ORGANIZATION OF LIFE: 1.2
SCIENTIFIC INQUIRY
Living Things are Organized:
The cell is the most basic unit of life, these cells are made of atoms which are the smallest unit of an
element (atoms are made of protons, electrons and neutrons). Atoms are adjoined together into
molecules which can be made of the same or different elements. Two types of cell states exist:
unicellular (one cell) or multicellular (an organism that is made of many cells). In those organisms that
are multicellular the cells fuse together to form tissues. Tissues are groups of cells that share a
common structure and function. Tissues fuse together to make organs which all have specific task(s)
such as plants, flowers, the kidney and brain. Organs exist in groups which form organ systems, in the
human body we have eleven organ systems. Those eleven organ systems in the human body form the
organism. The organism is an individual made of many organ systems. Organisms of the same species
(a group of organisms that can interbreed) form a population in an area. Communities exist of different
interacting populations such as three populations of lilies and two populations of honeybees. All of
these communities come together and interact with the physical environment such as a forest, this
forms an ecosystem. Lastly the biosphere are all the regions of Earth from the atmosphere to the crust
of Earth. Figure 1.4 shows these emergent properties of life.
Atom>Molecule>Cell>Tissue>Organ>Organ System>Organism>Population>Community>Ecosystem>Biosphere
Figure 1.4: Emergent properties of life from smallest to most large.
Organizing Diversity:
Taxonomy is the scientific study of classification and categorization of organisms. The founder of
taxonomy is Carl Linnaeus who devised a system known as binomial nomenclature. Binomial
nomenclature is a two part naming system that involves naming a species into what we commonly call
a scientific name. In classifying organisms we start at a inclusive level (includes many things) and then
narrow down that organism into more specific or less inclusive fields. Figure 1.5 shows the hierarchy
from most inclusive to least inclusive. Figure 1.6 shows an application of this terminology.
Domain>Kingdom>Phylum>Class>Order>Family>Genus>Species
Figure 1.5: Taxonomic hierarchy from most inclusive to least inclusive.
As you can see in Figure 1.6 a scientific name consists
of two parts as noted earlier when the term binomial
nomenclature was described. The scientific name of a
organism consists of the species and then a genus
name. The name should be written in italics or
underlined with the species name being capitalized.
Consider the example given in the figure: the leopard
has a scientific name of Panthera pardus, where the
first part of the name is the species and the second
being the genus.
Figure 1.6: Taxonomic hierarchy of the leopard (Panthera pardus).
The term domain refers to the three most inclusive groups: archaea, bacteria and eukarya. Domains
archaea and bacteria eveolved form the earliest known common ancestor and represent most of the
diversity on Earth. Both domains include those organisms that are prokaryotic meaning that the cells of
these organisms have no membrane bound nucleus. Eukarya is a more modern domain which likely
split from the domain archaea billions of years ago. This domain includes those organisms that are
eukaroytic meaning they have a membrane bound nucleus and are by generalization more complex:
protists, plants, fungi and animals are included in this domain. Figure 1.7 shows a illustration depecting
the three major domains, their relation to one another and common examples of organisms in each
domain.
Figure 1.7: Three domains of life: Bacteria, Archaea and Eukarya.
The next largest hierarchy is kingdom, the amount of kingdoms is constantly under modification. But for
now we will learn that six major kingdoms exist.
 (Eubacteria)- prokaryotic cells, adapted to all environments, can obtain food by a multiude of
means including absorbption, photosntheisze or chemosynthesize. Examples include: Bacteria
that reside in your mouth, gut, and those bacteria that can cause illness such as strep throat or
food poisoning.
 Archaebacteria- prokayortic cells, adapted to live in extreme environments such as vents at the
bottoms of oceans, in pools of acids and salts or even at temperatures where other forms of life
cannot exist. These are the most ancient of life forms on the planet.
 Protists- eukaroytic cells that can be uni- or multicellular, this kingdom shows the most diversity
in shape, size and how they obtain food. Organisms in this kingdom can be autotrophs (make
their own food) or can be heterotroph (ingest other organisms to get food). Protists can live in
almost any environment and include such things as slime molds, paramecium, water molds,
amoebas and algae.
 Plants- eukaroytic multicellular organisms that all photosynthesize to make food. Plants are
complex and include: mosses, ferns, conifers and flowering plants.
 Fungi: eukaroytic multicellular organisms that digest food outside of their body and then absorb
the needed products in their cells. Molds, mushrooms, yeasts and even ringworms are common
examples of fungi.
 Animals- eukaryotic multicellular organisms that must eat other living things to obtain materials.
This digestion is done inside the body in comparison to fungi where it is external. Animals have
extremely complex tissues such as nervous and muscular tissues which are only seen in this
kingdom. Animals include: sponges, corals, worms, insects, sea stars, fishes, frogs, birds and
mammals.