Essentials of Ecology

Links: refers to the Core Case Study. refers to the book’s sustainability theme. indicates links to key concepts in earlier chapters. 29

Key Questions and Concepts

2-1 What is science?

CONCEPT 2-1 Scientists collect data and develop theories,

models, and laws about how nature works.

2-2 What is matter?

CONCEPT 2-2 Matter consists of elements and compounds,

which are in turn made up of atoms, ions, or molecules.

2-3 How can matter change?

CONCEPT 2-3 When matter undergoes a physical or chemical

change, no atoms are created or destroyed (the law of conservation

of matter).

2-4 What is energy and how can it be changed?

CONCEPT 2-4A When energy is converted from one form to

another in a physical or chemical change, no energy is created or

destroyed (first law of thermodynamics).

CONCEPT 2-4B Whenever energy is changed from one form to

another, we end up with lower-quality or less usable energy than

we started with (second law of thermodynamics).

2-5 What are systems and how do they respond to

change?

CONCEPT 2-5A Systems have inputs, flows, and outputs of

matter and energy, and their behavior can be affected by

feedback.

CONCEPT 2-5B Life, human systems, and the earth’s life-

support systems must conform to the law of conservation of matter

and the two laws of thermodynamics.

Note: Supplements 1 (p. S2), 2 (p. S4), 5 (p. S31), and 6 (p. S39) can be used with this

chapter.

Science is an adventure of the human spirit.

It is essentially an artistic enterprise, stimulated largely by curiosity,

served largely by disciplined imagination,

and based largely on faith in the reasonableness, order,

and beauty of the universe.

WARREN WEAVER

Science Is a Search for Order

in Nature

Have you ever seen an area in a forest where all the

trees were cut down? If so, you might wonder about

the effects of cutting down all those trees. You might

wonder how it affected the animals and people living

in that area and how it affected the land itself. That is

what scientists Bormann and Likens (Core Case

Study) thought about when they designed their

experiment.

Such curiosity is what motivates scientists. Sci-

ence is an endeavor to discover how nature works

and to use that knowledge to make predictions about

what is likely to happen in nature. It is based on the

assumption that events in the natural world follow or-

derly cause-and-effect patterns that can be understood

through careful observation, measurements, experi-

mentation, and modeling. Figure 2-2 (p. 30) summa-

rizes the scientific process.

There is nothing mysterious about this process. You

use it all the time in making decisions. Here is an ex-

ample of applying the scientific process to an everyday

situation:

Observation: You try to switch on your flashlight and

nothing happens.

Question: Why didn’t the light come on?

Hypothesis: Maybe the batteries are dead.

Test the hypothesis: Put in new batteries and try to

switch on the flashlight.

2-1 What Is Science?

CONCEPT 2-1 Scientists collect data and develop theories, models, and laws about

how nature works.

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