The term ecosystem (or ecological system) refers to communities of organisms
and their environment. Ecosystems can vary greatly in size. Small ecosystems occur
in tidal pools, in a back yard compost pile, or in the rumen of an individual cow.
Larger ecosystems can include a lake or forest. Landscape-scale ecosystems comprise
still-larger regions. Ultimately, all of Earth's life and its physical environment
represents an ecosystem known as the biosphere.
With so much variation in what constitutes an ecosystem, it is useful to define
the barrier of the system that is being studied. Depending on the specific interests of
an ecologist, an ecosystem might be delineated as the shoreline vegetation around a
lake, or perhaps the entire water body, or maybe the lake plus all the land that drains
into the lake (a watershed).Ecosystems take various forms of energy and simple
inorganic materials, and create relatively focused combinations of these, occurring as
the total amount of biological material (the biomass) of plants, animals, and
microorganisms. Solar electromagnetic energy, captured by the chlorophyll of green
plants, is a common energy source of many ecosystems. The most important of the
simple inorganic materials are carbon dioxide, water, and ions or small molecules
containing nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, and some
other nutrients. Virtually all ecosystems (and life itself) rely on inputs of solar energy
to drive the physiological processes by which biomass is synthesized from simple
molecules. To carry out their various functions, ecosystems also need access to
nutrients. Unlike energy, which can only flow through an ecosystem, nutrients can be
utilized repeatedly. Through biogeochemical cycles, nutrients are recycled from dead
biomass back into living organisms. One of the greatest challenges facing humans
and their civilization is understanding the fundamentals of ecosystem organization—
how they function and how they are structured. This knowledge is absolutely
necessary if humans are to design systems that allow a sustainable utilization of the
products and services of ecosystems. An example of a disastrous influence of humans
on an ecosystem is the collapse of the cod fishery on the Grand Banks. This expanse
of the Atlantic Ocean off the Eastern Coast of Maine and Atlantic Canada was once
home to seemingly unlimited numbers of cod. However, over centuries destructive
fishing practices and overfishing decimated the cod stock to the point where the
species became nearly extinct. As of 2013, cod stocks have not recovered to
A population comprises all the individuals of a given species in a specific area
or region at a certain time. Its significance is more than that of a number of
individuals because not all individuals are identical. Populations contain genetic
variation within themselves and between other populations. Even fundamental
genetic characteristics such as hair color or size may differ slightly from individual to
individual. More importantly, not all members of the population are equal in their
ability to survive and reproduce.
Community refers to all the populations in a specific area or region at a certain
time. Its structure involves many types of interactions among species. Some of these
involve the acquisition and use of food, space, or other environmental resources.
Others involve nutrient cycling through all members of the community and mutual
regulation of population sizes. In all of these cases, the structured interactions of
populations lead to situations in which individuals are thrown into life or death
struggles. In general, ecologists believe that a community that has a high diversity is
more complex and stable than a community that has a low diversity. This theory is
founded on the observation that the food webs of communities of high diversity are
more interconnected. Greater interconnectivity causes these systems to be more
resilient to disturbance. If a species is removed, those species that relied on it for food
have the option to switch to many other species that occupy a similar role in that
ecosystem. In a low diversity ecosystem, possible substitutes for food may be non-
existent or limited in abundance.
Ecosystems are dynamic entities composed of the biological community and
the a biotic environment. An ecosystem's a biotic and biotic composition and
structure is determined by the state of a number of interrelated environmental factors.
Changes in any of these factors (for example: nutrient availability, temperature, light
intensity, grazing intensity, and species population density) will result in dynamic
changes to the nature of these systems. For example, a fire in the temperate deciduous
forest completely changes the structure of that system. There are no longer any large
trees, most of the mosses, herbs, and shrubs that occupy the forest floor are gone, and
the nutrients that were stored in the biomass are quickly released into the soil,
atmosphere and hydrologic system. After a short time of recovery, the community
that was once large mature trees now becomes a community of grasses, herbaceous
species, and tree seedlings.
What is an Ecosystem?
An ecosystem includes all of the living things (plants, animals and organisms)
in a given area, interacting with each other, and also with their non-living
environments (weather, earth, sun, soil, climate, and atmosphere). In an ecosystem,
each organism has its' own niche or role to play.
Consider a small puddle at the back of your home. In it, you may find all sorts
of living things, from microorganisms to insects and plants. These may depend on
non-living things like water, sunlight, turbulence in the puddle, temperature,
atmospheric pressure and even nutrients in the water for life. (Click here to see the
five basic needs of living things)
This is very complex, wonderful interaction of living things and their
environment has been the foundations of energy flow and recycle of carbon and
Anytime a ‘stranger’ (living thing(s) or external factor such as rise in
temperature) is introduced to an ecosystem, it can be disastrous to that ecosystem.
This is because the new organism (or factor) can distort the natural balance of the
interaction and potentially harm or destroy the ecosystem. Click to read on ecosystem
threats (opens in new page).
Usually, biotic members of an ecosystem, together with their biotic factors
depend on each other. This means the absence of one member or one biotic factor can
affect all parties of the ecosystem.
Unfortunately, ecosystems have been disrupted, and even destroyed by natural
disasters such as fires, floods, storms and volcanic eruptions. Human activities have
also contributed to the disturbance of many ecosystems and biomes.
Scales of Ecosystems
Ecosystems come in indefinite sizes. It can exist in a small area such as
underneath a rock, a decaying tree trunk, or a pond in your village, or it can exist in
large forms such as an entire rain forest. Technically, the Earth can be called a huge
The illustration above shows an example of a small (decaying tree trunk)
To make things simple, let us classify ecosystems into three main scales.
A small scale ecosystem such as a pond, puddle, tree trunk, under a rock etc.
A medium scale ecosystem such as a forest or a large lake.
A very large ecosystem or collection of ecosystems with similar biotic and a
biotic factors such as an entire rainforest with millions of animals and trees, with
many different water bodies running through them.
Sustainable development. Nature protection
Sustainable development is a process for meeting human development goals
resources and ecosystem services upon which the economy and society depends.
While the modern concept of sustainable development is derived most strongly from
the 1987 Brundtland Report, it is rooted in earlier ideas about sustainable forest
management and twentieth century environmental concerns. As the concept
developed, it has shifted to focus more on economic development, social
development and environmental protection.
Sustainable development is the organizing principle for sustaining finite
resources necessary to provide for the needs of future generations of life on the
planet. It is a process that envisions a desirable future state for human societies in
which living conditions and resource-use continue to meet human needs without
undermining the "integrity, stability and beauty" of natural biotic systems.
The Blue Marble, photographed from Apollo 17 in 1972, quickly became an
Sustainability can be defined as the practice of maintaining processes of
productivity indefinitely—natural or human made—by replacing resources used with
resources of equal or greater value without degrading or endangering natural biotic
natural systems with the social, political, and economic challenges faced by
humanity. Sustainability science is the study of the concepts of sustainable
development and environmental science. There is an additional focus on the present
generations' responsibility to regenerate, maintain and improve planetary resources
for use by future generations.
The Sustainable Development Goals (SDGs)
the "universal, integrated and transformative" 2030 Agenda for Sustainable
Development, a set of 17 Sustainable Development Goals (SDGs).
These icons represent the 17 headline SDGs. There are 169 targets under the
The goals are to be implemented and achieved in every country from the year
2016 to 2030.
development: at the confluence of
three constituent parts. (2006)
Sustainable development, or sustainability, has been described in terms of three
spheres, dimensions, domains or pillars, i.e. the environment, the economy and
society. The three-sphere framework was initially proposed by the economist René
Passet in 1979.
It has also been worded as "economic, environmental and social" or
fourth pillar of culture, institutions or governance.
Some hundreds of years ago people lived in harmony with nature, because
and nature are dramatic.
The twenty first century is a century of the scientific and technological
progress. The achievements of the mankind in mechanization and automation of
industrial processes, in chemical industry and conquering outer space, in the creation
of atomic power stations and ships are amazing. But at the same time, this progress
gave birth to a very serious problem – the problem of environment.
Ecology and the contamination of environment, is concerned with climate,
over-population in certain areas, deaths of plant and animals, chemical contamination
of seas, lakes and rivers as well as atomic experiments and dumping of atomic waste
from power stations. Floods, unexpected draughts, and the greenhouse effect are the
There are many consequences of damaging the environment. One of them is
acid rain. Another one is water shortage resulting from abuse of arable lands in
agriculture. The third one is destroying the ozone layer of the Earth through pollution
from factories and plants. The fourth problem is damage o water and soils. The fifth
one is damage to wildlife: numerous species of animals and plants can disappear. At
last, the most serious danger arising from damaging the environment is the result of
the abovementioned consequences. This is the danger for the life and health of the
programme in every country. Numerous anti-pollution acts passed in different
countries led to considerable improvements in environment. In many countries
purifying systems for treatment of industrial waters have been installed, measures
have been taken to protect rivers and seas from oil waters.
But the environmental problems have grown beyond the concern of a single
country. Their solution requires the co-operation of all nations.
If we are unable to learn to use the environment carefully and protect it from
damage caused by man’s activities, very soon we’ll have no world to live in.
New materials and technologies on service of the person
Dependence on properties of substances: their composition and structure
A living organism has a material structure to provide an environment for
complicated chemistry of living. Chemical and physical reactions provide energy to
maintain living functions and to renew structural material. Thus, consideration of
biological properties is a natural extension of physical and chemical properties.
To a large extend, biological functions of any materials are related to their
chemical and physical properties. However, reactions in biological systems are
catalyzed by enzymes. Furthermore, products of one reaction may be reactants for
another in a complicate scheme of reactions to maintain live. Malfunction of a
reaction causes trouble, leading to disease or death. Thus, biological properties
deserve special consideration.
Biological materials and biomaterial
Plasma, membrane, tissue, protein, lipid, enzyme, the digestive system, and the
central nervous systems are some examples of biological materials, for which
properties for consideration include growth and decay, turn over time, biological half
life, retention time, composition and its change, and active ingredient. These are
manifestation of physical and chemical properties of biological materials. However,
biological properties allow us to identify and solve the biological problems.
Biological materials had been studied by biologists, chemists, and engineers from the
macroscopic, molecular, and functional view points.
The chemistry of living is complex, and properties of biological materials
towards biomaterials are of great interest. The general reaction of biological materials
towards foreign biomaterials is expel (or rejection). Living tissues form a thin layer
around the inert biomaterial, but materials that irritate the tissues causes
inflammation. Most pure metals evoke severe tissue reaction due to their redox
reactions. However, aluminum and titanium are metals of choice, because the
formation of a thin oxide layer on their surface made them inert. Similarly, ceramics
are compatible to body fluid because they are made of the metal oxides. The nature of
the surface also affects the biological properties, rough ones enable tight attachment
Biological activities of materials can be divided according to biological
functions. Substances that provide nutrition, energy, and structural need are called
food, whereas those that disrupt the normal functions are called toxins. Substances
used to correct the abnormal biological functions are called medicines.
The term "polymer" derives from the ancient Greek word
meaning "many, much") and
μέρος (meros, meaning "parts"), and refers to a
molecule whose structure is composed of multiple repeating units, from which
originates a characteristic of high relative molecular mass and attendant properties.
Most polymers have the form of long, flexible chains. Having found out that,
chemists began synthesizing artificial polymers. This has led to the establishment of
industries producing synthetic fibres and numerous polymeric materials, many of
which were less expensive and superior in various ways to the natural materials.
Life depends fundamentally on organic polymers. These polymers provide not
only food but also clothing, shelter and transportation.
Indeed nearly all the material needs of man could be supplied by natural
organic products. The list of these materials and things made of them might br very
long: wood, fur, leather, wool, cotton, silk, rubber, oils, paper, paints and so on. The
organic polymers from which such things could be made include proteins, cellulose,
starch, resins, and a few other classes of compounds. Because of the complexity and
fragility of their molecules, the natural organic polymers, although known and used
Synthetic polymers now available already possess several of the properties
required in a structural material. They are light in weight, easily transported, easily
repaired, highly resistant to corrosion and solvents, and satisfactory resistant to
moisture. It would be necessary to add that they have long-lived durability and
resistance to high temperatures
One could list the principal products: such as fibres, synthetic rubbers,
coatings, adhesives and a lot of materials called “plastics”. Plastics and synthetic
coating are already in common use. It is desirable that they should be used on a large
scale, and get further development.
Drug development is the process of bringing a new pharmaceutical drug to the
market once a lead compound has been identified through the process of drug
discovery. It includes pre-clinical research on microorganisms and animals, filing for
regulatory status, such as via the United States Food and Drug Administration for
aninvestigational new drug to initiate clinical trials on humans, and may include the
step of obtaining regulatory approval with a new drug application to market the drug.
Timeline showing the various drug approval tracks and research phases
New chemical entities (NCEs, also known as new molecular entities or NMEs)
are compounds that emerge from the process of drug discovery. These have
promising activity against a particular biological target that is important in disease.
However, little is known about the safety, toxicity, pharmacokinetics, and
metabolism of this NCE in humans. It is the function of drug development to assess
all of these parameters prior to human clinical trials. A further major objective of
drug development is to recommend the dose and schedule for the first use in a human
clinical trial ("first-in-man" [FIM] or First Human Dose [FHD]).
In addition, drug development must establish the physicochemical properties of
the NCE: its chemical makeup, stability, and solubility. Manufacturers must optimize
the process they use to make the chemical so they can scale up from a medicinal
chemist producing milligrams, to manufacturing on the kilogram and ton scale. They
further examine the product for suitability to package as capsules, tablets, aerosol,
intramuscular inject able, subcutaneous inject able, or intravenous formulations.
Together, these processes are known in preclinical development as chemistry,
manufacturing, and control (CMC).
Many aspects of drug development focus on satisfying the regulatory
requirements of drug licensing authorities. These generally constitute a number of
tests designed to determine the major toxicities of a novel compound prior to first use
in humans. It is a legal requirement that an assessment of major organ toxicity be
performed (effects on the heart and lungs, brain, kidney, liver and digestive system),
as well as effects on other parts of the body that might be affected by the drug (e.g.,
the skin if the new drug is to be delivered through the skin). Increasingly, these tests
are made using in vitro methods (e.g., with isolated cells), but many tests can only be
made by using experimental animals to demonstrate the complex interplay of
metabolism and drug exposure on toxicity.
The information is gathered from this pre-clinical testing, as well as
information on CMC, and submitted to regulatory authorities (in the US, to the FDA),
as an Investigational New Drug application or IND.