with family members and friends before completing your journal entry. Save your work in your online portfolio.
Step 6:	In the discussion area, post the shortest and longest water cycle you were able to create. Compare these cycles with your classmates’ cycles. Are they similar? Did anyone create a water cycle that surprised you?

Now, post your reflection about your own household water usage. Compare it with your classmates’ answers. Does everyone have the same type of water usage? Is there anyone in your class whose family is practising water conservation? Keep a copy of this reflection in your course folder.

Reflect and Connect

ecological footprint: an analysis of human consumption of natural resources compared to the ability of Earth to recreate them

This analysis gives an estimate of the area (hectares) required for humans to live based on their given lifestyles—most North American lifestyles are not currently sustainable according to the analyses.

You now have a good understanding of the many paths that a water molecule can take through the hydrologic cycle. In this investigation you will have the opportunity to work in a group of two to four people with the goal to analyze Alberta’s societal use of water. Why? Because knowing your own community’s ecological footprint in relation to water use will help you determine how large an impact Alberta is having on global warming in comparison to the rest of the global community.

1.20. Lab 2

Lesson 3: Lab 2

Module 1—Energy Flow and the Cycling of Matter

Lesson 3 Lab: Societal Uses of Water

This investigation will allow you to look at water usage in Alberta. How much water do you use? What is the primary way you use water? To complete this investigation you need to access your Module 1: Lesson 3 Assignment. You will be creating a presentation for this assignment.

Your instructor will use the following rubric to evaluate your presentation.

Self-Check

SC 8. Answer review question 6 on page 40 of the textbook.

Check your work.

Self-Check Answers

SC 8.

Water is important to life because it dissolves and transports materials, stores heat that moderates the climate, and is required in metabolic processes.

Going Beyond

Read the following CBC article about Arctic clouds. Then, in the discussion area, explain why you think these clouds might be warming up the Arctic instead of cooling down the region. Try to incorporate into your explanation what you learned about water in this lesson as well as what you know about the albedo effect. Read at least two other explanations.

To find this CBC article, once again go to the CBC website. Type in the keywords “tech clouds.” Choose the article titled “Arctic clouds could reveal clues about global warming.”

In developing your answer, you may want to consult the following information:

Specific Heat Capacity of Ice and Water

Substance	Specific Heat Capacity (J/g•°C or kJ/kg•°C )
ice , H2O(s)	2.01
water, H2O(l)	4.19

Substance

Specific Heat Capacity

(J/g•°C or kJ/kg•°C )

ice , H2O(s)

2.01

water, H2O(l)

4.19

Module 1: Lesson 3 Assignment

Remember to submit the Assignment answers to your teacher as part of your Module 1: Lesson 3 Assignment.

1.21. Page 7

Lesson 3: Page 7

Module 1—Energy Flow and the Cycling of Matter

Lesson Summary

You explored the following essential question in this lesson:

What chemical and physical properties of water make water an important part of biogeochemical cycles?

As you explored this question, you learned about the hydrologic cycle and about water’s primary role as a solvent for many substances. As you will see in Lesson 4, the abundance and quality of water influences other biogeochemical cycles to allow for the transport of substances within the biosphere. You also learned that water is a polar molecule and that its polarity enables water molecules to form hydrogen bonds. Hydrogen bonds contribute to water’s high surface tension and its high heat capacity.

Finally, you determined that the use, or overuse, of water by society may eventually have a negative impact on the hydrologic cycle and the biosphere as a whole. You learned that approximately 70% of Earth’s surface is covered by water. Since a finite amount of water exists on Earth, the hydrologic cycle is necessary and cannot be jeopardized by human activities. Keep the hydrologic cycle in mind as you study other biogeochemical cycles in the next lessons. Get a better grasp of the magnitude of the role of water in keeping you and your backyard alive.

Lesson Glossary

adhesion: the tendency of unlike molecules to cling together because of attractive forces

Water is adhesive also due to polarity—the negative and positively charged molecules in water attract other ionic molecules.

cohesion: inter-molecular attraction between like-molecules of a substance

Water is strongly cohesive due to the polarity of its molecules.

ecological footprint: an analysis of human consumption of natural resources compared to the ability of Earth to recreate them

heat capacity: the amount of heat energy (J) required to change the temperature of one gram of substance by 1°C

Water has a high heat capacity of 4.19 J/g °C.

1.22. Lesson 4 Intro

Lesson 4

Module 1—Energy Flow and the Cycling of Matter

Lesson 4—Cycling of Matter

Get Focused

A photograph shows a recycle sign.

Imagine you are outside and this thought suddenly occurs to you: “What if all the nitrogen in the biosphere were used up?”

Actually, that thought probably wouldn’t suddenly jump into your head on the average day. But if it did you might have thought of it because, like all matter on Earth, the supply of nitrogen is finite. If nitrogen runs out, people are out of luck (nitrogen = proteins = people are made of proteins). Earth has compensated for this detail by its complex and simple processes for cycling matter.

So you have the simple answer for the question, “Why is the cycling of matter within the biosphere important to life on Earth?” Life couldn’t exist without it.

In Lesson 4 you will examine the cycling or recycling processes of carbon, oxygen, nitrogen, and phosphorus. You will also be able to give a more complex answer about how this cycling occurs and further explore the role of cycling in maintaining equilibrium in the biosphere.

Consider the following essential question as you complete this lesson:

How do carbon, oxygen, nitrogen, and phosphorus cycle through the biosphere?

Module 1: Lesson 4 Assignments

Your teacher-marked Module 1: Lesson 4 Assignment requires you to submit a response to the following:

Try This: TR 1 and TR 2
Lesson 4 Lab: Interdependence of Plants and Animals

You can access your Module 1: Lesson 4 Assignment. You can print off the assignment or save the download to your computer. Your answers can be saved on this document to your course folder.

You must decide what to do with the questions that are not marked by the teacher.

Remember that these questions provide you with the practice and feedback that you need to successfully complete this course. You should respond to all the questions and place these answers in your course folder.

1.23. Page 2

Lesson 4: Page 2

Module 1—Energy Flow and the Cycling of Matter

Explore

Read

How are primary producers connected to heterotrophs? Both are involved in providing necessary nutrients for each other. They both contribute to biogeochemical cycles. Reading page 42 of the textbook and page 43 up to “The Carbon and Oxygen Cycles” will introduce you to biogeochemical cycles and new vocabulary.

A photograph shows a person holding a green plant.

Self-Check

SC 1. Answer question 7 on page 43 of your textbook.

SC 2. What biotic and abiotic components are directly available as nutrients?

SC 3. What biotic and abiotic components are indirectly available as nutrients?

Check your work.

Self-Check Answers

SC 1.

Nutrients from slow cycling will eventually become a part of rapid cycling processes.

SC 2. Biotic components directly available as nutrients are living or recently living organisms. Atmosphere, soil, and water are abiotic components directly available as nutrients.

SC 3. Fossil fuels (fossilization) are biotic components, which are indirectly available as nutrients. Abiotic components indirectly available as nutrients are minerals in rock.

Read

Continue reading page 43 in the textbook, page 44 to the investigation, and page 46. Your textbook will introduce the carbon and oxygen cycles. On page 44 of the textbook, there is a "Web Link" with some wording and a link to an animation that will reinforce what has been presented in the textbook and highlight vocabulary. You may choose to watch the video first, or maybe you prefer to read something first and then watch a video. Try doing it one way, and then reverse the order. Decide which method is most helpful to you, and continue through the lesson.

The Recycling of Other Elements and Compounds

biogeochemical cycle: a diagram representing the movement of elements and compounds between living and non-living components of an ecosystem

In Lesson 3 you looked at how water is recycled through the biosphere. The idea of recycling also applies to other elements and compounds. The atoms of carbon, nitrogen, oxygen, phosphorus, and other elements that make up the bodies of living organisms are the same atoms present when life began on Earth. These materials must also be recycled. The processes involved in recycling the essential elements and compounds are referred to as biogeochemical cycles.

Although the word biogeochemical appears long, it is actually made up of three familiar parts—bio refers to life, geo refers to Earth, and chemical refers to elements and compounds. These cycles refer to the exchange between Earth and ecosystems of the elements essential to life.

This table gives a brief overview of the chemicals that you will be studying. The table also relates what these chemicals are used for in living organisms.

Element	Used in the production of . . .
carbon	carbohydrates, fats, proteins, hormones, vitamins
oxygen	carbohydrates, fats, proteins, hormones, vitamins, required for cellular respiration
nitrogen	proteins, nucleic acid (e.g., deoxyribonucleic acid (DNA))
phosphorus	cell membrane structural components, cellular energy molecules (e.g., adenosine triphosphate (ATP))

1.24. Page 3

Lesson 4: Page 3

Module 1—Energy Flow and the Cycling of Matter

The Carbon Cycle

All life on Earth is based on molecules containing carbon. Atoms of carbon form the framework for proteins, carbohydrates, fats, and other molecules important to biological systems. The carbon cycle begins with producers taking in carbon dioxide from the atmosphere. During photosynthesis, energy from the Sun is used by producers to convert carbon dioxide gas into energy-rich molecules of glucose to be used by living organisms as a source of food and energy. The simplified overall equation for photosynthesis is

Energy + 6 CO2(g) + 6 H2O(g) → C6H12O6(aq) + 6 O2(g)

Living organisms return carbon dioxide to the atmosphere by cellular respiration. The simplified overall equation for cellular respiration is

C6H12O6(aq) + 6 O2(g) → 6 CO2(g) + 6 H2O(l) + Energy

The movement of carbon through the carbon cycle is highly affected by carbon being stored in a variety of reservoirs, including fossil fuels, animal fossils, and the vast reserves of calcium carbonate in the world’s oceans.

carbon sink: a system that removes more carbon dioxide from the atmosphere than it releases into the atmosphere

peat: deep layers of mosses and plant remains unable to completely decompose due to the lack of oxygen in water-saturated soil

Reservoirs of carbon are called carbon sinks. Boreal forest ecosystems are now recognized as significant carbon sinks not only due to the trees that live there, but also because of the accumulation of peat in these wetland ecosystems. Peat bogs in Alberta are called muskeg. Recent studies of peat bogs in Siberia have revealed that some of these bogs have been around since the last ice age, which makes them at least 10 000 years old.

These studies have also determined that peat bogs absorb huge amounts of carbon—this makes them among the world’s top carbon sinks. Unfortunately, if peat bogs are drained and decomposition is allowed to occur, the carbon stored there is released as carbon dioxide. These ecosystems then become a source of carbon instead of a sink.

Click to view full-size image.

Watch and Listen

Follow the movement of carbon as carbon dioxide or carbohydrate molecules through various possible pathways in the biosphere.

Bio-DiTRL http://bio-ditrl.sunsite.ualberta.ca/

1.25. Page 4

Lesson 4: Page 4

Module 1—Energy Flow and the Cycling of Matter

The Oxygen Cycle

Each breath you take involves the essential process of extracting oxygen from the atmosphere. Most living things cannot survive without a source of oxygen. Even aquatic organisms take in dissolved oxygen from the water. Why is oxygen so essential? Oxygen reacts so intensely with other elements in chemical reactions that significant amounts of energy are released. Organisms can then use the energy released in these oxidation reactions.

Given the reactive nature of oxygen, it is natural to wonder why there is any oxygen left in the atmosphere. After all, if oxygen combines so readily with elements like iron to form oxidized mineral sediments, why hasn’t the oxygen all been used up? The answer is photosynthesis.

According to the fossil record, billions of years of photosynthesis by cyanobacteria living in warm, shallow seas created Earth’s current oxygen-rich atmosphere. Modern plants maintain this atmosphere by adding to the reserve of atmospheric oxygen. This atmosphere is balanced by cellular respiration where energy is released from the combustion of food molecules in the presence of oxygen gas.

Click to view full-size image.

Connections to the Carbon Cycle

The oxygen cycle has much in common with the carbon cycle—the sinks for carbon are the sources for oxygen, and vice versa. In both cases, the main processes responsible for cycling through ecosystems are photosynthesis and cellular respiration.

Despite these similarities, there are some important differences. Carbon dioxide comprises only about 0.03% of the atmosphere, whereas oxygen accounts for 21%. This means that the dynamic between carbon and oxygen is only a small part of the total oxygen system.

The total oxygen system also involves the cycling of other nutrients, such as sulfur, phosphorus, and nitrogen. To simplify matters, only the connection to carbon is shown in “The Oxygen Cycle” illustration.

When you study the nitrogen cycle, you will see another example of a process that connects to the total oxygen system.

Try This

TR 1. Sketch a unified diagram that identifies processes common to both the carbon cycle and the oxygen cycle. Identify the key forms in which carbon and oxygen will occur within both the oxygen cycle and the carbon cycle.

Self-Check

SC 4. Answer question 10 on page 46 of your textbook.

Check your work.

Self-Check Answers

SC 4.

10.

Deforestation reduces the amount of photosynthesis → less CO2 is removed from the atmosphere by plants, which reduces the amount of carbon and oxygen cycled through the biosphere. Deforestation also reduces the amount of energy available to primary consumers. Debris or leftover biomass will decompose, and carbon dioxide will be released to the atmosphere.
Burning fossil fuels releases carbon from slow cycling and quickly increases the amount of carbon in the atmosphere (relatively speaking).
Agriculture creates crops—photosynthesis takes in CO2 and provides energy (glucose) to consumers. However, agriculture often relies on deforestation for land, which will increase carbon dioxide as overall photosynthesis decreases (trees remove more carbon dioxide from the air than crops)

Read

acid deposition: the deposit of acid to land and water through acidic rain, snow, or sleet

Although the sulfur cycle is not one of the elements that you are required to explain, sulfur is still an important cycled element. Read about this element on page 46 of the textbook, starting at “The Sulfur Cycle.” Also read page 47 of the textbook and page 48 up to “The Nitrogen Cycle.” Acid deposition is a term in this reading that you should know.

Self-Check

SC 5. Answer question 11 on page 48 of the textbook.

SC 6. Answer question 12 on page 48 of the textbook.

SC 7. Is acid deposition limited to sulfur compounds? Why?

Check your work.

Self-Check Answers

SC 5.

Acid deposition is natural and returns sulfur to the soil and the ocean but too much deposition can damage plants and lakes. Nutrients may also be leached from the soil

SC 6.

Bacteria convert sulfur compounds and add the sulfur back to the soil.

SC 7. No, water molecules can combine with nitrogen, phosphate, and carbon molecules to create acidic solutions.

1.26. Lab

Lesson 4: Lab

Module 1—Energy Flow and the Cycling of Matter

Lesson 4 Lab: Interdependence of Plants and Animals

The sections of this lab that are to be submitted for assessment are indicated in your Module 1: Lesson 4 Assignment. Please place the answers to “Interdependence of Plants and Animals” on this document. Be sure to save the Assignment to your course folder.

Assignment

In previous science courses you learned about the important role undertaken by producers within ecosystems. They produce the oxygen you breathe and are the main source of energy for organisms. The combination of photosynthesis and cellular respiration demonstrates the linking, or interconnectedness, of biogeochemical cycles that act to maintain a balance, or equilibrium, with respect to the composition of gases found in the atmosphere.

To access this lab, go to this site:

Log on to the website. Talk to your teacher if you require a password.

Start the lab that comes up. You may work with a partner or you may ask classmates, using the discussion area, to help you with some of the questions.
Print the “Exploration Guide,” and follow the instructions.
Complete the lab in the “Exploration Guide.”
Answer the three questions in the “Exploration Guide.” There is space in your Module 1: Lesson 4 Assignment to copy and paste the guide questions and record your answers. You will be prompted to experiment with combinations of snails and plants until you are satisfied that you have observed the optimum ratio of snails to plants based on what you believe shows a stable mini-ecosystem.
Complete the self-checking “Assessment Questions” and check your answers. You should note which questions you had difficulty with. Print off or save a screen capture of these questions to your computer. You may be able to use these questions for a review.

1.27. Page 6

Lesson 4: Page 6

Module 1—Energy Flow and the Cycling of Matter

The Nitrogen Cycle

Nitrogen is critically important to life because it is a key component in biologically important molecules, such as protein and DNA. Since the atmosphere is composed of 78% nitrogen, it is reasonable to wonder why you can’t get your nitrogen from breathing. After all, more than three-quarters of every breath is nitrogen!

nitrogen fixation: the process of converting nitrogen gas into ammonia

nitrifying bacteria: a type of soil bacteria that converts ammonia into nitrates and nitrites

nitrification: the process of converting ammonia into nitrates or nitrites

denitrifying bacteria: a type of soil bacteria that converts nitrates in soil into nitrogen gas, releasing this gas to the atmosphere

denitrification: the process of converting nitrates in the soil into nitrogen gas

The trouble with this idea is that nitrogen gas, N2, is non-reactive; it takes a lot of energy to break up N2 molecules so single nitrogen atoms can be combined with other elements to form proteins. Plants and other producers have the same problem—they can’t use atmospheric nitrogen either. The plants rely upon bacteria to convert nitrogen gas, N2, into forms they can use.

These other forms of nitrogen include ammonia (NH3), nitrate ions (NO3-), and nitrite ions (NO2-). These nitrogen-containing substances are found in the waste products of many organisms and in dead and decaying organic matter.

Plants use nitrates or nitrites for their nutrients. For nitrogen gas to be used by plants, the gas has to be converted by certain types of bacteria into ammonia—this is done using a process known as nitrogen fixation.

The bacteria involved in nitrogen fixation are found in the soil and the nodules on the roots of plants called legumes. Other types of bacteria in the soil, known as nitrifying bacteria, convert ammonia into nitrates and nitrites by a process called nitrification.

Since all cycles have to be able to return to the starting point, another soil bacteria known as denitrifying bacteria converts nitrates into nitrogen gas. This process is known as denitrification. Other non-living processes—such as lightning—may convert nitrogen gas into nitrates.

Click to view full-size image.

Read

On this screen, there is text and video that will reinforce what you will be reading in the text. There is quite a bit of vocabulary associated with the nitrogen cycle such as denitrification, nitrogen fixation, and nitrification, so it may be advantageous to make definitions in your own words. You can also make drawings to show what each word means and where the word fits into the nitrogen cycle.

Self-Check

SC 8. How does the nitrogen cycle diagram, “Figure 2.16,” on page 49 of the textbook compare to the diagram titled “The Nitrogen Cycle.”

Check your work.

Self-Check Answers

SC 8. Both diagrams show the role of bacteria, plants, and decomposers in the process of cycling nitrogen. The diagram in the textbook shows a terrestrial and aquatic biotic community, outlines that nitrogen is added to water by runoff, and shows that human activities can add nitrates to the cycle. Decomposers are not shown in the biotic community, but they do exist there.

Watch and Listen

View the nitrogen cycle animation by choosing "4.163 Nitrogen Cycle" from the list.

Read

The phosphorus cycle is much less complex than the nitrogen cycle. What makes it less complex? In your textbook, read page 49, starting at “The Phosphorus Cycle.” Also read pages 50 and 52.

Self-Check

SC 9. Why do organisms need phosphorus?

SC 10. Describe the cycling of phosphorus.

eutrophication: excessive plant growth and decay caused by an excessive amount of chemical nutrients

SC 11. What happens to a water system when there is an increase in phosphorus?

SC 12. Why could this lead to eutrophication?

Check your work.

Self-Check Answers

SC 9. Organisms require phosphorus to make ATP, DNA, teeth, and bones. Phosphorus is also part of the cell membrane (i.e., phospholipid bilayer).

SC 10. Phosphorus is transported by water and doesn’t cycle through the atmosphere; phosphorus enters the soil through organisms by waste/decay (rapid cycling) and from the weathering of rock (slow cycling).

SC 11. An algal bloom can occur if there is too much phosphorus in a water system. An excess of nutrients encourages excessive plant growth, which leads to the eutrophication of lakes.

SC 12. Eutrophication would occur because excessive plant growth would block light to other photosynthetic plants, meaning less oxygen produced in the long term. Meanwhile, organisms flourish in the short term due to the increased plant growth but end up using up the available oxygen and contributing carbon dioxide. Also, decaying matter would increase, which would use up oxygen and increase carbon dioxide levels.

Try This

TR 2. Draw a unified diagram that illustrates how carbon, oxygen, nitrogen, and phosphorus cycle together through the biosphere.

Reflect and Connect

As you worked through Lesson 4, the Self-Check questions offered an opportunity to make predictions about what may happen when the biogeochemical cycles are altered in some way.

What would happen if you were missing one of the substances involved in biogeochemical cycles? Would you be able to enjoy your backyard or the outdoors in the same way as you always do? Hopefully, you are over any initial panic about the thought of running out of nitrogen, because you know that nitrogen cycles. Now you should be predicting what effect humans have on these cycles of carbon, oxygen, nitrogen, and phosphorus.

Reflect on the Big Picture

As seasons cycle, so do nutrients. How do you think seasons affect biogeochemical cycles? How are biogeochemical cycles part of the flow of energy? As you move through this module, focus on how balance and equilibrium are always present in every process that occurs in nature. You also need to think about how you and other people around you can have an effect on this balance.

Module 1: Lesson 4 Assignment

Remember to submit the Assignment answers to your teacher as part of your Module 1: Lesson 4 Assignment.

1.28. Page 7

Lesson 4: Page 7

Module 1—Energy Flow and the Cycling of Matter

Lesson Summary

You explored this essential question in this lesson:

How do carbon, oxygen, nitrogen, and phosphorus cycle through the biosphere?

Biogeochemical cycles are interactions between producers and consumers and between the abiotic and biotic components of an ecosystem. In effect, these cycles are like cereal because they provide essential nutrients! Since the nutrients (carbon, oxygen, nitrogen, and phosphorus) available in the biosphere are in limited supply, they must be cycled. Lesson 4 required you to be able to describe each cycle and make predictions about the consequence of alterations in each cycle—for example, deforestation can affect the carbon-oxygen cycles.