Introduction to Biological
Science
OBJECTIVES:
❚What are the criteria for defining life?
❚Hierarchy of organization of life
❚Brief overview of taxonomy
Criteria for life...
Living organisms are composed
of cells
❚ all living things are composed of cells and of
substances produced by cells (Cell theory)
❚ may be uni- or multicellular
❚ Ex. of single celled organism: bacteria, yeast,
Amoeba
❚ Ex of multicellular: oak tree, humans (billions)
❚ multicellular life dependent upon coordinated
function of cells
Living organisms grow and
develop
❚ Growth = increase in the amount of living
substance in an organism
❚ growth is due to an increase in mass brought about
by increase in size and/or number of cells
❚ may or may not be uniform in different parts of body
❚ may be determinant (termination of growth in
adulthood) or indeterminant
❚ development = all the changes that take place
during the life of an organism (Ex. Humans begin
as fertilized egg > embryo > fetus > infant > etc…)
Metabolism
❚ Metabolism = sum of all the chemical activities of
an organism
❚ includes chemical reactions essential to nutrition,
growth, repair of cells, conversion of energy to
usable forms…
❚ occurs continuously (to maintain balanced state, or
homeostasis)
Living organisms continuously
respond to stimuli
❚ Stimuli = physical or chemical changes in an
organism’s internal or external environment
❚ Ex: change in intensity of light; change in
temperature, pressure, or sound; soil, air, or water
quality; blood pressure levels; etc...
Living organisms are capable of
movement
❚ May or may not include locomotion (moving from
one place to another)
❚ may use flagella or cilia or other specialized
structures
❚ material within cells is in continuous motion
❚ do plants move?
❚ do organisms such as oysters, clams, or barnacles
move?
Living organisms continuously
interact with their environment
❚ Organisms take in and transform energy to utilize it
to carry out all cellular functions
❚ organisms exchange materials and energy with its
surroundings
❚ interactions between organisms and their
environment = ecosystems
❚ 2 major ecosystem processes:
❚ 1) cycling of nutrients (importance of decomposers)
❚ 2) flow of energy from sunlight to photosynthetic life
(producers or autotrophs) to organisms that feed on
producers (consumers or heterotrophs)
Living organisms reproduce
❚ All life only comes from living things
❚ asexual reproduction (without sex) results in a
duplicate copy of the parent
❚ sexual reproduction (production of egg and sperm
which fertilize to form a new individual) results in
offspring which are interaction of the genetic
material of mother and father (not a duplicate)
Thus, an organism needs
precise instructions to...
grow,
develop,
carry out metabolic processes,
move,
respond to stimuli, and
reproduce...
All of the info that an organism
needs...
❚ is coded in the form of DNA (deoxyribonucleic
acid) = INTERNAL PROGRAMMING
❚ and is delivered in the form of chemical
substances (Ex, hormones and enzymes) and
electrical impulses = INTERNAL
COMMUNICATION
Populations of living organisms
evolve
❚ Biological evolution is defined as any genetic
change in a population that is inherited over several
generations. These changes may be small or large,
noticeable or not so noticeable. Genetic variation
resulting from sexual reproduction is vital for
evolution and adaptation
❚ adaptation = trait that enhances an organisms
ability to survive in a particular environment
❚ ability to evolve and adapt enables species to
survive in a changing world
❚ theory of evolution is the basic unifying concept of
biology
Levels of organization of life
❚ Biosphere - The sum of all living things taken in
conjunction with their environment
❚ Ecosystem - The relationships of a smaller
groups of organisms with each other and their
environment
❚ Community - The relationships between groups
of different species
❚ Species - Groups of similar individuals who tend
to mate and produce viable, fertile offspring.
❚ Populations - Groups of similar individuals who
mate with each other in a geographic area
Levels of organization
❚ Individuals - One or more cells characterized by
a unique arrangement of DNA "information"
❚ Organ System - A group of cells, tissues, and
organs that perform a specific major function
❚ Organ - A group of cells or tissues performing
an overall function.
❚ Tissue - A group of cells performing a specific
function
❚ Cell - The fundamental unit of living things.
Each cell has some sort of hereditary material,
energy acquiring chemicals, structures, etc.
Levels of organization
❚ Organelle - A subunit of a cell, an organelle is
involved in a specific subcellular function (for
example the ribosome is the site of protein
synthesis)
❚ Molecules, atoms, and subatomic particles - The
fundamental functional levels of biochemistry.
Levels of organization,
illustrated
Levels of organization,
illustrated
Levels of organization,
illustrated
Levels of organization,
illustrated
Millions of organisms have
evolved on our planet…
❚ …thus, in order to study life, we need a system
for organizing, naming, and classifying forms
❚ taxonomy science of classifying and naming
organisms
❚ taxon - term applied to a group of organisms
comprising a given taxonomic category
❚ Linnaean system of binomial nomenclature
(each species assigned a genus and specific
epithet)
❚ properly written as Homo sapiens, or Homo
sapiens
Taxonomic classification is
hierarchical
Ex: taxonomic classification of humans
1)
KINGDOM – Animalia
2)
PHYLUM – Chordata
❚ Subphylum Vertebrata
3)
CLASS – Mammalia
4)
ORDER – Primates
❚ Suborder Anthropoidea (monkeys, apes, & humans)
❚ Superfamily Hominoidea (apes & humans)
5)
FAMILY – Hominidae
6)
GENUS – Homo
7)
SPECIES - sapiens
Recognized Kingdoms (6
Kingdom system)
❚ Eubacteria
❚ Archaebacteria
❚ Protists
❚ Fungi
❚ Plantae
❚ Animalia