Chapter 1:
The Science of Life
Biology – The study of life
Organism – Anything capable of carrying on
life processes
Branches of biology –
•There are many subtopics within biology –
a few examples we’ll hit upon this year:
•Biochemistry – Chemical substances and
processes in organisms
•Genetics – Inheritance – passing of traits
from one generation to next
Evolution – Change in organisms over time
Cell biology – Cell structure and function
Zoology – Animals
Anatomy – Structures of organisms
Physiology – Functions, activities, and
processes of organisms
Ecology – Interactions of organisms and
environment
Characteristics of Life
1. Made of cells
 Can be unicellular or multicellular
 Multicellular organisms - more
than 1 cell
Cells in these organisms are
considered specialized (have
certain jobs)
Examples: some fungus, plants,
and animals
Unicellular organisms - one cell
1 cell does all jobs for organism
Examples: bacteria, protists, and
some fungus
2. Organization – levels of
organization vary based on how
complex the organism is
 In general: cells tissues 
organs  organ systems 
organisms
 Cells are the smallest unit of life,
organisms the biggest
3. Living things use energy
 Heterotrophs are organisms that
obtain nutrients from food eaten
 Ex: some bacteria and
protists, fungus, & animals
 Autotrophs are organisms that
make their own food through
photosynthesis
 Ex: plants, some protists, and
some bacteria
4. Homeostasis
• Maintaining (relatively) constant
internal conditions (such as body
temperature, pH, blood pressure,
water balance) regardless of
external changes
 Examples: sweating or
shivering to maintain body
temperature
5. Living things grow and develop
 Growth – an increase in the number of
cells/ increase in the size
 Example – getting taller
 Development – Changes an organism
undergoes to reach adult form
 Example – baby  kid  teen 
adult
6. Living things reproduce
 Reproduction – production of
offspring
 Prevents extinction of species
 Can be sexual or asexual
•Asexual reproduction – only 1
parent; offspring has DNA identical
to parent
•Sexual reproduction – 2 parents,
each parent contributes ½ genetic
information to offspring; offspring
has mixed traits from parents
Classification
•Taxonomy – The science of
identifying, classifying, and naming
organisms
•Taxa –the categories into which
organisms are classified
The taxa:
Kingdom
Phylum (Division for plants)
Class
Order
Family
Genus
Species
King Phillip Came Over For Good
Spaghetti
Why can’t we just use common names?
•Not very specific
•Ex: What KIND of frog?
•Misleading
•Ex: Jellyfish is NOT a fish, ringworm is
NOT a worm
•Vary by language and geography
•Ex: Puma, mountain lion, and cougar
are ALL the same animal!
What was wrong with the early
systems of classification?
•Forgot to include bacteria, fungus
and protists
•Failed to show proper
relationships between organisms
•Too general – ex. Aristotle
classified animals by where they
lived (air, land, or water)
Modern system of classification:
Based in part on Carolus Linnaeus’ system of
binomial nomenclature (“two names”)
Grouped according to physical features and
their evolutionary history (phylogeny)
Those placed in the same genus will be most
closely related, those in different kingdoms
most distantly related
Ex: Those in genus Felis are more closely
related to each other than organisms in the
Kingdoms Plantae and Animalia are to each
other.
Writing scientific names:
Ex: Homo sapiens or Homo sapiens
Can be abbreviated H. sapiens
If typed – should be italicized.
If handwritten – should be underlined.
First word is genus – capitalized
Second word is species - lower case