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BIOLOGY. Greek BIO = life LOGIA = study of. BIOLOGY. Biology—the scientific study of living things “Living things”—All the diverse organisms descended from a single-celled ancestor (a single common ancestor). Define - “LIFE”.

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  • Greek

    • BIO = life

    • LOGIA = study of



  • Biology—the scientific study of living things

  • “Living things”—All the diverse organisms descended from a single-celled ancestor (a single common ancestor)

Define life

Define - “LIFE”

  • Dictionary - “the condition which distinguishes animals & plants from inorganic objects & dead organisms”

  • Dead (Dictionary) = “deprived of life”

Scientific principles

Scientific Principles

  • Natural Causality - all events can be traced to natural causes

  • Uniformity in Time & Space - forces (natural laws) acting today are the same as those of past

  • Common Perception - all humans perceive natural events in the same way (senses)

Scientific principles1

Scientific Principles

  • Scientific Principles Underlie All Scientific Inquiry

    • Natural Causality Is the Principle That All Events Can Be Traced to Natural Causes

    • The Natural Laws That Govern Events Apply Everywhere and for All Time

    • Scientific Inquiry Is Based on the Assumption That People Perceive Natural Events in Similar Ways

  • The Scientific Method Is the Basis for Scientific Inquiry

  • Science Is a Human Endeavor


  • Common Perception does not mean or result in Common Interpretation.

  • Interpretation is influenced by external factors, such as, the cultural, social, and philosophical background of the observer(s).

  • Science focuses on quantifiable measures NOT abstract value systems.

Life is more than the sum of its parts

Life Is More Than the Sum of Its Parts

  • Biologists study life by thinking about it at different levels of organization

  • Nature’s organization begins at the level of atoms, and extends through the biosphere

  • The quality of life emerges at the level of the cell

  • Each level of organization in nature has emergent properties– a characteristic of a system that does not appear in any of its component parts

A pattern in life s organization

A Pattern in Life’s Organization

  • Atoms

    • Fundamental building blocks of all substances

  • Molecules

    • Consisting of two or more atoms

  • Cell

    • The smallest unit of life

  • Tissue

    • Specialized cells organized to perform a collective function

A pattern in life s organization1

A Pattern in Life’s Organization

  • Organ

    • Structural unit of interacting tissues.

  • Organ system

    • A set of interacting organs

  • Multicelled organism

    • An individual consisting of one or more cells

A pattern in life s organization2

A Pattern in Life’s Organization

  • Population

    • Individuals of the same species in the same area

  • Community

    • Populations of all species in the same area

  • Ecosystem

    • A community and its environment

  • Biosphere

    • All regions of the Earth where organisms live

Life s levels of organization

Life’s Levels of Organization






organ system

Levels of organization in nature

Levels of Organization in Nature

Levels of organization in nature1

Levels of Organization in Nature

How do living things differ from nonliving things

How do living things differ from nonliving things?

  • All things, living or not, consist of the same building blocks—atoms; atoms join as molecules.

  • The unique properties of life emerge as certain kinds of molecules become organized into cells.

  • Higher levels of life’s organization include multicelled organisms, populations, communities, ecosystems, and the biosphere.

  • Emergent properties occur at each successive level of life’s organization.

How living things are alike

How Living Things Are Alike

  • Continual inputs of energy and the cycling of materials maintain life’s complex organization

  • Organisms sense and respond to change

  • All organisms use information in the DNA they inherited from their parent or parents to develop and function

Attributes of living organisms

Attributes of Living Organisms



  • Homeostasis

    • Organisms use receptors to help keep conditions in their internal environment within ranges that their cells can tolerate

Energy and life s organization

Energy and Life’s Organization

  • Energy

    • The capacity to do work

    • Not cycled; flows through the world of life in one direction

  • Nutrients

    • Atoms or molecules essential in growth and survival that an organism cannot make for itself

    • Cycled between organisms and the environment

Producers and consumers

Producers and Consumers

  • Producers

    • Acquire energy and raw materials from the environment

    • Make their own food (photosynthesis)

  • Consumers

    • Cannot make their own food

    • Get energy by eating producers and other organisms



  • Living Things Acquire and Use Materials and Energy

  • Living things acquire energy and nutrients from the environment


sunlight energy

A Producers harvest energy from the environment. Some of that energy flows from producers to consumers.


plants and other

self-feeding organisms

B Nutrients

that become

incorporated into the cells of producers and consumers are eventually released by decomposition. Some cycle back to



animals, most fungi,

many protists, bacteria

C All of the energy that enters the world of life eventually flows out of it, mainly as heat released back to the environment.


A Energy inputs from the environment flow through producers, then consumers.

energy input, mainly from sunlight

B Nutrients become incorporated into the cells of producers and consumers. Some nutrients released by decomposition cycle back to producers.


plants and other

self-feeding organisms

nutrient cycling


C All energy that enters an ecosystem eventually flows out of it, mainly as heat.

animals, most fungi,

many protists, bacteria

energy output, mainly heat

Organisms sense and respond to change

Organisms Sense and Respond to Change

  • Organisms sense andrespond to change both inside and outside the body

  • The body’s internal environment consists of all body fluids outside of cells

  • The internal environment must be kept within certain ranges of composition, temperature, and other conditions

  • By sensing and adjusting to change, organisms keep conditions in the internal environment within a range that favors cell survival (homeostasis)

Response to a stimulus

Response to a Stimulus

Organisms use dna

Organisms Use DNA

  • DNA is the basis of similarities in form and function among organisms

  • Details of DNA molecules differ – the source of life’s diversity

  • DNA

    • Deoxyribonucleic acid

    • Carries hereditary information that guides development and functioning

Development and growth

Development and Growth

  • DNA guides ongoing metabolic activities that sustain the individual through its lifetime

  • Development

    • Multistep process by which the first cell of a new individual becomes a multicelled adult


  • Growth

    • In multicelled species, an increase in the number, size, and volume of cells

  • Maintenance

    • In multicelled species, the upkeep, repair, and/or replacement of cells

  • All organisms receive their DNA from one or more parents

  • Reproductionincludes various processes by which individuals produce offspring

    • Inheritancerefers to the transmission of DNA to offspring

How are all living things alike

How are all living things alike?

  • A one-way flow of energy and a cycling of nutrients sustain life’s organization.

  • Organisms sense and respond to conditions inside and outside themselves; they make adjustments that keep conditions in their internal environment within a range that favors cell survival, a process called homeostasis.

  • Organisms develop and function based on information encoded in their DNA, which they inherit from their parents. DNA is the basis of similarities and differences in form and function

How living things differ

How Living Things Differ

  • Living things differ in their observable characteristics

  • Various classification schemes help us organize this variation, which we call Earth’s biodiversity

  • biodiversity

    • Scope of variation among living organisms

Summary of life s characteristics

Summary of Life’s Characteristics

Basics of classification

Basics of Classification

  • Organisms can be classified into broad groups depending on whether they have a nucleus or not

  • Nucleus

    • A sac with two membranes that encloses and protects a cell’s DNA

Organisms with no nucleus

Organisms With No Nucleus

  • Bacteria and archaea are two types of organisms whose DNA is not contained within a nucleus

  • Bacteria

    • The most diverse and well-known group of single-celled organisms that lack a nucleus

  • Archaea

    • Single-celled organisms that lack a nucleus but are more closely related to eukaryotes than to bacteria

Bacteria no nucleus

Bacteria – no nucleus

Clockwise from upper left, a bacterium with a row of iron crystals that acts like a tiny compass; a common resident of cat and dog stomachs; spiral cyanobacteria; types found in dental plaque.

Archaea no nucleus

Archaea – no nucleus

Archaea resemble bacteria, but are more closely related to eukaryotes. Left, an archaeon from volcanic ocean sediments. Right, two types of archaea from a seafloor hydrothermal vent.

Animated figure life s diversity

ANIMATED FIGURE: Life's diversity

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  • Eukaryotes are organisms whose DNA is contained within a nucleus

  • Some eukaryotes live as individual cells; others are multicelled

  • Eukaryotic cells are typically larger and more complex than bacteria or archaea



  • Protistsare the simplest eukaryotes

  • As a group they vary a great deal, from single-celled consumers to giant, multicelled producers

  • Many biologists view “protists” as several major groups



Protists are a group of extremely diverse eukaryotes that range from giant multicelled seaweeds to microscopic single cells. Many biologists are now viewing “protists” as several major groups.


A protist (domain Eukarya)





oral groove


10 micrometers

This light micrograph of a Paramecium illustrates the

complexity of these large, normally single, eukaryotic

cells. Some protists photosynthesize, but others ingest

or absorb their food. Many, including Paramecium, are

mobile, moving with cilia or flagella.



  • Fungi are multicelled eukaryotes such as mushrooms

  • Many are decomposers

  • All are consumers that secrete substances that break down food outside of the body and absorb the released nutrients



Fungi are eukaryotes. Most are multicelled. Different kinds are parasites, pathogens, or decomposers. Without decomposers such as fungi, communities would be buried in their own wastes.


The kingdom Fungi (domain Eukarya)

An exotic mushroom found in Peru. Most fungi are

multicellular. Fungi generally absorb their food, which is

usually the dead bodies or wastes of plants and animals. The

food is digested by enzymes secreted outside the fungal

body. Most fungi cannot move.



  • Plants are multicelled eukaryotes that live on land or in freshwater environments

  • Most are photosynthetic producers

  • Plants and other photosynthesizers also serve as food for most of the other organisms in the biosphere



Plants are multicelled eukaryotes, most of which are photosynthetic. Nearly all have roots, stems, and leaves. Plants are the primary producers in land ecosystems.


The kingdom Plantae (domain Eukarya)

This butterfly weed represents the flowering plants, the

dominant members of the kingdom Plantae. Flowering

plants owe much of their success to mutually beneficial

relationships with animals, such as these pearl crescent

butterflies, in which the flower provides food and the

insect carries pollen from flower to flower, fertilizing

them. Plants are multicellular, nonmotile eukaryotes that

acquire nutrients by photosynthesis.



  • Animals

    • Multicelled consumers that ingest tissues or juices of other organisms

    • Herbivores graze; carnivores eat meat; scavengers eat remains of other organisms; parasites withdraw nutrients from the tissues of a host

    • Develop through stages that lead to the adult form

    • Actively move about during at least part of their lives



Animals are multicelled eukaryotes that ingest tissues or juices of other organisms. All actively move about during at least part of their life.


The kingdom Animalia (domain Eukarya)

A wrasse rests on a soft coral. Animals are multicellular;

animal bodies consist of a wide assortment of tissues and

organs composed of specialized cell types. Most animals can

move and respond rapidly to stimuli. The coral is a member

of the largest group of animals: the invertebrates, which lack

a backbone. This group also includes insects and mollusks.

The wrasse is a vertebrate; like humans, it has a backbone.

Organizing information about species

Organizing Information About Species

  • Each type of organism, or species, is given a unique name

  • We define and group species based on shared traits

  • Taxonomy is the science of naming and classifying species

The tree of life

The Tree of Life

The binomial system

The Binomial System

  • Carolus Linnaeus standardized a two-part naming system that we use today

  • The first part is the genus, a group of species that share a unique set of features

  • The second part is the specific epithet

  • Genus name plus specific epithet designate one species

    • Example: the dog rose Rosa canina

Taxonomic classification

Taxonomic Classification

  • We rank species into ever more inclusive categories: genus, family, order, class, phylum, kingdom, and domain

  • Each rank, ortaxonis a group of organisms that share a unique set of features

  • Each higher taxon consists of a group of the next lower taxon

The three domain system

The Three-Domain System

A three domain system sorts all life into three groups – Bacteria, Archaea and Eukarya.

The six kingdom system

The Six-Kingdom System

A six kingdom system divides Eukaryotes into four kingdoms.

Taxonomic classification1

Taxonomic Classification

A rose by any other name

A Rose by Any Other Name . . .

  • A species is assigned to higher taxa based on some subset of heritable traits it shares with other species

    • Morphological traits (observable characteristics)

    • Physiological traits (functional characteristics)

    • Behavioral traits (responses to certain stimuli)



  • Traits vary a little within a species

  • There can be tremendous differences between species; such species look very different, so it is easy to tell them apart

  • Species that share a more recent ancestor may be harder to tell apart

The biological species concept

The Biological Species Concept

  • Evolutionary biologist Ernst Mayr defined a species as groups of individuals that potentially can interbreed, produce fertile offspring, and do not interbreed with other groups

  • This “biological species concept” is useful in many cases, but it is not universally applicable

  • For now it is important to remember that a “species” is a convenient but artificial human construction

How do we keep track of all the species we know about

How do we keep track of all the species we know about?

  • Each species has a unique, two-part scientific name.

  • Classification systems group species on the basis of shared, inherited traits

Life s diversity

Life’s Diversity

  • Of an estimated 100 billion kinds of organisms that have ever lived on Earth, as many as 100 million are with us today

The science of nature

The Science of Nature

  • Judging the quality of information before accepting it is called critical thinking

  • Scientists practice critical thinking by testing predictions about how the natural world works

Thinking about thinking

Thinking About Thinking

  • Critical thinking is the deliberate process of judging the quality of information before accepting it

  • Critical thinking considers the supporting evidence, alternative interpretations, and biases contained in a message

  • Being conscious about learning can help you decide whether to allow new information to guide your beliefs and actions

How science works

How Science Works

  • Science is the systematic study of the observable world and how it works

  • Generally, a researcher observes something in nature and uses inductive reasoning to form a hypothesis (testable explanation) for it

    • Inductive reasoning – arriving at a conclusion based upon one’s observations

  • The researcher then uses deductive reasoning to make a predictionabout what might occur if the hypothesis is correct

    • deductive reasoning – logical process of using a general premise to draw a conclusion about a specific case

  • Experiments


    • Experiments are tests designed to support or falsify a prediction

    • Researchers investigate cause-and-effect relationships by changing or observing variables

    • An independent variable is defined or controlled by the person doing the experiment

    • A dependent variable is an observed result that is supposed to be influenced by the independent variable

    The scientific method

    The Scientific Method

    • Experiments are performed on an experimental groupas compared with a control group, and sometimes on models

    • Conclusions are drawn from experimental results (data); a hypothesis that is not consistent with data is modified

    • Making, testing, and evaluating hypotheses is called the scientific method

    The scientific method1

    The Scientific Method

    What is science

    What is science?

    • The scientific method consists of making, testing, and evaluating hypotheses

    • It is a way of critical thinking, or systematically judging the quality of information before allowing it to guide one’s beliefs and actions

    • Experiments measure how changing an independent variable affects a dependent variable

    Sampling error in experiments

    Sampling Error in Experiments

    • Researchers often test or survey a subset of a population, area, or event, then use the results to make generalizations

    • Results may differ from results of the same experiment performed on the whole group

    • Sampling erroris a difference between results from a subset and results from the whole

    • Small sample size increases the likelihood of sampling error in experiments

    Sample size affects sampling error

    Sample Size Affects Sampling Error


    B The jar is hidden from Natalie’s view before she removes her blindfold. She sees one green jelly bean in her hand and assumes that the jar must hold only green jelly beans.

    D The larger sample leads Natalie to assume that one-fifth of the jar’s jelly beans are green (20 percent) and four-fifths are black (80 percent). This sample more closely approximates the jar’s actual green-to-black ratio of 30 percent to 70 percent. The more times Natalie repeats the sampling, the greater the chance she has of guessing the actual ratio.

    A Natalie, blindfolded, randomly plucks a jelly bean from a jar. The jar contains 120 green and 280 black jelly beans, so 30 percent of the jelly beans in the jar are green, and 70 percent are black.

    C Still blindfolded, Natalie randomly picks out 50 jelly beans from the jar. She ends up picking out 10 green and 40 black ones.

    Stepped Art

    Figure 1-13 p16



    • In cases like flipping a coin, it is possible to calculate probability of an expected result

    • Probability

      • The measure, expressed as a percentage, of the chance that a particular outcome will occur

      • Depends on the total number of possible outcomes

    • Analysis of experimental data often includes calculations of probability

    Statistical significance

    Statistical Significance

    • If a result is very unlikely to have occurred by chance alone, it is said to be statistically significant

    • Statistically significant refers to a result that is statistically unlikely to have occurred by chance

    • In science, every result – even a statistically significant one –has a possibility of being incorrect



    • Variation in a set of data is often shown as error bars on a graph

    • Error bars may indicate variation around an average for one sample set, or the difference between two sample sets

    Error bars in a graph

    Error Bars in a Graph

    How do scientists reduce sampling error and bias in research

    How do scientists reduce sampling error and bias in research?

    • Researchers minimize sampling error by using large sample sizes and by repeating their experiments

    • A statistical analysis can show the probability that a result has occurred by chance alone

    • Science is a self-correcting process because it is carried out by an aggregate community of people systematically checking one another’s ideas

    The nature of science

    The Nature of Science

    • Scientific theories are our best descriptions of reality

    • Science helps us to be objective about our observations, in part because it is limited to the observable

    Theories and laws

    “Theories” and “Laws”

    • A scientific theoryis a long-standing hypothesis that has not been disproved after many years of rigorous testing

    • Like all hypotheses, a scientific theory can be disproven by a single observation that falsifies it

    • A law of nature describes a phenomenon that has been observed to occur consistently, but for which we do not have a complete scientific explanation

    The limits of science

    The Limits of Science

    • Science deals with observations of the natural world which produce objective data that can be measured without bias

    • Science does not measure moral, aesthetic, or philosophical standards vary from one society to the next

    • Neither does science address the supernatural, or anything that is “beyond nature”

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