Invitation to Biology
Chapter 1
1.1 Impacts/Issues:
The 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
Video: Lost worlds and other
wonders
Exploring New Guinea
A rare golden-mantled tree kangaroo
1.2 Life’s 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
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
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 system’s component parts
Levels of Organization in Nature
Animation: Life’s levels of
organization
Active Figure: Levels of
organization
1.3 Overview of Life’s Unity
All living things have similar characteristics
Require energy and nutrients
Sense and respond to change
Reproduce with the help of DNA
Energy Sustains Life’s
Organization
One-way flow of energy through the
biosphere and cycling of nutrients among
organisms sustain life’s organization
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: plants
Consumers
Organisms that get energy and carbon by feeding on
tissues, wastes, or remains of other organisms
Example: animals
Energy Flow and Material
Cycling
sunlight
energy A Producers harvest energy
from the environment. Some
of that energy flows from
producers to consumers.
PRODUCERS
plants and other
self-feeding organisms
B Nutrients that
become incorporated
into the cells of producers
and consumers are
eventually released by
decomposition. Some
cycle back to
producers.
CONSUMERS
animals, most fungi,
many protists, bacteria
C All energy that enters the world
of life eventually flows out of it,
mainly as heat.
Stepped Art
Fig. 1-3a, p. 6
Fig. 1-3b, p. 6
Animation: One-way energy flow
and materials cycling
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
Response to Stimuli
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
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
1.4 Introduction to Life’s
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
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
Life’s Diversity:
Three-Domain Classification System
Animation: Life’s diversity
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
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
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
Animation: Three domains
break
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
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
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
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)
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)
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
Making Observations: A Field
Study
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
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
Examples of Scientific Theories
Animation: An example of the
scientific method
1.7 The Power of Experiments
Natural processes are often influenced by
many interacting variables
Variable
A characteristic or event that differs among
individuals
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
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
Potato Chips and Stomachaches
Hypothesis
Olestra® causes intestinal cramps.
Prediction
People who eat potato chips made with Olestra will be more
likely to get intestinal cramps than those who eat potato
chips made without Olestra
Experiment
Control Group
Eats regular
potato chips
Experimental Group
Eats Olestra
potato chips
Results
93 of 529 people
get cramps later
(17.6%)
89 of 563 people get
cramps later
(15.8%)
Conclusion
Percentages are about equal. People who eat potato chips
made with Olestra are just as likely to get intestinal cramps
as those who eat potato chips made without Olestra.
These results do not support the hypothesis.
Stepped Art
Fig. 1-10, p. 14
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
Peacock Butterfly Defenses
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
Results: Peacock Butterfly
Experiment
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
Sampling Error
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
Animation: Sampling error
1.8 Impacts/Issues Revisited
Biologists constantly discover new species
Mouse lemur (Microcebus lehilahytsara),
discovered in Madagascar in 2005
Digging Into Data:
Peacock Butterfly Predator Defenses