Chapter 1

The Science of Biology

What is SCIENCE?

Science: A process of investigation, using observation, experimentation and reasoning.

Science has limitations-it is not always absolutely and eternally correct!!

Experimentation must be objective and reproducible!

Science vs. Non-science

• Biology• Chemistry• Geology• Physics• Meteorology

• Art• Astrology• Philosophy• Religion• Extrasensory

Perception

Biology

The study of living things

Biology includes….

EcologyGeneticsBehavior

AnatomyDiversity

Evolution

Microbiology

Biology studies living things….

What does it mean to be “living”?

Characteristics of Life• What qualifies something as “living” versus “non-

living?”

• Consider these points complexity movement response to stimulation

• A life-defining property must be exclusive to living things

Use the paper provided to record whether each of the following slides shows a living or non-living object!

How do you determine

LIVING from non-living things?

Properties of Life

• All living things share five basic properties: Cellular organization Metabolism Homeostasis Growth and Reproduction Heredity

5 Basic Properties of Life

1. Cellular organization all living things are comprised of at least one

cell• single cell (bacteria) up to trillions of cells (human)

Smallest level of organization that can be considered “alive”

Membrane-bound May contain organelles Explained by the Cell Theory

2. Metabolism all living things process energy which is used to power other

processes

Energy source can vary• Autotrophs• Heterotrophs

Nutrients are turned into energy through cellular processes• Photosynthesis• Cellular respiration

– Glycolysis– Krebs Cycle

5 Basic Properties of Life

3. Homeostasis all living things maintain stable internal

environments to optimize conditions for metabolism and other processes

5 Basic Properties of Life

4. Growth and reproduction all organisms have the capacity for growth

and reproduction Often a trade-off between the two Different life-strategies

• Semelparity vs. Iteroparity

5 Basic Properties of Life

Basic Properties of Life5. Heredity all organisms pass genetic information across

generations from parents to offspring Theory of Heredity

• Gregor Mendel Gene Theory

Properties of Life

• All living things share five basic properties: Cellular organization Metabolism Homeostasis Growth and Reproduction Heredity

Taxonomy

Living things are very diverse…Scientists need a system to name and

classify things!

We call this system….

Taxonomy

• Began with Linnaeus• Binomial nomenclature

Genus + species (ie) Homo sapiens

• Hierarchical Classification (Domain) Kingdom Phylum Class Order Family Genus species

Taxonomy Mnemonics!• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• species

• King

• Phillip

• Came

• Over

• For

• Good

• spaghetti!

• Keep

• Patty’s

• Class (in)

• Order

• For

• Goodness

• sake!

The Six Kingdoms of Life

ProtistaBacteriaArchaea

AnimaliaPlantaeFungi

Scientists group organisms based on similarities into six kingdoms

Classifying Life’s Diversity

• Each of the six kingdoms are assigned, on the basis of cell structure into one of three domains Bacteria Archaea Eukarya

Classification of living things

• Taxonomy Identifying and classifying organisms

according to specific criteria Each taxon is more exclusive than the one

before it Ultimately, each organism has its own Genus

species combination that includes a unique set of traits

• e.g. Homo sapiens = modern humans

KINGDOM(Animalia)

PHYLUM(Chordata)

CLASS(Mammalia)

ORDER(Primates)

FAMILY(Hominidae)

GENUS(Homo)

SPECIES(sapiens)

Figure 1.4

The Organization of Life

• Living things function and interact with each other on many levels

• The organization of life is a hierarchy of levels of increasing complexity Cellular Organismal Ecological (populational)

Cellular Level

• Molecules Atoms combine to

make molecules

• Organelles Structures within cells

that perform dedicated functions

• Cells Membrane-bound

untis

Organismal Level• Tissues

Collection of cells that work together to perform a specialized function

• Organs Group of tissues formed together to perform specialized functions

• Organ systems group of related organs that work together

• Organism Individual living thing resulting from organ systems working

together to achieve homeostasis

Ecological (populational) Level• Population

Group of organisms of same species living together

• Species All populations of a specific

kind of organism

• Community Populations of different

organisms that interact with one another living in a particular area

• Ecosystem Created by communities that

interact with each other

The Organization of Life

• At higher levels of the living hierarchy, new properties become apparent that were absent at the lower levels

• These emergent properties result from the interaction of diverse but simpler components

• Many higher order processes that are hallmarks of life are emergent properties metabolism consciousness

Biological Themes

• The study of life is organized around general themes

• 5 biological themes emerge repeatedly at any hierarchical level of biological study: Evolution Flow of energy Cooperation Structure determines function Homeostasis

EVOLUTION• Evolution is genetic

change in a species over time

• The mechanism for evolution is natural selection

• The diversity of life is explained by evolutionary processes

The Flow of Energy• all living things require

energy• energy from the sun flows

through the living world • organisms acquire energy

differently• how much energy is

available determines how many and what kinds of organisms can live together in an ecosystem

Detritus

Decomposerfood web

Soil nutrient pool

Cooperation• As energy and other

resources are limiting, many organisms have evolved cooperation as a means of survival

• Symbiosis-Relationship between 2 species living in same community

• Mutualism• Parasitism• Commensalism

Structure Determines Function

• Evolution favors structures that function in an adaptive manner

• Many structures are specialized for a particular function

• The convergence of structure and function occurs at levels of the organizational hierarchy

Homeostasis

• Homeostasis is a physiological condition of “steady-state”

• The internal environment of organisms is remarkably stable

• Organisms act to control their internal environments so that the complex processes of metabolism function efficiently

How Scientists Think

• Science is a process of investigation, using observation, experimentation, and reasoning

• REMEMBER Science is not always 100% correct Individuals are not completely without bias Science is limited

• it is limited to organisms and processes that can be observed and measured

• science cannot be relied upon to solve all problems

How Scientists Think

• Deductive reasoning uses general principles to explain specific observations It’s not a scientific approach Top down (general to specific)

• This form of reasoning is common to many disciplines, including mathematical proofs politics computing

How Scientists Think

• Inductive reasoning is the way of discovering general principles from examination of specific observations Bottom-up (specific to general)

• Scientists employ inductive reasoning by forming and testing possible explanations for specific observations

• These possible explanations are called hypotheses

Deductive vs. Inductive Reasoning

• Two boys are playing with a soccer ball• The boys use 2 different approaches to explain

the result of kicking the ball into the air• Boy 1: “I've noticed that every time I kick a ball up, it

comes back down, so I guess this next time when I kick it up, it will come back down too”.

• Boy 2: “I know that Newton’s law of Gravity states that what goes up must come down, so if I kick a ball in the air, it must fall back down to the ground”.

• Boy 2• Uses known theory or

law to predict the result of an event

• Top-down (starting big and getting small)

• Boy 1• Uses observations to

predict the result of an event

• Bottom-up (starts small and gets big)

Deductive vs. Inductive

Many times, cases can be supported using both inductive and deductive arguments. They are not mutually exclusive!

Stages of a Scientific Investigation

• Biology is a dynamic science with new ideas appearing and replacing old ones

• Scientists systematically conduct experiments to evaluate hypotheses about observed phenomena

• These experimental results can either support or refute a proposed hypothesis

• They also lead to more questions and more experimentation!

Science in Action

• The scientific process has 6 steps: Observation Hypothesis Predictions Testing Controls Conclusion

Stages of a Scientific Investigation

1. Observation science begins with careful observation of natural

phenomena These observations lead to questions

2. Hypothesis scientists make an educated guess that might be

true often scientists formulate multiple ideas about a

phenomenon; these are called alternative hypotheses

Stages of a Scientific Investigation

3. Predictions if a hypothesis is correct, then specific

consequences can be expected

4. Testing scientists conduct experiments to attempt to

verify predictions made by hypotheses

5. Controls experiments usually employ a parallel design

• scientists use a control to assess the influence of potential factors, called variables

• conditions stay the same in the control in comparison to the variable condition

6. Conclusion a hypothesis that has been tested and not

rejected is tentatively accepted

Stages of a Scientific Investigation

The scientific process

Theory and Certainty• The term “theory” means different things

to different audiences To scientists

• a theory represents certainty and is a unifying explanation for a broad range of observations

• Scientists’ acceptance of theory is provisional

To the general public• a theory implies a lack of knowledge or guess

Four Theories Unify Biology as a Science

1. The Cell Theory

2. The Gene Theory

3. The Theory of Heredity

4. The Theory of Evolution

The Cell Theory

• 1665 Cells first discovered by Robert Hooke• 1839 German biologists Schleiden & Schwann put

forth Cell Theory based on many observations of theirs and others

• Theory States: the cell is the most basic unit of life all organisms are composed of at least one cell all cells come from pre-existing cells

The Gene Theory

• Genetic information is encoded in molecules of deoxyribonucleic acid (DNA)

• Genes encode specific proteins or RNA or act to regulate other genes

• The Theory States: the proteins and RNA

encoded by an organism’s genes determine what it will be like in terms of form and function

The Theory of Heredity

• 1865 Gregor Mendel’s theory of heredity gave rise to the field of genetics

• The Theory States: Genes are passed down through generations

as discrete units, they do not blend together Chromosomal theory of inheritance located

Mendelian genes on chromosomes

The Theory of Evolution• 1859 Charles Darwin• The theory of evolution explains

the unity and diversity of life as “descent with modification” All living organisms are related to

one another in a common tree of descent

• The Theory States Changes in genes passed from

parents to offspring result in changes in future generations of a population

Changes will thrive in population if they are adaptive

Natural selection is the major mechanism for this change