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Chapter 1

Biology, the Study of Life

Organisms Are Characterized by Diversity and Unity

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1.1 Life is diverseFigure 1.1 Many diverse forms of life are found on planet Earth

Despite this diversity, biologists are able to group organisms based on shared similarities.

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1.2 Life has many levels of organization

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Three most relevant levels of organization are:

Cell

Multicellular Organism

Biosphere

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Cells

The basic unit of structure and function of all organisms

Made of Atoms: the basic building blocks of all matter Molecules: atoms bonded together

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The Multicellular Organism

Most of the living things we see Made of

Cells: basic unit of structure and function of all organisms

Tissue: a group of cells working together Organs: various tissues working together Organ Systems: various organs working

together

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The Biosphere

Most complex level of organization Made of

Populations: all members of one species in one area

Communities: the populations of various organisms in an area

Ecosystem: the communities interacting with their physical environment

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Emergent Properties

Emergent Properties: traits due to the interactions between the parts that make up the whole

Each level of organization is more complex and has more properties than the previous level

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1.3 Organisms share the same characteristics of life

Seven Characteristics of All Life Order Response to Stimuli Regulation of Internal Environment Acquisition of Materials and Energy Reproduction and Development Genetic Inheritance Evolutionary Adaptations

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Order

Cells, tissues, organs, and organ systems are highly ordered in an organism

Allows organism to function as a complete system

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Figure 1.3A The eye of an insect illustrates the orderliness of living structures

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Response to Stimuli

Organisms interact with their environment Example: Plants grow toward light

Behavior – response to stimulus Behaviors to search and compete for energy,

nutrients, shelter, and mates

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Figure 1.3B Plants respond to light

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Regulation of Internal Environment

Homeostasis: the ability of organisms to maintain a state of biological balance Ex: temperature, moisture, and acidity (pH)

Organisms have intricate and unconscious feedback and control mechanisms to maintain homeostasis Also might use a nervous system to create a behavior

to maintain homeostasis Ex: Getting a bite to eat

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Figure 1.3C Iguanas basking in the sun

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Acquisition of Materials and Energy

Organisms need nutrients and energy to live Food provides nutrients, the building blocks of cells,

and energy, the capacity to do work Metabolism: all chemical reactions that occur in

a cell Photosynthesis: process that transforms solar

energy into chemical energy that can be used by organisms

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Figure 1.3D Living things acquire materials and energy and they reproduce

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Reproduction and Development

Life comes only from life All life can reproduce – make another organism

like itself Bacteria, protists, and unicellular organisms split in

two Most multicellular organisms reproduce through the

union of sperm and egg

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Genetic Inheritance

The instructions for an organism’s metabolism and organization are encoded in its genes

Gene: a segment of DNA (deoxyribonucleic acid) that carries the information for how an organism is to be ordered

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Evolutionary Adaptations

Adaptations: modifications that make organisms suited to their way of life They are the product of evolution

Evolution: process by which a species changes through time Species: a group of similarly constructed individuals

capable of successful interbreeding

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The Theory of Evolution

Explains the diversity and unity of all life Natural Selection: mechanism of evolution

developed by Charles Darwin A new variation allows certain members of a species

to produce more offspring than others With successive generations, more individuals will

have that new variation

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Classification Helps Us Understand Diversity

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1.4 Taxonomists group organisms according to

evolutionary relationships Taxonomy: The discipline of identifying and

classifying organisms according to their evolutionary history and relationships

Levels of classification (specific to general) Species, Genus, Family, Order, Class, Phylum,

Kingdom, and Domain

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Table 1.4 Levels of Classification

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Domain

The largest classification category Three domains: Bacteria, Archaea and Eukarya

Bacteria and Archaea are prokaryotes and lack a membrane-bound nucleus

Eukarya are eukaryotes and have membrane-bound nucleus

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Figure 1.4A Domain Archaea

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Figure 1.4B Domain Bacteria

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Kingdoms

Domain Eukarya has four kingdoms Protista: The protists - unicellular and multicellular

organisms either photosynthetic or not Fungi: The fungi - multicellular, heterotrophic mostly

decomposers Plantae: The plants - multicellular photosynthetic

organisms Animalia: The animals - multicellular, heterotrophic

and mostly mobile

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Figure 1.4C The four kingdoms in domain Eukarya

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Scientific Names

Binomial Nomenclature uses two words (the genus name and specific epithet) to name organisms Ex: Phoradendron tomentosum

Scientists avoid common names and use Latin to avoid confusion

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The Biosphere Is Organized

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1.5 The biosphere is divided into ecosystems

Figure 1.5 Grassland, a major ecosystem 1 - 33

Organization in the Biosphere

The organization of life extends into the biosphere the zone of air, land, and water where organisms live Populations: all members of one species in one area Communities: the populations of various organisms

in an area Ecosystem: the communities interacting with their

physical environment

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1.6 Most of the biosphere’s ecosystems are now threatened

Humans tend to modify existing ecosystems

The most biologically diverse ecosystems are severely threatened Rain forests Coral reefs

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Scientists Observe, Hypothesize, and Test

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1.7 The natural world is studied by using scientific methods

Biology is the scientific study of life The scientific process often uses the

scientific method, which has four steps Observation Hypothesis Testing Conclusion

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The Scientific Method

Observation: what scientists can sense in the world around them

Hypothesis: an explanation for a natural event that can be tested

Testing: using either observation or experimentation to disprove a hypothesis

Conclusion: the results are analyzed and the hypothesis is supported or rejected

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Figure 1.7 Flow diagram for the scientific method

Scientific Theory

Different from ‘theory’ used in common speech, a scientific theory is not a speculative idea

Scientific theories are supported by a broad range of observations, experiments and data

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Biological Theories

Theory Concept

Cell All organisms are composed of cells and new cells only come from preexisting cells

Gene Organisms contain coded information that dictates their form, function, and behavior

Evolution All living things have a common ancestor, but each is adapted to a particular way of life

Homeostasis The internal environment of an organism stays relatively constant – with a range protective of life

Ecosystem Organisms are members of populations that interact with each other and with the physical environment within a particular locale

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1.8 Control groups allow for comparison of results

When performing an experiment, the environmental conditions must be kept constant, except for the experimental variable, which deliberately changes Test groups are exposed to the

experimental variable Control groups are not

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Figure 1.8A Pigeon pea/winter wheat rotation study 1 - 43

Ecological Importance of Pigeon Pea Study

Legumes, namely pigeon peas, improve soil to produce a yield far better than using nitrogen fertilizer over the long haul Root nodules on the pigeon peas supply nitrogen

compounds When the roots decay, the extra nutrients are

released into the soil

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APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES

1.9 DNA barcoding of life may become a reality

The Consortium for the Barcode of Life (CBOL) proposes that an organism’s DNA could be the basis for identifying any species Could help people identify pests and find

antivenoms

Figure 1.9 This ant is the jumper ant, Myrmecia pilosula, and is not a fire ant 1 - 45

Connecting the Concepts: Chapter 1

The goal is to understand the scientific process and learn the basic concepts of general biology

The ultimate goal of science is to understand the natural world in terms of theories The theory of evolution is the unifying concept of

biology because it pertains to all aspects of living things

The cell theory states that all forms of life are cellular in nature

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