Introduction to Biology
Studying Life’s Diversity and
Intricate Processes
Biological Inquiry
 Bio = of living things
 Biological Science: observation, identification,
experimental investigation and theoretical
explanation of natural phenomena
 What are the Characteristics of Living Things?
 What are Fundamental Concepts that Relate
to these Characteristics?
 How Do Biologists Study Living Things?
What are common
characteristics of living things?
 Properties of Life
organization involving cells
energy use and metabolism
response to environmental changes
regulation and homeostasis
growth and development
reproduction
biological evolution
Concept: New Properties Emerge at
Each Level in the Biological Hierarchy
Principle of Emergent Properties
New characteristics arise out
of the arrangement and
interactions of the components
of a complex system
(whole > sum of the parts)
organization
Organizational Hierarchy of Life
Most
Complex biosphere
inhabitable regions of earth
ecosystem
coral reef (living + nonliving)
community
coral reef populations
population
school of fish
organism
fish
organ system
nervous system
organ
brain
tissue
nervous tissue
cell
neuron
organelle
nucleus
macromolecule
DNA
molecule
nucleotide
Least
atom
nitrogen
Complex sub-atomic particles protons, neutrons, electrons
Concept: Cells are an Organism’s Basic
Units of Structure and Function.
Two types of cells
Prokaryotic
 Archaea and Bacteria
 few internal membranes
 no membrane-bound nucleus
Eukaryotic
 Protists, Fungi, Animals, Plants
 extensive internal membranes
 membrane-bound nucleus
organization
Concept: Structure and Function are Correlated
at all Levels of Biological Organization.
How is red blood cell structure suited
to its function of carrying oxygen?
organization
Energy Use and
Metabolism
 Energy = ability to do work
 Energy conversion = change
of one form of energy to
another
 Metabolism = sum of
chemical reactions in an
organism
 Heterotrophic: other feeder
 taking in organic molecules
produced by other organisms
 Autotrophic: self-feeder
 photosynthesis = using the
energy of the sun to produce
organic molecules
Concept: The Continuity of Life is Based
on Heritable Information in DNA.
The molecule of heredity =
DNA = deoxyribonucleic acid
reproduction
regulation
Per 23
chromosomes
Now estimated
at 30,000
genes
Proteome: all
proteins produced
in a cell or
organism
Genome: complete
genetic
composition of an
organism
Genomes and Proteomes reveal evolutionary relationships
Concept: The Continuity of Life is Based
Nuclear
on Heritable Information in DNA.
division
retaining the
original
chromosome
number
Nuclear division
reducing the
chromosome
number, leading to
sperm or eggs
Concept: The Continuity of Life is Based
on Heritable Information in DNA.
Growth = increase in size
Development = change in characteristics
growth and development
Concept: Feedback mechanisms
regulate biological systems.
Concept: Feedback mechanisms
regulate biological systems.
Living things maintain homeostasis
= a relatively stable internal condition
regulation and homeostasis
response to environmental changes
Plant Responses to Sunlight
Alfalfa leaves oriented
toward sunlight to
maximize photosynthesis
Desert plant leaves
oriented vertically
to minimize water loss
http://plantsinmotion.bio.indiana.edu/plantmotion/movements/tropism/tropisms.html
response to environmental changes
Concept: Evolution Accounts for
the Unity and Diversity of Life
Two mechanisms of evolutionary change
Vertical Descent with Mutation: through
changes in DNA, new species arise
from pre-existing species
Natural Selection: individuals with traits
that provide an advantage in the
current environment are more likely to
survive and reproduce
response to environmental changes
biological evolution
Concept: Evolution Accounts for
the Unity and Diversity of Life
Vertical Descent with Mutation
Concept: Evolution Accounts for
the Unity and Diversity of Life
Natural Selection leads to a change
in the genetic characteristics of a
population  evolution
Adaptation = characteristic that
promotes survival and reproduction
The Unity and Diversity of Living Things
An Evolutionary Tree of Life
The Three Domains of Life Represent the Earliest
Branches in Evolutionary History
Contains
multiple
kingdoms
How Do Biologists Study Living Things?
Discovery Science
 Collect Data without a pre-stated
hypothesis
 Make Observations = objective
notations of a phenomenon
 Can lead to formulation of
hypotheses
 Example: determine how many
amphibian species are present in a
specific environment
How Do Biologists Study Living Things?
Hypothesis-based Science
 Ask Questions or make Observations
 Formulate an Hypothesis: tentative
answer to well-framed question
 Make Predictions based on hypothesis
 Test Predictions by Conducting
Experiments
 Analyze experimental data
 Determine whether data supports
hypothesis
How Do Biologists Study Living Things?
Biology 21 Definition
•An Hypothesis will have
– Two measurable variables
– Precise relationship between them
(relationship = prediction)
The relationship between
DNA content and length of
the cell cycle is a direct
proportion.
How Do Biologists Study Living Things?
A good hypothesis is
 Testable
 experiments can be designed to test
predictions from the hypothesis
 experimental results must be
repeatable
 Falsifiable
 allows scientists to eliminate
alternative hypotheses
How Do Biologists Study Living Things?
•Testing hypotheses
– Controlled Experiment
• test designed to determine the effect of
one factor while keeping all other factors
constant
• experimental = sample treated to test for
effect of the factor being studied
• control = sample treated like experimental
in all ways EXCEPT for the factor being
studied
Use of a Controlled Experiment
Increasing dose of almonds on subjects with hyperlipidemia.
Full almond = 73 grams/day
Control = whole wheat muffins (>5% saturated fat)
Half almond = half dose almond + half dose muffins
All supplements provided equal amounts of energy in the diet.
Jenkins, et al., 2002, Circulation 106:1327
How Do Biologists Study Living Things?
• Supported Hypotheses
•Theory = broad explanation of a natural
phenomenon that has been supported by
a large body of evidence
•Principle or Law = theory that has been
supported over a long period of time
– Cell Principle
• All living things are composed of cells and cell
products; all cells come from pre-existing cells.
– Principle of Evolution
– Principle of Emergent Properties