ORGANISMS AND ENVIORNMENTS - I
Q. 1. Explain the term ecology.
Ans:
i. Ecology is the branch of biology which deals with the interactions among biotic and abiotic
in an environments.
factors
ii. Biotic factors include all living organisms while the abiotic factors include the physical environment.
iii. The term ecology was coined by Ernst Haeckel by combining two words, oikos (meaning
dwelling place) and logos (meaning study).
house or
Q. 2. Define ecosystem.
Ans: An ecosystem is the functional unit of nature, where organisms interact with each other and with their
surroundings.
Q. 3. Explain the difference between habitat and niche.
Ans: Difference between habitat and niche:
Habitat
Niche
1.
The place where an organism lives is called its
habitat.
Niche explains the role of organism in the area
where it lives.
2.
Habitat explains the place of residence of an
organism and the environmental factors
which are present there.
Niche describes the functional role of the
organism in the community.
3.
Habitat describes the ‘address’ of the
organism.
Niche describes the ‘profession’ of the
organism.
Q. 4. What is meant by ecological niche? What are the different types of niches?
Ans:
1. Ecological Niche: Ecological niche is an inclusion term which describes the functional role of the
organism in the community together with the microhabitat where it lives.
2. Types of Niche: There are three types of niches viz., spatial or habitat niche, trophic niche and
multidimensional niche.
i. Spatial niche: The physical space occupied by the organism is called spatial niche.
ii. Trophic niche: The trophic position of the organism and its functional role is called trophic
niche.
iii. Multidimensional niche: This is also known as hyper volume niche. It describes the position of the
organism in the environmental gradients.
Q. 5. Give scientific reason:
The concept of ecological niche significant in ecology.
Ans:
i. The ecological niche of an organism when describes gives a complete and comprehensive idea
about how that organism transforms energy, hoe does it behave, how does it respond to and modify its
physical and biotic environment and what are the constrains on it from species in its area, etc.
ii. The niche also tells the differences between the species at the same physical place or at different
place.
iii. It can even describe the same species at more than one location. Therefore, the concept of
ecological niche is significant in ecology.
Q. 6. Explain the concept of ecosystem.
Ans:
1. Ecosystem is an interacting, interdependent complex made up of entire biotic community in a
definite area along with its abiotic environment.
2. The interactions of the living organisms with each other and with their physical environment causes
the functioning of the ecosystem.
3. Structure of ecosystem: Structure of the ecosystem includes the follo0wing aspects:
i. The composition of the biological communities such as species, numbers, biomass and distribution.
ii. The quantity and the distribution of non-living components such as nutrients, water, etc.
iii. The range or gradient of conditions of existence, such as temperature, light, etc.
4. Functions of an ecosystem:
i. Biology energy flow.
ii. Productivity of the ecosystem.
iii. Photosynthesis and respiration that take place in the ecosystem.
iv. Nutrient cycles operating in the ecosystem.
v. Regulation of the environment by the organisms and the regulation of the organisms by the
environment in turn.
vi. Interactions of biotic and abiotic components of ecosystem.
Q. 7. What are the types of the ecosystems? Give their suitable examples.
Ans:
i. Ecosystems are of two types, viz. natural ecosystem and artificial ecosystem.
ii. Natural ecosystems: The ecosystems which operate under natural conditions without any
much
major interference by man are called natural ecosystems. E.g. terrestrial ecosystems such
aas grasslands,
forests, deserts, etc. or aquatic ecosystems such as lakes, river, wetland, etc.
iii. Artificial ecosystems: The man engineered ecosystems which are maintained artificially by man by
the addition of energy are called artificial ecosystems. These ecosystems are depend
upon manipulations
from human beings. E.g. croplands, aquarium, aquaculture, etc. are the types of artificial ecosystems.
Q. 8. What are the different components of the ecosystem?
Ans:
i. There are two main components of the ecosystem, viz, abiotic components and biotic components.
ii. Abiotic components include all the inorganic substances such as P, S, C, N, H, etc., their
distribution and amount available in an ecosystem and organic compounds such as proteins,
carbohydrate, lipids, etc., along with the climate of that region.
iii. Biotic components include all the living organisms living in an ecosystem. The living organism may
be autotrophic or producers and converters or transducers. These are either green
plants having
photodynthetic abilities or chemosynthetics micro organism the heterotropic
organisms are called
consumers. They can either be macroconsumers or microconsumers.
i) Macroconsumers are herbivores, carnivores, omnivores as per the order in which they appear
in the food chain.
ii) Herbivores are primary consumers while the carnivores are secondary consumers.
iii) Omnivores can be secondary or tertiary consumers.
iv) Microconsumers are decomposing organisms and hence they are also called decomposers. They
have saprophytic mode of nutrition. Bacteria, actinomycets and fumgi are some of the microconsumers.
v) Microconsumers decxompose complex organic compounds from dead and living
and release the inorganic nutrients obtained from them, back to the environment.
protoplasma
Q. 9. What are the two spatial patterns in an ecosystem? Describe them briefly.
Ans:
i. There are two spatial patterns recognize in an ecosystem viz, zonation and stratifaction.
ii. Zonation is the spatial attern which occurs horizontly along the ground. Along a horizontal
the density and distribution of the spices keep on varying.
gradient,
iii. Stratafiction is the spatial pattern which occurs vertically. This is determined by the height of
organism. Such stratification is seen in forest community where trees of different spices grow to
different heights.
Q.10. What is productivity of an ecosystem?
Ans:
i. Productivity is defined as the amount o f organic matter accumulated in any unit time. It is the
rate of production in an ecosystem in a specified time.
ii. Productivity can be primary or seciondary in nature.
iii. Primary productivity describe the autotrophic, photosynthetic or chemosynthetic organism. The rate
at which the radiant energy is converted and stored by these producers is considered as the primary
productivity. Primary productivity is classified into two types viz. gross primary productivity and net primary
productivity.
iv. Gross primaruy productivity is the total rate of photosynthesis including the organic matter used up
during respiration. This is depicted as chlorophyll content as chl/g dry weight/unit
area of
photosynthetic number as CO2 fixed/g chl/hour.
v. Net primary productivity is the actual amount of organic matter stored by green plants apart from its
use in respiration. The balance of gross photosynthesis and respiration and other plant losses such as deatuh,
etc. gives the net primary productivity.
vi. Secondary productivity is the rate of energy storage at the level of the consumers. This
productivity depends upon the foods material that is used directly or indirectly from the producers.
Which is the later converted into suitable form.
vii. Net productivity gives the rate of storage of organic matter which is not used by the consumers. This
is equivalent to net primary productivity minus consumption by the
consumers. This is expressed as
2
production of C g/m /day.
Q.11. Write a short note on “Decomposition”.
Ans:
i. Decomposition is the process carried out by the decomposers organism.
ii. The role of decomposition is very important as through it nutrient recycling takes place.
iii. Most of the bacteri, actinomycets and fungi are decomposers.
iv. They convert the dead and decaying organic matter into simpler compounds. These simpler
inorganic substances return that to the environment.
v. Decomposition takes place through detritus food chain in start from the dead organic matter.
Detritus eating organism called detritivores like earthworm, etc. breakdown the detritus into smaller
fragments. Therefore this first step podf decomposition is called fragmentation.
vi. Water soluble inorganic nutrients seep into the soil after fragmentation. These nutrients get
precipitated as salts. Therefore