Survey of Ecology
By: Barry Perlman
v 1.0
SURVEY OF ECOLOGY
INSTRUCTIONS
Welcome to your Continental Academy course “Survey of Ecol ogy”. It is
made up of 5 indi vidual l essons, 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:
ƒ Click on the “Send a Message” link on the left side of the home
page
ƒ Select “Academic Guidance” in the “To” field
ƒ Type your question in the field provided
ƒ Then, click on the “Send” button
ƒ
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You will receive a response within ONE BUSINESS DAY
SURVEY OF ECOLOGY
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
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Lesson ................................................................................................................ 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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1
LESSON 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:
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Physics
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.
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Chemistry
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.
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Geology
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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Meteorology
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.
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Oceanography 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
into theories.
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 wrong with
doing this. Perhaps you should have done an
experiment or test. The simplest one would have been to ask your friends
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 the
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 set of
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 lighter
ones. It was not until the early 17th century that the Renaissance scientist
Galileo Galilae proved the idea false by
doing some simple tests that showed that
gravity acts equally on different objects.
Why, then, did the great Greek civilization
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 argued
that even with the most carefully placed controls, outcomes would be
affected.
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 (quantum
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 errors get smaller at
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
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 were simply wrong. Galileo showed
that objects fall at the same rate regardless of how heavy they were.
Modern science began at that time.
Even though scientists like Galileo tested their ideas, they did not do true
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 not
until the first scientific societies formed in the
19th century Europe that formal rules about
experiments came about. These consisted of
having control groups, obtaining repeated results and gathering proper data
for analysis. Even though these
societies came up with the basic
method outlined at the beginning of
this lesson, they were the first to
realize that it was not the only
method useful for science.
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2
Chance
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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3
Theory 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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4
Summary
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
b)
geology
c)
d)
astronomy
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
b)
ocean life
c)
the universe
d)
life
8. After forming working hypotheses, you should next _________.
a)
test it
c)
b) refine it more
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do initial observations
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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5
LESSON 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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6
LESSON 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 everincreasing 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 giant
tree for example. The essence of life itself
is to grow, multiply and to increase the total
energy within its system. This could apply
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 eventually
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 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.
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Early 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.
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Life 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.
The fossil record shows that at the end of
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 that
the dinosaurs were indeed cold blooded and needed warm temperatures to
survive. The fossil record does not reveal this type of information. We
know that cold-blooded lizards survived, like alligators and the Komodo
dragons. Why would some animals survive and not others?
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 climate
changes brought on by the glaciers
resulted in changes in their
environment. Perhaps it was the
combination of both natural and
fabricated changes that resulted in
their extinction.
What should we gather from our study of the history of life upon our planet?
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 because they are all connected.
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 Sun. This
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 altitudes.
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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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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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.
7
THE 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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“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.
20
The 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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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. Because
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. Our
air is made of around 79% Nitrogen and 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)
b)
reproduction
growth
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
b)
ultra-violet
c)
gamma
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)
b)
photosynthesis
DNA
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
40
2.d
3.d
4.a
5.b
6.c
7.d
8.c
9.d
10.a
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8
LESSON 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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9
LESSON 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.
21
Ecosystems 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.
22
Continental 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 onehalf 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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SURVEY OF ECOLOGY
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) here 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 prey.
Predators can kill by brute force, by
suffocation (such as boa constrictors), by
injecting poison, or in the case of Man, by
the use of weapons.
Population control becomes the basic relationship between predator and
prey. In a limited area in which only one primary predator and one primary
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 number
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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 Lynx.
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 decrease because the predator kills them off. As the Snowshoe
Hair population begins to drop, the Lynx population does likewise because
its source of food has decreased.
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SURVEY OF ECOLOGY
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.
55
Figure 3
SURVEY OF ECOLOGY
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
b)
56
halocline
c) ooze
d)
varve
SURVEY OF ECOLOGY
4. _________ make their own food.
c) animals
a) autotrophs
b) heterotrophs
d)
all organisms
5. Heterotrophs are considered ____________.
c) scavengers
a) producers
b) consumers and decomposers d) parasites
6. Primary consumers include:
a)
herbivores
c)
plants
b)
carnivores
d)
tigres
7. When two organisms that share a common living space or food, this is
called:
a)
Mutualism
c)
Commensalism
b)
Parasitism
d)
Symbiosis
8. In the case of _________ both organisms benefit from the
relationship.
a)
Mutualism
b)
Commensalism
c)
Symbiosis
d)
Parasitism
9. The tiers on the food pyramid are called ______ levels.
a)
hierarchy
b) trophic
c)
energy
d) quantive
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10. The top carnivore is at the _____ of the food chain.
a)
top
b) bottom
c) middle
d) anywhere
ANSWERS
1.c
58
2.b
3.a
4.a
5.b
6.b
7.c
8.a
9.b
10.a
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10
™
11
LESSON 3 THINGS TO REMEMBER
A 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 midDecember.
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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 bags if
customers do not bring in their own
containers to take groceries home in.
We bury many solid wastes in giant
landfills at the present. While landfills
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 adequate way of
storing solid wastes has been found.
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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
Forest
20%
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 reradiated infrared energy.
Figure 3
Figure 3. shows how the Greenhouse
Effect occurs with infrared radiation being trapped inside the glass walls of
the greenhouse.
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 greenhouse effect. Our
global surface temperatures are warmer than they ought to be at our
distance from the Sun. Without a slight greenhouse effect, our planet might
not be livable, but too much would have the opposite effect.
The central
question is whether the greenhouse effect is increasing since the activities
of Man began. This is mainly due to the increase in carbon dioxide and
methane produced on Earth. Even a slight increase in global temperature
could bring us out of the last ice age faster than projected. Warming of the
atmosphere by a few degrees would probably result in a faster melting of
our remaining polar ice caps. This would result in an increase in sea level
when the ice became ocean water and began flooding of low-lying areas.
A central questions remains: how much has the level of these gases risen
as the result of our presence? We have to understand that the impact of
human civilization was minimal up to the Industrial Revolution. Until that
time, the human population was far less than now. We did not pave over
large sections of the planet. We had not burned vegetation to clear large
areas for farming; such as we do now in the Brazilian rain forest. We did
not burn large amounts of hydrocarbons such as petroleum and coal.
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However, since the Industrial Age, we have taken huge amounts of carbon
out of the ground, which was locked in the ground for hundreds of millions
of years. Now, within a few hundred years, a mere second in geologic
time, we have removed this carbon from the underground vault and
released it through burning into the atmosphere and soil. We were not
aware of all of the consequences of doing this.
Many people argue that the greenhouse effect is largely unproven science.
Much of this was due to the lack of evidence at the time, but new evidence
demonstrates that the cause and effects of greenhouse action are clearly
visible.
Figure 4. Historic Levels of CO2
Figure 4 shows how the average carbon dioxide level has increased over
time, and especially after 1800 when the Industrial Revolution started.
Fabricated emissions increased exponentially after 1850. The data was
taken from small bubbles of air, which became trapped in ice in places like
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Antarctica. Scientists have analyzed these tiny bubbles to find out how
much carbon dioxide was present when they were made.
Finally, Figure 5 shows that the
average global temperature has been
climbing since 1850. While it is less
than one degree in 150 years, it
appears to be increasing rapidly. Is
this mere coincidence? We will let
the reader decide.
Figure 5
PRACTICE QUESTIONS
1. The person who first described the problems of unlimited
population growth was:
a)
Watson
c)
Darwin
b)
Malthus
d)
Lyell
2. When a population growth curve reaches its maximum level, it is
said to become:
a)
symptotic
c)
asymptotic
b)
exponential
d)
linear
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3. The Earth’s population is now slightly more than ______ people.
a)
10 billion c)
100 million
b) 10 million
d) 1 billion
4. The largest rate of increase in population took place after ____.
a)
1800
c)
1950
b)
1900
d)
1700
5. The stone-age is known as the ________.
a)
Chalcolithic
b)
Neolithic d)
c)
Paleolithic
Irolithic
6. Transpiration and evaporation return water to the _____.
a) ground
c) air
b) bodies of water
d) snow
7. The largest threat to the ozone layer is ______.
a) CFCs
c) birds
b) Oxides
d) airplanes
8. The Earth’s average surface temperature was the highest in 2005
since accurate records have been kept for the last ____ years.
a) 400
c) 50
b) 500
d) 125
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9. The most important greenhouse gas is:
a) carbon dioxide
c) ammonia
b) methane
d) oxygen
10. In the greenhouse effect, _________ radiation gets trapped.
a) gamma
c) visible light
b) ultra-violet
d) infra-red
ANSWERS
1. b
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2.b
3.a
4.c
5.c.
6.c
7.a
8.d
9.a
10.d
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LESSON 4 THINGS TO REMEMBER
™ The stone age is known as the Paleolithic age
™ The study of early man is called Anthropology
™ The industrial revolution began in the 1800s
™ A key to making Ozone is ultraviolet radiation
™ The term “biodegradable” means that a substance breaks down its
environment
™ About ¾ of all solid wastes generated by Man come from mining
™ The Earth’s average surface temperature was the highest in 2005 since
accurate records have been kept for the last 125 years
™ The most important greenhouse gas is Carbon Dioxide
™ The amount of greenhouse gases in the atmosphere historically has
been known from studying ice cores
™ The highest albedo is from clouds
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LESSON 5: ECOLOGY AND TECHNOLOGY
It is a natural process for many animals and plants to become extinct over
time. This slow process is what scientists call the “background extinction
rate”. The Earth has also gone through at least six mass extinctions in the
last half billion years or so, as evidenced by the fossil record. The
dinosaurs became extinct about 65 million years ago. We think it was due
to a large impact caused by an asteroid. We are not quite sure of what
caused the other mass extinctions. A rapid change in the environment may
have caused it. Biologists now estimate that 99.9% of all species that ever
existed on the planet became extinct.
The opposite of extinctions are periods when life goes through biodiversity.
In this way, a greater number of species adapt to their environments. This
helps to insure that life will survive the next great change. It also helps to
insure that the next mass extinction event would not wipe out all life on
Earth.
When we talk about animals and plants that
may become extinct, we now have to look at
humans as the possible cause. Our impact
upon nature has been great in terms of global
warming and other activities. These have
already led to the extinction of such animals
as the Dodo, the Great Auk, and the
Passenger Pigeon, due to over-hunting.
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In 1973, Congress passed the Endangered Species Act. The act makes it
illegal to import or trade any product made from a threatened or
endangered species. The law also gives U.S. Fish and Wildlife Service and
the National Marine Fisheries Service
authority to create a list of Threatened and
Endangered Species. People cannot hunt,
injure, collect or kill species on this list.
A Threatened Species is one whose
numbers have declined to the point that it could become an Endangered
Species through further losses. In order to protect them, we have put in
place a number of measures. We have created natural wildlife preserves.
They focus on establishing entire groups by keeping the natural balance
within them. The elimination of non-native species, and the introduction of
native species whose numbers have gone down are all tools to make such
efforts successful.
Being a listed species on the Threatened or Endangered Species list is
important, but it does not insure that a species will recover. Each federal
agency is responsible under the law to prepare a plan for recovery of each
species, but most of these plans only exist on paper and funds are often
lacking.
In spite of this, there are success stories. The case of Florida sea turtles is
among them. Florida has the largest area of habitable coastline to its area
of any state. Florida has been an important breeding ground for various
species of sea turtles, including the Leatherback, Loggerhead, Hawksbill,
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and Green. Sea turtles lay their eggs in the sand. Mother turtles slowly
crawl out of the ocean during egg-laying season and dig nests above the
high tide line, in which they lay dozens of eggs. The eggs hatch, and the
baby sea turtles come up to the surface, usually all at once. From there,
they make the dangerous journey down to the ocean. Predators such as
birds devour many, and the few survivors that reach the water face further
perils from marine predators. Few of the baby turtles live compared to the
numbers that are hatched.
In recent years, human activity has
affected the turtles’ environment.
Beaches have become recreation
grounds. Humans have frequently
destroyed nests on purpose or
accidentally. Condominiums and other
sources of nighttime light have further
affected the number of survivors.
Confused by the lights, baby turtles crawl towards them rather than in the
direction of the ocean. Many die on roadways above the beaches.
The State of Florida has developed a number of programs and laws to
protect the nests. Officials are creating fenced off areas where eggs are
laid. They also reduced the number of lights in certain areas and have
begun maintaining turtle hatcheries. As the result of these efforts, the sea
turtle population is making a slow comeback.
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Various treaties have also helped in protecting wildlife, such as the
Convention on International Trade in Endangered Species (CITES) in
1975. The treaty, signed by nearly 150 countries, makes it illegal to trade
or sell endangered or threatened species. Many countries have
established limited fishing laws and have established protected areas used
by migratory birds. These protected routes help to insure that many of
them continue to survive.
Perhaps one of the most important uses of such treaties has been to
prevent many types of whales from becoming extinct. Whales are the
largest mammals, often longer than
100 feet in length. Since the early
1800s, Man has been their only real
predator. Humans have hunted
whales for their oil. People burned
whale oil in lamps and used it as a
lubricant for fine machinery such as
watches. Once drilling of petroleum
was discovered, the whaling industry
declined. However, many countries like Russia and Japan still hunted
them for food. Before treaties, certain species such as the Blue, Sperm
and Right whales were rapidly disappearing. Governments created
treaties to limit whale hunting; even with such interventions, many marine
biologists question whether the Blue Whale can recover from extinction due
to their low population.
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Species extinctions are a normal process. They happen over time.
However, Man has added to this process with activities that have reduced
or eliminated many species. To counter this, lawmakers have passed
various laws and treaties. Nevertheless, species may have already passed
beyond point of possible recovery.
While the number of many species has declined, there are some success
stories. Prompted by laws, a number of protected species are making
spectacular comebacks. Here is the story of a few of them.
The Hawaiian Green Sea Turtle
This sea turtle lives in the Hawaiian Islands. It
makes its nests about 500 miles west of Hawaii
at an atoll known as the French Shoals. The
government made a protected wildlife area by
President Roosevelt in 1909. Hawaiians have
hunted the turtles for their skin for a number of
decades. The turtles breed slowly. Only 67
nesting females existed in 1973. This was not
enough to sustain the species without help. Today, their numbers have
increased to over 400 nesting females, largely because of strict
enforcement of laws and heavy penalties. Hawaiians have joined the effort
to increase the turtles’ population by including them on nature watch tours
for visitors. They have even spawned a homegrown industry of sorts. The
vendors sell turtle tea shirts, hats and wildlife art. Local residents have
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learned that preserving the sea turtles is better for the local economy than
hunting them for their skins.
The Palila
The Palila is a small bird that lives in Hawaii. We have protected them
since 1966. After a lawsuit brought by the Sierra Club and the State of
Hawaii, the court ordered funds to restore the
numbers of this bird. Nature confined the birds
to a small area on one island. Fire, storms or
diseases could have wiped out this small
number of about 3,000 birds. With the funds, a
new game reserve was set up on the other side
of the mountain, and breeding centers were
established. Relocation of existing birds and the introduction of new
hatchlings have resulted in increases in population. While the animals are
on the upswing, biologists estimate that it will still take many decades in
order for their numbers to return to previous levels.
The Whooping Crane
In the early 1940s there were only 21 Whooping Cranes left in the wild.
People reduced the crane's population by hunting. Plumes of the
Whooping Cranes were very popular for women’s hats. The efforts to
preserve this species have been extensive. We studied migration routes
and set up breeding centers around the country. The normal migration
route of the Whooping Crane was from Canada to Texas; however, many
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predators and bad weather reduced the numbers of birds along these
routes.
A Canadian-American team established a new migration route for the birds
from Florida to Wisconsin. Another more spectacular effort was to train
some of the birds to follow a human flying
an ultra-light plane equipped with a puppet
crane head. The plane accompanies the
birds on the migration route from
Wisconsin to Florida and actually shows
them the route to fly and where to land for
food along the way. Although the bird is
still on the endangered list, it has made a
spectacular come back.
The Grizzly Bear
The Grizzly Bear once roamed a vast area of
the Great Plains and Southern Canada. By
the mid 1900s, the population was reduced to
fewer than 150 bears in the Northwestern
United States. We passed laws to force ranchers not to kill them. Many
ranchers would kill the Grizzlies because they would poach livestock and
represented a threat to their farms. The State of Wyoming began to
reimburse the ranchers more than a half million dollars for livestock losses.
Ranchers stopped killing Grizzlies because of the laws. Now there are
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more than 600 bears in the same section of the country. This comeback
has resulted in the consideration of removing the bear from the endangered
species list.
The Bald Eagle
The Bald Eagle is part of the Great Seal of the
United States. It is a symbol of power and
authority. By the early part of the last century,
the Bald Eagle was in trouble. Their numbers
declined to fewer than 10,000 pairs. Accidental
poisoning, clearing of land, and hunting added
to this decline. In 1940, Congress passed the
Bald Eagle Protection Act, which prohibited the killing of Bald Eagles for
any reason. After World War II, the introduction of the pesticide DDT
almost destroyed the remaining population. We found only about 400 Bald
Eagle nesting pairs by 1963, in the U.S. In the early 1970s, the United
States EPA outlawed DDT. Many groups began to concentrate on
monitoring the population of the Bald Eagle. These efforts have restored
the Bald Eagle population to nearly 8,000 pairs. As a result, bald eagles
are no longer on the endangered list.
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The Southern Sea Otter
At one time, hundreds of thousands of Sea Otters ranged from Southern
California to Alaska. By the early last century, the number of Sea Otters
living off the coast of California fell to
almost zero. Perhaps the biggest reason
behind this was the destruction of whales
in Alaska reduced the food supply for
Orcas. Orcas fed on the whales. When
the whale population declined, the Orcas
then moved closer to shore and began to
eat Sea Lions and Sea Otters. We
passed laws to protect the Whales and
relocate fishing further off shore, which
allowed the Sea Otters to rebound in this area. We now estimate the
population at more than 2,500.
The California Winter Run Chinook salmon
There were only 200 salmon in
California's Rivers in 1994. Several
dams along the river caused this
decline because they prevented the
Salmon from going upstream to
reproduce. A lawsuit forced the United
States to classify the species as
endangered. Salmon could once again migrate as the result of the suit.
Special spillways were built so the fish could swim above the dams to their
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spawning areas. Because of this effort, there are now over 10,000 salmon.
Another effort forced some of the mining companies in the area to prevent
heavy metals from entering the waters and threatening the fish.
The Kioto Accords
We have already discussed the effects of global warming, which affects
every place on Earth. The average surface temperature of the planet has
increased by only a few degrees. This is probably the result of the
increased levels of greenhouse gases.
The United States is by far the
biggest producers of these gases.
The Framework
In 1994 and 1995, the United Nations sponsored a global conference on
earth’s climate. The U.N. found that the increased levels of greenhouse
gases could have disastrous effects. The framework led to a set of plans
that eventually became the Kioto Accords in 1997. A majority of industrial
nations met in Japan to work out the facts. After much debate,
governments agreed that global warming was
real, and they also agreed to do something
about it.
Eighty-four countries signed the Kioto Accords,
which established target levels of greenhouse
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gases for the period of 2008 to 2012. Based on 1990 levels, the United
States volunteered to reduce emissions to the 93% level. Other countries
agreed to their own levels. All nations agreed to total cuts of 5%.
While the agreement goes far to create target goals, it fell short in one
area. Some countries did not agree on how to apply it. They voted to put
it into effect on February 16, 2005. Several nations questioned the ways
to reduce greenhouse gases. The United Nations has scheduled future
meetings to clarify this area.
The Gaia Hypothesis
Chemists first proposed the Gaia hypothesis in the late 1970s. It is an idea
that the Earth behaves like a live creature that automatically adjusts itself in
order to keep a balance between life and the planet. James Lovelock
came up with the idea in the 1960’s and wrote in a book about it in 1979.
The Self-Regulating Earth
Lovelock took the idea of Mother Earth and gave it a modern scientific
interpretation. He described Gaia as “a complex entity involving the Earth's
biosphere, atmosphere, oceans, and soil”. He also said the whole thing
regulates itself. The Earth seeks the best physical and chemical
environment for life. Through Gaia, the Earth keeps a balance or a
constant set of conditions.
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The interesting part of the Gaia hypothesis is the
idea that the Earth is like a simple living thing.
This idea is not new. James Hutton (1726-1797),
the father of geology, once explained the Earth
as a kind of great organism. In addition, Lewis
Thomas, a medical doctor and skilled writer,
wrote the same words in his famous essays, The
Lives of a Cell.
Whether the Earth is a cell or more like an organism, is largely a matter of
opinion, we leave this topic to others. The key point is that the Earth acts
as a self-regulated set of forces that work together to maintain a balance.
The balance involves the input of energy from the sun and the loss of
energy into space.
In its most basic way, the Earth acts to regulate the flow of energy from the
sun at a constant rate. The energy is also unlimited. The Earth captures
this energy as heat. The energy creates photosynthesis. Long-wave
radiation returns back to space. On the other hand, the mass of the Earth is
limited. While energy flows through the Earth, matter cycles within the
Earth.
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Summary
The Earth has been around
for 4 ½ billion years. Life has
existed on it for most of that
time. Some have claimed
that there might be an active
(if not intelligent) interaction
between the two. Many
scientists do not believe in
the Gaia hypothesis. They
say that it is too much of a
leap of faith to assume that it
exists. One problem with the idea is that it might lead us to a false sense of
security. If we tip the balance of life with the by-products of our civilization,
we might expect that the Earth will correct itself. Therefore, we do not have
to take any active measures to counter what we have done. The debate
will continue as we explore our own role on the planet. We still have to
define our responsibilities as inhabitants of Earth.
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PRACTICE QUESTIONS
1. Baby sea turtles are attracted by ______ and head in the wrong
direction after hatching.
a)
noises
c)
b) smell of human food
lights
d) other turtles
2. Mass extinctions:
a) have never occurred
b) have occurred several times in the geologic record
c) occur every thousand years or so
d) only occurred once
3. An example of a species threatened by pesticides is/are:
a) the Chinook Salmon
c) the Pahila
b) the Bald Eagle
d) the Grizzly Bear
4. An example of a law that has served to protect threatened and
endangered species is the:
a) Utopian Act
c) the Hunting Act
b) the Crown Act
d) the Endangered Species Act
5. The Kioto Protocol was established by:
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a) the United States
c) environmental groups
b) several countries
d) the United Nations
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6. The Kioto protocol has a target reduction of greenhouse gases of ____%
by 2008-2012.
a) 5
c) 1
b) 10
d) 50
7. There were several countries that attended and refused to sign the
protocol.
a) True
b)
False
8. Several nations questioned the means to carry out the protocol.
a) True
b) False
9. The Gaia hypothesis was first formulated by:
a) Lovelock
c) Margulis
b) Hutton
d) none of these
10. The Gaia hypothesis claims that the Earth is:
a) non adjustable
b)
c) self regulating
counter-productive
d) 4.5 billion years old
ANSWERS
1.c
2.b
3.a
4.d
5.d
6.a
7.a
8.a
9.a
10.c
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12
LESSON 5 THINGS TO REMEMBER
™ Mass extinction has occurred several times in the geologic record
™ The passenger pigeon is an example of an extinct species
™ A species whose members have dwindled to such low numbers that
extinction is possible in the near future is called endangered
™ An example of a law that has served to protect threatened and
endangered species is the Endangered Species Act
™ Methods used in increasing the populations of threatened and
endangered species include gathering public interest, re-introduction of
native species, and breeding facilities and programs
™ In recent years, law suits have forced implementation of environmental
laws
™ There were several countries that attended and refused to sign the Kioto
protocol
™ Several nations questioned the means to carry out the Kioto protocol
™ The Framework Convention on Climate was held in 1994-1995
™ Baby sea turtles are attracted by lights and head in the wrong direction
after hatching
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END OF COURSE REVIEW
™ Paleontologists study ancient life on Earth including dinosaurs
™ Even though you can’t do an experiment to test an idea, the idea could
still be right
™ Testing comes after forming a working hypothesis.
™ Ecology is the study of the balance between organisms and their
environment
™ Living species are known as biotic
™ The study of astronomy includes life
™ The “scientific method” goes back to the ancient Greeks
™ Chance plays an important role in science for some discoveries
™ Entropy involves the loss of energy over time
™ All life forms reproduce and grow
™ A cell splitting in two is an example of meiosis
™ A change that helps an organism adjust to its surroundings is an
example of adaptation
™ The great age of mammals is called the Cenozoic age
™ The extinction of the dinosaurs was about 65 million years ago
™ Most of our fossil fuels come from forests dating to the Carboniferous
period
™ Aerobic bacteria need oxygen
™ The shortest wavelengths of visible light are violet
™ The longest wavelengths of the electromagnetic spectrum are radio
™ Using an applied force of one Newton to push an object one meter
across ice requires one joule
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™ In respiration, sugars are broken down into carbon dioxide, water, and
energy
™ Sugars are made in a process called photosynthesis
™ The Phosphorus Cycle is a closed cycle system
™ An area that an organism roams is known as its habitat
™ An arctic area with few scrubs is known as Tundra
™ A geographic region that supports one or more ecosystems is a biome.
™ The original super-continent is called Pangea
™ Heterotrophs do not make their own food
™ Primary consumers include plant eaters or grazers
™ Symbiosis occurs when two organisms that benefit from each other due
to a link in their metabolic process
™ In the case of Mutualism, both organisms benefit from the relationship
™ The number of predators in an area determines the number of prey
™ Food chains and webs represent how energy flows within an ecosystem
™ The tiers on the food pyramid are called trophic levels
™ The person who first described the problems of unlimited population
growth was Darwin
™ The Earth’s population is more than 10 billion people
™ Evaporation returns water to the air
™ The largest threat to the ozone layer is CFCs
™ The term “biodegradable” means that a substance breaks down in
nature
™ The most abundant gas in the atmosphere is nitrogen
™ In the “greenhouse effect” infrared radiation is important
™ The highest reflectivity of the Sun’s heat and light is from clouds
™ Mass extinctions are not unusual over hundreds of millions of years
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™ The dodo is an example of an extinct species
™ An example of a law that has served to protect threatened and
endangered species is the Endangered Species Act
™ A species whose numbers have been reduced is know as threatened
™ Inviting the adoption of pets is not a method used in increasing the
populations of threatened and endangered species
™ The Kyoto Protocol was established by the United Nations
™ The Kyoto Protocol has a target reduction of greenhouse gases of 5% in
the next several years
™ Lovelock first discovered the Gaia hypothesis which treats the Earth as
a kind of living organism
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