Chapter 1 Invitation to Biology
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Transcript of Chapter 1 Invitation to Biology
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