Living VS. Non-Living
organisms, such as humans, require many systems for their life
processes. Less complex living things may lack the
complex systems of more complex organisms, but they still
carry on the basic life activities. While
non-living things may carry on some of these life processes,
they do not carry on all of them, or these activities do not
interact in a manner allowing the non-living thing to
components of living things in humans and other organisms,
from organ systems to cell organelles, interact to maintain a
balanced internal environment. This balanced internal
environment is called dynamic equilibrium or homeostasis.
To successfully accomplish this, organisms possess many
control mechanisms that detect internal changes and correct
them to restore the internal balance of the
organism. If an organism fails to maintain
homeostasis, this may result in disease or death.
Non-living things possess few control mechanisms to maintain
The greater the diversity, or number of
different species of organisms in an ecosystem, the
ecosystem is more stable and likely to last. These
ecosystems contain many different kinds of organisms carrying
on a variety of different nutritional modes. Organisms
can be categorized by the function they serve in an ecosystem.
Each species in an ecosystem has a role for which it is best
suited. In general, no two species have the same role in an
ecosystem. This allows different species to coexist
successfully and helps maintain the stability of the
ecosystem. Ecosystems are stable due to the
interactions among the many different populations. These
interactions contribute to the overall maintenance and
continued existence of the ecosystem.
levels of organization for structure and function of living
things include cells, tissues, organs, organ systems, and
whole organisms. The organs and systems of the body help to
provide all the cells with their basic needs to carry on the
life functions. The cells of the body are of different kinds
and are grouped in ways that help their function.
living things are composed of one or more cells, each capable
of carrying out the life functions. The organelles
present in single-celled organisms often act in the same
manner as the tissues and systems found in many celled
organisms. Single-celled organisms perform all of the
life processes needed to maintain homeostasis, by using
specialized cell organelles.
Cells have particular structures or organelles that
perform specific jobs. These structures perform the life
activities within the cell. Just as body systems are
coordinated and work together in complex organisms, the cells
making up those systems must also be coordinated and organized
in a cooperative manner so they can function efficiently
Inside the cell a
variety of cell organelles, formed from many different
molecules, carry out the transport of materials, energy
capture and release, protein building, waste disposal, and
information storage. Each cell is
covered by a membrane that performs a number of important
functions for the cell as well.
Humans and many other organisms require multiple systems
for digestion, respiration, reproduction,
circulation, excretion, movement, coordination, and immunity.
The systems collectively perform the life processes.
Once nutrients enter
a cell, the cell will use those raw materials for energy or as
building blocks in the synthesis of compounds necessary for
life. The energy we initially obtain must must be
changed into a form cells can use. A type of protein called an
enzyme allows for these changes to occur within the
Neurotransmitters and hormones allow
communication between nerve cells and other body cells
as well. If nerve or hormone signals are changed,
this disrupts communication between cells and will
adversely effect organism homeostasis.
Additionally, the DNA molecule contains the
instructions that direct the cellís behavior through
the synthesis of proteins.
This page and the links at the left are designed to aid students in
reviewing the following topics which will appear on the New
York State Living Environment Regents Examination;
characteristics of living vs. non-living things, some
aspects of population diversity, organizational levels
in living things, cell structure and function, life
functions, and cellular communication. In addition, students may test their knowledge of the material presented here by accessing multiple-choice questions from past Regents Exams.