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Chapter 1

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Why a Study of Biology is Important

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


So then, what is biology?

Biology is 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.– The causes for events in nature 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


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.


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.


Components of the Scientific Method

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


The Scientific Method in Action


Observation, Questioning and Exploration

An observation is a thoughtful and careful recognition of an event or a fact.

The careful observation of a phenomenon leads to a question.– 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.


Constructing Hypotheses

Once the question is asked, scientists propose answers.

These answers are hypotheses. Hypotheses must:

– be logical– account for all current information– be testable– make the least possible assumptions


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


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


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.


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 ample experimental data, it leads to a theory.


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 identified Modifications 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.


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 and e-mail.


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.

– The discovery of microorganisms has led to a dramatic decrease in infectious disease and food preservation.


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.


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.


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.


The Science of Biology

Biology is the study of living things. Theoretical biology

– Evolutionary biology, animal behavior, biochemistry

Applied biology– Medicine, crop science, plant breeding, wildlife

management


What makes something alive?

Living things can manipulate energy and matter.


Characteristics of Living Things

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.



Responsive processes– Organisms react to changes in their

environment.Irritability: the ability to recognize that

something in its surroundings has changed (a stimulus) and respond to it quickly.

Individual adaptation: a longer term response to an environmental change.

Evolution: changes in a population over time.



Control processes– Enable organisms to carry out metabolic

processes in the right order.Coordination: Enzymes coordinate metabolic

reactions.Regulation: Enzymes are regulated in order to

maintain homeostasis.Unique structural organization

– Organisms are made of cells.


Levels of Biological Organization

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.


Levels of Biological Organization

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.


The Significance of Biology in our Lives

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


Biological Research Improves Food Production

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Chapter 1 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into