Maintenance in living things does not depend on the janitor in
your high school—it encompasses five of the nine functions that
all things need to be considered "living," in addition to
locomotion, which increases an organism's chances of survival.
The Maintenance Functions
Nutrition
Nutrition includes all activities regarding obtaining and
processing materials for energy, growth, repair, and regulation.
In autotrophic nutrition, organic compounds are made from
inorganic compounds, and energy to drive metabolism is provided
by the environment. Heterotrophic nutrition, on the other
hand, is used by organisms that are unable to make organic
molecules for inorganic raw material, so they must obtain organic
molecules from the environment instead.
Transport
Transport consists of two parts. Absorption is the process by
which end products of digestion and other dissolved solids and
gases enter the fluids and cells of an organism. Circulation
consists of the transport of materials within multicellular
organisms.
Respiration
Respiration produces chemical energy through either cellular,
enzyme-controlled reactions, or through gas exchange, where gas
diffuses passively between an organism and its environment. In
cellular reactions, potential energy of organic molecules are
transferred into more available forms and then stored, while
hydrolysis releases energy which can then be used for metabolic
activities.
Excretion
Excretion is the removal of cellular waste products such as
carbon dioxide, water, mineral salts, and nitrogenous wastes.
Toxic wastes produced by the organism are normally released in
animals and sealed off and stored in plants, while nontoxic
wastes may be retained, released, or recycled in other metabolic
activities.
Regulation
Regulation of the body is produced in two ways: nerve control,
which depends on the functioning of nerve cells or neurons; and
chemical control, which coordinates body processes through
chemical activity of hormones in plants and animals.
Locomotion
Locomotion increases an organism's chances of survival by
increasing opportunities for obtaining food, shelter, mating, and
by enabling the organism to move away from predators and toxic
wastes.
Now you try it...