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BCLN BIOLOGY 11 – Rev July 2014

Unit 3 ~ Learning Guide Name: _______________

INSTRUCTIONS

Using a pencil, complete the following notes and questions as you work through the related lessons. You are required to have this package completed BEFORE you write your unit test. Do your best and ask questions about anything that you don't understand BEFORE you write the unit test.

3.1 NOTES: INTRODUCTION TO ECOLOGY

YOU SHOULD WATCH THE IMPORTANCE OF BIODIVERSITYVIDEO BEFORE PROCEEDING ANY FURTHER!

What is Ecology?

Ecology is __________________________________

________________________________________________________________. In other words, ecology has to do with the _____________________________ _____________________________ and with how the _______________________________________________________________________________ parts of an environment fit together and how one affects the other.Ecologists often study _________________________ ______________________. An ecosystem is _______ ______________________________________________________________________________________________________________________.

Ecosystems can cover large areas, such as the brush grasslands of the Central Okanagan Valley or the coastal Douglas fir ecosystems on Vancouver Island. Ecosystems can also be small, such as a single tide pool or a rotting log. Ecosystems are made up of _______________________________________________________.

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The biotic and abiotic components of an ecosystem are closely tied. ___________________________________________________________________________________________________________________________________________________________________________________ Different kinds of organisms play different roles in the environment. Plants make usable energy from sunlight and basic nutrients, animals consume the plants, other animals may consume those animals, and if any of these organisms die, bacteria and fungi are largely responsible for breaking down and using the nutrients that were once used by the organism and returning them to the earth. These nutrients can then again be used by the plants. ________________ __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________. When studying ecosystems we must look at all of the interactions of all of the components of that ecosystem.

Ecologists seek to explain: Life _____________________________________________________ _________________________________________________ of organisms the movement of materials and energy through living communities the _________________________________________________________, and the ___________________________________________________________ in

context of the environment.

Levels of Organization

Where does the ecosystem fit within the various levels of organization?

The Biosphere

The biosphere is the ______________________________________ _____________________ of organization. The biosphere is a thin layer around the earth that includes ________________________________________. This thin layer includes the _______________________________________ ________________________________________. Most organisms live within the first few meters of the surface of land and oceans. The biosphere has been divided into distinct regions based on the dominant forms of plant life and prevailing climate. These regions are referred to as Earth's biomes.

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The Ecosystem

There are many ecosystems within each biome. Ecosystems include the ________________________________________________________________________________________________ in a particular place. Example: A pond.The pond contains a variety ______________________________________ _________________________________. These organisms interact in ways that affect their survival. They are all a part of the pond food web. ________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Communities

Communities are defined as ______________

____________________________________________________________________________________

Populations

Populations are defined as ____________________

____________________________________________________________________________________

Organism

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This is the simplest level of ecological organization. Organism refers only to the _____________________________________. Research at this level involves things like adaptations.

This is what the levels of organization look like: Note the location of the ecosystem in this hierarchy.

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Niche

Although not part of the level of organization __________________________ ______________________________________________________ extremely important and ____________________________________________________.

A way of life. The organisms JOB in its habitat!

___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ all contribute to its niche.

Here are a few important definitions:

o ______________________________________: The range of conditions a species can potentially tolerate and the range of resources it can potentially use.

o ______________________________________: The range of resources the species actually uses.

Any differences between the fundamental and realized niches are due to _____________________________________________________________________________________________________________________.

o ______________________________________: tend to have broad niches as they can tolerate a wide range of conditions and use a variety of resources.

o ______________________________________: have a narrower niche as they tend to operate in more specific conditions and use specific resources.

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YOU SHOULD WATCH THE BASIC ECOLOGYVIDEO BEFORE PROCEEDING ANY FURTHER!

Human Impact

Human presence has _____________________ _________________________________. Humans change existing ecosystems. The human increase in population threatens the stability and diversity of the planet.

It is ironic that this instability threatens the human population itself. For example, the destruction of the rain forest may lead to an increase in carbon dioxide which raises the world temperature. _____

_________________________________________________________________________. Many of these organisms are needed for humans to survive.

It is estimated that there are over _____________ _______________________________. Only 2 million have been identified. __________________ ___________________________________________________________________________________________________________________________and the development and over harvesting natural resources. Extinction occurs naturally but ____________________________________________________________ _____________________________. The extinction of species reduces valuable resources available to humans.

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3.1 PRACTICE: INTRODUCTION TO ECOLOGY

1. Please relate organism to population to community to ecosystem to biosphere.

2. A (an) __________________________ is when populations within a community interact with one another and the environment.

3. All organisms that live in one common area make up a (an) _____________________________.

4. When many populations live together it is called a (an) ____________________.

5. All living things on earth make up the ___________________________.

6. When the human population increases in size the ecosystem becomes ___________________________.

7. Burning fossil fuels produces a mass amount of Carbon Dioxide. The ____________________________ is able to filter the majority of this waste.

8. A (an) ___________________________ is many animals that have similar characteristics and has the capability to produce offspring.

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9. When the environment changes and the members of species are unable to adapt to the change, the outcome will most likely lead to _____________________________.

3.2 NOTES: ENERGY FLOW IN ECOSYSTEMS

Food Chain versus Food WebThere are many relationships within a given ecosystem. Perhaps the most obvious type of relationship is a ___________________________________. We can use

_________________________________________________________________________________________________________________________________________________________________________________________________________. A food chain is a ______________________________________________________ ______________________________________________________________________________________. Food chains simply describe ________________________________________________. They _________________________________________________________________ in an ecosystem, _____________________________ ________________________. They are useful for looking at simple relationships between specific members of an ecosystem.

In reality, ______________________________________________

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_________________________________________. This network is ___________________________________. Food webs more clearly _______________________________________________________________________________. The more organisms that are included, the more complex the food web becomes. You should note that the arrows in a food chain or web _______________________________________ _________________________________________________________. In other words, you could replace the arrow with the words "__________________________.”

Feeding relationships are only a small portion of the many types of relationships that exist in ecosystems. The components of ecosystems interact with each other in many complex ways. _________________________________________________________ ________________________________________________________________. Some organisms work together to achieve common goals. Climatic variations, natural disasters, and human activities all affect the organisms in an ecosystem. ____________ _______________________________________________________________________________________________________________________. This energy originates from the sun.

Organism Trophic Type Prey/Food Predators/Grazersalgae primary producer --- krill, fish, blue

whalesbirds carnivorous

consumerkrill, fish seals, killer whales

blue whales planktivorousconsumer

algae, krill killer whales

fish omnivorousconsumer

algae, krill birds, seals, killerwhales

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killer whales top consumer blue whales, fish,birds, seals

---

krill herbivorousconsumer

algae fish, blue whales,birds

seals carnivorousconsumer

fish, birds killer whales

Flow of Energy

_________________________ is the ultimate source of energy for all living things. How does energy flow through an ecosystem?

Producers are _________________________________ ____________________________________________________________________________________________________________________________________. These organisms are _______________________ because they make their own food. Examples of autotrophs are plants, photosynthetic bacteria, and algae.

Consumers are _________________________________________________ __________________________________________________________. These organisms that eat other things are called _________________________.

Following is an explanation of the various levels of consumers.

o Primary consumers, called __________________ ___________________________________. A cow eating grass would be an example.

o Secondary consumers can be ______________

______________________________________________________________________. A bear would be a good example for the omnivore as they can eat various berries or fish.

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o Tertiary consumers at the top of the food chain ________________________________________. A cougar is only one example of a tertiary consumer.

o Decomposers __________________________ __________________________. ______________ ________________________ are examples of decomposers. It is estimated that each acre of soil has 1 ton of active bacteria.

Energy Pyramids and Energy Flow

The idea of a food web is fairly simple. Most students are familiar with the idea that plants produce energy from the sun by photosynthesis, animals eat plants, other animals eat those animals, and the dead organisms are decomposed by detritus (bacteria and fungi). The different viewpoint here is that __________________________

__________________________________________________ in the food web.

In a food web the direction of the __________________________________________ ___________________________________. Because _________________________ ______________________________ (the transfer is not 100% efficient) ____________ _____________________________________________________________________________________________________________________________________. This is the concept of a ______________________________________.

Each level of the pyramid is referred to as a _______________________________ and _________________________________________________________________________________________________________________________________________________________________. There is generally a _____________________________ of

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the food chain.

This energy loss can be depicted using an ___________________________________.

Notice the pyramid is ___________________________________________________ _________________________________________________. The mass (weight) and numbers of organisms ___________________________________________________. In an Ocean Energy Pyramid it takes about 1000 kilograms of phytoplankton to support 0.2 kilograms of tuna (1 can).

YOU SHOULD WATCH THE TROPHIC RELATIONSHIPSVIDEO BEFORE PROCEEDING ANY FURTHER!

The Role of Photosynthesis and Respiration

If the sum is the ultimate source of energy for all organisms then how is that energy captured? The suns energy is captured by producers in a process called photosynthesis. Photosynthesis is the ______________________________________ _______________________________________________________________________________________________________________________. In plants, this process occurs in specialized cell organelles called ______________________. Photosynthesis is the process that _________________________________________ __________________________________ that is the base of the energy pyramid.

The chemical reaction that takes place in chloroplasts (say inside a tree leaf) uses the light energy from the sun to convert ________________________________________ ________________________________________________________________________________________________________________________________________.

Cellular respiration is the ________________________________________________ ____________________________________________________________________________________________________________ (adenosine triphosphate) that can do work inside cells. This process occurs in specialized cell organelles called ________________________.

The chemical reaction that takes place in mitochondria (say inside a muscle cell) uses ____________________________________________________________________________________________________________________, the energy currency of cells.

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It is important to note that _______________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________.

As well as being transferred as an energy source, carbon transfers between organisms through photosynthesis and respiration. ____________________________________ ______________________________________________________________________________________________________________________________________________________________________________________________. When an organism dies and is broken down this carbon is again released in its simple form of carbon dioxide. Respiration also gives off carbon dioxide. The carbon cycle is of environmental concern because the destruction of forests and the burning of fossil fuels is increasing the amount of carbon in the atmosphere. __________________________ ______________________________________________________________________ __________________________________________________________________________________________________________.

Bioaccumulation

______________________________________________________________________________ such as petroleum-based pesticides, and other toxins, ______________________. When a consumer eats these toxins, ___________________________ _______________________________________________________________________________. Bioaccumulation then is the increase in concentration of a substance in living organisms as they take in contaminated air, water, or food.

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Bioaccumulation is a problem in the north because of higher concentrations of toxic pollution. Also, northern animals have a lot of fat to keep them warm, toxins accumulate mostly in fat.

Biomagnification

When such a _____________________________

___________________________________________________________________________________________________________________. See the example beside of the increase in DDT concentrations as we move up tropic levels. Note that organisms at the top of the food chain have the highest level of biomagnification. In other words, the higher the trophic level the greater the risk of fat-soluble toxin acquisition and concentration in the tissues.

3.2 PRACTICE: ENERGY FLOW IN ECOSYSTEMS

1. Please compare and contrast food chains and food webs.

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2. Please write the chemical equation for:

a. photosynthesis and identify which organelle performs this process. (2 marks)

b. cellular respiration and identify which organelle performs this process. (2 marks)

3. Please compare and contrast photosynthesis and cellular respiration with respect to energy flow, purpose, and organisms involved. (6 marks)

4. Please explain, with respect to energy flow and the concept of biological pyramids, why there is always fewer numbers and less biomass at the top of a food pyramid.

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5. Please explain the difference between bioaccumulation and biomagnification.

3.3 NOTES: SYMBIOSIS

What is Symbiosis?

The word symbiosis comes from the Greek roots "sym" meaning _________________ and "biosis" meaning _________________________. Symbiosis describes situations in which animals live with each other.

Whenever two organisms of different species __________________________________ ___________________________ often but not always to the benefit of both organisms, that's symbiosis. Symbiosis can occur between ______________________________ ______________________________________________________. Some symbiotes are so closely intertwined that it's difficult to tell where one organism ends and the other begins. And in the case of plant/animal symbiotes, it can be difficult to tell whether the organisms are plants, animals, or a little bit of both.

There are three main types of symbiosis;1. ________________________________________2. ________________________________________3. ________________________________________

1. Parasitism (+/-)

In parasitism the __________________________________________________ _____________________________. Parasitism does not often result in immediate death of the host organism. There are two types of parasites:

a. Ectoparasites: __________________________ – ticks, fleas, leeches. Endoparasites: _________________________ – bacteria, protists, worms.

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2. Commensalism (+/0)

In biology, commensalism is a relation between individuals of two species in which one species obtains either nutrients, shelter, support, or locomotion from the __________ species, which ___________________________________. The commensal relation is often between a larger host and a smaller commensal; the host organism is unmodified, whereas the commensal species may show great structural adaptations.

A commensal relation based on shelter is seen in ______________________________________________________________________________________________________________, where they are protected from predators. In another example _________________________________ often follow cattle and __________________________________ ________________________. __________________ from the cow without injuring the cow. However, ____

____________________________________________________________ from the egret.

3. Mutualism (+/+)

Mutualisms are ecological interactions between two species ____________________________________ ______________________. A species may be so dependent that it cannot ______________________ ________________________. In other cases, a species can interact mutualistically with more than one partner or even live without its partner(s) under certain conditions. Although ________________________ __________________________________________________________, we still expect each species to be "selfish" and to evolve traits that provide the maximum possible fitness benefit while minimizing cost.

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An example of mutualism takes place between Ants and Bull’s horn. Ants get food from the shrub and in return protects the shrub from herbivores.

___________________________________________________________________________________________________________________________. The pollinators obtain nutrients from the flowering plants and in turn, carry the pollen from one plant to another for plant fertilization. Flowers lure pollinators with _______________________________________________________________.

3.3 PRACTICE: SYMBIOSIS

1. Please complete the following table on symbiosis.

Symbiosis:An interaction between two different organisms living in close physical association where at least one organism benefits from the relationship.

mutualism commensalism parasitism

Definition

Symbolic Representation

+/+

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Facial Representation /

Example

3.3 NOTES: PROPERTIES OF POPULATIONS

What is a population?

A population is _________________________________________________________ ___________________________________________________________________________________________________. A population can be defined by any boundary. For example we could talk about the population of humans at your school, the population of your city, the population of your province, etc.

When scientists study populations they focus on the population as a whole, and look at characteristics such as _______________________________________________ ______________________________________. These characteristics help determine the size of the population. Recent consensus for the world's human population is that humans have now reached 7 billion!!!

Sometimes population size is easy to measure (example: trees and plants).

In other situations it is difficult to measure the population size. This would occur when an animal is ________

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_____________________________________________________________________________________. In these situations, estimates of population size are made.

YOU SHOULD WATCH THE POPULATION ECOLOGYVIDEO BEFORE PROCEEDING ANY FURTHER!

Population Density

Population density is ____________________________________________________ ____________________________________. It is expressed as the number of individuals per unit area or volume.

Example: the population density of humans in the US is about ______________ ___________________________________

Example: the population density of humans in Japan is about _______________ _____________________________________

When considering population density the population's __________________________________________ needs to be considered. Dispersion describes the _____________ _________________________________________________________. Dispersion patterns will depend on the scale at which you observe the population and there are three basic types of dispersion patterns.

1. Clumped Distribution:

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__________________________________________________________________________________________________________. Can also occur due to _______________________________ ______________________.

Examples: Zebras in herds, birds in flocks.

2. Even Distribution (uniform).

______________________________________________________________________________________. Usually individuals try to get as far away as possible from each other ___________ _______________________________________________________________.

3. Random Distribution.

_____________________________________________________________________________________________ Random dispersal of organisms _________________________________________________________________________________________________________________________.

Example: seed dispersal is by the wind and birds.

Population Dynamics

___________________________ is the amount by which a population’s size changes in a given time. All populations are _________________________________________ ____________________________. Whether a population grows, shrinks, or remains the same size depends on four processes: __________________________________ ____________________________________________.

The dynamics of a population are also determined by other factors such as Life Expectancy (___________________________________________________________ ___________________) and Age Structure (__________________________________ ______________________________________). For example, important population processes vary with age. Very old individuals _________________________________. Populations with a _______________________________________________________ ________________________________________________. This scenario changes for different species as their rate of survival at different stages in life varies. A _________________________________ is used to illustrate the likelihood of the survival of different species at different ages.

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Type I survivorship curve. Humans and elephants - _____________________________________________________________________

Type II survivorship curve. Some birds - _____________ _____________________________________________________________________

Type III survivorship curve. Oysters, salmon, & insects - ________________________________________________________________________________________________________________________________________________________________________________

Population Growth Rate

Populations of organisms change in number over time. _________________________ ___________________________________________________________________________________________________________________________. This may result in the complete elimination of a population of organisms or possibly the _____________ ________________________________________________________..As previously stated, whether a population grows, shrinks, or remains the same size depends on four processes: ________________________________________________ _________________________________________________

Births (b) = _______________________________________________________ Deaths (d) = _____________________________________________________ Emigration(e) = __________________________________________________

_______________________________________________________________ Immigration(i) = ___________________________________________________

________________________________________________________________

When a population changes in number we can calculate its ______________________using the following equation:

r = (( b + i ) - (e + d)) / n

In order to figure out the growth rate(r) of a certain population, ___________________ _____________________________________________ must be added together first. These are the immigrants (i) and the births (b). Next, _________________________ ___________________ are subtracted. These are the emigrants (e) and the deaths (d). This number is then divided by the total number of

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organisms in the initial population (n).

A ___________________________________________ from the formula means _____ ___________________________________________, while a ___________________ ________________________________ means that ___________________________ ______________________________________.

3.3 PRACTICE PART 1 of 2: PROPERTIES OF POPULATIONS

1. Please define population.

2. Please define population density.

3. Please identify and describe the three patterns of population dispersion.

4. Please identify and describe the three patterns of survivorship curves.

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5. If a population of 5000 plants is on an isolated island (no immigration or emigration), and 400 new plants are sprouting in the population for every 200 that are dying:

a. What is the growth rate of the population?

b. How many plants would there be after 3 years at this growth rate?

6. If a population of 10 000 mice are on the island, and 40 swim off the island while 50 swim on, and 5000 mice are born in the population for every 6000 that are dying:


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b. How many mice would there be after a period of 2 years?

Models of Population Growth

When studying how populations grow scientists have developed two basic models to describe how a population might change over time as it grows.

1. The Exponential Model (J curve)

The Exponential Model _____________

____________________________________________________________________________________. The larger the population gets the faster it grows. It is assumed that the birth rate and death rates remain constant and that ________________________________________________________________________________________________.

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Predictions Based on Exponential Model.

The graph of exponential growth shown below has a characteristic J-shaped curve. Something is said to increase or decrease exponentially if its rate of change must be expressed using exponents. A graph of such a rate would appear not as a straight line, but as ______________________ ___________________________________________________.

As this model indicates, _______________________________________ ________________, but, ______________________________. We can use this model to predict that the population will grow indefinitely and at an increasingly rapid rate.

Limitations of the Exponential Model.

How well does it match the growth pattern of real populations? Real populations _________ grow like this, but under rare conditions and for only _______________________________. In reality, the population will ____________________________________________________________________________________________. There will be a ______________ _________________________________________________________.

2. The Logistic Model (S curve)

The Logistic Model builds on the exponential growth model and _________________________________________________________________________________________________________________________________________________________________________________________. This model incorporates some new terms:

Carrying capacity (K) -

________________________________________________________________________________________________________________________

Steady State - ____________ ___________________________________________________________

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___________________________________________________________________________________________________________

When the population size is small and resources are abundant, the birth rates are high and death rates are low. As the population grows it hits a period of _____________________________________. As the population reaches the ecosystem's ______________________________, the growth rate slows resulting from_________________________________ ___________________________________________________. For all populations at carrying capacity the birth rate equals the death rate. This population is said to be at a __________________________ where the ___________________________________________________________________________________________________. This may be the result of reaching the carrying capacity of the environment or in response to other limiting factors.

Limitations of the Logistic Model:

The logistic model assumes the carrying capacity remains constant. ___________________________________________________________________________________________________________________________________________________________________________________________________________________. In response population sizes will also fluctuate.

Population Regulation

There are many factors that affect immigration, emigration, births and deaths and consequently the population growth rate. These factors can be categorized into two groups of limiting factors:

1. ______________________________________________ or2. _______________________________________________

1. Density-independent factors.

It has been observed that when there are _________________________ _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________. Therefore, abiotic factors are density-independent.

Examples: Weather, floods, fires, cold-snap. These factors reduce the

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population size by the same proportion__________________________ ___________________________________.

2. Density-dependent factors.

___________________________________________________________________________________________________________________________________________________________________________________________________. Therefore, they are termed density-dependent factors.

When populations become crowded organisms have to compete with one another for resources such as food, water, space, mates etc. Competition among members of the same species is a density-dependent limiting factor. The more individuals there are the faster resources become limited.

Competition between members of different species is a major force behind evolutionary change. In this case competition results from _____________________________________________. This is when two or more species __________________________________________ _______________________ and ____________________________ ____________________________. When two species compete, both find themselves under pressure from natural selection to change in ways that reduces their competition.

Example: Darwin's finches - Several species of birds eat a different size seed.

Example: Resource limitations - lack of food. ______________________ _________________________________________________________

Density dependent factors will _________________________________ _________________________________________________________

Cyclic Population Fluctuations

All populations ______________________________________. Some of these fluctuation are ___________________________________________________________ ______________________________________________________________ linked to fluctuations of predator/prey populations within a given ecosystem.

Example: ____________________ Population numbers fluctuate due to predator-prey interactions. _______

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________________________________________________________________________________________________________. However, there will soon be ___________ _________________ and as a result of the increased predation, the hare population will decrease. ________________________________________________________________________________________________________________________________________________________________________________________. This decrease in lynx population is good for the hare and hare numbers will increase again. This increase will be followed, with a _________, __________________________________________________, leading to a decrease in hare, then a decrease in lynx, and so on. This growth pattern will continue with all populations even if fluctuations are slight. ________________ _____________________________________________________________________________________________________________________.

Adaptations in Predator-Prey Relationships

Natural selection favours adaptations that ________________________________ ______________________________ and the _______________________________ ___________________________. This concept explains many of the interesting features seen amongst organisms. Some examples are: a rattlesnake's keen sense of smell, a spider's webs, sharp teeth in wolves as well as _____________________ ________________________________________, thorns in plants and chemical deterrents found in poison oak.

Perils of small populations

It is important to note that _________________________________________ ______________________________________________. Environmental disturbances such as storms, fires, floods, or disease can have dramatic effects on small populations. Disease outbreaks can wipe out the entire population. In small populations inbreeding is more likely to occur. When this occurs the offspring of related parents often have fewer offspring, are more susceptible to disease, and have a shorter life span. Inbreeding will also often lead to diseased genetic variability and may reduce the population's ability to adapt.

Be sure that you understand that a species ability to survive is based on its biotic potential. Biotic potential is _____________________________________________ __________________________________________________________________. Full expression of the biotic potential of an organism is restricted by __________________ ______________________________________________________________________________________________________________________________________________________. It is generally only reached when environmental conditions are very favorable. A species reaching its biotic potential would exhibit

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________________ _________________________________________________________________________________ that is, how many offspring are produced per mother.


1. Scientists model population growth in many ways:

a. Please compare and contrast the exponential growth model and the logistic growth model. It is ideal to draw the graphs (make sure they are appropriately and completely labelled) and then to explain what each curve is representing. (6 marks)

b. What model is the better representation of growth in the vast majority of populations? Why? (2 marks)

2. Population growth can be influenced by density-independent factors and density-dependent factors.

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a. Please give an example of a density-independent factor and how it influences population growth.

b. Please give an example of a density-dependent factor and how it influences population growth.

3. Using pictures/symbols and as few words as possible (this is a critical-thinking challenge) clearly explain cyclic population fluctuations amongst predators and their associated prey.

3.4 NOTES: SUCCESSION

What is Succession?

Just as the people living in your neighborhood can come and go, _________________ _____________________________________________. One way a community can change is if external conditions shift. If the weather in a certain geographical area suddenly gets colder, certain populations will be better off and will thrive, while others will shrink and disappear.

However, change in communities is not always caused by external factors; __________________________________________________________________________________________. The success of a particular population in a particular area will

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change the environment to the advantage of other populations. In fact, the originally successful population often changes the environment to its own detriment. In this way, the populations within a community change over time, often in predictable ways. __________________________________________________________________________________________________________________________________________________________________________________. Successional change in a community is the ______________________________________________________ ___________________________________________________________.

Succession can either begin with Primary Succession, which is __________________ ________________________________________________________________________________________________________________________________________________________________________________________, or Secondary Succession, which is _______________________________________________________________ ____________________________________________________ (natural disaster like a forest fire or human activities such as logging). Primary Succession takes much longer (centuries) than Secondary succession (decades).

Succession begins when populations move into geographic areas. _________________ _________________________________________________ is referred to as a pioneer species. If this pioneer population is successful in its new location, it will change the environment in such a way that new populations can move in (Intermediate species). This will continue until eventually, the community reaches a point where the mixture of populations creates no new changes in the environment. At this point, ______________ ______________________________________________________________ are said to make up a climax community. While individuals within a climax community will come and go, ______________________________________________________ _________________________________________________________________________________________________________________________________..

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YOU SHOULD WATCH THE ECOLOGICAL SUCCESSIONVIDEO BEFORE PROCEEDING ANY FURTHER!

Succession in Action

Imagine a catastrophic event: a forest fire rages through the Okanagan Mountain Park of British Columbia. The fires burn everything and leave behind a barren, rocky expanse. The population of trees that once lived in this area can’t grow back because the fire has changed the ground composition. This rocky ground, however, proves ideal to lichens, the ________________________ _____________________. The lichens colonize the rocks and thrive. As part of their life process, lichens produce acids that _________________________________________________. As lichens need solid places to survive: they become victims of their own success. Mosses and herbs are well suited to living in the shallow soil environment created by the lichen, and they __________________________________________________________________.

The mosses and herbs continue to build up the soil. _____________________ ______________________________________________________________________________________________________________________________________________________________. Eventually the land becomes suitable for shrubs and then for trees. The early dominant trees in the community will be species like poplar, which thrive in bright, sunlit conditions. As more trees grow in the area, however, there is less sunlight, and maples, which grow in shade, supplant the sun-starved poplars. The maples eventually dominate the community, because they don’t change the soil

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composition and thrive in their own shade. ____________________________________ ____________________________________________________________, with maple as the dominant species. ________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________..A term that you should also be familiar with is ___________________________. Keystone Species is _____________________________________________________ ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________. Keystone species help to support the ecosystem (entire community of life) of which they are a part. A classic keystone species is a small predator that prevents a particular herbivorous species from eliminating dominant plant species. Since the prey numbers are low, the keystone predator numbers can be even lower and still be effective. Yet without the predators, the herbivorous prey would explode in numbers, wipe out the dominant plants, and dramatically alter the character of the ecosystem.

Salmon are keystone species in many BC ecosystems as many other organisms are dramatically influenced by their presence, absence and health.

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3.4 PRACTICE: SUCCESSION

1. Ecosystems in BC frequently experience ecological succession:

a. Please define ecological succession.

b. The Athabasca Glacier in BC is rapidly receding due to recent global warming trends. Please explain the type of ecological succession that will be occurring in its wake. You may describe in a paragraph format, step wise format, or well labelled diagram however, be sure to identify all key steps and to explain all important terms.

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c. Every year BC experiences numerous large forest fires. Please explain the type of ecological succession that will be occur in the wake of the fires. You may describe in a paragraph format, step wise format, or well labelled diagram however, be sure to identify all key steps and to explain all important terms.

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~ END OF BIOLOGY 11 UNIT 3 LEARNING GUIDE ~

UNIT 3 ANSWER KEY

3.1 PRACTICE: INTRODUCTION TO ECOLOGY

1. Please relate organism to population to community to ecosystem to biosphere.

Organisms refer to the various living things that can be found living within populations, communities, ecosystems and the biosphere. A population refers to all the individuals of a single species living within a given area that are able to mate and reproduce. A community refers to all the interacting populations within an area whereas an ecosystem refers to the populations and the abiotic factors that interact within a given area. The biosphere includes all ecosystems and indeed, anywhere on or in land, water or air that living organisms can be found.

2 - 9. Answers are not provided for fill-in the blank question.

3.2 PRACTICE: ENERGY FLOW IN ECOSYSTEMS

1. Please compare and contrast food chains and food webs.

Food chains and food webs both show feeding relationships and the flow of energy from one organism to another. However, food chains show very simple, direct feeding relationships whereas as food webs are expanded to show more complex feeding relationships within an ecosystem.

2. Please write the chemical equation for:

a. photosynthesis and identify which organelle performs this process. (2 marks)

Solar Energy + H20 + C02 C6H12O6 (carbohydrate) + O2 chloroplast

b. cellular respiration and identify which organelle performs this process. (2 marks)

C6H12O6 (carbohydrate) + O2 Energy (in the form of ATP) + H20 + C02mitochondria

3. Please compare and contrast photosynthesis and cellular respiration with respect to energy flow, purpose, and organisms involved. (6 marks)

In photosynthesis, autotrophs such as plants and photosynthetic bacteria, convert solar energy to carbohydrates for storage and further self-use by the mitochondria. In cellular respiration, autotrophic organisms convert the

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carbohydrates produced by their chloroplasts into a more user friendly-form of energy (ATP) that can be used to run cellular processes. In contrast, heterotrophic organisms cannot produce their own carbohydrate from solar energy and therefore, must consume them by eating the autotrophs. The heterotrophs' mitochondria then perform cellular respiration to convert the consumed carbohydrates into ATP to run their cellular processes.

4. Please explain, with respect to energy flow and the concept of biological pyramids, why there is always fewer numbers and less biomass at the top of a food pyramid.

Ninety percent of the energy either produced or consumed at any given trophic level is used to actually sustain the life processes of that level. This means that there is only approximately ten percent of the energy left over to sustain the next trophic level up. As there is less energy available, fewer organisms and biomass can exist at the next level, leading to the characteristic pyramid shape of organism number and biomass as we move up the trophic levels.

5. Please explain the difference between bioaccumulation and biomagnification.

Bioaccumulation and biomagnification both refer to the build-up of toxins over time. However, bioaccumulation refers to the build-up within a single individual over time whereas biomagnification refers the fact that the levels of such toxins increase within the organisms such that the higher an organism is on the food chain the greater the concentration of toxins within the organisms


1. Please define population.

A population is a group of organisms that are of the same species that live in a particular location together at the same time.

2. Please define population density.

Population density refers to the number of organisms within the same population in a given area (for example 20 cougars in 2000 km2 represents a population density of 1 cougar/100 km2). Population density essentially measures how crowded a species is.

3. Please identify and describe the three patterns of population dispersion.

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4. Please identify and describe the three patterns of survivorship curves

5. If a population of 5000 plants is on an isolated island (no immigration or emigration), and 400 new plants are sprouting in the population for every 200 that are dying:

a. What is the growth rate of the population? Equation: r = [(b + i)- (e + d)]/n

Where r represents growth rate, b represents birth rate (= 400 sprouting), i represents immigration (assume 0 as none mentioned), e represents emigration rate (assume 0 as none mentioned) and d represents death rate (= 200 deaths) and n represents the total number of individuals in the original population (= 5000)

Substitution: r = 400-200/5000 Evaluate: r = 0.04

b. How many plants would there be after 3 years at this growth rate?

While there is an equation to solve this, it is not in the notes so here's how you can do it long hand

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Equation: For each year: population = r(n) + n

Substitute and Evaluate:After year 1: population = 0.04(5000) + 5000

= 5200After year 2: population = 0.04(5200) + 5200

= 5408After year 3: population = 0.04(5408) + 5408

= 5624

6. If a population of 10 000 mice are on the island, and 40 swim off the island while 50 swim on, and 5000 mice are born in the population for every 6000 that are dying:


Equation: r = [(b + i)- (e + d)]/n

Where r represents growth rate, b represents birth rate (= 5000), i represents immigration (= 50 e represents emigration rate (= 40) and d represents death rate (= 6000 deaths) and n represents the total number of individuals in the original population (=10 000)

Substitution: r = [(5000 + 50) – (6000 + 40)]/10 000 Evaluate: r = - 0.099

b. How many mice would there be after a period of 2 years?

Equation: For each year: population = r(n) + n

Substitute and Evaluate:After year 1: population = -0.099(10 000) + 10 000

= 9010After year 2: population = -0.099(9010) + 9010

= 8118


1. Scientists model population growth in many ways:

a. Please compare and contrast the exponential growth model and the logistic growth model. It is ideal to draw the graphs (make sure they are appropriately and completely

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labelled) and then to explain what each curve is representing. (6 marks)

Exponential growth models assumes that growth occurs in an unlimited fashion. The growth rate would exponentially increase as the population numbers that are reproducing increase. This is rarely the case as there is generally limited resources such as limited food or space.

Logistic growth models account for the limiting resources. There is an initial exponential growth rate followed by a more stable growth rate once a population reaches the limits of its resources. When/where the growth rate stabilizes is the carrying capacity which represents the number of organisms that an environment can support over a prolonged period of time.

b. What model is the better representation of growth in the vast majority of populations? Why? (2 marks)

The logistic growth model is generally the better representation of growth as the vast majority of population face limited resources such as food and shelter.

2. Population growth can be influenced by density-independent factors and density-dependent factors.

a. Please give an example of a density-independent factor and how it influences population growth.

Density-independent factors are any factors that can affect population growth regardless of size of population such as pH of water or temperature or a flood.

b. Please give an example of a density-dependent factor and how it influences population growth.

Density-dependent factors are any factors that can affect population growth depending on the size of the population such as intra-species competition for food, water and space.

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3. Using pictures/symbols and as few words as possible (this is a critical-thinking challenge) clearly explain cyclic population fluctuations amongst predators and their associated prey.

Initially…few = very few as not enough food

Overtime, which attracts more

Such that as they get eaten

Which then leads to fewer as there are fewer available to eat…

…taking us back to the beginning of the cycle.

3.4 PRACTICE: SUCCESSION

1. Ecosystems in BC frequently experience ecological succession:

a. Please define ecological succession.

Ecological succession refers to the gradual and sequential change within a

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community due to interactions between the various biotic and abiotic factors.

b. The Athabasca Glacier in BC is rapidly receding due to recent global warming trends. Please explain the type of ecological succession that will be occurring in its wake. You may describe in a paragraph format, step wise format, or well labelled diagram however, be sure to identify all key steps and to explain all important terms.

As a retreating glacier leaves nothing but bare rock behind the community would experience primary succession as follows:

c. Every year BC experiences numerous large forest fires. Please explain the type of ecological succession that will be occur in the wake of the fires. You may describe in a paragraph format, step wise format, or well labelled diagram however, be sure to identify all key steps and to explain all important terms.

As a forest fire leaves soil and some living organisms behind the community would experience secondary succession as follows:

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