Survey of EcologySurvey of EcologyBy: Barry Perlman

v 1.0By: Barry Perlman

v 1.0

SURVEY OF ECOLOGY

I N S T R U C T I O N S

Welcome to your Continental Academy course “Survey of Ecol ogy”. It is made up of 5 indi vidual lessons, as listed in the Table of Contents. Each lesson includes practice questions with answers. You will progress through this course one lesson at a time, at your own pace. First, study the lesson thoroughly. Then, complete the lesson reviews at the end of the lesson and carefully check your answers. Sometimes, those answers will contain information t hat you will need on the graded lesson assignments. When you are ready, complete the 10-question, multiple choice lesson assignment. At the end of each lesson, you will find notes t o help you prepare for the online assignments. All lesson assignments are open-book. Continue work ing on the lessons at your own pace until you have finished all lesson assignments for this course. When you have completed and passed all lesson assignments for this course, complete the End of Course Examination. If you need help understanding any part of the lesson, practice questions, or this procedure:

Click on the “Send a Message” link on the left side of the home page

Select “Academic Guidance” in the “To” field

Type your question in the field provided Then, click on the “Send” button You will receive a response within ONE BUSINESS DAY

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About the Author…

Barry Perlman has been an educator in South Florida for more than thirty years. He has a Bachelor’s Degree in Earth and Space Sciences from Boston University, and a Master of Science Degree from Nova-Southeastern University in Science Education. Mr. Perlman has taught in various public and private schools within the State of Florida and serves as an adjunct faculty member for Nova-Southeastern University and Broward Community College, where he has been teaching for over 25 years. Mr. Perlman has had many accomplishments in the fields of science and education including the directorship of several planetariums and as a museum director. He was principal investigator for three experiments carried onboard the space shuttle Columbia, including its final mission. Mr. Perlman is also President of E-Class Solutions Inc. a company specializing in distance learning strategies, and he has been listed in Who’s Who in the World and Who’s Who in American Education.

Survey of Ecology SC20 Editor: Barry Perlman

Copyright 2008 Home School of America, Inc.

ALL RIGHTS RESERVED

The Continental Academy National Standard Curriculum Series

Published by: Continental Academy 3241 Executive Way Miramar, FL 33025

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The processes of the life sciences and how organisms interface with their environments are studied. Biology, chemistry, earth sciences, physical sciences, and other related fields add to this study.

Student should develop an understanding of the structure of the atom

Student should develop an understanding of the structure and

properties of matter

Student should develop an understanding of chemical reactions

Student should develop an understanding of motions and forces

Student should develop an understanding of conservation of energy

Student should develop an understanding of interactions of energy and

matter

Student should develop abilities and understandings about scientific

inquiry

Student should develop an understanding of biological evolution

Student should develop an understanding of interdependence of

organisms

Student should develop an understanding of matter, energy and

organization in living systems

Student should develop an understanding of behavior of organisms

Student should develop an understanding of the cell

Student should develop an understanding of the molecular basis of

heredity

Student should develop an understanding of population growth

Student should develop an understanding of natural resources

Student should develop an understanding of environmental quality

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TABLE OF CONTENTS

0Lesson ................................................................................................................Page

Lesson 1-- Science and Ecology ........................................................................... 7

Lesson 2-- Life and its Workings ......................................................................... 21

Lesson 3 --Population and Regulation .................................................................. 43

Lesson 4 --The Human Factor .............................................................................. 61

Lesson 5 --Ecology and Technology ……….……………………...………...............81

End of Course Review…………………………………………………………………. 97

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1LESSON 1: SCIENCE AND ECOLOGY

Ecology is the study of how living

organisms interact with their

environment and with each other. The

environment is made of both living

(biotic) and non-living (abiotic) things.

In recent years, ecology has taken on a

larger meaning. It is the study of the

balance between organisms and their environment. We often hear it take it

to mean the delicate balance that exists between living things (including

Man) and the environment.

A related subject, Environmental Science, is the study of the environment.

It is man relating to nature. Ecology and environmental science are

closely related. You might ask,

"Why should we study ecology?"

The answer is simple. The study of

ecology is important to our survival.

We need to understand our role as

part of nature. If we cannot

understand problems we might be

creating, we cannot hope to solve

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them. Science is the study of natural things. Technology is the application

of science in order to make life better. Technologists study ways to apply

scientific knowledge.

Ecology includes the following sciences. These are:

1 3Physics

Physics is the study of how the physical laws of nature work. It is the most

basic science. All of the other

sciences build upon the relationships

between matter, energy, time and

space. Ecologists need to know

physics in order to understand how

animals and plants use energy.

1 4Chemistry

Chemistry is the science of putting atoms

together to make new materials. Chemists

break bonds between atoms to make new

things. They also take apart groups of

atoms called molecules. They build new

substances by bonding them together.

Ecologists must know chemistry in order to

understand the non-living part of the

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environment. They must also know the chemistry of life. Organic

chemistry deals with the basic chemicals of life. Biochemistry is how these

chemicals work inside living things.

1 5Geology

Geology is the study of the solid parts of the Earth. Geologists study the

way nature wears down landforms. They also study how mountains build

up over time. They also study the running water and ground water that life

depends on. They need to understand how ground water moves through

underground layers in order

to understand water

pollution.

Geologists also study the

history of the Earth. They

also play an important role

in our understanding of

ecology. Paleontologists

are geologists who study

ancient life. In order to

understand the direction of life, we must first understand where it came

from. In order to understand how we can stop species from becoming

extinct, we must study what happened to them in the past.

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1 6Meteorology

Meteorology is the study of the Earth’s atmosphere. Meteorologists study

day-to-day weather and the long-term effects of climate. Global warming

and acid rain affect life on earth. Our atmosphere is made up of several

layers. Some of these prevent harmful radiation from the Sun from

reaching the ground.

1 7Oceanography and Astronomy

Oceanography is the study of the oceans. Some oceanographers study

ocean currents and the relationships

between the oceans and the

atmosphere. Some study life in the

oceans. We study this science in order

to understand the ecological problems

in the aquatic environment.

Astronomers study the universe and the

Earth as a planet. We must study it in order to understand how the Sun’s

energy affects the planet. We have to know what causes the seasons and

how much solar energy the earth receives in order to understand how

systems of living things work.

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The Methods of Science

The Scientific Method is important because it

allows scientists to do their research and

advance scientific knowledge. As you will see,

there are many methods used in science, and

no one

special way will fit all cases.

The scientific method has a number of steps:

1. Observe nature.

2. Ask a question about what you see.

3. Make a hypothesis about the question.

4. Do background research.

5. Make a working or testable hypothesis.

6. Do an experiment to test your hypothesis.

7. Collect, reduce and study the data.

8. Affirm, deny or modify your original hypothesis in the form of a

conclusion.

9. Publish or share the results.

The general method consists of coming up with an idea about how or why

something works, and then testing that idea to see if you are right.

For example, you observe that a certain owl makes nests in darkly colored

trees. After reading about owls, you say, “I believe that this type of owl

makes its nests only in dark colored trees.”

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You would then go to test your idea by creating a fair experiment that would

prove or disprove the idea. Perhaps you would observe 50 owls and the

trees they made their nests in. You make sure they had a choice of

different colored trees. After a period of observing, you might arrive at a

conclusion that would support or deny your original hypothesis.

We did not use this scientific approach all the time. The ancient Greeks

believed in making observations and arriving at hypotheses and theories.

They did not believe in doing experiments. They formed initial ideas, and

then observed nature as their follow-up. If their

observations did not change, they made their ideas

to theories.

ng with

s

e

t of

in

However, even the best ideas can be wrong. For

example, some of your friends turn and walk away

from you. You might have an idea that they do not

like you any more. There is only one thing wro

doing this. Perhaps you should have done an

experiment or test. The simplest one would have been to ask your friend

if they are upset with you. If they say “no,” and everything is fine, it would

mean that all of your ideas were just plain wrong. That is exactly why th

Greeks wrongly obtained false ideas about the world. They believed that

there were only four elements or “essences” that made up the physical

world (air, earth, fire and water). Two thousand years later, a simple se

experiments showed this to be wrong. Our modern science of chemistry

was then born. It was the same for the idea that the Earth was the center

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of the universe. Aristotle thought that heavier objects fell faster than lighte

ones. It was not until the early 17th century that the Renaissance scient

Galileo Galilae proved the idea false by

doing so

r

ist

me simple tests that showed that

ravity acts equally on different objects.

n

d

st carefully placed controls, outcomes would be

ffected.

m

,

s get smaller at

g

Why, then, did the great Greek civilizatio

not do experiments? Well, the ancient

Greeks believed that doing an experiment

interfered with what nature herself would do

if left alone. In other words, putting things

in a test tube or otherwise doing

experiments would yield false results,

because Man was now an active participant in the process. It was argue

that even with the mo

a

This idea was not a bad one. Although the absence of experiment was a

flaw in their way of doing science, it took the creation of modern (quantu

physics) to show why. Simply put, this field states that at the smallest

level, the exact place and speed of a small particle cannot be determined.

This is because the act of seeing is not entirely passive. In order to get the

exact place and speed which would be needed to make a 100% prediction

one must observe the particle by bouncing light off it. This in turn affects

the result by an uncertain amount. Of course, these error

larger scales by using math, but they do not disappear.

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It is interesting that the Greeks were not entirely wrong, and we have

ere simply wrong. Galileo showed

at objects fall at the same rate regardless of how heavy they were.

ot

onsi

epea

g of

re the first to

realize that it was not the only

method useful for science.

included their problem with experiments into modern science.

By the time of the Columbus in the 1400s, people were beginning to find

out that the old ideas of the Greeks w

th

Modern science began at that time.

Even though scientists like Galileo test

experiments in the modern sense. He called

what he did as a “trial”, rather than an

experiment. If his formulas predicted that a

cannon ball would land a certain distance away,

so he would shoot the cannon balls and see if

they fell at the predicted distances. It was n

until the first scientific societies formed in the

19th century Europe that formal rules about

experiments came about. These c

having control groups, obtaining r

for analysis. Even though these

societies came up with the basic

method outlined at the beginnin

this lesson, they we

ed their ideas, they did not do true

sted of

ted results and gathering proper data

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2Chance

Scientists sometimes make accidental discoveries. Many of these

discoveries changed the world. When Galileo looked at the sky with an

early telescope, he had no idea that he would see mountains on the Moon,

sunspots, and moons of Saturn and Jupiter. When Robert Hook looked

into his early microscope at a drop of water, he had no idea he would see

small organisms in it. When Karl Jansky pointed his radio antenna to the

sky, he had no idea that he would discover radio waves coming from outer

space and become the father of radio astronomy.

Perhaps the most noted chance discovery of all time was the discovery of

penicillin. In 1928, Alexander Fleming, a British scientist, took a one-week

vacation. He left some Petri dishes on his desk that had bacteria growing

in them. By accident, some fungal spores drifted into his laboratory from a

lab downstairs during his absence. When he returned from vacation, he

was amazed to find that in one dish that the spores found their way into,

the bacterial growth had stopped. He realized that some chemical that the

penicillium fungal spores made had killed the bacteria. This quickly led to

the production of that chemical he dubbed “penicillin.” It became the world’s

first antibiotic drug and saved millions of lives since then. Fleming later

coined the saying “Chance favors the prepared mind”. Fleming knew what

he was looking at when he saw the dead bacteria in the culture dish. His

mind was trained so that he did not overlook what was accidentally put in

front of him.

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3Theory in Science

Albert Einstein was one of the most famous

scientists in history, yet he never did an

experiment. Einstein was a scientist who

did "thought experiments." It was not

possible to do them with the large scale he

worked with. Just about all we know about

astronomy comes from observations of

what is beyond the Earth. We cannot go

out and put the Moon in test-tube, yet

further observations provide our ideas about the universe. Astronomy

lends itself more to the Greek way of doing science by making further

observations that make hypotheses into theories and then into laws.

Up until now, we have not spoken of the word “Law” in science. A Law is a

theory that has withstood the test of time, is simple, and contains a basic

truth. The “Law of Gravity” for example, states how the forces between

objects vary with distance and the mass of the object. The most important

thing to remember about laws is that they are rejected if even one

exception is found.

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4Summary We have been rather complete in the description of the scientific method in

order to dispel the idea that most people have that there is a single method

used in science. While science is not a random thing, there are many

paths to take. Ecology is made up of many sciences. Some would call it

a combined science.

In this course, we will introduce ideas from related sciences, as they are

necessary to understand ecological principles. In each case, it is important

to understand the methods used by ecologists in their pursuit of knowledge.

PRACTICE QUESTIONS 1. Ecology is ___________________________.

a) the study of animals.

b) the study of animals and plants

c) the study of the balance between organisms and their

environment

d) the study of all life on Earth

2. Non-living species are:_______.

a) abiotic c) ecosystic

b) biotic d) biologic

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3. Ecology is a __________ science.

a) basic c) whole

b) secondary d) derived

4. Ecology is a technology rather than a science.

a) True b) False

5. The study of ground water falls into _________.

a) meteorology c) astronomy

b) geology d) physics

6. The study of marine biology is in the field of ________.

a) meteorology c) chemistry

b) astronomy d) oceanography

7. The study of meteorology includes __________.

a) climate c) the universe

b) ocean life d) life

8. After forming working hypotheses, you should next _________.

a) test it c) do initial observations

b) refine it more d) publish it

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9. Flemming said that chance favors the _______ mind.

a) open c) prepared

b) closed d) learned

10. The so-called “modern scientific method” was not developed until

a) the 1900s c) this century

b) the 1800s d) 1492 ANSWERS 1. c 2.a 3.d 4.b 5.b 6.d 7.a 8.a 9.c 10.b

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5LESSON 1 THINGS TO REMEMBER

Ecology is a science

The term “ecology” is over 100 years old

Physicists apply the Laws of Thermodynamics to solve real world

problems

Paleontologists study ancient life on Earth

Chance plays an important role in science, especially in certain

discoveries

Even though you can’t do an experiment to test an idea, the idea could

still be right

After forming a working hypothesis, you should next test it

Flemming said that chance favors the prepared mind

Ecology is the study of the balance between organisms and their

environment

Non-living species are known as abiotic

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6LESSON 2: LIFE AND ITS WORKINGS

In order to understand the field of ecology, we

must understand what life is. In general, living

things:

- can grow

- can reproduce

- manage energy

- adapt to its environment

- gain rather than lose energy

Let us briefly explain each one. First, life

grows. A young organism will increase its size. It also reproduces itself.

Without this function, life would not have evolved and all species would

eventually die. A cell reproduces itself by splitting in half. In this process,

the cell divides. Then, each half-sized new cell then grows back to normal

size and the process begins again.

Third, life manages energy. Even at the smallest level of the cell, nothing

on this planet has come even close to the level of energy complexity shown

in even a simple cell.

Fourth, life adapts to its environment. Because the environment always

changes, life must also change in order to survive.

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Last, life gains energy. All things in the universe run down. A flashlight

will eventually run out of power. Stars will eventually burn out. Energy is

lost in an outward direction. The ultimate reason for this turns out to be the

expansion of the universe itself.

The total amount of energy in the universe is spreading out into an ever-

increasing volume. This type of energy is called entropy. Therefore, the

amount of energy in any one piece of the universe is decreasing over time.

However, life seems to be the exception. A

small seed will eventually grow into a gian

tree for example. The essence of life itself

is to grow, multiply and to increase the

energy within its system. This could ap

to the entire “biomass” of life on Earth,

which is the total amount or mass of living

things on the planet. At one point nearly

four billion years ago, the biomass

consisted of just one cell, which eventua

increased to all of the organisms we have today. In that sense, the

biomass has gained energy. It has gone against the direction of things

running down. That is

t

total

ply

lly

the nature of living things.

In order to know where life is heading, we must know where life has been.

From the fields of astronomy and geology, we know that the age of the

Earth is about 4.8 billion years. At the beginning of the Earth’s formation,

there was no land or air, only a ball of materials held together by gravity.

This “proto-planet” as it is called, began to change or separate much like

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milk and cream. The pull of gravity was directed towards the center of

mass, the same as it is today at the center of the Earth. On the early Earth,

the same situation existed. Heavy materials tended to fall towards the

center with light materials rising in the opposite direction just like is found in

the milk and cream.

The lightest materials were gases that drifted upwards to form the

atmosphere. In the meantime, there was no crust or solid surface for the

first billion years or so. The molten material cooled down enough to

become a solid. It would have been impossible for life to form before a

solid crust formed. High temperatures would have prevented life from

forming. The hot material would break any bonds that formed between

chemicals needed for life.

1 8Early Life

We have found some rare “fossils” (remains or

traces of early life forms found in rocks) of one

celled organisms in New Zealand that are

considered to be the earliest surviving records

of life on Earth. They date back to about 3.6

billion years. Nature has destroyed them by

now. These one-celled organisms had no hard

parts to create casts and molds. Finding such

fossilized remains is therefore difficult. In the mid 1990s, researchers

found what appear to be fossil bacteria in a meteorite that came from the

planet Mars! That meteorite may be as old as the New Zealand rocks.

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What was life like 3.6 billion years ago like? There probably was not as

much oxygen as there is at present. Early bacteria probably did not need

oxygen. Many biologists think that the primitive (anaerobic) bacteria

changed our atmosphere by making oxygen and releasing it into the

atmosphere, thus increasing the Oxygen levels. This would have allowed

aerobic bacteria to arise.

1 9Life Evolves

Life on earth first appeared in the seas, and

that is where it remained for over three billion

years. During most of that time, life grew as

celled animals and plants. Around 2/3 of a

billion years ago, life began to appear on land.

In the oceans, the first animals with hard body

parts (shelled animals) appeared. The first

vertebrates or animals with backbones also

appeared in the form of fishes then about 400

million years ago; the first plants appeared on land, followed by insects and

the first amphibians. By the end of the Paleozoic or “early era,” the first

reptiles had appeared. Some of these would evolve into dinosaurs.

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At the end of the Paleozoic Era, an important

event happened. Rocks of that period show

physical evidence of widespread glaciers.

There is evidence that many species became

extinct. Ice fields know as glaciers have

occurred at times throughout Earth’s history.

The last set of glaciers occurred within the

last million years. During those times, ice

sheets advanced from the North and South

poles changing the Earth’s climate as temperatures fell. Life had to adjust

to these changes. Some life forms were not able to adapt, so they became

extinct.

We know that there was an even earlier extinction event that occurred

during what is known as the Carboniferous or “carbon bearing” period

around 300 million years ago. During this time, the Earth was warm, and

giant tropical forests covered the world.

Then for some reason, most of the plants died. Over time, remains became

rock in the form of coal and liquid petroleum. Most of the world’s coal and

oil reserves come from plants of this period. The Carbon left the biosphere.

After the events of the Paleozoic Era, sometimes called the “age of

invertebrates,” the great Mesozoic Era or “age of the dinosaurs” arose.

Geologists have divided the era into three periods. During the Triassic

Period, the first small dinosaurs or “terrible lizards” and the first winged

reptiles appeared. By the Jurassic and Cretaceous periods, the first

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feathered birds appeared. The first warm-blooded mammals appeared

also, but they were very small and lived in

crevices in rocks.

f

t

s to

We

o

s survive and not others?

The fossil record shows that at the end o

the Cretaceous Period, over 95% of the

species of animals and plants became

extinct. At first, scientists thought that

the Earth’s climate must have changed,

and the dinosaurs failed to adapt to the

colder climate and died out. However,

there are many problems with this theory. First, we do not really know tha

the dinosaurs were indeed cold blooded and needed warm temperature

survive. The fossil record does not reveal this type of information.

know that cold-blooded lizards survived, like alligators and the Komod

dragons. Why would some animal

Today, another theory has replaced the climatic change model. This is the

asteroid impact model. Around twenty years ago, geologists began to

notice a thin layer of rock that contained the element Iridium between

layers of rock. This layer was deposited 65 million years ago when the

dinosaurs died out. Iridium is an element that would come from an object

like an asteroid from outer space. This suggested that a terrible event on a

global scale created this layer.

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Then, geologists found the “smoking gun”, a crater located off the Yucatan

peninsula in Mexico, which is about 30 miles wide and dates back to the

same time. Scientists calculate that an

asteroid five miles wide created the crater and

produced energy equal to that of thousands of

atomic bombs. Such an impact would have

produced a huge cloud of gas and debris much

as major volcanic eruptions do today. This

cloud surrounded the globe and drastically

altered the Earths climate for centuries.

We do not know for sure of course, that such

an event was responsible for the mass extinction event that happened on

our planet. However, even though the impacts of such large asteroids are

quite rare, we know they have occurred at various times over the Earth’s

long history. They are also likely to happen again. So far, a great volume

of evidence exists to make this the leading theory. The lesson learned is

that not all extinction events are predictable. The idea that the dinosaurs

died out because of not being able to adapt may not be true. They lived

from about 220 million years ago to 65 million years ago, a period of over

155 million years. Man, on the other hand, has only been around for about

a million years.

The last great era, called the Cenozoic or “recent era,” is the age of

mammals. The dinosaurs disappeared and the warm-blooded creatures

that gave live birth to their young emerged as the dominant species.

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Recently (within the last million years or so) other creatures have become

extinct as well. The great wooly mammoths and mastodons, the giant

ground sloths and saber-toothed tigers that once roamed North America

are now all gone. Some believe that

Man hunted them to extinction. We

know in some cases, the rapid clima

changes brought on by the g

resulted in changes in their

environment. Perhaps it was the

combination of both natural and

fabricated chang

te

laciers

es that resulted in

eir extinction.

t?

because they are all connected.

th

What should we gather from our study of the history of life upon our plane

First, we know extinctions happen naturally, and are usually the result of a

rapid change in the environment. These changes occur by geological

events or by changes in our Sun’s output or even astronomical events.

We also know that when we affect one part of the ecological chain, we

usually affect other parts as well

Energy is the ability to do work. In physics, it is a force applied across a distance or force multiplied by the distance. For example, in the English

system of units, a force of one pound that would push an object for one foot

is called the one foot-pound. In the metric system of units, we would use

the unit of force called a Newton (4.45 Newton's = 1 Pound) and a distance

of 1 meter to derive the Newton-Meter, also known as the Joule.

Physicists classify energy according to three types: radiation energy, such

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as that produced by the Sun; kinetic energy, or the energy of objects in

motion; and potential energy, or stored energy, such as the energy battery

or coiled spring. In reality, the first two types of energy are the only ones

manifesting themselves in the universe. Potential energy shows itself to

us.

In the case of life, energy shows itself in complicated ways. Where does

life get its energy? There is only one

answer; the Sun. Certainly, there is

heat energy escaping from the Earth in

the form of volcanic eruptions and

geysers like those found in Yellowstone

National Park. Almost all of the energy

life receives comes from the Sun. This

energy converts itself by making

complex chemicals by life. Organisms

break down these chemicals in their

bodies. Life releases kinetic energy in order to function.

The Sun emits electromagnetic energy. This energy travels at the speed

of light, or 186,000 miles per second! This energy can circle the globe

seven and a half times a second, and it takes a little over 6 minutes to

travel the 93 million miles from the Sun to the Earth. The Sun's

wavelengths (the distance between waves) vary from radio waves (the

longest) to gamma rays (the shortest). The Electromagnetic Spectrum

arranges itself as follows, from the longest waves to the shortest:

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We shall briefly discuss each of these and how they affect life. First, radio

waves have almost no effect on life. The energy in each wave above

increases as we go from the longest to the shortest waves. We might think

the longer waves contain more energy per wave, but the opposite is true.

Radio waves are very weak, and the television transmitters on Earth put

out much more combined energy in the radio portion of the spectrum than

our star, the Sun.

Microwaves are familiar to us all, from cell phone towers to cooking. Water

molecules vibrate at the same rate as these waves. Microwaves heat up

water very quickly. Any food containing water (and most does) heat up

quickly in a microwave oven. As with radio waves, however, the Sun does

not put out enough microwave radiation to affect the Earth’s life very much.

You feel infrared rays in the form of heat. This radiation has a major effect

on the Earth and therefore life on it. Heat determines climate, and climate

determines the types of life that can exist there. For example, we routinely

use “heat lamps” keep things warm. The amount of direct infrared energy

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coming from the Sun is not that great. We

feel the reflected infrared energy the most.

Do this experiment. Place the palm of your

hand down on a sidewalk. Where do you

feel the most heat; on your palm, or on the

back of your hand facing the Sun? The

answer is on your palm. You actually feel

more infrared energy reflected off the

sidewalk than that coming from the

is why temperatures are colder on mountains.

Their tops are further from the reflecting surface down below, producing the

heat energy, and it can get cold enough to produce snow at those altitud

Sun. This

es.

Why is the energy from the Sun re-radiated in the form of infrared?

Energy from visible light waves striking the Earth’s surface is not reflected

as light waves all of the time. Some of the light is absorbed directly, thus

heating up the surface. Some of the remaining portion of the light is

reflected as infrared. Some of the reflected visible light waves stretch out

and become infrared waves. Dark surfaces will reflect more infrared,

while light colored surfaces reflect less infrared and more of the visible light

that strikes it. Water for example, reflects very little infrared and therefore

appears black on infrared film or with infrared sensing satellite cameras.

Surfaces covered by plants will reflect some infrared, but not as much as

areas without vegetation, such as deserts, which produce warmer climates.

We are all familiar with visible light. The longest wavelengths of visible light

are red and the shortest are violet. The order of colors from longest to

shortest wavelengths is: Red, Orange, Yellow, Green, Blue, Indigo, and Violet. (See the graph shown) The percentage of the entire

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SURVEY OF ECOLOGY

electromagnetic spectrum we can see with our eyes is only about one

percent of the total range of wavelengths, so we only “see” a small portion

of the whole spectrum of energy waves from radio to gamma.

Ultraviolet, X-Rays, and Gamma Rays are grouped together because there

are layers in our atmosphere that block most of these high-energy waves

from ever reaching the ground. In a later section, we shall see how the

Earth’s ozone Layer blocks most of the harmful ultraviolet rays that cause

sunburn and skin cancers. We will show how Man’s activities have

changed this important layer. If it were not for those protective layers, the

harmful and high-energy waves striking our planet would have made it

impossible for life to evolve.

One of the factors that determines how much of the Sun’s radiated energy

affects the Earth is called “Albedo”. The amount of energy reflected by an

object makes up the amount of Albedo. In our case, we do not just mean

the energy from visible light, but the sum total of all electromagnetic energy

striking our planet. An albedo of 50 percent would mean that 50% of the

energy goes up the planet, while 50% is reflected or re-radiated back out

into space. A planet with a low albedo would therefore be warmer than a

planet with a high albedo even though both are the same size and same

distance from the Sun.

Energy changes when the oceans and land absorb it. “Conduction” and

“convection” carry the energy. Conduction is the direct transmission of

heat energy by a material. For example, heat energy conducts itself down

a metallic rod when one end is heated. The hot surfaces of land can also

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SURVEY OF ECOLOGY

transmit heat energy to the air above them. This is the mechanism that

creates the weather. Once the air is heated, it carries its energy to other

places by the second process, convection. In convection, heat moves by

taking a warm mass of air and physically

moving it by winds to other areas of the

planet. Moving air carries the energy,

causing most of the Earth’s weather

systems, and climatic variations that

affect life.

The Sun creates the energy needed for

life. Electromagnetic radiation, of many

types, strikes the Earth’s surface and provides energy for the production of

climates and weather. As we shall see later, it also provides energy for the

photosynthesis that plants need to convert carbon dioxide into oxygen and

to produce food.

7THE CHEMISTRY OF LIFE Chemicals make up all life, and chemicals are composed of atoms. The

science of chemistry focuses on how to put atoms together to make new

substances and how to take them apart to make other substances. The

atom was once thought to be the smallest particle of dividable matter.

There are 92 naturally occurring atoms. The only difference between them

is the number of protons in their center or “nuclei”. Hydrogen, the simplest

element, has only one proton in its nucleus. Helium has two. The largest

atom is uranium with 92 protons in its nucleus. Chemists have developed a

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SURVEY OF ECOLOGY

“periodic table” in which the atoms are arranged according to how many

protons are in the nucleus. This creates the atomic number. The number

of protons determines each element in the table. Every atom, except

hydrogen, has one or more neutrons in its

nucleus, as well as the positively charged protons. The neutrons are not

electrically charged and only

affect the atom’s total mass.

2 0The Role of Carbon Carbon is an element with

six protons in its nucleus,

giving it the atomic number of six. Ordinary carbon also has six neutrons

and six electrons. Two electrons are arranged in the innermost shell, and

the other four are found in the second shell

away from the nucleus. The outermost shell

can contain eight electrons, which means that

the Carbon atom can share all four of these

electrons with other atoms. This arrangement

creates a definition of four. This also allows

Carbon to form many bonds with other atoms. Silicon also has a definition

of four and can form many bonds, but only Carbon can form the most

complex ones. This is why Carbon forms the center of all life on Earth. No

other atom can do this.

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SURVEY OF ECOLOGY

In the field of ecology, a “limiting factor” explains how much an environment

can supply a certain population of organisms. If we were to consider the

biomass as a whole, the number of Carbon atoms available to it, would be

the ultimate “limiting factor” for how much the biomass could be. The

amount of raw materials limits the amount of life and the most important of

these raw materials is Carbon. When we look at the other types of atoms

that are most used to make up living things, we find that they include

Hydrogen, Oxygen, and Nitrogen. These elements seem to be plentiful,

and are not as much of a limiting factor as Carbon atoms.

We might ask, “Where are the Carbon atoms located that the biomass of

the Earth can use?” The answer is that they are located

in the atmosphere, the oceans or hydrosphere, and in

the “lithosphere” or solid (crust) of the Earth. For the

latter, we would have to say the upper crust because

it is only within a certain shallow depth. Carbon

atoms travel to the surface by geological processes.

Carbon atoms that are too deep in the crust of the

Earth cannot travel to the surface. The true limiting

factor from the number of Carbon atoms available to

make life is one we must take into consideration when

we try to determine how big the biomass could become.

One chemical molecule DNA makes life possible. James Watson and

Francis Crick discovered DNA in 1959. They called it the “blueprint of life.”

DNA is found in the nucleus of all cells. DNA creates the genetic code for

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the cell and the organisms that the cells make. In its simplest sense, a

DNA molecule resembles a twisted ladder or a spiral staircase. The edges

of the ladder are made of amino acids. A DNA molecule can contain

billions of these rungs, and the order of the four types of rungs can make

up an almost infinite number of mathematical combinations.

DNA is also at the heart of reproduction. We know that cells reproduce by

splitting in two. Each half, in turn, grows back to full size. It is actually the

DNA that splits first, to form an identical copy of.

Chemical cycles involving each element are responsible for transferring

energy between life forms and their

environment. This is done by chemical

reactions that occur within the cell and

outside the cell in the environment.

there is a limited supply of chemicals to

conduct reactions that liberate energy, the

process must be renewable. Otherwise, the

chemical reactions necessary would only occur once. The ultimate source

of the energy needed to drive these reactions is our own star, the Sun. O

air is made of around 79% Nitrogen and

Because

ur

only about 20% Oxygen.

Oxygen enters our body through the lungs. Lung tissue allows it to be

absorbed into our blood. The blood carries it to the trillions of cells in our

bodies. Inside the cells, oxygen reacts with sugar (glucose) to form carbon

dioxide, water and energy. Water and other waste products filter the blood

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through the kidneys. The carbon dioxide leaves the body through the lungs

in a process known as “respiration.”

In a similar process called “photosynthesis,” plants take the carbon dioxide

out of the air and combines with water to release pure oxygen back into the

atmosphere. At the same time, plants make glucose, which later becomes

food for animals. In photosynthesis, the plants use a chemical called

“chlorophyll” which gives plant leaves

their green appearance. Radiation (light)

from the Sun provides the energy for

photosynthesis to occur. It is necessary to

have enough photosynthesis occurring to

balance the amount of respiration from

the entire biomass.

The nitrogen cycle is more complex in many ways than the Oxygen cycle.

Nitrogen is an essential component of

proteins and amino acids. As

previously stated, the air is 79%

nitrogen, so air is the main source of

the Nitrogen available to the

biosphere. The nitrogen in the air

provides chemicals that plants can

use to make the amino acids and

proteins. First, however, the nitrogen must find its way into the soil in the

form of usable chemicals. This process happens in several ways.

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First, lightning in the Earth’s atmosphere converts Nitrogen gas into nitrous

oxide.

There are also some direct ways that Nitrogen converts itself to the

chemicals needed to make necessary chemicals for life. Some plants

have nodules on their roots that contain Nitrogen-fixing bacteria. These

bacteria perform the above changes.

While plants make the amino acids and proteins from nitrogen-bearing

compounds, there must be a process to return free Nitrogen gas to the air.

When plants and animals decay after death, this decay converts the

nitrogen that is released in the form of salts and nitrates.

Many other chemical cycles that take place perform the energy regulation

of animals and plants. One of these is the Phosphorus Cycle. Phosphorus

is found only in the soil and water and is ingested by animals when they

eat. The Phosphorus then returns to the ground in the form of animal

urine. Thus, the phosphorus system is a closed system.

PRACTICE QUESTIONS 1. A cell splitting in two is an example of:

a) entropy c) growth

b) reproduction d) none of these

2. Changing to live in a different environment is an example of:

a) growth c) entropy

b) mutation d) adaptation

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3. The oldest fossils date to about ____ billion years ago.

a) 2 c) 6.8

b) 8 d) 3.6

4. The extinction of the dinosaurs is now thought to be due to:

a) a collision from an asteroid c) lack of food

b) a change in climate d) none of these

5. The longest wavelengths of visible light are the color:

a) blue c) yellow

b) red d) orange

6. The shortest wavelengths in the electromagnetic spectrum are:

a) infra-red c) gamma

b) ultra-violet d) radio

7. Which atom most resembles Carbon for chemical bonding ability?

a) Oxygen c) Aluminum

b) Nitrogen d) Silicon

8. Crick and Watson unraveled the mystery of ________.

a) sugars c) DNA

b) photosynthesis d) phosphates

9. Most of the air we breathe is made up of _________.

a) oxygen c) carbon

b) helium d) nitrogen

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10. In respiration _________ is broken down into Carbon dioxide,

water and energy.

a) glucose c) chlorophyll

b) nitrogen d) iron oxide

ANSWERS 1.b 2.d 3.d 4.a 5.b 6.c 7.d 8.c 9.d 10.a

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8LESSON 2 THINGS TO REMEMBER

Entropy involves the loss of energy over time

All life forms reproduce

The blueprints of all cells are chemicals called DNA

The oldest fossils date to about 3.6 billion years ago

The Newton-Meter is most often felt as heat

Infrared radiation is most often felt as heat

Earth’s biomass is limited mainly by the amount of carbon atoms

Most of the air we breathe is made up of nitrogen

Glucose is made in a process called photosynthesis

The Phosphorus Cycle is a closed system

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9LESSON 3: POPULATION AND REGULATION

The Cell

The cell is the basic unit of life. It contains the nucleus, which directs all

activity taking places inside of it. The nucleus contains the DNA, which is

the blueprint of life. Outside of the nucleus, various organelles make

chemicals that allow the cell to function. Plant cells also have green

chlorophyll that conducts photosynthesis. They also have thick walls that

appear like rectangles. Animal cells do not have these rectangular walls.

The basis for heredity is contained

within each cell’s DNA. The DNA

carries all of the information to make

new organisms. In this lesson, we

shall see how these organisms

interact with each other and the

environment in which they live.

2 1Ecosystems and Habitats

An “ecosystem,” first named by A.G. Tansley in 1935, is a unit of living and

non-living components that interact to form a stable or balanced system.

Ecosystems typically extend over large areas. The study of ecosystems is

done through observation and by making comparisons with other

ecosystems.

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A “habitat” is an area within an ecosystem area that an organism lives. For

example, the habitat of a certain species of bird like the blue heron might

be near the shoreline of lakes. The water lily occupies the surface of

freshwater lakes and ponds. A pond community extends into a number of

localized habitats. A “niche” occupies a particular location within a habitat.

Niches define the nature of a habitats source of food in the case of animals.

2 2Continental Drift

Biomes define a geographic region that supports one or more ecosystems.

One of the main reasons that we now

have different biomes is that the

continents have undergone dramatic

changes since forming the crust of the

Earth. They broke apart from a single

land mass called Pangea over 250

million years ago. Because of this,

today we can divide the world into about

nine major regions. The groups of animals living in each of these regions

called “Biomes”. Scientists now know that migration took place between

biomes.

The Earth is divided into many biomes, which Biomes become terrestrial

(land) and aquatic (watery) types. This following is a partial list of biomes:

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Taiga, Tundra, Steppe, Savanna, Desert, Tropical Rain Forest, Fresh

Water, and Deep Ocean.

Taiga: “Taiga” is also known as coniferous forest. In this biome, coniferous trees

do not shed their leaves because the growing season is too short to allow

them to shed and regrow their leaves each year. Their leaves are hardy

and survive throughout the winter. Despite of the harshness of each

winter, many species of plants and animals exist in the Tiaga. These

include mammals like badgers, wolves, bears, wolverines, elks and even

rodents. Birds like finches and thrushes are also plentiful. These birds can

split fur cones with their modified beaks to obtain food. Insects in this area

include beetles, wasps, moths and flies. Perhaps the most famous animal

that lives in this area is the Siberian tiger, an animal that is especially

adapted to live with harsh winters.

Tundra: Tundra” is a word that means an open

and desolate stretch of country. Tundra

biomes are found either north of the

northern Arctic Circle or south of the

Antarctic Circle. There are only

patches of coniferous forest in valleys.

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For most of the year, the ground is frozen, but during the extremely short

summer months, the temperature can rise above freezing for very short

periods.

As we go closer to each pole of the earth, the climate becomes “polar”.

These climates are extremely cold and it is possible in the areas to have

more than 24 hours of darkness (up to six months at the poles). There is

hardly any rain, so only the hardiest plants can survive. Animals such as

wolves, bears, caribou, arctic hares and foxes live in the tundra. Seals and

penguins also live there.

Steppe: A “steppe” is primarily grassland. It exists in areas where summers are hot

and winters are cold. There are very few trees. Scientists find the largest

steppe in the world on the continents of Europe and Asia. The grass

extends for thousands of miles across each continent. In North America,

we call the steppe the great prairie. This is where our wheat is grown as

well as other crops. Biologists find bison in the great prairies in North

America. For economic reasons, cattle and sheep have now replaced the

bison. In Asia, the Saiga Antelope was hunted almost to extinction. In the

southern hemisphere, the steppe is known as the Pampas and exists

primarily in Argentina.

The steppes of the world provide much of the human population with its

source of food, both in terms of grain and in animals. It would not take

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much of a global climatic shift to dramatically alter these areas. The

change would result in catastrophic results for humankind.

Savanna: Tall species of grass that may

grow as high as one and one-

half meters lives in the Savanna.

There is much rainfall during

certain times of the year and

many varieties of trees that live

in the savanna. Much of

northern Africa just south of the

Sahara Desert is savanna. Insects are also plentiful and frequently include

termites and vast swarms of locusts and grasshoppers. Birds are plentiful

in the savanna with many migratory species being present.

In addition, large, round species of birds such as ostriches, peacocks and

emus live there. The

mammals of the

savanna are generally

large such as buffalos,

antelopes, zebras and

lions.

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Deserts: Rainfall in deserts is usually less than ten inches per year. Most deserts

are extremely hot and are located near the equator. At night, in some

deserts like the Gobi in Mongolia, temperatures are below freezing. Most

deserts support little or no vegetation apart from a few shrubs. The wide

space between desert plants means that there is very little competition for

available water. Most animals in the desert exist by burrowing below the

surface of the sand and include small lizards and insects. Because of the

natural insulation that both animals and plants demonstrate in the desert

environment, there is a smaller amount of interaction between species than

in other biomes.

Tropical Rain Forest: The tropical rain forest contains the most species of animal and plant life on

Earth. It extends around the world near the equator on the continents of

South America and Africa and into the

Indo-Pacific region. The rain forest

has high temperatures throughout the

year; it also has high amounts of

rainfall.

These conditions allow for a great

abundance of life, with more species

of plants per square acre than

anywhere else on the planet. Smaller

mammals must navigate their way cautiously through the underbrush. The

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rain forest is also home to the largest variety of reptiles on Earth. This is

because reptiles are cold blooded. We find snakes like the South

American Anaconda (the largest snake in the world) her

e also.

In addition, there is a tremendous variety of birds, including toucans and

parrots, which feed on the tropical fruits located in this biome. Insects are

also numerous, including termites that assist in the decay of trees. The

termites are also a source of food for birds and other animals.

Fresh Water: We find bodies of fresh water all over the world, including rivers, ponds,

lakes and inland seas. They are relatively shallow and generally less than

1,000 meters deep as opposed to oceans, which average almost four times

as deep. The life that inhabits these bodies of water varies with the depth

of water, which in turn varies with temperature and light.

Only the top few centimeters of a lake

for example, will receive sunlight in

sufficient quantity to heat the water.

The light simply does not penetrate

below that level. The mixing layer

distributes this warm water within the

top 10 meters.

Wind driven waves mix the upper layer to make one uniform temperature.

Below that is the colder bottom water. Here, the water does not mix, and

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life forms are radically different. In between, there is a boundary called the

“Thermocline”, where temperature drops suddenly.

Shallow Ocean: The force of the wind drives surface currents. Wind is the primary mover of

waters, but large currents are created by the landmasses that the moving

water strikes. These ocean currents tend to move in large circular motions.

The North Atlantic Ocean, for example, rotates in a slow clockwise

direction. Life forms in the oceans follow a food chain that begins with

phytoplankton at the bottom of the chain and ending with species such as

large fish. Because the phytoplankton is the beginning of the food chain,

the surface currents of the oceans determine how much phytoplankton

exists.

The Deep Ocean: The deep ocean biome extends from the

edges of the continental margins or

shelves to the deep ocean abyss. Here,

life forms that swim are not as numerous

as those nearer to the surface, although

strange animals do exist here. These

animals are able to withstand the

tremendous pressures that exist at these

depths, and many have their own built-in

lights along their bodies.

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Living organisms exist in harmony with their environment. However, we

can classify them into groups called Producers, Consumers and

Decomposers. Each one has a vital roll to play with respect to one another

based upon how they obtain energy from the environment.

Autotrophs and Heterotrophs

Many organisms are called autotrophs because they make their own food.

Some autotrophs get their initial energy from chemical reactions in their

environment. Other autotrophs, such as plants, obtain their energy from

the Sun and use it to make their own food in the form of simple sugars.

Heterotrophs, in turn, use the autotrophs

for their own food sources. These include

all animals. Ecologists consider

autotrophs to be producers, because they

produce the food for themselves and

other non-producers. We call

heterotophs “consumers” because they

consume or use autotrophs for their food

supply. We can divide heterotrophs into

two groups. Primary consumers include

plant eaters, while secondary consumers include the animals that prey on

them, such as lions, tigers and Man.

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Another type of heterotroph becomes decomposers; these organisms

include certain types of bacteria, fungi, and simple one-celled animals

called protozoa. They exist on the decaying remains of other organisms.

PREDATORS AND PREY

The relationships between organisms take on sometimes-complex forms.

Many organisms exist by sharing a common place. Some live together

either to each other’s advantage or to the advantage of themselves. In

such cases, the other organism can either remain unaffected or become

negatively affected.

We can classify the relationships among organisms into the several forms.

Mutualism: Two organisms are dependant on each other by a link in metabolic processes. These organisms can

be of different species in these cases either

organism can benefit from the association.

Commensalism: Two organisms share a common food or a common

living.

Parasitism: One organism obtains food from a host organism. One organism benefits, while the other is to some

degree adversely affected.

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Symbiosis: Two organisms live together and each provides the

other with something they need.

Predators hunt, kill and eat other animals known as prey. They perform the

same function as carnivorous plants like the Venus fly trap and insects like

the black widow spiders that devour their mates. Predators are a most

important part of ecological balance. The numbers of predators in an area

determines the numbers of prey, and that in turn determines the numbers

of predators.

Predators generally develop specific hunting methods to obtain their prey.

Predators can sneak up on prey by

carefully approaching from behind. They

can remain almost motionless until it is

time to strike. Like the cheetah, some

predators can simply outrun their pre

Predators can kill by brute force, by

suffocation (such as boa constrictors), by

injecting poison, or in

y.

the case of Man, by

e use of weapons.

ary

ber

th

Population control becomes the basic relationship between predator and

prey. In a limited area in which only one primary predator and one prim

prey exist, an increase in predators would result in a decrease in its prey.

This decrease would limit the food supply available to the predators and

result in a decrease in their numbers as well. The decrease in the num

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of predators would allow for an increase in the number of prey. This cycle

is illustrated in Figure 1.

In the above diagram, the thick line

marks the population of the

Snowshoe Hair, while the thinner line

marks its natural predator, the Ly

As we can see, the Lynx population

increases as the prey or natural

source of food increases. Once the

Lynx population reaches a high

point, the Snowshoe hair population

begins to dec

nx.

rease because the predator kills them off. As the Snowshoe

e Hair population begins to drop, the Lynx population does likewise becaus

its source of food has decreased.

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SURVEY OF ECOLOGY

55

This pattern follows roughly a ten-year cycle. The cycle of the Lynx lags

behind as the result of the population trends of the prey.

FOOD CHAINS AND WEBS Food chains begin with producers. On land, this would include plants of all

types, and in the oceans would begin with algae. The next tier or ‘trophic’

level becomes the Primary Consumers. These include grazing animals

such as sheep and cows on land, and crustaceans in the oceans. We call

the third tier or secondary level, tertiary. Here can be found the fishes in

the oceans and on land various carnivores such as wolves. There may be

tertiary consumers for the next tier, such as humans on land or sharks in

the ocean. Tertiary consumers are generally carnivores. We reserve the

term “top” for the species at the top of

the food chain. In each of these chains,

there may be as few as two tiers, but

there are usually no more than five tiers

or levels.

An energy pyramid like the one on the

left models a food chain. [See Figure 2]

The lowest level of the pyramid represents the initial producers within the

ecosystem. The ascending levels of the pyramid become smaller.

Pyramids represent either the decreasing number or populations of

organisms at each higher level, or the total amount of biomass represented

by each group.

SURVEY OF ECOLOGY

56

Figure 3 Food webs are interwoven food

chains, and involve a great number

of organisms. Some animals can

feed on a variety of other animals or

plants. This leads to a relationship

among the chains that make up the

web. Figure 3 shows a simple food

web.

Each of the organisms becomes a series of complex food chains. These

may vary with seasons or other environmental conditions.

PRACTICE QUESTIONS 1. An area that a particular organism occupies is known as its:

a) biome c) habitat

b) niche d) range

2. A coniferous forest is known as:

a) Tundra c) Stepp

b) Tiaga d) Savanna

3. An area in the oceans or other bodies of water, where the

temperature drops off is called the:

a) thermocline c) ooze

b) halocline d) varve

SURVEY OF ECOLOGY

4. _________ make their own food.

ls

. Heterotrophs are considered ____________.

c) scavengers

. Primary consumers include:

b) rnivores d) tigres

r food, this is

called:

d) Symbiosis

relationship.

. The tiers on the food pyramid are called ______ levels.

a) autotrophs c) anima

b) heterotrophs d) all organisms

5

a) producers

b) consumers and decomposers d) parasites

6

a) herbivores c) plants

ca

7. When two organisms that share a common living space o

a) Mutualism c) Commensalism

b) Parasitism

8. In the case of _________ both organisms benefit from the

a) Mutualism c) Symbiosis

b) Commensalism d) Parasitism

9

a) hierarchy c) energy

b) trophic d) quantive

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10. The top carnivore is at the _____ of the food chain.

b) bottom

NSWERS

a) top

c) middle d) anywhere

A .c 2.b 3.a 4.a 5.b 6.b 7.c 8.a 9.b 10.a

1

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1 0LESSON 3 THINGS TO REMEMBER

1 1A geographic region that supports one or more ecosystems is a

biome

The original super-continent is called Pangea

Secondary consumers include tigers

The Sun is the ultimate source for the energy obtained by producers

The number of predators in an area determines the number of prey

The number of prey determines the number of predators

Mosquitoes and ticks are an example of Parasitism with humans

Food webs consist of many food chains

Food chains and webs represent how energy flows within an

ecosystem

There are more producers than consumers

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LESSON 4: THE HUMAN FACTOR

R.T. Malthus first began the study of populations. He said that without

various checks on growth, the number of many animals, including humans,

would grow at increasing rates until the Earth was covered. However,

limited resources would prevent this from happening. This would stop any

further population growth. He realized that there had to be a constant and

firm checking process to limit populations.

Population Limits

Figure 1. shows the growth in

population while the limiting

factors are not involved. The

environment levels the growth

rate. The growth curve is not

always followed. These may

include times when too many organisms have to compete with each other

for limited resources. If population growth gets too large, it is called

"asymptotic."

The Rise of Humans

Man has had a tremendous impact on every ecosystem of the world, yet he

is a recent introduction to the planet. Man has caused much extinction

among plants and animals. We have caused many problems for living

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things (including ourselves) with our technology. With the same

technology, we have interfered with nature’s own extinction plans. We are

also beginning to use the same technology that caused the problems in

order to solve many of them.

The Arrival of Man

In order to understand how we have affected life on the planet, it is

necessary to understand how recently we arrived on earth. We will fit the

history of the Earth into a calendar year in order to understand this. Let us

pretend that the Earth was formed on January 1st, the first day of the year.

The present date and time is at 12:00 midnight New Year’s Eve. The

whole history of the Earth squeezes into the twelve months that have taken

place from January 1 through December 31.

On this scale, the 4.8 billion year estimated

age of the Earth becomes twelve months,

and each month represents 400 million

years. On this scale, life did not begin until

the Earth cooled off enough to form a solid

crust. The oldest fossils we find are about

3.5 billion years old. This would mean that

life first appears in mid-March.

The first clams did not appear until 550

million years ago, which would be around

late November on our time scale. The

earliest dinosaurs arrived around 200 million years ago or around mid-

December.

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They died out 65 million years ago, which would be around December 26.

The earliest manlike creatures did not appear until about 2 million years

ago, or around 8 PM on New Year’s Eve. Modern man did not appear until

around 500,000 years ago or around 11 PM on the clock. Written history

fits itself into the last 1/100 of an hour, or about the last 36 seconds of the

clock!

The earliest age became the Paleolithic or “Stone Age”. Man used stone

tools and there is evidence that he hunted animals like the Mammoth.

Then, about 5,000 B.C. something happened. Man settled down and

formed civilizations. The earliest civilization arose in the Middle East

(known as Iran today).

The Industrial Age

The Industrial Revolution

developed the machine

tools that allowed for mass

production. Many people

had already moved to cities

for better job opportunities;

this move created factories whose pollution affected nature. The Industrial

Revolution lasted well into the 19th century. Another important factor that

shaped the modern world was the dramatic rise in human population,

shown below in Figure 1.

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In ancient times, the total number of people living on the planet was only a

few hundred thousand. By 1800, it was still fewer than a billion people. It

rose to about 2 ½ billion people by 1950 and then climbed to 6 billion

people by the year 2000. Today, world population is about 10 billion

people, which has put a strain on the Earth's resources.

World Population Growth, 1750–2150

Source: United Nations, World Population Prospects, the 1999.

.

Figure 1. World Population Growth

Pollution Pollution can be either natural or fabricated. Any type of substance or

condition that pollutes or negatively affects the environment becomes a

pollutant. Natural pollution can happen from things like volcanic eruptions.

Man causes pollution on a global scale. To understand Man’s impact, we

will first study the role of water in the environment.

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The hydrologic cycle keeps water fresh and usable by living organisms.

Water is essential for all life, and without this cycle, life would not exist on

Earth.

The Hydrologic Cycle

Pollutants in water come from many sources. Disease-causing bacteria and

viruses can cause severe illnesses and even death. Plant fertilizers are

natural products of farming. They keep soil rich. However, they run off

into bodies of water such as ponds and lakes causing algae and other

growths that take the natural oxygen out of the water and cause fish kills.

Sewage plants also increase the level of pollution in bodies of water.

Construction, mining and run-off from rainwater from cities also add to the

problem.

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Disasters caused by pollution are not uncommon. The well-known Exxon

Valdez disaster in 1989 resulted in an oil spill that coated over 1,000 miles

of shoreline in Alaska. It destroyed thousands of animals. A large oil ship

went aground and spilled millions of gallons of oil into the sea.

Solid Waste By far the largest pollutants on land are solid wastes. Most solid wastes

come from mining and oil production. Only about 1½ % of the total solid

wastes that affect the land come from cities and household activities. Over

75% of all solid wastes come from mining and related sources. The

remaining 23% of solid wastes come from industry and agriculture.

Unfortunately, the definition of “hazardous

waste” does not include that made by oil and

gas drilling. It also excludes the many

hundreds of thousands of small businesses

because regulations do not affect them. The

United States has less than 5% of the world's

people, but we provide over 50% of all

hazardous wastes.

One of the ways that we can reduce these wastes is by recycling. There

are two types of recycling. Primary recycling completely remakes waste

products. An excellent example of this is paper. Recycled paper used in

many newspapers is made almost entirely of previously used paper.

Secondary recycling uses only part of what is recycled to make other

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products. Many products today have labels that say that they are

“biodegradable”. Generally, this means that they can be broken down into

simpler chemicals. However, this term is sometimes misleading. It simply

means that a waste product can break down. However, the chemicals that

it breaks down into can be harmful to the environment. As of 2005, about

1/3 of all waste products that are discarded onto land are recycled in the

United States. In Europe, it is a bit

higher. In the Netherlands, for

example, there is a charge at

supermarket registers for plastic bag

customers do not bring in their own

s if

ontainers to take groceries home in.

s

.

ate way of

storing solid wastes has been found.

c

We bury many solid wastes in giant

landfills at the present. While landfill

provide a relatively cheap source of

disposal, they have their drawbacks: (1) toxic gases from landfills were

released into the atmosphere, adding to the greenhouse affect (2) landfills

take up space and (3) it takes many years to break down these wastes. U

S. Landfills are now responsible for nearly 40% of all of the nations.

Methane emissions are about 10% globally. Other methods of disposing

solid wastes are being studied. We can make storage facilities above

ground, but these are very expensive. Presently, no adequ

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The Atmosphere

In addition to carbon dioxide and methane that contribute to what are called

"green house gasses", there are two other forms of pollutants to the

atmosphere. The first one is acid rain. By burning fossil fuels in power

plants, we produce water vapor that contains sulfuric- acid. It enters the

rain that falls to the earth as part of the hydrologic cycle.

While the acidity of the rain is not great, it is enough to affect ponds and

lakes to the point where certain species disappear. The acid also attacks

some of the sensitive leaves of plants in various areas. The problem of

acid rain will not go away until cleaner burning power plants are made.

Another form of pollution is in the form of chloro-flouro carbons (CFCs).

These chemicals attack the ozone layer. We find the ozone layer high in

the atmosphere of the Earth. It is very important to life on the surface of

the planet. The ozone layer blocks ultraviolet radiation from reaching the

surface of the Earth and damaging life forms. If it were not for the ozone

layer, we would become sunburned in minutes.

Ozone

The Sun recharges the Ozone layer each

day. However, CFCs emitted from spray

cans and air conditioners break down the

ozone layer. CFCs act as “catalyst”,

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which is a substance that causes chemical reactions to take place but do

not become involved in those reactions. Even a small amount of CFCs can

break apart an amount of Ozone equal to the size of a large classroom.

We have made CFC propellants for spray cans for many years. Many

countries have signed treaties agreeing to substitute other chemicals for

CFCs. In the United States, mechanics must inspect car air conditioning

units to make sure that there are no leaks before they recharge them with

CFCs. Because small amounts of CFCs can destroy so much Ozone,

scientists were worried for years that we could be destroying the Ozone

layer around the planet. In the late 1980s, a satellite found a hole in the

Ozone layer above Antarctica. Many scientists argued that we had finally

opened a hole in the Ozone layer. Other scientists argued that the hole

might have been there all the time. Studies have shown that even a small

increase in the amount of ultraviolet radiation reaching the surface of the

Earth would result in hundreds of thousands of cases of skin cancers per

year.

Scientists have also studied

global warming for some time.

The hurricane season of 2005

produced some of the worst

storms in 125 years of recorded

history. The storms happened

during the same year that the

world’s warmest average surface

temperatures were recorded.

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Many scientists have questioned if this has been a mere coincidence, or if

we are beginning to experience the effects of global warming. The

average surface temperature of the Earth is critical to all life on the planet.

Sudden changes could result in catastrophic effects for all life forms.

Our Earth is able to support life because its surface has the right

temperature range for life to be able to grow. An average DNA molecule is

billions of links long. If the temperature on Earth were too high, long

molecule chains could not form. Chemical bonds would not operate to form

such chains. Most life on this planet lives in a temperature range from 0

degrees Celsius to around 30 degrees Celsius. This range is due in part

to our average distance from the Sun (about 93,000,000 miles). This

allows for just the right amount of solar energy to strike the Earth. Some of

the energy is reflected back into space. The amount of radiation

determines a planet’s albedo. For any distance from the Sun, a planet with

a high albedo would reflect a larger amount of energy back into space.

This would mean a smaller amount of energy absorbs itself into the planet’s

surface. Because the absorbed energy heats up the surface, a planet with

high albedo develops lower surface temperatures.

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Figure 2. Albedo

Figure 2 shows how the Earth manages the amount of

solar energy it receives. The Earth’s albedo is about

30%, which means that only about 30% of the sun’s

energy is reflected back into space.

While 30% of the Sun’s energy reflects back into space, different portions

of the Earth are responsible for differing amounts, as shown below.

Surface Albedo Clouds 90%

Oceans and Lakes 10%

Desert 30%

Grasslands 20%

Forest 10%

Concrete 15%

Asphalt 10%

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Changing the amount of each of the

above surfaces would affect the

average surface temperature of the

Earth. For example, if any surface with

an albedo below 30% increases, the

Earth would appear darker and the

surface would get warmer than it is

today. If the albedo of a surface higher

than 30% increases the surface

temperature of the globe would decrease. An increase in cloud cover over

time would result in a colder planet, while an increase in grasslands, forest

and surfaces that are found in cities such as concrete and asphalt would

mean higher global temperatures. At present, we are destroying available

grassland and forests, while increasing surfaces covered with asphalt and

concrete, all of which result in a warming effect globally.

In addition to the effects of albedo, there is the “Greenhouse Effect”.

Gases in our atmosphere trap some of the energy that the Earth sends

back out into space. When you enter a greenhouse, you notice how much

warmer it is inside. There may be snow on the ground outside, but it is

noticeably warmer inside. Only a thin pane of glass exists for the walls of

the greenhouse. Sunlight consists of various wavelengths of energy, which

pass through the transparent glass to enter the greenhouse. Once inside,

they strike various surfaces. Part of the light is reflected, and a portion gets

absorbed. The light energy turns into heat. Some of that energy reflects

itself in the form of Infrared waves. Infrared radiation exists at slightly

longer wavelengths than red, and so we do not see them, but we feel them

as heat. It is the infrared waves that we feel when we place the palm of the

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hand above a sidewalk. While the Sun warms the top of our hand facing it,

you actually feel more heat radiated from the sidewalk because of the re-

radiated infrared energy.

Figure 3. shows how the Greenhouse

Effect occurs with infrared radiation being trapped inside the glass walls of

the greenhouse.

Figure 3

How, then, does the greenhouse effect operate on Earth? The answer lies

in our atmosphere. It contains mostly nitrogen and oxygen, but also has

other gases like carbon dioxide and Methane. Although these gases are

less than one percent of the total gases in the

atmosphere, they play an important role in

creating a partial greenhouse effect for the

planet. These gases make over 80% of the

greenhouse effect for the planet.

If too much of these greenhouse gases get

into the air, we could have a ‘run-away

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greenhouse effect.’ Global temperatures would cause widespread forest

fires that add more carbon dioxide to the atmosphere. If the Earth were to

experience a run-away greenhouse effect, the surface temperatures and

carbon dioxide levels would resemble the planet Venus. On that planet,

temperatures are twice as hot as a pizza oven and a lethal atmosphere of

carbon dioxide blankets the planet.

The Earth, however, also benefits from the partial