Ecosystem Interactions and Energy Unit
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Ecosystem Interactions and Energy
At the end of this unit, I will be progressing towards mastering the following NGSS
Standards:
Engineering Practices:
 Developing and using models
 Using mathematics and computational thinking
 Engaging in argument from evidence
Disciplinary Core Ideas:
 LS 2-1: Use mathematical and/or computational representations to support explanations of factors that
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affect carrying capacity of ecosystems at different scales.
LS 2-2: Use mathematical representations to support and revise explanations based on evidence about
factors affecting biodiversity and populations in ecosystems of different scales.
LS 2-4: Use mathematical representations to support claims for the cycling of matter and flow of energy
among organisms in an ecosystem.
LS 2-8: Evaluate the evidence for the role of group behavior on individual and species’ chances to survive
and reproduce.
Cross Cutting Concepts:
 Cause and effect: Empirical evidence is required to differentiate between cause and correlation and
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make claims about specific causes and effects.
Scale, proportion, and quantity: The significance of a phenomenon is dependent on the scale,
proportion, and quantity at which it occurs. Using the concept of orders of magnitude allows one to
understand how a model at one scale relates to a model at another scale.
Systems and system models: Models (e.g., physical, mathematical, computer models) can be used to
simulate systems and interactions—including energy, matter, and information flows—within and
between systems at different scales.
Energy and matter: Energy cannot be created or destroyed—it only moves between one place and
another place, between objects and/or fields, or between systems. Energy drives the cycling of matter
within and between systems.
Stability and change: Much of science deals with constructing explanations of how things change and
how they remain stable.
Roots, Prefixes and Suffixes I will understand are:
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a-, bio-, im-, em-, natal-, mortal-, gene-, different-, logis-, exponent-,
The terms I can clearly define are:
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biomass, trophic level, producer, consumer, abiotic, biotic
population, immigration, emigration, natality, mortality
logistical growth, exponential growth, carrying capacity (K)
density-dependent factors, density-independent factors, limiting factors, predator, prey
dispersion, clumped, uniform, random
innate behavior, evolution, natural selection, genetic variation, selective pressure, differential
reproduction, heredity
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The assignments I will have completed by the end of this unit are:
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Ecosystem Interactions and Energy PreReading
Acrostic Poem for the 6 Common
Elements of Life
Building Biology Words
Looking at Biomes to Study Systems and
Matter
Organic Building Blocks
Traveling Nitrogen Passport
Ecosystem Interactions and Energy Study
Guide
Parts of an Ecosystem Review
Population Ecology Notes
Estimating Population Size: Mark and
Recapture
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Population Ecology Reading
Oh Moose!
Examining Population Density and
Dispersion
Human Population Pyramids
Understanding Exponentials
The History of Human Population Growth
Exploring Growth Models – Viva Amoeba
Population Trends
Population Trends Storyboard
Population Trends Predator-Prey Model
Predator-Prey Relationships
Group Behavior Google Presentation
Common Core: Genes and Social Behavior
Study Guide
Ecosystem Interactions and Energy Pre-Reading
Ch. 2 (pg. 32-49) & Ch. 4 (pg.90-110) & Ch. 5 (pg. 116-135)
What are biotic and abiotic
factors? Define and give
examples of each.
Create a Venn diagram to
compare/contrast consumers
and producers. Include the
terms autotroph and
heterotroph. Provide
examples of each.
What role do detritivores and
decomposers have in an
ecosystem?
Explain how energy moves through food chains and where/how energy is lost.
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Define biomass. What happens to
the amount of biomass at each tropic
level?
Label the image below to show the following:
 Producers
 Primary consumers
 Secondary consumers
 Where is the most/least biomass found?
 Where is the largest/smallest population?
Define biogeochemical cycle.
Draw an example of how carbon
or nitrogen cycles through the
ecosystem.
Use terms Carbon and/or
Nitrogen fixation. In your
diagram, show how elements
cycle from abiotic to biotic forms.
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What is nitrogen fixation and
why is it necessary?
What are limiting factors and
how do they affect population
size? Provide examples in your
explanation.
What is the difference between
immigration and emigration?
What is carrying capacity? Give
examples of things that influence
an environment’s carrying
capacity.
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Label the lines below as representing exponential growth or logistic growth. Below each
graph, briefly explain how the population is changing over time and then predict what will
happen to the populations in the future.
Define biodiversity.
Why is biodiversity
important?
List and briefly
explain threats to
biodiversity.
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Using the graph below, explain how the total red fox population has changed over time.
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Acrostic Poem for the Six Common Elements of Life
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus
Sulfur
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C
H
O
N
P
S
Building Bio logy Words
My word part and
definition
Bio- =
My partner’s word part
and definition
-logy =
Our Word Parts
Combined
Translation
Biology
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What Makes Something Alive?
Introduction:
All living things, no matter how different they may be, share common characteristics.
Instructions:
Before we begin, let’s take a moment to explore what makes something alive. Why do we consider
plants to be living or biotic, but a set of keys to be abiotic or not alive? What characteristics do all
living things have in common?
In this activity, you will rotate around the room and examine objects in the jars. As you explore,
create some form of graphic or table to group/classify these objects as being biotic or abiotic in the
space below.
Be prepared to share your ideas with the class.
What are the survival needs of all living things? What characteristics to all living things share. Come
up with 5 characteristics or survival needs.
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What Makes Something Alive?
Now that the class brainstorm is complete, respond to the following prompt:
What makes something alive? In other words, what characteristics do all living things share, despite their
differences? Support your claim with concrete evidence and examples.
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Levels of Organization
Label the diagram below. After labeling, be sure to define levels, as you see fit.
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Ecosystem Interactions and Energy – Common Core Practice
Referring to the food web diagram on the next page:
a) Classify the producers and consumers as autotroph or heterotroph (label on the diagram).
b) What is the limitation to this model?
If matter and energy “cycles” through a system, what might be missing from this model? Add the
missing component to the diagram.
c) Highlight one food chain from the food web, starting from a producer and cycling back to the
producer.
d) Describe how matter cycles through your food chain. In your description, emphasize atoms and
molecules.
e) Describe how energy cycles through your food chain. In the discussion of energy, quantify how
much energy is available to move on to the higher trophic levels. In addition, quantify how much
energy leaves the trophic system and enters the surrounding environment.
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All Organisms Use Energy: Food Web
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Intentionally Left Blank for
additional brainstorming, diagrams, or notes
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Looking at Biomes to Study Systems and Matter
As we analyze the video on biomes and ecosystems, we will define systems. In the space below,
draw a conceptual representation of a system.
If an organism is a system, where is matter entering and leaving this system? Label the diagram
below. Emphasize nitrogen and carbon cycles. Use terms carbon fixation and nitrogen fixation in
labels.
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Looking at Biomes to Study Systems and Matter
Exactly, what is a
system? Try to define
it. What are other
examples of systems?
What are some abiotic
vs. biotic parts within
these systems? How do
they interact?
What happens to
matter within a
system? How does
matter move through
the abiotic and biotic
components?
How does matter build
mass?
Can matter within a
system be lost or
destroyed? (demo after
the video)
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Modeling Organic Compounds
Using the research on the opposite page, draw an organizational model that represents the four
organic compounds and the elements that make them up. Work with your group, use poster paper
to create your model. You have 15 minutes to complete this activity on your poster paper, so be
efficient with your time.
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Organic Building Blocks
1. Producers, or autotrophs, are found on the first trophic level of the food web. Using the sun as an
energy source, what type of “matter” do producers or autotrophs make? (Hint: think about
photosynthesis…)
2. Based on your response to the above question, what atoms make up this matter? (Use mobile
technology to help you.)
3. From carbohydrates like sugar (glucose as an example), matter can be converted to lipids (fats),
amino acids (to build protein), and nucleic acids (DNA).
a) What atoms are found in lipids, commonly known as fats?
b) What atoms are found in amino acids and proteins?
c) What atoms are found in nucleic acids?
4. Do all three elements (atoms) found in carbohydrates exist in lipids, proteins and nucleic acids?
5. In addition to these three basic elements found in carbohydrates, what additional atoms do you
need to build amino acids and proteins?
6. In addition to these three basic elements found in carbohydrates, what additional atoms do you
need to build a nucleic acid?
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Organic Building Blocks
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Organic Building Blocks
7. Examine the ecosystem on the opposite page. Consider the following questions as we discuss
this image as a class. We will be labeling the diagram, per your teacher’s instructions, during the
discussion.
a) What organisms do you see in this ecosystem? Are these biotic or abiotic?
b) What abiotic components do these organisms interact with in order for them to get the elements
necessary to support life? Give specific examples or the abiotic components and what elements
these components will contribute.
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At the end of your journey through the Nitrogen Cycle, complete the following:
1.
Write a paragraph about your trip through the nitrogen cycle. Include information about
(1) where you went, and (2) how you got to each destination.
2.
Do some research and look up the Nitrogen cycle. Create a similar diagram specifically
documenting your journey through the nitrogen cycle, based on this activity.
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Review: Parts of an Ecosystem
Use the following info-graphic to define organism, population, and community.
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Population Dispersion Patterns
Concept Cards: Density Independent Factors vs. Density Dependent Factors
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Population Ecology Notes
(Use your textbook, pages 92-104 to fill out your notes)
What is population
density?
Population density is:
Dispersion is the ______________ of spacing of a _______________ in an
What is dispersion? List
the three types.
area.
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_______________________
___________________ ________________ determines dispersion patterns.
Density independent factors do not depend on
What are density
independent factors?
________________________________________________
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Usually __________________
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Include ________________________ (ex. flood, drought, extreme
heat or cold, tornadoes, hurricanes)
What are density
dependent factors?
Density dependent factors depend on
________________________________________________
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Often __________ (ex. predation, disease, parasites,
competition)
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Define population growth
rate and its characteristics.
Population growth rate explains ______________________
________________________________________________
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Natality: __________ rate
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Mortality: __________ rate
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Emigration: number of individuals moving
___________________ a population
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Immigration: number of individuals moving
___________________ a population
Describe exponential
growth.
Exponential growth starts slow (called the _______________ phase)
Exponential growth is illustrated by a ___________________ curve.
It is also called ________________________ growth.
All populations grow exponentially until _________________
________________________________________________________________
__________________ become limited and population growth slows.
Describe logistic growth.
Logistic growth is illustrated by a ______________________ curve.
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Describe logistic growth,
continued
Logistic growth occurs when _______________________________________
__________________________________________at the carrying capacity. (K)
A population stops increasing when:
What is carrying capacity?
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births __________ deaths
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emigration _________ immigration
The ___________________________________________ that an environment
can support for the long term is the carrying capacity,
represented by the letter “K.”
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Estimating Population Size: Mark and Recapture
Introduction
One of the goals of population ecologists is to explain patterns of species distribution and
abundance. In today’s lab we will learn some methods for estimating population size and for
determining the distribution of organisms.
Measuring Abundance: Mark-Recapture
Mobile animals are usually simpler to define as individuals, but harder to count, because they
tend to move around, mix together, and hide from ecologists. Quadrats are not a good
approach with mobile animals because immigration and emigration in and out of the study
site make it hard to know what area the entire population occupies. For largemouth bass in
a farm pond, you could easily draw a line around a map of the population, but how would
you define the edges of a population of house sparrows in your community? Although house
sparrows tend to be more concentrated in towns and urban areas, they do not stop and turn
back at the city limit sign. For zoologists, a fuzzy definition of the space occupied by the
population often forces an arbitrary designation of the survey group, such as the
"population" of robins nesting on your campus in the spring. Knowing the number of animals
in a designated study area is interesting, but we must bear in mind that the ecological
population is defined in terms of interactions among organisms of the same species, and not
by the ecologist's convenience.
After defining the individual and establishing the limits of the population you wish to count,
your next task is to choose a counting method. Arctic and prairie habitats lend themselves to
accurate survey by aerial reconnaissance. This approach works poorly in forests, at night,
underwater, or in soil habitats. If animals can be collected or observed in a standard time or
collecting effort, you can get an idea of relative abundance, but not absolute numbers. For
example, the number of grasshoppers collected in 50 swings with an insect net through an
old field community produces
data that could be used to compare relative abundance in different fields, but would not tell
you how many grasshoppers were in the population.
For estimates of absolute numbers, mark-recapture methods can be very effective. The first
step is to capture and mark a sample of individuals. Marking methods depend on the species:
birds can be banded with a small aluminum ankle bracelet, snails can be marked with
waterproof paint on their shells, butterflies can have labels taped to their wings, large
mammals can be fitted with collars, fish fins can be notched, and amphibians can have
nontoxic dyes injected under the skin.
Marked animals are immediately released as close as possible to the collection site. After
giving the animals time to recover and to mix randomly with the whole population, the
ecologist goes out on a second collecting trip and gathers a second sample of the organisms.
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The size of the population can then be estimated from the number of marked individuals
recaptured on the second day.
The assumption behind mark-recapture methods is that the proportion of marked
individuals recaptured in the second sample represents the proportion of marked
individuals in the population as a whole. In algebraic terms,
R = M
S
N
M = Animals Marked and Released
N = Population Size
R = Animals Recaptured on the Second Day
S = Size of the Sample on the Second Day
Let’s consider an example. Let’s say you want to know how many box turtles are in a wooded
park. On the first day, you hunt through the woods and capture 24 turtles. You put a spot of
paint on the shell of the turtles found, and release them all the turtles back where you found
them. A week later, you return to the same area and capture 60 turtles. Of these 15 are
marked, and 45 are unmarked. Since you know how many were marked (M), sampled (S),
and re-captured (R), you can figure out the size of the whole population (N).
15 = 24
60 N
This can be rearranged algebraically to N= (24) (60)
15
N = 96 turtles
This method is called the Lincoln-Peterson Index of population size. In the rearranged
version of the general formula, notice that the smaller the number of recaptures, the larger
the estimate of population size. This makes good biological sense, because if the population
is very large, the marked animals you release into the wild will be mixing with a greater
number of unmarked animals, so you will recapture a lower percentage of them in your
second sample.
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Estimating Population Size: Mark and Recapture Lab
Objective: You will be expected to estimate the size of a sample population using the markrecapture technique. Be able to apply the technique to new population problems and
compare the mark and recapture technique to other methods of population estimating.
Opening Discussion: If you were in charge of a team given the responsibility to determine
the number of sunfish in Horseshoe Lake, discuss with your partner how would you
accomplish this task and describe in detail below. A bulleted list is okay.
Draw a model of what you discussed:
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Technique 1: Sampling
A technique called sampling is sometimes used to estimate population size. In this procedure,
the organisms in a few small areas are counted and projected to the entire area. For instance,
if a biologist counts 10 squirrels living in a 200 square foot area, she could predict that there
are 100 squirrels living in a 2000 square foot area.
1. A biologist collected 1 gallon of pond water and counted 50 paramecium. Based on the
sampling technique, how many paramecium could be found in the pond if the pond were
20,000 gallons.
2. What are some problems or limitations with this technique? What could affect its
accuracy?
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Technique 2 - Mark and Recapture
In this procedure, biologists use traps to capture the animals alive and mark them in some
way. The animals are returned unharmed to their environment. Over a long time period, the
animals from the population are continued to be trapped and data is taken on how many are
captured with tags. A mathematical formula is then used to estimate population size.
Procedure:
1. You will receive a bag that represents your population (beans, pennies, chips, beads)
2. Capture “animals” by removing them randomly from the bag. Record the number
that was originally captured.
3. Place a mark on them using tape.
4. Return the “animals” to the container.
5. With your eyes closed, select a handful of “animals” from the container. This is the
recapture step. Record the number of “animals” captured the 2nd time and the
number of animals that have a mark on the data table.
6. Return the “animals” to the bag and repeat. Do 10 recaptures.
7. When the ten recaptures are completed, enter the total number captured on the
data table.
8. Also enter the total number of recaptured that have a mark
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Data Table
Original Number Marked _________
Trial
Number
Number
Captured
Number
Recaptured
with mark
1
2
3
4
5
6
7
8
9
10
Average
Calculations
Set-up an equation that will help you determine the population size of your animals. (Hint:
use a technique involving ratios, and the variables M, N, R, and S. If you can’t remember what
the variables stood for, look back on the previous reading to help you.) Brainstorm on your
whiteboard with your lab group, and your teacher will check your ratios. Record your
equation below.
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1. What is the mean estimation of your population? Show your calculations below:
Estimated Population Size ___________
2. Count how many “animals” are really in your population.
Actual Population Size: ____________
3. Compare the actual size to the estimated size.
underestimate?
Did you overestimate or
4. Repeat the experiment, this time add another 10 data fields to the ten trials you
already have in order to have a larger sample size.
Trial
Number Number
Number Captured Recaptured
with mark
11
12
13
14
15
16
17
18
19
20
Average
(over 20 trials)
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5. Recalculate your estimated population size, using the formula. (Show calculations
below)
Estimated Population Size _____________
6. How does sample size affect the accuracy of the mark and recapture method?
7. What might be some limitations or problems with the mark and recapture method?
8. Choose one limitation and suggest how to solve this problem.
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Sample Calculations: Given the following data, estimate the size of a butterfly
population in Wilson Park.
1. A biologist originally marked 40 butterflies in Wilson Park. Over a month long
period butterfly traps caught 200 butterflies. Of those 200, 80 were found to have
tags. Based on this information, what is the estimated population size of the
butterflies in Wilson Park? (Show calculations)
2. In what situations would sampling work best for estimating population size, in what
situations would mark & recapture work best? You’ll probably have to think about
this one. Justify your claims.
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Population Ecology Reading
Directions: Read and mark the following text about population ecology. Number your
paragraphs. Circle “essential terms,” and highlight definitions, explanations,
phenomena, or processes.
A population is a group of organisms of the same species that live in a certain
area. Ecologists regularly monitor the number of organisms in many populations, but
why do they do this? Why do we care if the number of organisms in an area is growing
or shrinking?
Well, populations that are growing and shrinking can be indicators of potential
problems occurring in the organisms’ environment, and gives ecologists a “heads up”
if something is going wrong. But it is not enough to simply know if the number of
organisms in an area is going up or going down; ecologists need to know why the
number of organisms is fluctuating. So, one of the main questions ecologists ask
themselves is this: Why is a population’s size going up or going down?
There are many factors that can cause a population’s size to change. But first,
you must understand the basic reasons behind why a population grows or shrinks. Any
population, whether it be humans, chipmunks, the mold growing on bread, or the
bacteria living in your intestines, will grow if more organisms are being created, or born,
than are dying. If a population has more organisms dying than are being born, then the
population will shrink. The number of births in a population is called the birth rate (also
referred to as natality). The number of organisms that are dying in a population is
called the death rate (also referred to as mortality). Thus, if the birth rate is greater than
the death rate, a population will grow. If the death rate is greater than the birth rate,
then the population will decrease in size.
While populations would probably like to continue to grow in size, a population
of organisms cannot grow forever—its growth will be limited, or stopped, at some
point, and the death rate will be greater than the birth rate. A population’s growth is
limited by two general factors: density-independent factors and density-dependent
factors. Why are these factors named in such a complicated way? Well, actually, these
names aren’t as complicated as they seem; in fact, they can even help you remember
what each of the terms means.
To understand why scientists named these factors in the way they did, you must
first understand the concept of population density. A population’s density is NOT
whether or not the population will float or sink. Population density refers to how
many organisms there are in one particular spot. If a population’s density is very high,
that means there are a lot of organisms crowded into a certain area. If a population’s
density is low, that means there are very few organisms in an area.
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Now that you know about population density, we can talk about the difference
between the two types of limiting factors. If a factor that stops a population’s growth
is influenced by the population’s density, then it is called a density-dependent limiting
factor. If the population’s density does not influence whether or not the factor stops
the population’s growth, then it is called a density-independent limiting factor.
Density-independent limiting factors that can stop a population from growing
can be such things as natural disasters, temperature, sunlight, and the activities of
humans in the environment. Natural disasters such as tornadoes, floods, and fires will
stop a population from growing no matter how many organisms are living in a certain
area. The same goes for the temperature of an area and the amount of sunlight an area
receives—if the temperature increases due to global warming, or if the ash kicked up
into the atmosphere from an asteroid smashing into the earth blocks out a lot of
sunlight for a few decades, these will both cause a decrease in a population’s numbers,
no matter how large or small the population was to begin with. Human activities that
alter the environment will also decrease the amount of organisms in a population, no
matter the size of the population.
Density-dependent limiting factors come into play when a population reaches a
certain number of organisms. Thus the number of organisms in the population matters
when talking about density-dependent limiting factors. For example, when a population
reaches a certain size, there won’t be enough resources (food, shelter, water) for all of
the organisms. This could cause the population to stop growing when it reaches the
maximum number of organisms that can be supported, or “carried,” by the
environment. This number is known as the population’s carrying capacity. Each
population of organisms has a different carrying capacity, depending on the area in
which it lives and the amount of resources available in that area. Below is a graph of a
bacteria population that has reached its carrying capacity:
This type of population growth is
called logistic population growth; it
represents what actually occurs as a
population’s numbers get too large for
the environment to support it. First
there is a lag phase, where population
growth is slow. Then the population
will increased rapidly (exponential
phase) due to the abundance of
resources. In other words, there are no
limiting factors. The bacterial growth
began to slow down towards the end
after 3 hours. Once the population
numbers leveled off, roughly equal numbers of bacteria were dying as being born.
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Before a population reaches its carry capacity,
it experiences a period of rapid growth. This
period of growth is called exponential
population growth, because, mathematically, the
population is adding organisms at an exponential
rate. During this time period, there are plenty of
resources available for all organisms, so more
organisms are being born than are dying. The
graph for exponential population growth looks
sort of like the graph for logistic population
growth, only without the flat “leveling off” line at
the end of it.
Create an essential terms
list of your reading here.
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Write a summary of your reading.
Oh Moose!
Objectives: In this activity, you will identify three limiting factors that animals need to
survive. Limiting factors are factors that limit the growth of a population. Examples of
limiting factors are elements of habitat, such as food, water, and shelter. If animals do not
have these necessities, their chances for survival and reproduction are greatly reduced, and
they may die.
Activity Overview:
In this simulation, ¼ of the class will act as “moose” while ¾ of the class will become the
components of habitat. Each moose must find three habitat essentials: food, water, and
shelter. When a moose is looking for food, it holds his hands (hooves) over its stomach. When
a moose is looking for water, it holds its hands over its mouth. When a moose is looking for
shelter, it holds its hands over its head.
At the beginning of each round, a moose can decide what to look for. Once a moose has
chosen what to look for, it cannot change until the beginning of the next round.
Each player in the habitat group randomly chooses to be one of the essentials – food, water,
or shelter – at the beginning of each round. These students will use the same hand gestures to
indicate their identity.
The moose group and the habitat group will be standing apart across a field with your backs
facing each other. Your teacher will ask all the players to make hand gestures for food, shelter,
or water. On the count of three, all students will turn around to see the other group.
Moose continues to hold their hand gestures and run or walk to a player at the other line
displaying the same habitat gesture. They escort the habitat person back to the moose line,
because “successful” moose are able to survive and reproduce. If a moose does not obtain its
needed essential, it “dies” and turn into a habitat component in the next round.
Your teacher will keep track of the number of moose at the beginning of each round of play.
The game will be played for 8 – 15 rounds.
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Oh Moose!
Data table:
Time in
0
Years
Number
of Moose
Population
Graph:
Title:
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1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
Oh Moose!
Analysis:
1. Examine your graph and analyze it. Create a line of best fit with your teacher, using the
raw data. Determine if there are any parts of the graph that demonstrates fast growth
phase of your population, a leveling off of the population, or a decline in your
population. Highlight these 3 growth phases on your graph.
a. Calculate the growth rate of where the population increases the fastest.
b. Calculate the growth rate when population begins to level off.
c. Calculate the growth rate when the population begins to decline.
2. Analyze the data on the graph. Explain areas in the graph where the birth rate exceeded
the death rate. Use the graph to defend your answer.
3. Are there any periods on the graph where the death rate and the birth rate were equal?
If so, explain where. Use the graph to defend your answer.
4. Are there any periods on the graph where the death rate exceeded the birth rates? Use
the graph to defend your answer.
Page | 81
5. Define “limiting factor”, then explain which limiting factors caused a decline in the
population of moose.
6. Explain the difference between density dependent and density independent factors,
then determine if the limiting factors in this simulation were density dependent or
density independent.
7. Define carrying capacity, and then defend if your moose population ever reached its
carrying capacity.
Page | 82
Understanding Exponentials
Consider this:
An employer offers you two equal jobs for one hour each day for fourteen days. The first pays $10
an hour. The second pays only 1 cent per hour, but the rate doubles each hour. In the graph below,
graph a model of which job you think will pay the best rate over the course of 14 days. You will
need to graph two lines, one that represents the rate of pay for job 1, and the second line that
represents the rate of pay for job 2.
Rate of Pay for Job 1 vs. Job 2
Understanding Exponentials
After creating your initial model, complete the following calculations:
Job 1: Paid $10/hour for 14 days. Calculate the RATE of pay for 14 days in the 2nd row. In the 3rd
row, calculate the total amount of pay over the 14 days
Day 2
3
4
5
6
7
8
9
10
11
12
13
1
Rate
$10
$10
Total $10
Pay
$20
14
$10
Job 2: Pays only 1 cent per hour, but the rate doubles each hour. Calculate the RATE of pay for 14
days in the 2nd row. In the 3rd row, calculate the total amount of pay over the 14 days
Day
1
2
3
$.01
$.02
$.04
Total $.01
Pay
$.03
Rate
4
5
6
7
8
9
10
11
12
13
Page | 83
14
Understanding Exponentials
After completing the calculations from the previous page, revise your original model. Label
your new graphical model with the lag phase and exponential phase.
Rate of Pay for Job 1 vs. Job 2
Now, how much would your employer owe you if you stayed at this job for another 2 weeks?
What would happen if this type of growth took place within a population?
Page | 84
The History of Human Population Growth
Page | 85
The History of Human Population Growth
On the grid provided on the opposite page, graph the data below. Once the data is graphed, use the graph to answer
the questions.
Questions (after the graph is completed):
1. If you had to compare the shape of the graph to a letter in the alphabet, what does it look like?
2. If growth slowed down considerably, what letter of the alphabet would the shape of the curve begin to
look like?
3. At the current rate of growth, the population is projected to reach approximately 10 Billion by 2050.
What do you think this growth rate will mean in terms of resources and quality of life?
4. Can this rate of growth go on forever? Why or why not?
5. How is this graph different from a population pyramid? What does this graph reveal?
Page | 86
Exponential Growth
Page | 87
Logistic Growth: Staying at Carrying Capacity (K)
Page | 88
Population Trends
Do Fruit flies and rabbits show similar trends in population growth?
Fruit Fly Population Growth
Days
Number of Fruit
flies
5
100
10
105
15
1000
20
1600
25
2400
30
3350
35
8000
40
13,150
Page | 89
Rabbit Population Growth
Page | 90
Generations
Number of Rabbits
1
10
2
50
25
100
37
200
55
300
72
310
86
320
100
320
Population Trends Analysis: Use the tables and graphs to answer the following questions:
1. What type of growth pattern does the fruit fly population exhibit?
2. Does the rabbit population experience the same type of growth as the fruit flies? Explain.
3. Does either graph indicate there is a carrying capacity for the population? If so, when does
the population reach its carrying capacity?
4. What is the maximum number of individuals that can be supported at that time?
5. Using the storyboard template provided, tell a story about the population that reached its
carrying capacity. Be sure to include the following: logistical growth, exponential growth,
carrying capacity, and density dependent as well as density independent factors that may
affect the population growth.
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Freeology.com – Free Teaching Resources
______________________________________
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______________________________________
Name(s): ______________________________________________________________Date: ___________ Period: _______
Storyboard
______________________________________
______________________________________
______________________________________
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Page | 92
Population Trends Predator-Prey Model
Animals such as foxes and cats often prey on rabbits. Based on the growth curve of the rabbit
population in the previous activity, what might happen if a group of predators move into the rabbits’
habitat during the tenth generation and begin eating rabbits? Revise the original graph that you drew
on page 65. In this model, you should have two lines: one line to represent your rabbit population
and another line to represent your predator population. Make sure to include a legend in your
model. Do your best in drawing your model. You will get the chance to revise your model, as you
learn more about predator-prey relationships.
Page | 93
Population Trends Predator-Prey Model Revision
Examine your initial predator-prey model that you created on page 68. Your teacher may choose a
few student models to display on the projector and analyze. Go over the various student models and
analyze the flaws in each model. After you analyze various flaws, re-vise your predator-prey graph
model here on this graph. Use the space below the graph to explain your revised predator-prey
graph. If you do not have enough space to write, continue on the back of the page.
Page | 94
Predator-Prey Simulation
Objective: To simulate predator prey interactions, the numbers of predator and prey in their
“ecosystem” will be recorded and graphed.
Materials:
1. 200 small squares cut from index cards (approximately 1 inch squared) -- The small
squares represent the prey population (or hares)
2. 50 large squares cut from index cards (cut index cards in half) -- The large squares
represent the predator population (or mountain lion)
3. Data table and blank graph to graph
Instructions: Create an ecosystem by taping a square that is 11” x 17” using blue painter’s tape or
use 11” x 17” construction paper. (please clear all objects)
1. On your data table generation 1, start by recording 1 predator and 3 prey.
2. Drop 3 “prey” or hares on your grid. (randomly dispersed)
3. Drop 1 “predator” or mountain lion onto the grid and attempt to make the card touch
4.
5.
6.
7.
8.
9.
as many “prey” as possible. In order to survive, the predator must capture at least 3 prey.
It will be impossible for your predator to survive at this point.
Remove any “prey” captured or eaten. Remove any predator that did not eat at least 3
hares. (They starved). Record your data for the 1st generation, under the number of prey
remaining and the number of predator remaining.
The “prey” population doubles each generation. Count how many hares you have left on
your table, double that number and add prey cards to the table, and disperse them
evenly. Record the number in the data table under the 2nd generation “number of
hares”. (It should be 2x the number you have under the “hares remaining” for
generation 1)
Your predator died during the first round, but that’s okay, a new predator moves in for
the second round. If your predator died, put 1 in the “number of predators” for
generation 2 to represent the new arrival. Repeat the dropping procedure and record
your data for the second generation.
Again, number of prey doubles, if your predator didn’t “capture” 3 prey, it died. But a
new one moves in for the next round. Keep going, adding to the number of prey each
round.
Eventually your predator will be able to capture enough prey to survive. Guess what
happens? The number of predators doubles. Add to your predator population by adding
predator cards. Now when you drop your predators, you will be dropping more than
one. Don’t forget to remove any “captured” prey. Don’t forget to remove predators that
do not eat at least 3 prey. Don’t forget to make predators that survive reproduce and
double in number.
Continue to record the data through 20 generations.
Page | 95
Predator-Prey Data Table
Generations
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Page | 96
Number of
Mountain Lions
(Predator)
Number of Hares
(Prey)
Number of
Mountain Lions
(Predators)
Remaining
Number of
Hares (Prey)
Remaining
Predator-Prey Graph: Construct a graph. On the X-axis, put generations 1 through 20, on the Yaxis you will have the population numbers for each generation (number of predators, number of
prey). Use one line for the predator and one line for the prey to graph the data. Provide a legend!
Title: ________________________________________________________
Legend:
Page | 97
Analysis Questions
1. What is a carrying capacity?
2. Did the predator and prey reach carrying capacity in this simulation? If so, are the carrying
capacities of the predator and the prey population the same?
Explain.
3. What affects the carrying capacity of prey populations?
4. What affects the carrying capacity of predator populations?
5. What type of graph did you create? Explain.
6. Which population always increased first? ________________Why?
7. Which population always decreased first? _________________ Why?
Page | 98
8. How long did a cycle of increase and decrease take for hares? ______
For mountain lions? _____
9. Which population was almost always in greater numbers?
10. Which population was almost always in smaller numbers?
11. What effects did the rabbit population have on the mountain lion population?
12. What effects did the mountain lion population have on the rabbit population?
13. Keep in mind that as in any simulation, certain assumptions are made and many variables are
overlooked. What other limiting factors could subject a natural population to pressure and
disturbance? Name and explain at least four factors. Within your explanation, classify each factor as
density dependent or density independent.
Page | 99
Predator-Prey Relationships
Ecologists gather data about population densities of different organisms in order to understand how
these organisms interact with their environments. The graph in Figure 1 represents a growth curve
for the population of a single species. This type of curve is called a logistic growth curve. From
this curve, you can read the carrying capacity of the population. Carrying capacity is the number
of individuals that can be supported in an environment with the resources available. When the
population has reached carrying capacity, the curve will level off.
1. Time is represented on the
-axis.
2. The number of individuals is represented on the
-axis.
3. At which point on the curve (I, II, III) is the population increasing at the fastest rate?
4. At which point on the curve (I, II, III) is the population leveling off?
5. At which point on the curve (A or B) has the population reached the carrying capacity or the
maximum population density for its environment?
6. What would happen to the growth curve if the temperature suddenly dropped, a pollutant
or a new predator were introduced, thus making the environment less than ideal for this
organism?
Page | 100
Examine the following graphs of populations that have reached their carrying capacity. Remember that
the carrying capacity (K) of any population can be found on the graph of population growth. Carrying
capacity has been reached when the logistic population curve levels off.
7. Populations tend to fluctuate over time.
This population growth curve for sheep has
been normalized, which means that a smooth
curve has been drawn to show approximate
carrying capacity. What is the carrying capacity
of the sheep in this environment?
8. A population of daphnia in a pond has
been shown to have a growth curve like the one to
the right. How long does it take this population
to reach carrying capacity?
9. What is the carrying capacity of this population?
10. The graph to the right shows the population growth
curve for a population of bacteria in two different
media. Since this is their environment, what is the
difference between the carrying capacity of this population
in Medium 154 and the EpiLife medium?
11. It takes large mammals a greater amount of time to
reach carrying capacity than it does for a population
of small animals or bacteria. What is the carrying
capacity of this deer population in its present
environment?
How can a population of deer be kept at or near
in their environment? (Hint: Think of something that
will limit the growth of the deer population.)
Page | 101
In the tundra, where both reindeer and wolves live, the number of reindeer in a herd does not
exceed the carrying capacity of the environment. In 1944, the United States Coast Guard
transported 29 reindeer to St. Matthew Island in the Bering Strait. St. Matthew Island has the typical
climate for tundra, but no wolves live there. The graph shown in Figure 2 represents the growth
curve for the reindeer population there.
12. What is the increase in the reindeer population increase between 1945 and 1963?
13. What is the decrease in the reindeer population decrease between 1963 and 1966?
14. Did the reindeer exceed the carrying capacity of their environment?
Explain your answer
15. Why do you think the population increased so rapidly in less than 20 years?
16. Why do you think that the population declined so rapidly, from 6000 to 42, in 3 years?
17. What do you think would have happened if wolves had been brought to the island with the
reindeer
Page | 102
Group Behavior
Within populations, animals can exhibit group behaviors. Examples of behaviors include herding,
flocking, colonies, hunting, migrating, kin altruism, reciprocity, swarming, territoriality, migrating,
schooling, shoaling, and swarming. All of these behaviors benefit the group in survival and
reproduction.
You will work with your classmates to analyze a particular behavior and put together one or two
Google Presentation slides to teach the rest of the class about your behavior. You will need to
conduct independent research to determine how the behavior increases the chances of the
population’s survival and reproductive capacity.
Your Google Presentation slide will need to include the following:
 Title of your group behavior
 Definition of your behavior
 At least two examples of the behavior in different species
 Choose images that represent these examples
 Explanations of how the behavior benefits the population in survival and reproduction.
As a class, you will all be working off of the same Google Presentation. So, it is extremely
important that you do not interfere with another group’s slide during this process.
Page | 103
Type of behavior
Page | 104
Claim: Why do
individuals take part in
these behaviors?
Evidence/ Examples:
To support your claim
Type of behavior
Claim: Why do
individuals take part in
these behaviors?
Evidence/ Examples:
To support your claim
Page | 105
Central Dogma of Molecular Biology
Genes and Social Behavior in a Population
How Do Genes Work?
Genes are often called the blueprint for life, because they tell each of your cells what to do and when
to do it: be a muscle, make bone, carry nerve signals, and so on. And how do genes orchestrate all
this? They make proteins. In fact, each gene is really just a recipe for a making a certain protein.
And why are proteins important? Well, for starters, you are made of proteins. 50% of the dry weight
of a cell is protein of one form or another. Meanwhile, proteins also do all of the heavy lifting in your
body: digestion, circulation, immunity, communication between cells, motion-all are made possible by
one or more of the estimated 100,000 different proteins that your body makes.
But the genes in your DNA don't make protein directly. Instead, special proteins called enzymes uses
the DNA as a template to build a single-stranded molecule of RNA. This RNA leaves the nucleus and
travels out into the cytoplasm of the cell. There, protein factories called ribosomes read the mRNA
code and use it to make the protein specified in the DNA recipe.
If all this sounds confusing, just remember: DNA is used to make RNA, then RNA is used to make
proteins-and proteins run the show.
Page | 106
Common Core Practice: Use the information from the reading and the diagram on the
opposite page to explain the genetic basis for behavior. In other words, how do genes influence
social behavior in a population?
Page | 107
r and K reproductive strategies
Organisms that live in stable environments tend to make few, "expensive" offspring. Organisms that
live in unstable environments tend to make many, "cheap" offspring.
Imagine that you are one of the many invertebrate organisms which existed during the Cambrian or one of
their descendents living today. Maybe you live in a tide pool which is washed by waves. A storm appears
on the horizon. The waves increase in height. You feel yourself being dashed upon the rocks or into the
mouth of a much larger and predatory animal. Finally, you begin to see your brothers and sisters die, one
by one, as the forces of nature change your unpredictable environment.
If you could design a "strategy" to overcome the problems created by an unpredictable environment, you
would have two choices - go with the flow or cut and run to a more stable environment.
Suppose you stayed. Then, one thing you could do would be to increase the number of offspring. Make lots
of cheap (requiring little energy investment) offspring instead of a few expensive, complicated ones
(requiring a lot of energy investment). If you lose a lot of offspring to the unpredictable forces of nature,
you still have some left to live to reproductive age and pass on your genes to future generations. Many
invertebrates follow this strategy - lots of eggs are produced and larvae are formed but only a few survive
to produce mature, reproductive adults. Many insects and spiders also follow this strategy.
Alternatively, you could adapt to a more stable environment. If you could do that, you would find that it
would be worthwhile to make fewer, more expensive offspring. These offspring would have all the bells
and whistles necessary to ensure a comfortable, maximally productive life. Since the environment is
relatively stable, your risk of losing offspring to random environmental factors is small. Large animals,
such as ourselves, follow this strategy.
Plants are also subject to the same sorts of forces as animals. Some live in unstable environments such as a
floodplain near a river or a gap in the forest caused by falling trees. Others live in a quite stable environment,
such as a climax forest.
Page | 108
The two evolutionary "strategies" are termed r-selection, for those species that produce many
"cheap" offspring and live in unstable environments and K-selection for those species that produce
few "expensive" offspring and live in stable environments.
Of course, the animal or plant is not thinking: "How do I change my characteristics?" Natural selection is
the force for change, not the individual's conscious decision. But, natural selection has produced a gradation
of strategies, with extreme r-selection at one end of the spectrum and extreme K-selection at the other end.
The following table compares some characteristics of organisms which are extreme r or K strategists:
r
K
Unstable environment, density independent
Stable environment, density dependent
interactions
small size of organism
large size of organism
energy used to make each individual is low
energy used to make each individual is high
many offspring are produced
few offspring are produced
late maturity, often after a prolonged period of
early maturity
parental care
short life expectancy
long life expectancy
individuals can reproduce more than once in their
each individual reproduces only once
lifetime
type III survivorship pattern
type I or II survivorship pattern
in which most of the individuals die within a
in which most individuals live to near the maximum
short time
life span
but a few live much longer
Page | 109
The terms "r-selected" and "K-selected" come from a description of the population growth regimes
of the two types of organisms.
If you are in an unstable environment, you are unlikely to ever have population growth to the point where
density dependent factors come into play. The population is still at low values relative to the carrying
capacity of the environment and thus is growing exponentially with intrinsic reproductive rate r (when it is
not subject to environmental perturbations.), hence the name r-strategist.
An extreme K-strategist lives in a stable environment which is not seriously affected by sudden,
unpredictable effects. Thus the population of a K-strategist is near the carrying capacity K.
Page | 110
Surviorship curves give us additional insight into r and K-selected strategies. Notice that the vertical
axis of the survivorship plots is on a log scale and that horizontal axis is scaled to the maximum
lifetime for each species.
One of the interesting differences between r and K strategists is in the shape of the survivorship curve. We
can generate a survivorship curve by ploting the log of the fraction of organisms surviving vs. the age of
the organism. To compare different species, we normalize the age axis by stretching or shrinking the curve
in the horizontal direction so that all curves end at the same point, the maximum life span for individuals
of that species. Notice that the vertical axis is on a log scale, dropping from 1.0 (100%) to 0.1 (10%) to 0.01
(1%) to 0.001 (0.1%) in equally spaced intervals.
Extreme r-strategists, such as the oyster, lose most of the individuals very quickly, relative to the maximum
life span for the species. But, a very few individuals do survive much longer than the rest. But, for extreme
K-strategists, such as man, most individuals live to old age (again relative to the maximum life span for the
species).
These survivorship data are very valuable when studying the ecology of various organisms. Two
components are involved in reproduction: 1) How many females survive to each age and 2) the average
number of female offspring produced by females at each age. By using these data, we can compute the
intrinsic rate of reproduction, r, a key parameter in models of population growth.
Page | 111
Population Study Guide
1. According to the predator-prey graph
to the left, which line represents the
predator?
Predator-Prey Relationship Cottontale vs. Red Fox
1600
1400
1200
Which line represents the prey?
Population
1000
Series1
800
Series2
How do you know?
600
400
200
0
5/7/1990
9/19/1991
1/31/1993
6/15/1994
10/28/1995
3/11/1997
7/24/1998
12/6/1999
Dates
2. According to the graph, the prey population decreases when the predator population does
what?
3. What is a habitat?
4. In the following blank squares, draw what a clumped, uniform, random dispersion pattern
looks like.
Clumped
5. What determines dispersion patterns?
Random
Dispersed
6. Wildflowers tend to have a random dispersion pattern. Infer why this may be the case.
Page | 112
7. In the blank graphs below, sketch what an exponential growth model and a logistical
growth model look like. For the logistical growth model, label carrying capacity (k). To
the right of the graphs in the box, jot down some notes or information about the
characteristics of each of the growth models.
Exponential Growth Model
Logistical Growth Model
8. Define carrying capacity. Then, give examples of how carrying capacity can be lowered
or increased.
9. Contrast the reproductive strategy of an r-strategist with a k-strategist.
Page | 113
10. What is the difference between immigration and emigration?
11. Define the terms below in your own words:
a. Population –
b. Community –
c. Ecosystem –
12. Suppose that you capture 10 individuals of a rare subspecies of brook trout from an
impounded watershed. You place a pit tag (a very small radio activated tag) in the body
cavity of each individual and then release these fish. You come back a month later and
capture 20 fish and find that four of these are individuals that you had previously
captured and released. Calculate the population size, N. Show all of your work!
13. Suppose that a naturalist determines that there are 500 deer in a rectangular forest that is
5 miles wide and 10 miles long. What will the density of the deer be per square mile?
Page | 114
Common Core Practice: Analyzing a text
ESLAF DAM BREAKS
Heavy rains over the western portion of the state caused the Eslaf Dam to burst last night. The dam
ruptured at 6 p.m. Pacific Time. As a result, water from the Eslaf River overflowed its banks and
flooded a huge area of the state. Farmers reported many of their crops were ruined because of
water standing in the fields. Others reported large amounts of topsoil being carried away by the
rushing waters. Some forest areas were also flooded, causing some animals to seek safer, high
ground. People in the flood area are warned not to drink the water without first boiling it. Boiling
will kill the microbes and remove unsafe pollutants. Flood damage is estimated in the millions of
dollars. Luckily, no loss of human life has been reported.
Answer the following questions about the article:
1. According to the newspaper article, is soil being lost or gained? ___________________
What statement of evidence from the article do you have to support this claim? (Use a
direct quote from the article.)
2. According to the newspaper article, is food supply being reduced or is it increasing?
____________________________________
What statement of evidence do you have to support this claim?
3. Is the drinking water safe? ____________________
What statement of evidence from the article do you have to support this claim?
4. Are habitats increasing or decreasing? _____________________
What statement of evidence from the article do you have to support your claim?
5. Define “limiting factors”.
6. What factors could limit the size of populations of animals and plants in this area and
why?
Page | 115
Use the graph below to answer the following questions:
7. Which curve(s) show the effect of a density dependent factor?
8. Which curve(s) show the effect of a density independent factor?
9. Which curve(s) show a likely r-strategist’s growth curve?
10. Which curve(s) show a likely k-strategist’s growth curve?
11. What is the carrying capacity of organism B?
12. What is the carrying capacity of organism C? (draw a trend line for the data on the graph)
Page | 116
13. Draw two trend lines (one for each type of paramecia. Use two different colored lines.)
14. Calculate the highest growth rate for each paramecium based on your trend line.
15. Label the “lag phase” and “exponential phase”. Explain these phases and use evidence
from the graph to support your explanation.
16. Predict why these two organisms have different carrying capacities.
Page | 117
17. Bluestripe snapper often swim together in large groups going in the same direction. This
is called “schooling”. Write a paragraph below that answers the following questions:
a. How does the population benefit from schooling?
b. How does the individual benefit from schooling?
c. Explain how the behavior (schooling) is connected to the genetics of bluestripe
snapper. Include the terms protein, DNA, RNA, and gene in your explanation.
Page | 118
Ecosystem Interactions and Energy Unit Study Guide
Part 1: Review – here is a checklist of topics…
Complete each of the following tasks to help yourself prepare for the upcoming test.
 Can you explain the factors affecting biodiversity and populations in ecosystems?
 What is the role of group behavior on individual and species’ chances to survive and
reproduce?
 Can you determine how matter flows through the ecosystem?
 Do you know the law of conservation of matter and what it means?
 Can you explain the factors that affect carrying capacity?
 Go back to your Cornell notes for this unit. Cover the right side of the page and attempt to
answer the questions on the left side. Review any areas where you struggled or needed to
look at your notes for information.
 How is your writing? Can you support your ideas and claims with evidence from reading
material, diagram, research, and observations?
Page | 119
Ecosystem Interactions and Energy Unit Concept Map
(see reference page 14 for directions)
Page | 120
Ecosystem Unit Parent/ Significant Adult Review Page
Name
Student Portion
Period
Unit Summary (write a summary of the past unit using 5-7 sentences. Use your concept map to
guide your writing):
What is your favorite assignment in this unit and why:
Adult Portion
Dear Parent/ Significant Adult:
This Interactive Notebook represents your student’s learning to date and should contain the work
your student has completed. Please take some time to look at the unit your student just completed,
read his/ her reflection and respond to the following
Ask your child to defend why a pencil sharpener is not a living organism.
Which activity did your student feel helped them learn the best? Please explain why :
Parent/ Significant Adult Signature:
Page | 121