Q1: Define Ecology
Answer: Ecology is a scientific study of the interactions
between organisms and the environment. Ecology
integrates all areas of biological research and informs
environmental decision.
Q2: What is the scope of Ecology Research?
Answer: Ecology study can be broadly classified as:
a. Organismal Ecology
b. Population Ecology
c. Community Ecology
d. Ecosystem Ecology
e. Landscape Ecology
f. Global Ecology
In nutshell, Ecology study advocates protection of
nature and the environment.
Q3: Define Ecosystem.
Answer: An environment comprises of all living (biotic)
and non-living (abiotic) things that occur naturally on
the Earth or any of its region. All these living organisms
interact with each other and their growth, reproduction
and other activities are affected by the abiotic
components of ecosystem.
Q4: Is garden an example of Ecosystem?
Answer: Yes. In an garden, all biotic components (e.g.
plants, trees, animals like rats, frogs, birds, insects etc.)
interact with each other and with abiotic components
(garden soil, water etc.) for their growth and
reproduction and other activities. Thus garden forms an
ecosystem.
Q5: Give examples of natural ecosystems.
Answer: Forests, ponds, lakes, sea, oceans, coral reefs,
rivers etc.
Q6: Give examples of human made (artificial )
ecosystems.
Answer: Gardens, Crop-fields etc.
Q7: Name different abiotic factors that affect the
ecosystem.
Answer: Temperature, water, sunlight, salinity, rocks,
soil, precipitation and wind.
Q8: What do you mean by biogeochemical cycle?
Name examples of biogeochemical cycles exist in
ecosystem.
Answer: A biogeochemical cycle is a pathway by which
a chemical element or molecule moves through both
biotic and abiotic compartments of Earth. These are
critical to life and hence for the ecosystem sustenance.
A few examples of the biogeochemical cycles are:
Nitrogen Cycle
Water Cycle
Carbon Cycle
Oxygen Cycle
Phosphorus Cycle
Q9: What do you mean by biosphere?
Answer: Biosphere is the area on the earth where life
exists. It includes about 20 kilometers upwards in the
atmosphere and 11 kilometer downwards. In the
Biosphere different plants and animals are present. This
diversity of life is an important characteristic of earth.
Q10: Define food chain.
Answer: The pathway of transfer of food from one
trophic level to another is known as food chain.
Q11: What are trophic levels?
Answer: Trophic levels are the feeding levels in an
ecosystem. The trophic levels of living beings
represent their placement in a food chain. It also tells
the order of consumption and energy transfer
throughout the ecosystem (or environment).
In general 4 or 5 trophic levels exist in a food chain.
These are:
Producers or Autotrophs: Producers make up the
first trophic levels that supports the other trophic
levels. It consists mainly of green plants and certain
types green algae and some types of bacteria. They
convert solar energy (photosynthesis) into food
consumable by other organisms.
Primary Consumers: These are the consumers which
feed upon producers. In general these are herbivores.
Examples are horse, cow, deer, insects, zoo planktons
(shrimps, protists etc.) and birds.
Secondary Consumers : Secodnary or second level
consumers eat primary consumers. In general these
are omnivores and carnivores. On land, secondary
consumers cover many small mammals and reptiles that
eat insects, as well as large carnivores that eat rodents
and grazing mammals. In aquatic ecosystems, secondary
consumers are mainly small fish that eat plankton.
Tertiary Consumers : These are third level consumers
which feed on secondary consumers. E.g. snakes eating
rodents, Lion, bear etc.
Quanternary Consumers : Fourth level consumers are
defined in a few food chains. E.g. hawks eating owls or
snakes.
All food chains end up with top predators, animals
having little or no natural enemy.
Q12: Define Dertivores
Answer: Dertivores or Decomposers are the consumers
that get energy from dead organic matter (detritus).
Important groups of dertivores are prokaryotes and
fungi. These organisms secrete enzymes to digest
organic matter. They link the consumers and primary
producers of an ecosystem.
Q13: Explain energy relationship with trophic
levels.
Answer: The energy relation ship within trophic levels
can be represented in a form of pyramid as shown in
the figure. Following conclusions are arrived:
a. In a biosphere, energy transfer takes place only
through food chains.
b. Each food chain can be considered as an energy
chain.
c. The energy that is captured by the autotrophs does
not revert back to the solar input and the energy which
passes to the herbivores does not come back to
autotrophs. As it moves progressively through the
various trophic levels it is no longer available to the
previous level.
d. Plants utilize only 50% of the total available energy
for their life processes. But each of the trophic levels
utilizes 90% of their available energy for their metabolic
activities. Remaining 10% of the energy alone is
transferred to the next trophic level. This is the reason
long food chains are not commonly seen in nature.
Q14: Explicate the principle of food web.
Answer: Each organism is generally eaten by two or
more other kinds of organisms which in turn are
eaten by several other organisms. So instead of a
straight line food chain, the relationship can be shown
as a series of branching lines called a food web.
Q15: Define biological magnification.
Answer. It means accumulation of poisonous materials
in successive trophic levels in a food chain. This
happens when a toxin is ingested or eaten and moved
up the food chain from one organism to another
organism. As it moves up the food chain the toxin levels
gets magnified or more concentrated. DDT is one
example of harmful substance that have contaminated
food chains.
Q16: Explain Ozone depletion and its impact on our
environment?
Answer: Life on the Earth is protected from the
damaging Ultra-violet radiation by a layer of ozone
molecules $(O_3)$ The amount of ozone began to drop
sharply in 1980. This decrease has been linked to
synthetic chemicals like chrolo-fluoro-carbons (CFCs)
which are used in refrigerants and in fire extinguisher.
1. UV radiation causes a Chlorine atom to break away
from CFC molecule.
2. The free chlorine atoms hits on ozone molecule and
pulls away one oxygen atom from it.
3. A free oxygen atom hits the chlorine monoxide
molecule which results another chlorine atom.
4. In this way free chlorine will continue to delete
ozone in stratosphere. One Chlorine atom can destroy
more than 100,000 ozone molecules before it is
removed from stratosphere.
Decrease ozone levels in stratosphere increase the
intensity of UV radiation. Its consequences can be very
harmful and may lead to an increase in skin cancers
and cataracts among humans. UV radiation are also
harmful to crops and other primary producers and may
lead to unpredictable results.
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