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TWIRTEENTH EDITION

Enger • Ross • Bailey

CHAPTER 1

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Chapter opener 01

1.1 The Significance of Biology in Your Life

Consider how your future will be influenced by how the following questions are ultimately answered：

How can we reduce the probability that new strains of disease-causing bacterial will evolve?

Is DNA testing reliable enough to be admitted as evidence in court cases ? Why is there an epidemic of obesity in the United States? Can physicians

and scientists manipulate our genes in order to control certain disease conditions we have inherited ?

Will the thinning of the ozone layer of the upper atmosphere result in increased incidence of skin cancer ?

Will a vaccine for AIDS be developed in the next 10 years ? Will new, inexpensive, socially acceptable methods of birth control be

developed that can slow world population growth ? Are human activities really causing the world to get warmer ? How dose extinction of a species change the ecological situation where it

once lived ?

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Why study biology?

To be an informed citizen.An understanding of biology is

important to address a number of social issues today.– DNA testing– Birth control – Global warming– AIDS

Example 1： Human population should be slowed. Killing infants and forced sterilization.

Example 2： Mad Cow Disease.

It is important to recognize that science has a role to play but that is does not have the answers to all our problems. (Social and Philosophical Questions)

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1.2 Science and Scientific Method

The science that deals with life.What is science?

– A process used to solve problems and understand natural events.

– Involves the scientific method.

Basic assumptions in science

Scientists approach their work with some basic assumptions– Natural events have specific causes.– Those causes can be identified.– Natural events follow general rules and

patterns.– A recurrent natural event has a common

cause.– Different people can observe the same

natural events.– Natural laws hold true regardless of time

and place. Example: Lightning

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Scientists look for cause and effect relationships

Events that happen simultaneously are correlated, but– may or may not have a cause and effect

relationship.– Example: Autumn and falling leaves

Events have a cause and effect relationship– when one event happens as a direct result of a

preceding event.– Example: Lightning causes thunder.

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The scientific method

A way of gaining information about the world that involves– forming possible solutions to questions.– rigorous testing to determine if the solutions

are supported.– continual checking and rechecking to make

sure that previous conclusions are still supported.

– modification of unsupported conclusions.

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Components of the scientific method

Observation Questioning and exploration Forming and testing hypotheses Evaluation of new information Review by peers

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The scientific method in action

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Observation, questioning and exploration

An observation is a thoughtful and careful recognition of an event or a fact (see next slide).

The careful observation of a phenomenon leads to a question (see next slide).– How does this happen?– What causes it to occur?

The question must be testable. Scientists then explore scientific

publications to find any information that has been gathered about the question.

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Figure 1_03

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Figure 1_04a

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Figure1_04b

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Constructing hypotheses

Once the question is asked, scientists propose answers.

These answers are hypothesis. Hypotheses must:

– Be logical– Account for all current information– Be testable– Make the least possible assumptions

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Testing hypotheses

Hypotheses need to be tested to see if they are supported or disproved.– Disproved hypotheses are rejected.– Hypotheses can be supported but not proven.

There are several ways to test a hypothesis:– Gathering relevant historical information.– Make additional observations from the natural

world.– Experimentation

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Experimentation

An experiment is a re-creation of an occurrence. – It tests whether or not the hypothesis can be

supported or rejected. Experiments must be controlled.

– This means that all aspects except for one variable must be kept constant.

– They usually include any two groups. Experimental group: variable is altered Control group: variable is not altered

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Experimental design

– The variable that is altered is called the independent variable.

Experiments should have only one independent variable.

– The variables that change in response to the independent variable are called dependent variables.

Changes in the dependent variables are documented as data.

– Data from the experiment is analyzed and hypotheses are rejected and revised or supported.

A sample experiment Hypothesis: Male sex hormones produced by the

testes stimulate male birds to sing. Experimental group: Male birds with testes removed at

birth. Control group: Male birds subjected to a similar

surgery that were allowed to develop normally with testes.

Independent variable: presence or absence of testes. Dependent variable: presence of singing behavior Data: Male songbirds without testes do not exhibit

singing behavior. Conclusion: Hypothesis is supported.

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Figure 1_05

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Experimental data

Experiments must:– Use large numbers of subjects or must

be repeated several times (replication)– Be independently reproducible.

The validity of experimental results must: – Be tested statistically.– Be scrutinized by other scientists.

If the hypothesis is supported by large experimental data, it leads to a theory.

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Theory

A theory may be defined as a widely accepted, plausible general statement about a fundamental concept in science.– The germ theory states that infectious

diseases are caused by microorganisms.Many diseases are not caused by

microorganisms, so we must be careful not to generalize theories too broadly.

– Theories continue to be tested.Exceptions identifiedModifications made

A scientific law

A scientific law is a uniform and constant fact of nature that describes what happens in nature.– An example: All living things come from pre-

existing living things. Scientific laws promote the process of generalization.

– Inductive reasoning– Since every bird that has been studied lays eggs,

we can generalize that all birds lay eggs. Once a theory becomes established, it can be used to

predict specific facts.– Deductive reasoning– We can predict that a newly discovered bird

species will lay eggs.

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Scientific communication

Data is shared with the scientific community through research articles published in scientific journals.

– These articles are usually scrutinized by other scientists before they are published.

Scientists present preliminary data at conferences.

Scientists collaborate directly by phone, e-mail, and skype.

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1.3 Fundamental attitudes in science

Scientists must distinguish between opinions and scientific facts. – Scientists’ opinions may become facts if

supported by data. A good scientist must

– be skeptical.– not be biased.– be honest in analyzing and reporting data.

The critical difference between science and non-science is that in science, one can test the principle. In non-science, one may not be able to.

Theoretical vs. Applied Science

Initially, some scientific data seems to be purely informational and not very practical.

Practical applications usually follow the discoveries of basic science.

– The discovery of the structure of DNA has led to new drug treatments for many diseases. (antibiotics, hormones, enzymes)

– The discovery of microorganisms has led to a dramatic decrease in infectious disease and food preservation. (vaccination against rabies, pasteurization for the preservation of food)

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Science vs. Nonscience

Scientists continually challenge and test principles to determine cause-and-effect relationships.– Biology, Physics, Chemistry, Astronomy

Nonscientists cannot test their hypotheses directly and often cannot establish cause-and-effect relationships.– History, Literature, Philosophy, Art, Sociology,

etc.

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Pseudoscience

A deceptive practice that uses the language of science to convince people into thinking that a claim has scientific validity.

– Marketing claims of nutritional supplements.

– Marketing claims of organic foods.

Fig. 1.11 Pseudoscience- “Nine out of 10 Doctors Surveyed Recommend Brand X”

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Limitations of science

The scientific method can only be applied to questions that have a factual base.

Questions of morality, values, social issues and attitudes cannot be tested scientifically.

Science is limited by scientists.– People are fallible.– The sun orbits the earth.

But, science is self-correcting.– New data shapes new

hypotheses.– The earth rotates on its axis,

so maybe the earth orbits the sun.

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1.4 The science of biology

The study of living things. Theoretical biology

– Evolutionary biology, animal behavior, biochemistry

Applied biology– Medicine, crop science, plant

breeding, wildlife management

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What makes something alive?

Living things can manipulate energy and matter.

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Characteristics of living things (I)

Metabolic processes– Organisms gain and store energy in

the chemical bonds in the nutrients they take in.

Generative processes– Organisms grow by increasing the

number of cells.– Organisms reproduce either sexually

or asexually.

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Characteristics of living things (II)

Responsive processes– Organisms respond to changes in

their environment.Irritability: the ability to recognize a

stimulus and respond to it quickly.Individual adaptation: a longer term

response to an environmental change.

Evolution: changes in a population over time.

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Characteristics of living things (III)

Control processes– Enable organisms to carry out metabolic

processes in the right order. Coordination: Enzymes coordinate metabolic

reactions. (e.g., handling nutrients) Regulation: Enzymes are regulated in order to

maintain homeostasis. (e.g., exercise) Unique structural organization

– Organisms are made of cells.– Each kind of organism has specific

structural characteristics

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Levels of biological organization (I)

Biosphere—the worldwide ecosystem. Ecosystem—communities that interact with

one another in a particular place. Communities—populations of different

organisms interacting with each other in a particular place.

Population—a group of individual organisms in a particular place.

Organism—an independent living unit.

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Levels of biological organization (II)

Organ system—many organs that perform a particular function.

Organ—many tissues that perform a particular function.

Tissue—many cells that perform a particular function.

Cell—simplest unit that shows characteristics of life.

Molecules—specific arrangements of atoms.

Atoms—the fundamental units of matter.

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Significance of biology

Biology has significantly contributed to our high standard of living.

For example: Advanced food production Significant progress in health Advances in disease control Advances in plant and animal

breeding Advances in biotechnology Progress in genome studies

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Biological research improves food production

Edward Jenner and the Control of Smallpox

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The Consequences of Not UnderstandingBiological Principles

Lack of Understanding … Ecological Systems The damage Caused by Exotic Species Ethical Concerns

Major advances in health care Many people lack even the most basic health

care, while the rich nations of the world spend millions of dollars to have cosmetic surgery …

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Figure 1_20a

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Figure 1_20b

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Future Directions in Biology

Control of the human population Curing hereditary disease Between genetic info. and such diseases

Alzheimer’s disease Stroke Arthritis Cancer AIDS

Ecology: Climate change, pollution, human population