Q.29. Define the term biodiversity. “ India is Mega diversity Nation” comment on these statements. (AKTU. - 2013-14)
Ans. Biodiversity refers to the variety and variability among living or-ganisms and ecological complexes in which they occur. Major components in biodiversity are : ecosystem diversity, species diversity and genetic diversity.
Biogeographical Classification Of India: -
India lying at the junction of Tropical, Eurasiam and Indo Malayan biogeographic realms is among the twelve ‘Mega biodiversity countries in the world. The other countries of mega diversity are Mexico, Columbia, Madagascar, Equador, Peru, Brazil, Zaire, China, Malaysia, Indonesia and Australia.
On geographical basis, India consists of three well defined regions:
(a) The trans - Himalayan mountainous zone including the north - esastern hill ranges.
(b) The Indo- Gangetic Plain; and
(c) The peninsula (including the Eastern and Western Ghats and the Vubdgta - Satpura Ranges)
However, these regions when considered together with occurrence of characteristics plants and animal species were further divided into 12 regions known as biogeographic regions. Recently Wildlife Institute of India has regrouped them into 10 biogeographic zones. It is to clarify that all the these ten zones are not rich in biodiversity but they do certainly have characteristics and rare species of plants and animals, some of them perhaps not available anywhere in the world. As far as biodiversity rich ones are concerned, one has to look for tropical moist and dry forests (India has about 70% of forest area under these types ) and marine ecosystems such as continental shelf, estuaries, mangroves and coral reefs etc.
Q.30. Write in detail about the functions of
ecosystem. (AKTU. - 2014 - 15)
Ans. By
the ecosystem we mean:
· The rate of biological energy flow i.e.,
the rates of production and respiration of the community.
· The rate of nutrient (minerals) cycles;
and
· Biological or ecological
regulation including both regulation of environment by the organisms (e.g.
nitrogen-fixing bacterias, etc.) and regulation of organisms by enviroment
(e.g. photoperiodism, etc.).
Q.31. What are bio indicators? Discuss the
various types of bio-indicators.
(AKTU. - 2014 - 15)
Ans. A
bio indicator is an organism or biological response that reveals the presence
of the pollutants by the occurrence of typical symptoms or measurable
responses, and is therefore more qualitative. These organisms (or communities
of organisms) deliver information on alterations in the environment or the
quantity of environmental pollutants by changing in one of the following ways:
physiologically, chemically or behaviourally. The information can be deduced
through the study of:
· their content of certain elements or
compounds
· their morphological or cellular structure
· metabolic-biochemical processes
· behaviour, or
· population structure(s).
The importance and relevance of
biomonitors, rather than man-made equipment, is justified by the statement:
"There is no better indicator of the status of a species or a system than
a species or system itself."
The use of a
biomonitor is described as biological monitoring (abbr. biomonitoring) and is
the use of the properties of an organism to obtain information on certain
aspects of the biosphere. Biomonitoring of air pollutants can be passive or
active. Passive methods observe plants growing naturally within the area of
interest. Active methods detect the presence of air pollutants by placing test
plants of known response and genotype into the study area.
Bioaccumulative
indicators are frequently regarded as biomonitors.
Depending on the organism
selected and their use, there are several types of bio-indicators. Such as
Plant indicators, Animal indicators and toxins, Microbial indicators and
chemical pollutants, Microbial indicators in oil and gas exploration,
Microalgae as bio-indicators for water quality, ECOTOX, Macroinvertebrate
bio-indicators. Here we describe some of them -
Plant indicators: -
The presence or absence of
certain plant or other vegetative life in an ecosystem can provide important
clues about the health of the environment: environmental preservation. There
are several types of plant biomonitors, including mosses, lichens, tree bark,
bark pockets, tree rings, leaves, and fungi.
Lichens are organisms comprising
both fungi and algae. They are found on rocks and tree trunks, and they respond
to environmental changes in forests, including changes in forest structure –
conservation biology, air quality, and climate. The disappearance of lichens in
a forest may indicate environmental stresses, such as high levels of sulfur
dioxide, sulfur-based pollutants, and nitrogen oxides.
The composition and total
biomass of algal species in aquatic systems serves as an important metric for
organic water pollution and nutrient loading such as nitrogen and phosphorus.
There are genetically engineered
organisms, that can respond to toxicity levels in the environment; e.g., a type
of genetically engineered grass that grows a different colour if there are
toxins in the soil.
Animal indicators
and toxins: -
An increase or decrease in an
animal population may indicate damage to the ecosystem caused by pollution. For
example, if pollution causes the depletion of important food sources, animal
species dependent upon these food sources will also be reduced in number:
population decline. Overpopulation can be the result of opportunistic species
growth. In addition to monitoring the size and number of certain species, other
mechanisms of animal indication include monitoring the concentration of toxins
in animal tissues, or monitoring the rate at which deformities arise in animal
populations, or their behaviour either directly in the field or in a lab.
Microbial
indicators and chemical pollutants: -
Microorganisms can be used as
indicators of aquatic or terrestrial ecosystem health. Found in large
quantities, microorganisms are easier to sample than other organisms. Some
microorganisms will produce new proteins, called stress proteins, when exposed
to contaminants such as cadmium and benzene. These stress proteins can be used
as an early warning system to detect changes in levels of pollution.
Microbial
indicators in oil and gas exploration: -
Microbial Prospecting for oil
and gas (MPOG) is often used to identify prospective areas for oil and gas
occurrences. In many cases oil and gas is known to seep toward the surface as a
hydrocarbon reservoir will usually leak or have leaked towards the surface
through buoyancy forces overcoming sealing pressures. These hydrocarbons can
alter the chemical and microbial occurrences found in the near surface soils or
can be picked up directly. Techniques used for MPOG include DNA analysis,
simple bug counts after culturing a soil sample in a hydrocarbon based medium
or by looking at the consumption of hydrocarbon gases in a culture cell.
Microalgae as
bio-indicators for water quality: -
Microalgae have gained attention
in the recent years due to several reasons because of their greater sensitivity
to pollutants than many other organisms. In addition they occur abundantly in
nature, they are an essential component in very many food webs, they are easy
to culture and to use in assays and there are few if any ethical issues
involved in their use.
ECOTOX: -
ECOTOX is an automatic bioassay
device used to test the quality of water samples, by the detection of toxic
chemicals. It is small piece of hardware containing a miniaturized microscope
linked to a camera, an observation cuvette, pumps to mix the water samples with
the microalgae; everything being connected to a computer equipped with
software. One of the biggest advantages of this device is the automated
measurements and analysis, which reduces the risks of personal error. Moreover,
it is easy to use, quite cheap and fast: only 10 min are necessary to test a
water sample and the corresponding control. The determination of the samples
quality is derived from analysis of several parameters related to the movement
of the microalgae. All measurements are made automatically with real time image
analysis.
