Chapter 1:
The Science of Life
Biology – The study of life
Organism – A living thing; anything that can
carry out life processes independently
Branches of biology –
•There are many subtopics within biology –
a few examples we’ll hit upon this year:
•Biochemistry – Study of the chemistry of life
•Genetics – Study of how organisms pass traits
to their offspring
Evolutionary theory – Study of changes in types
of organisms over time
Cell biology – Study of life on the cellular level
Microbiology – Study of microscopic organisms
Botany – Study of plants
Zoology – Study of animals
Physiology – Functions, activities, and
processes of organisms
Ecology – Study of how organisms interact with
eachother and the environment
Properties of Life
1. Cellular organization
 Cell – a highly organized, tiny
structure that in enclosed in a thin
covering called a membrane
 A cell is the smallest unit capable
of all life functions
•Organisms can be unicellular or
multicellular
•Multicellular organisms – more than
1 cell
•Cells in these organisms are
considered specialized (have
certain jobs)
•Examples: some fungus, all
plants, all animals
Unicellular organisms - one cell
•1 cell does all jobs for organism
•Examples: bacteria, protists, and
some fungus
There are various levels of cellular
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
2. Homeostasis
• Maintaining a stable internal
environment in order to function
properly (such as body
temperature, pH, blood pressure,
water balance) regardless of
changes in the external
environment
 Example: sweating or shivering
to maintain body temperature
3. Metabolism – the sum of all of the
chemical reactions carried out in an
organism
• Reactions carried out to obtain
energy
• Organisms can obtain energy in one
of two ways: heterotrophs and
autotrophs
•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. Responsiveness – living
organisms must respond to their
external environment
• Ex: plants bend toward the
light, birds fluff feathers to stay
warm in winter
5. Reproduction – the process by which
organisms make more of their own
kind from one generation to the next
 Prevents extinction of species
 Can be sexual or asexual
6. Heredity – process through which an
organism passes on its own traits to its
offspring during reproduction
•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
7. Growth - an increase in the number
of cells/ increase in the size
 Example – getting taller
 As organisms grow, they may
change, or develop
 Development – Changes an
organism undergoes to reach adult
form
 Example – baby  kid  teen 
adult; tadpole to frog; caterpillar to
butterfly
Classification
•Taxonomy – The practice of naming
and classifying organisms
•Taxa –the categories into which
organisms are classified
The taxa:
Domain
Kingdom
Phylum (Division for plants)
Class
Order
Family
Genus
Species
Did King Phillip Come Over For Good
Spaghetti???
Domain Archaea –
Unicellular prokaryotes
May have been first cells
Live in aquatic
environments that
lack oxygen or
are too salty, too
hot, or too acidic
for most other
organisms – like
primitive Earth(?)
Domain Bacteria
Unicellular prokaryotes
Found almost
anywhere – in
soil, water,
atmosphere,
on and inside
living
organisms
Domain Eukarya
Cells contain membrane-bound
nucleus
Four Kingdoms within –
Protists (Protista)
Fungus (Fungi)
Plants (Plantae)
Animals (Animalia)
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!
•A robin in one country is not the same as
what is named a robin in another country
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 Carl Linnaeus’ system of
binomial nomenclature (“two names”)
Grouped according to:
physical features (morphology)
the ancestral relationships between
species (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