Invitation to Biology

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Invitation to Biology

• Chapter 1

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1.1 Impacts/IssuesThe Secret Life of Earth

• Biology
• The systematic study of life
• We have encountered only a fraction of the
  organisms that live on Earth
• Scientists constantly discover new species
• Extinction rates are accelerating

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Video Lost worlds and other wonders
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Exploring New Guinea

• A rare golden-mantled tree kangaroo

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1.2 Lifes Levels of Organization

• The building blocks (atoms) that make up all
  living things are the same ones that make up all
  nonliving things
• The unique properties of life emerge as certain
  kinds of molecules become organized into cells

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Lifes 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

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Lifes 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

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Nature and Life

• Nature
• Everything in the universe, except what humans
  have manufactured
• Emergent property
• A characteristic of a system that does not appear
  in any of a systems component parts

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Levels of Organization in Nature
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Animation Lifes levels of organization
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Active Figure Levels of organization
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1.3 Overview of Lifes Unity

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

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Energy Sustains Lifes Organization

• One-way flow of energy through the biosphere and
  cycling of nutrients among organisms sustain
  lifes organization
• Energy
• The capacity to do work
• Nutrient
• Substance that is necessary for survival, but
  that an organism cant make for itself

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Organisms and Energy Sources

• Producers
• Organisms that make their own food using energy
  and simple raw materials from the environment
• Example plants
• Consumers
• Organisms that get energy and carbon by feeding
  on tissues, wastes, or remains of other organisms
• Example animals

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Energy Flow and Material Cycling
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Stepped Art
Fig. 1-3a, p. 6
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Fig. 1-3b, p. 6
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Animation One-way energy flow and materials
cycling
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Organisms Sense and Respond to Change

• Organisms sense and respond to change to keep
  conditions in their internal environment within a
  range that favors cell survival (homeostasis)
• Homeostasis
• Set of processes by which an organism keeps its
  internal conditions within tolerable ranges
• Receptor
• Molecule or structure that responds to a stimulus

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Response to Stimuli
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Organisms Grow, Develop and Reproduce

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

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Organisms Grow, Develop and Reproduce

• Reproduction
• Process by which parents produce offspring
• Inheritance
• Transmission of DNA from parents to offspring
• DNA (Deoxyribonucleic acid)
• Molecule that carries hereditary information
  about traits

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1.4 Introduction to Lifes Diversity

• The millions of species on Earth vary greatly in
  details of body form and function
• Each species is given a unique two-part name that
  includes genus and species names
• Species
• A type of organism
• Genus
• Group of species that share a unique set of traits

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Classification Systems

• Classification systems group species according to
  traits and organize information about species
• One system sorts all organisms into one of three
  domains Bacteria, Archaea, and Eukarya
• The eukaryotes include plants, protists, fungi
  and animals

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Lifes Diversity Three-Domain Classification
System
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Animation Lifes diversity
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Prokaryotes

• Prokaryotes
• Single celled organisms in which DNA is not
  contained in a nucleus
• Bacterium
• A member of the prokaryotic domain Bacteria
• Archaeans
• A member of the prokaryotic domain Archaea

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Eukaryotes

• Eukaryotes
• Organisms whose cells typically have a nucleus
• Fungus
• Eukaryotic consumer that obtains nutrients by
  digestion and absorption outside the body
• Protists
• Eukaryotes that are not plants, animals, or fungi

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Eukaryotes

• Plant
• Typically a multicelled, photosynthetic producer
• Animal
• Multicelled consumer that develops through a
  series of embryonic stages and moves about during
  all or part of the life cycle

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Animation Three domains
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• break

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1.5 The Nature of Scientific Inquiry

• Critical thinking
• Mental process of judging the quality of
  information before deciding whether or not to
  accept it

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The Scope and Limits of Science

• Science is a way of looking at the natural world
  which helps us to communicate our experiences
  without bias by focusing only on testable ideas
  about observable phenomena
• Science does not address the supernatural
• Science
• The systemic study of nature

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1.6 How Science Works

• Researchers make and test potentially falsifiable
  predictions about how the natural world works
• Generally, scientific inquiry involves forming a
  hypothesis (testable assumption) about an
  observation then making and testing predictions
  based on the hypothesis
• A hypothesis that is not consistent with the
  results of scientific tests is modified or
  discarded

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Common Research Practices

• 1. Observe some aspect of nature
• 2. Frame a question about your observation
• 3. Propose a hypothesis (a testable explanation
  of the observation)

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Common Research Practices

• 4. Make a prediction a statement based on a
  hypothesis, about some condition that should
  exist if the hypothesis is not wrong
• 5. Test the accuracy of the prediction by
  experiments or gathering information (tests may
  be performed on a model)

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Common Research Practices

• 6. Assess the results of the tests (data) to see
  if they support or disprove the hypothesis
• 7. Conclusions Report all steps of your work and
  conclusions to the scientific community

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Making Observations A Field Study
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A Scientific Theory

• Scientific theory
• A hypothesis that has not been disproven after
  many years of rigorous testing
• Useful for making predictions about other
  phenomena

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Laws of Nature

• Law of nature
• Generalization that describes a consistent and
  universal natural phenomenon for which we do not
  yet have a complete scientific information
• Example gravity

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Examples of Scientific Theories
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Animation An example of the scientific method
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1.7 The Power of Experiments

• Natural processes are often influenced by many
  interacting variables
• Variable
• A characteristic or event that differs among
  individuals

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The Power of Experiments

• Experiments simplify interpretations of complex
  biological systems by focusing on the effect of
  one variable at a time
• Experiment
• A test to support or falsify a prediction

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Experimental and Control Groups

• Experimental group
• A group of objects or individuals that display or
  are exposed to a variable under investigation
• Control group
• A group of objects or individuals that is
  identical to an experimental group except for one
  variable

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Potato Chips and Stomachaches
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Stepped Art
Fig. 1-10, p. 14
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Example Butterflies and Birds

• Question
• Why does a peacock butterfly flick its wings?
• Two hypotheses
• Exposing wing spots scares off predators
• Wing sounds scare off predators
• Two predictions
• Individuals without spots are eaten more often
• Individuals without sounds are eaten more often

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Peacock Butterfly Defenses
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Experiments and Results

• Four groups of butterflies were exposed to
  predators (birds)
• Butterflies without spots
• Butterflies without sounds
• Butterflies without spots or sounds
• Control group
• Test results support both original hypotheses

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Results Peacock Butterfly Experiment
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Sampling Error

• Biology 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

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Sampling Error
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Probability

• Researchers try to design experiments carefully
  in order to minimize sampling error
• Statistically significant
• Refers to a result that is statistically unlikely
  to have occurred by chance

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Animation Sampling error
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1.8 Impacts/Issues Revisited

• Biologists constantly discover new species
• Mouse lemur (Microcebus lehilahytsara),
  discovered in Madagascar in 2005

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Digging Into DataPeacock Butterfly Predator
Defenses