BIOLOGY
The Study of Life
Biologists study questions about
• How living things work
• How they interact with their
environment
• How they change over time
Biologists actively work to solve real world
problems such as
• Improving our
food supply
• Curing disease
• Preserving our
environment
Characteristics of Life
Organization
Response to
and cells
Stimuli
Growth and
Development
Homeostasis
Reproduction
Metabolism
Change
through time
Organization and cells
-All living things, whether made up of one cell or many cells
have some degree of organization
• Cells- smallest unit that
can perform life’s functions
• Unicellular- organisms
composed of one cell
• Multicellular- organisms
that are made up of more
than one cell
Levels of Organization
Response to Stimuli
• Organisms can respond to a
stimulus- a physical or chemical
change in the internal or external
environment
• Organisms must be able to
respond and react to changes in
the environment to stay alive
• Example: An owl’s eyes dilate when
it gets dark to help them see better
https://www.youtube.com/watch?v=jGIbUK4nw00
Homeostasis
• The maintenance of a
stable level of internal
conditions even though
environmental
conditions are
constantly changing
• Example: Owl’s feathers
fluff up in the cold to trap
a layer of insulating air
next to their bodies
Metabolism
The sum of all the
chemical reactions in the
body
• Example: An owl’s metabolism
allows the owl to extract and
modify the chemicals trapped
in its nightly prey and use
them as energy to fuel activities
and growth
Growth and Development
• the growth of living things results
from the division and
enlargement of cells
• Development is the process by
which an organism becomes a
mature adult
• A human body is composed of
trillions of specialized cells which
originated from a single fertilized
egg
Reproduction
• Reproduction, unlike the other characteristics, is not essential to the
survival of an individual organism
• Reproduction is essential for the continuation of the species
• Organisms transmit hereditary information, DNA, to their offspring
• Gene- is a short segment of DNA that contains the instructions for one trait
• During sexual reproduction, hereditary information recombines from
two organisms from the same species
• In asexual reproduction one organism is able to make an identical copy
of itself
Change through Time - EVOLUTION
• Organisms change
slowly over time as
their environment
changes
• This factor helps us
explain the diversity
of life forms we see
today
THEMES Of LIFE
Diversity
Unity
Interdependence
Evolution
Diversity
• variety
• There are single celled and multicellular organisms
• There are organisms that live in
ice and ones that live in hot
springs
• We have identified more than 1.5
million species on Earth, with
many more still to be identified
Unity
• Features that all living
things have in common
• Genetic code
• Organelles that carry out
all cellular activities
• All living things share
certain genes, but no two
types of organisms have
the same full set of genes
DOMAINS OF LIFE
• Three Domains of Life
• Bacteria- prokaryotes (simplistic organism)
found in more common environments
• Archae- prokaryotes (simplistic organisms)
that live in extreme environments such as
hot springs, high salinity ecosystems
• Eukarya- consists of protists, fungi, plants,
and animals
Interdependence of Organisms
• Ecology - studies organisms interacting with each
other and with the environment
• Ecosystems - communities of living species and
their physical environment
• Organisms depend on each other, minerals, nutrients,
water, gases, heat, and other aspects of the physical
world
• Example: a panther eats a bird, which eats nuts from a
tree. The tree needs carbon dioxide and water. Carbon
dioxide is a main byproduct of all animals
• Humans have had a
huge impact on the
world’s environment
• We have cleared vast areas
of the rain forests for the
rare wood that grows only
there. The rain forests are
the biggest filters of
greenhouse gases on our
planet
EVOLUTION of LIFE
• (Descent with modification) - the process in which the
inherited characteristics within a population change over
generations
• Natural selection- organisms that have certain favorable
traits are better able to survive and reproduce
successfully than organisms that lack these traits
• Adaptations are traits that improve an individual’s
ability to survive and reproduce
• Example: Rabbits with white fur and short ears living in a
snowy place as opposed to somewhere that gets no snow