BIOLOGY: Today and TomorrowBIOLOGY: Today and Tomorrow, 4e, 4estarr starr evers evers starrstarr

Chapter 1Invitation to Biology

1.1 The Secret Life of Earth

Biology The scientific study of life

We have found only a fraction of the organisms on Earth Scientists constantly discover new species Extinction rates are accelerating

Example: New Guinea’s Foja Mountains

“Pinocchio Frog”

Extinction is happening at 1000x faster than normal, thanks to us humans!

Life’s Levels of Organization

Atom Fundamental building block of all matter

Molecule An association of two or more atoms

Cell Smallest unit of life

Organism An individual; consists of one or more cells

Life’s Levels of Organization

Population Group of individuals of a species in a given area

Community All populations of all species in a given area

Ecosystem A community interacting with its environment

Biosphere All regions of Earth that hold life

ANIMATED FIGURE: Life’s levels of organization

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What is Life?1.3 How Living Things Are Alike

Life is organized in successive levels with new properties emerging at each level.

All living things have similar characteristics Require energy and nutrients Sense and respond to change Reproduce with the help of DNA

Organisms Require Enery and Nutrients

Energy The capacity to do work

Nutrient Substance that is necessary for survival, but that an

organism can’t make for itself

Organisms and Energy Sources

Producers Organisms that make their own

food using energy and simple raw materials from the environment

Example: photosynthesis in plants

Consumers Organisms that get energy and

carbon by feeding on tissues, wastes, or remains of other organisms

Example: animals

ANIMATED FIGURE: One-way energy flow and materials cycling

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Organisms Sense and Respond to Change

Homeostasis Set of processes by which an organism keeps its internal

conditions within tolerable ranges by sensing and responding to change

Organisms Grow and Reproduce

Organisms grow, develop, and reproduce based on information encoded in DNA, which they inherit from parents

Growth Increase in size, volume, and number of cells in

multicelled species

Development Multistep process by which the first cell of a new individual

becomes a multicelled adult

Organisms Grow and Reproduce

Reproduction Process by which parents produce offspring

Inheritance Transmission of DNA from parents to offspring

DNA (Deoxyribonucleic acid) Carries hereditary information that guides development

and functioning

1.4 How Living Things Differ

Living things differ in observable characteristics, or traits ie. Biodiversity (Scope of variation among living organisms)

Classification Systems

Organisms can be grouped based on whether they have a nucleus

Nucleus Sac with two membranes that encloses a cell’s DNA

One system sorts all organisms into one of three domains: Bacteria, Archaea, and Eukarya

Prokaryotes Prokaryotes

Single celled organisms in which DNA is not contained in a nucleus. Examples include Bacterium Archaeon

More closely related to eukaryotes than to bacteria

Collectively, the most diverse representatives of life!

A) Bacteria are the most numerous organisms on Earth. Left, a bacterium with a row of iron crystals that acts like a tiny compass; right, spiral cyanobacteria.

Bacteria and Archaea

B) Archaea may resemble bacteria, but they are more closely related to eukaryotes. These are two types of archaea from a hydrothermal vent on the seafloor.

Bacteria and Archaea

Eukaryotes Eukaryotes

Organisms whose cells typically have a nucleus These can be single or multi-celled and are usually

larger, and more complex than prokaryotes

Examples include Fungus

Eukaryotic consumer that obtains nutrients by digestion and absorption outside the body

Protists Eukaryotes that are not plants, animals, or fungi

Eukaryotes

Examples continued…

Animals Multi-celled consumer that develops through a series of

embryonic stages and moves about during all or part of the life cycle

Plant Typically a multi-celled, photosynthetic producer

Some Eukaryotes

1.5 What is a “Species?”

Taxonomy is the science of naming and classifying species A species is a unique kind of organism A genus is a group of species that share unique traits

Every species is given a unique two-part scientific name consisting of its genus and species Example: Lion: Panthera leo

Taxa

Each rank, or taxon is a group of organisms that share a unique set of traits Morphological (structural) traits Biochemical traits Behavioral traits (response to stimuli)

Each taxon consists of a group of the next lower taxon Species, genus, family, order, class, phylum, kingdom,

and domain “Dumb kids playing catch on freeways get smashed “

Taxonomic Classification

EukaryaPlantae

ApialesApiaceaeDaucuscarotawild carrot

MagnoliophytaMagnoliopsida

domainkingdom

phylumclass order

familygenus

speciescommon name

Eukarya PlantaeMagnoliophytaMagnoliopsidaRosalesCannabaceaeCannabissativamarijuana

Malus

apple

Eukarya PlantaeMagnoliophytaMagnoliopsidaRosalesRosaceae

domestica

Eukarya PlantaeMagnoliophytaMagnoliopsidaRosalesRosaceaeRosaacicularisprickly rose

Eukarya PlantaeMagnoliophytaMagnoliopsidaRosalesRosaceaeRosacaninadog rose

Identifying Species

How do we decide if similar-looking organisms belong to different species or not?

Early naturalists classified species according to what they looked like and where they lived

Today’s biologists compare biochemical traits such as DNA sequence

Four butterflies, two species

Biological Species Concept

“Biological species concept” Ernst Mayr defined a species as one or more

groups of individuals that potentially can interbreed, produce fertile offspring, and do not interbreed with other groups

ANIMATED FIGURE: Classification systems

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The Scientific Method

The Scientific Method

Prediction Statement, based on a hypothesis, about a condition that

should exist if the hypothesis is correct

Model Analogous system used for testing hypotheses

Experiment Test designed to support or falsify a prediction

The Scientific Method

Variable

Characteristic that differs among individuals or over time

Experimental group Group of individuals who are exposed to a variable

Control group Group not exposed to the variable being tested.

Data Factual information from experiments or surveys

Experiment: Potato Chips and Stomachaches

1.7 Analyzing Experimental Results

Researchers experiment on subsets of a group, which may result in sampling error

Sampling error Difference between results derived from testing an entire

group of events or individuals, and results derived from testing a subset of the group

Sampling Error

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.

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.

Sampling Error

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

Sampling Error

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.

Probability

Researchers try to design experiments carefully in order to minimize sampling error

Probability The measure, expressed as a percentage, of the chance

that a particular outcome will occur

Statistically significant Refers to a result that is statistically unlikely to have

occurred by chance

Bias in Interpreting Results

Researchers risk interpreting their results in terms of what they want to find out (bias)

Science is a self-correcting process because scientists continuously retest and recheck each other’s ideas

ANIMATION: Height Graph

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1.8 The Nature of Science

Scientific theory Hypothesis that has not been disproven after

many years of rigorous testing Can never be proven absolutely Can be disproven by a single observation or result

that is inconsistent with it

Law of Nature

A scientific theory differs from a law of nature

Law of nature Generalization that describes a consistent natural

phenomenon for which there is incomplete scientific explanation

Example: Laws of thermodynamics

1.9 The Secret Life of Earth (revisited)

Earth hosts at least 100 million species

Recently discovered species include a leopard in Borneo; a wolf in Egypt; a dolphin in Australia; and spiders in California

You can find information about the 1.8 million species we know about in the Encyclopedia of Life (www.eol.org)

A new species of trapdoor spider