Chapter 1 Biology: Exploring Life -...

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© 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko

PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey

Chapter 1 Biology: Exploring Life

Figure 1.0_1 Chapter 1: Big Ideas

Themes in the Study of Biology

The Process of Science

Biology and Everyday Life

Evolution, the Core Theme of Biology

THEMES IN THE STUDY OF BIOLOGY

© 2012 Pearson Education, Inc.

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1.1 All forms of life share common properties

  Biology is the scientific study of life.

  Properties of life include

1.  Order—the highly ordered structure that typifies life,

2.  Reproduction—the ability of organisms to reproduce their own kind,

3.  Growth and development—consistent growth and development controlled by inherited DNA,

4.  Energy processing—the use of chemical energy to power an organism’s activities and chemical reactions,


1.1 All forms of life share common properties

5.  Response to the environment—an ability to respond to environmental stimuli,

6.  Regulation—an ability to control an organism’s internal environment within limits that sustain life, and

7.  Evolutionary adaptation—adaptations evolve over many generations as individuals with traits best suited to their environments have greater reproductive success and pass their traits to offspring.


Figure 1.1

(1) Order

(2) Reproduction

(3) Growth and development

(4) Energy processing

(7) Evolutionary adaptation

(6) Regulation

(5) Response to the environment

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1.2 In life’s hierarchy of organization, new properties emerge at each level

  Biological organization unfolds as follows:

–  Biosphere—all of the environments on Earth that support life,

–  Ecosystem—all the organisms living in a particular area and the physical components with which the organisms interact,

–  Community—the entire array of organisms living in a particular ecosystem,

–  Population—all the individuals of a species living in a specific area,



–  Organism—an individual living thing,

–  Organ system—several organs that cooperate in a specific function,

–  Organ—a structure that is composed of tissues and that provides a specific function for the organism,

–  Tissues—a group of similar cells that perform a specific function,

–  Cells—the fundamental unit of life,



–  Organelle—a membrane-bound structure that performs a specific function in a cell, and

–  Molecule—a cluster of small chemical units called atoms held together by chemical bonds.


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Figure 1.2 Biosphere

Madagascar

Ecosystem: Forest in

Madagascar

Community: All organisms in

the forest

Population: Group of ring-tailed

lemurs

Organism: Ring-tailed lemur

Organ system: Nervous system

Organ: Brain

Tissue: Nervous tissue

Nerve

Spinal cord Brain

Organelle: Nucleus

Cell: Nerve cell

Nucleus Atom

Molecule: DNA


  Emergent properties are –  new properties that arise in each step upward in the

hierarchy of life,

–  from the arrangement and interactions among component parts.


1.3 Cells are the structural and functional units of life

  Cells are the level at which the properties of life emerge.

  A cell can

–  regulate its internal environment,

–  take in and use energy,

–  respond to its environment,

–  develop and maintain its complex organization, and

–  give rise to new cells.


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  All cells

–  are enclosed by a membrane that regulates the passage of materials between the cell and its surroundings and

–  use DNA as their genetic information.



  There are two basic types of cells.

1.  Prokaryotic cells

–  were the first to evolve,

–  are simpler, and

–  are usually smaller than eukaryotic cells.

2.  Eukaryotic cells

–  contain membrane-enclosed organelles, including a nucleus containing DNA, and

–  are found in plants, animals, and fungi.


Figure 1.3

Eukaryotic cell

Membrane

Prokaryotic cell

DNA (no nucleus)

Organelles

Nucleus (membrane- enclosed)

DNA (throughout nucleus)

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  Systems biology models the complex interactions of biological systems, ranging

–  from the functioning of the biosphere

–  to the complex molecular machinery of a cell.



  Cells illustrate another theme in biology: the correlation of structure and function.

  Structure is related to function at all levels of biological organization.


1.4 Living organisms interact with their environment, exchanging matter and energy

  Living organisms interact with their environments, which include

–  other organisms and

–  physical factors.

  In most ecosystems

–  plants are the producers that provide the food,

–  consumers eat plants and other animals, and

–  decomposers act as recyclers, changing complex matter into simpler mineral nutrients.


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1.4 Living organisms interact with their environment, exchanging matter and energy

  The dynamics of ecosystems include two major processes:

1.  The recycling of chemical nutrients from the atmosphere and soil through producers, consumers, and decomposers back to the environment.

2.  The one-way flow of energy through an ecosystem, entering as sunlight, converted to chemical energy by producers, passed on to consumers, and exiting as heat.


Figure 1.4 Ecosystem

Sunlight

CO2

Heat

Chemical energy (food)

Producers (such as plants)

Water and minerals taken up by tree roots

Cycling of chemical nutrients

Decomposers (in soil)

Consumers (such as animals)

CO2

O2 O2

Figure 1.4_1

Ecosystem

Sunlight

Producers (such as plants)

Consumers (such as animals)

Heat

O2 O2

CO2

Chemical energy (food)

CO2

Water and minerals taken up by tree roots

Cycling of chemical nutrients

Decomposers (in soil)

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EVOLUTION, THE CORE THEME OF BIOLOGY


1.5 The unity of life is based on DNA and a common genetic code

  All cells have DNA, the chemical substance of genes.

 Genes

–  are the unit of inheritance that transmits information from parents to offspring,

–  are grouped into very long DNA molecules called chromosomes, and

–  control the activities of a cell.


1.5 The unity of life is based on DNA and a common genetic code

  A species’ genes are coded in the sequences of the four building blocks making up DNA’s double helix.

–  All forms of life use essentially the same code to translate the information stored in DNA into proteins.

–  The diversity of life arises from differences in DNA sequences.


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Figure 1.5

A

T

T

C

C

G G C

T A

A T

G C

A

G C

G C

A T

1.6 The diversity of life can be arranged into three domains

 We can think of biology’s enormous scope as having two dimensions.

1.  The “vertical” dimension is the size scale that stretches from molecules to the biosphere.

2.  The “horizontal” dimension spans across the great diversity of organisms existing now and over the long history of life on Earth.



  Diversity is the hallmark of life.

–  Biologists have identified about 1.8 million species.

–  Estimates of the actual number of species ranges from 10 to 100 million.

  Taxonomy names species and classifies them into a system of broader groups.


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  The diversity of life can be arranged into three domains.

1.  Bacteria are the most diverse and widespread prokaryotes.

2.  Archaea are prokaryotes that often live in Earth’s extreme environments.

3.  Eukarya have eukaryotic cells and include

–  single-celled protists and

–  multicellular fungi, animals, and plants.


Figure 1.6

Domain Bacteria

Domain Archaea

Domain Eukarya

Bacteria

Archaea

Protists (multiple kingdoms)

Kingdom Fungi Kingdom Animalia

Kingdom Plantae

1.7 Evolution explains the unity and diversity of life

  The history of life, as documented by fossils, is a saga of a changing Earth

–  billions of years old and

–  inhabited by an evolving cast of life forms.

  Evolution accounts for life’s dual nature of

–  kinship and

–  diversity.


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  In 1859, Charles Darwin published the book On the Origin of Species by Means of Natural Selection, which articulated two main points.

1. A large amount of evidence supports the idea of evolution, that species living today are descendants of ancestral species in what Darwin called “descent with modification.”

2. Natural selection is a mechanism for evolution.



  Natural selection was inferred by connecting two observations.

1.  Individuals in a population vary in their traits, many of which are passed on from parents to offspring.

2.  A population can produce far more offspring than the environment can support.


Figure 1.7C

Elimination of individuals with certain traits

Reproduction of survivors

Population with varied inherited traits 1

3

2

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  From these observations, Darwin inferred that

–  those individuals with heritable traits best suited to the environment are more likely to survive and reproduce than less well-suited individuals,

–  as a result of this unequal reproductive success over many generations, an increasing proportion of individuals will have the advantageous traits, and

–  the result will be evolutionary adaptation, the accumulation of favorable traits in a population over time.


THE PROCESS OF SCIENCE


1.8 Scientific inquiry is used to ask and answer questions about nature

  The word science is derived from a Latin verb meaning “to know.” Science is a way of knowing.

  Scientists

–  use inductive reasoning to draw general conclusions from many observations and

–  deductive reasoning to come up with ways to test a hypothesis, a proposed explanation for a set of observations.The logic flows from general premises to the specific results we should expect if the premises are true.


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1.8 Scientific inquiry is used to ask and answer questions about nature

  How is a theory different from a hypothesis? A scientific theory is

–  much broader in scope than a hypothesis,

–  usually general enough to generate many new, specific hypotheses, which can then be tested, and

–  supported by a large and usually growing body of evidence.


1.9 Scientists form and test hypotheses and share their results

 We solve everyday problems by using hypotheses.

–  A common example would be the reasoning we use to answer the question, “Why doesn’t a flashlight work?”

–  Using deductive reasoning we realize that the problem is either (1) the bulb or (2) the batteries.

–  Further, a hypothesis must be

–  testable and

–  falsifiable.

–  In this example, two hypotheses are tested.


Figure 1.9A_s1

Observation

Question

Hypothesis #1: Dead batteries

Hypothesis #2: Burned-out bulb

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Figure 1.9A_s2

Observation

Question



Prediction: Prediction: Replacing batteries will fix problem.

Replacing bulb will fix problem.

Experiment: Experiment: Test prediction by replacing batteries.

Test prediction by replacing bulb.

Figure 1.9A_s3

Test falsifies hypothesis. Revise hypothesis or pose new one.

Observation

Question



Prediction: Prediction: Replacing batteries will fix problem.

Replacing bulb will fix problem.

Experiment: Experiment: Test prediction by replacing batteries.

Test prediction by replacing bulb.

Test does not falsify hypothesis. Make additional predictions and test them.


  An actual research project demonstrates the process of science.

  Scientists began with a set of observations and generalizations that

–  poisonous animals are brightly colored and

–  imposters resemble poisonous species but are actually harmless.

  They then tested the hypothesis that mimics benefit because predators confuse them with the harmful species.


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  The scientists conducted a controlled experiment, comparing

–  an experimental group consisting of artificial king snakes and

–  a control group consisting of artificial brown snakes.

–  The groups differed only by one factor, the coloration of the artificial snakes.

–  The data fit the key prediction of the mimicry hypothesis.


Figure 1.9B

Figure 1.9C

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Figure 1.9D

Figure 1.9E

Coral snakes present

Artificial king snakes

Artificial brown snakes

84%

0

20

40

60

80

100

Coral snakes absent

17% 16%

Perc

ent o

f tot

al a

ttack

s on

art

ifici

al s

nake

s

83%


  Science is a social activity with most scientists working in teams.

  Scientists share information in many ways.

  Science seeks natural causes for natural phenomena.

–  The scope of science is limited to the study of structures and processes that we can directly observe and measure.

–  Hypotheses about supernatural forces or explanations are outside the bounds of science, because they generate hypotheses that cannot be tested by science.


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1.11 EVOLUTION CONNECTION: Evolution is connected to our everyday lives

  Evolution is a core theme of biology.

  Evolutionary theory is useful in –  medicine,

–  agriculture,

–  forensics, and

–  conservation.


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