Exploring Life Chapter 1

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Exploring LifeChapter 1

• Advanced Placement Biology
• Liberty Senior High School
• Mr. Knowles

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Life

• Defies a simple, one-line definition.
• Lends itself to mysticism.

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What is biology?
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Biology

• Bios Greek for life
• Logos Greek for study or thought
• Biology - the study of living things

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• Concept 1.1 Biologists explore life from the
  microscopic to the global scale.
• The study of life
• Extends from the microscope scale of molecules
  and cells to the global scale of the entire
  living planet.

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What does it mean to be alive?

• What characteristics define life?
• What are the criteria for something to be alive?

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What does it mean to be living?

• Some Characteristics
• 1. Order- have a hierarchical organization (Fig
  1.3).

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A Hierarchy of Biological Organization

• The hierarchy of life
• Extends through many levels of biological
  organization

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• From the biosphere to organisms

1.a. biome
2. Ecosystems
3. Communities
4. Populations
5. Organisms
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• From cells to atoms.

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Order Beyond the Organism

• Population- a group of individuals of same
  species occupying a given area at the same time.
• Community- a number of interacting populations in
  a common environment.

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Order in Biology

• Ecosystem- organisms (biotic) interacting with
  their nonliving (abiotic) environment.
• Biomes- major groupings of plants, animals, and
  microorganisms that occur over a wide geography
  and have distinct characteristics (ex. deserts,
  tropical rainforests)

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The Emergent Properties of Systems

• Biological systems are much more than the sum of
  their parts.
• Due to increasing complexity
• New properties emerge with each step upward in
  the hierarchy of biological order

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The Power and Limitations of Reductionism

• Reductionism-
• Involves reducing complex systems to simpler
  components that are more manageable to study.

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• The study of DNA structure, an example of
  reductionism
• Has led to further study of heredity, such as the
  Human Genome Project

Figure 1.9
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A Closer Look at Ecosystems

• Each organism
• Interacts with its environment.
• Both organism and environment
• Are affected by the interactions between them.

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Ecosystem Dynamics

• The dynamics of any ecosystem include two major
  processes
• Cycling of nutrients, in which materials acquired
  by plants eventually return to the soil
• The flow of energy from sunlight to producers to
  consumers

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Energy Conversion

• Activities of life
• Require organisms to perform work, which depends
  on an energy source.
• The exchange of energy between an organism and
  its surroundings involves the transformation from
  one form of energy to another.

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• Energy flows through an ecosystem
• Usually entering as sunlight and exiting as heat

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What does it mean to be living?

• 2. Responsiveness or Sensitivity- have a response
  to stimuli.
• Chemotactic
• Phototactic
• Thigmotropic
• Gravitropic

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Is fire alive?
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A Closer Look at Cells

• The cell
• Is the lowest level of organization that can
  perform all activities required for life

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The Cells Heritable Information

• Cells contain chromosomes made partly of DNA, the
  substance of genes
• Which program the cells production of proteins
  and transmit information from parents to offspring

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• The molecular structure of DNA
• Accounts for it information-rich nature.

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What does it mean to be living?

• 3. Growth, Development, and Reproduction- all use
  hereditary molecules to pass genetic information
  to offspring.

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Two Main Forms of Cells

• All cells share certain characteristics
• They are all enclosed by a membrane
• They all use DNA as genetic information
• There are two main forms of cells
• Eukaryotic
• Prokaryotic

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• Prokaryotic cells
• Lack the kinds of membrane-enclosed organelles
  found in eukaryotic cells.

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What does it mean to be living?

• 4. Regulation- have regulatory mechanisms to
  coordinate functions (transportation of
  nutrients, wastes, etc.) maintain homeostasis.

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Feedback Regulation in Biological Systems

• A kind of supply-and-demand economy
• Applies to some of the dynamics of biological
  systems.
• The output, or product, of a process regulates
  that very process -feedback regulation.

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• In negative feedback
• An accumulation of an end product slows the
  process that produces that product.

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• In positive feedback
• The end product speeds up production.

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Question Are viruses alive?
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Grouping Species The Basic Idea

• Diversity is a hallmark of life.
• Taxonomy
• is the branch of biology that names and
  classifies species according to a system of
  broader and broader groups

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• Classifying life

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The Three Domains of Life

• At the highest level, life is classified into
  three domains
• Bacteria
• Archaea
• Eukarya
• Domain Bacteria and domain Archaea
• Consist of prokaryotes
• Domain Eukarya, the eukaryotes
• Includes the various protist kingdoms and the
  kingdoms Plantae, Fungi, and Animalia

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• Lifes three domains

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Unity in the Diversity of Life

• As diverse as life is
• There is also evidence of remarkable unity

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• Concept 1.4 Evolution accounts for lifes unity
  and diversity
• The history of life
• Is a saga of a changing Earth billions of years
  old

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Theodosius Dobzhansky

• Nothing in biology makes sense except in the
  light of evolution.
• The American Biology Teacher (1973)

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• The evolutionary view of life
• Came into sharp focus in 1859 when Charles Darwin
  published On the Origin of Species by Means of
  Natural Selection

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• The Origin of Species articulated two main
  points
• Descent with modification
• Natural selection

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Natural Selection

• Darwin proposed natural selection
• As the mechanism for evolutionary adaptation of
  populations to their environments

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• Natural selection is the evolutionary process
  that occurs
• When a populations heritable variations are
  exposed to environmental factors that favor the
  reproductive success of some individuals over
  others.

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Darwin, 1835, Galapagos
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• Darwin proposed that natural selection
• Could enable an ancestral species to split into
  two or more descendant species, resulting in a
  tree of life

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• Concept 1.5 Biologists use various forms of
  inquiry to explore life
• At the heart of science is inquiry
• A search for information and explanation, often
  focusing on specific questions
• Biology blends two main processes of scientific
  inquiry
• Discovery science
• Hypothesis-based science

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Discovery Science

• Discovery Science
• Describes natural structures and processes as
  accurately as possible through careful
  observation and analysis of data.

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Types of Data

• Data
• Are recorded observations.
• Can be quantitative or qualitative.

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Induction in Discovery Science

• In inductive reasoning
• Scientists derive generalizations based on a
  large number of specific observations. Ex. Cell
  Theory- All organisms are made of cells
  specific observations? one generalization

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Hypothesis-Based Science

• In science, inquiry that asks specific questions
• Usually involves the proposing and testing of
  hypothetical explanations, or hypotheses.

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Deduction The Ifthen Logic of
Hypothesis-Based Science

• In deductive reasoning
• The logic flows from the general to the specific.
  Ex. If all organisms are made of cells and
  humans are organisms, then humans are composed of
  cells.
• Makes a deductive prediction general to the
  specific

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The Scientific Method- Away of Looking at Life!
Click for the Method
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A Biological Example of a Theory

• How can living things change over time?

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Why do male and female lions look different?
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• Concept 1.6 A set of themes connects the
  concepts of biology
• Underlying themes
• Provide a framework for understanding biology

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• Eleven themes that unify biology

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Common Themes in Biology

• Science as a Process
• Evolution
• Energy Transfer
• Continuity and Change
• Relationship of Structure and Function
• Regulation
• Interdependence in Nature
• Science, Technology, and Society

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How many moths do you see?