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BIOLOGY M.C.Q [1M]

STD 12 - 12. ecosystem · Bihar Board (BSEB) STD 12 Science (BSEB - English Medium). 399 questions.

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M.C.Q [1M]

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MCQ 11 Mark
In an ecosystem if the Net Primary Productivity ($NPP$) of first trophic level is $100 \times\left(\mathrm{kcal} \mathrm{m}^{-2}\right) \mathrm{yr}^{-1}$, what would be the $GPP$ (Gross Primary Productivity) of the third trophic level of the same ecosystem?
  • A
    $x\left(\mathrm{kcal} \mathrm{m}^{-2}\right) \mathrm{yr}^{-1}$
  • ✓
    $10 x\left(\mathrm{kcal} \mathrm{m}^{-2}\right) \mathrm{yr}^{-1}$
  • C
    $\frac{100 x}{3 x}\left(\mathrm{kcal} \mathrm{m}^{-2}\right) \mathrm{yr}^{-1}$
  • D
    $\frac{x}{10}\left(\mathrm{kcal} \mathrm{m}^{-2}\right) \mathrm{yr}^{-1}$
Answer
Correct option: B.
$10 x\left(\mathrm{kcal} \mathrm{m}^{-2}\right) \mathrm{yr}^{-1}$
b
$NPP$ at first trophic level would be the $GPP$ for second trophic level. $NPP$ at second trophic level would be $GPP$ for third trophic level. Therefore, $100 x\left(\mathrm{kcal} / \mathrm{m}^2 / \mathrm{yr}\right)$ would be $GPP$ at second trophic level and $100 x$ $\times 10 \%\left(\mathrm{kcal} / \mathrm{m}^2 / \mathrm{yr}\right)$ i.e., $10 \times\left(\mathrm{kcal} / \mathrm{m}^2 / \mathrm{yr}\right)$ energy would be $GPP$ at third trophic level.
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MCQ 21 Mark
Identify the correct statements:

$A.$ Detrivores perform fragmentation.

$B.$ The humus is further degraded by some microbes during mineralization.

$C$. Water soluble inorganic nutrients go down into the soil and get precipitated by a process called leaching.

$D$. The detritus food chain begins with living organisms.

$E$. Earthworms break down detritus into smaller particles by a process called catabolism.

Choose the correct answer from the options given below:

  • A
    $D, E, A$ only
  • ✓
    $A, B, C$ only
  • C
    $B, C, D$ only
  • D
    $C, D, E$ only
Answer
Correct option: B.
$A, B, C$ only
b
The detritus food chain begins with detritus that is dead organic matter. The saprotrophic bacteria and fungi breakdown detritus into simpler inorganic substances by a process called catabolism.
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MCQ 31 Mark
In the equation GPP $- R = NPP$ (GPP is Gross Primary Productivity)(NPP is Net Primary Productivity)$R$ here is
  • A
    Reproductive allocation
  • B
    Photosynthetically active radiation
  • C
    Respiratory quotient
  • ✓
    Respiratory loss
Answer
Correct option: D.
Respiratory loss
d
A considerable amount of $GPP$ is utilised by plants in respiration. Gross primary productivity minus respiration losses $(R)$, is the net primary productivity.

So $R =$ Respiratory loss

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MCQ 41 Mark
Detritivores breakdown detritus into smaller particles. This process is called :
  • ✓
    Fragmentation
  • B
    Humification
  • C
    Decomposition
  • D
    Catabolism
Answer
Correct option: A.
Fragmentation
a
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MCQ 51 Mark
Given below are two statements:

Statement $I:$

Decomposition is a process in which the detritus is degraded into simpler substances by microbes.

Statement $II:$

Decomposition is faster if the detritus is rich in lignin and chitin

In the light of the above statements, choose the correct answer from the options given below:

  • A
    Both Statement $I$ and Statement $II$ are incorrect
  • ✓
    Statement $I$ is correct but Statement $II$ is incorrect
  • C
    Statement $I$ is incorrect but Statement $II$ is correct
  • D
    Both Statement $I$ and Statement $II$ are correct
Answer
Correct option: B.
Statement $I$ is correct but Statement $II$ is incorrect
b
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MCQ 61 Mark
Which of the following statements is incorrect?
  • A
    Energy content gradually decreases from first to fourth trophic level
  • B
    Biomass decreases from first to fourth trophic level
  • ✓
    Energy content gradually increases from first to fourth trophic level
  • D
    Number of individuals decreases from first trophic level to fourth trophic level
Answer
Correct option: C.
Energy content gradually increases from first to fourth trophic level
c
Energy content does not remain trapped permanently in any organism. It is passed on to various trophic levels in food chain.

Hence, energy content gradually decreases from first $\left(T_{1}\right)$ to fourth $\left(T_{4}\right)$ trophic level by following ten percent law proposed by Lindemann.

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MCQ 71 Mark
The rate of decomposition is faster in the ecosystem due to following factors $EXCEPT$
  • ✓
    Detritus richer in lignin and chitin
  • B
    Detritus rich in sugars
  • C
    Warm and moist environment
  • D
    Presence of aerobic soil microbes
Answer
Correct option: A.
Detritus richer in lignin and chitin
a
The rate of decomposition is slow if it contains lignin, chitin, tannins (Phenolics) and cellulose.
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MCQ 81 Mark
Match the trophic levels with their correct species examples in grassland ecosystem.

$(a)$ Fourth trophic level $(i)$ Crow
$(b)$ Second trophic level $(ii)$ Vulture
$(c)$ First trophic level $(iii)$ Rabbit
$(d)$ Third trophic level $(iv)$ Grass

Select the correct option :

$(a)\quad(b) \quad(c) \quad(d)$

  • A
    $(i)\quad(ii) \quad(iii) \quad(iv)$
  • ✓
    $(ii)\quad(iii) \quad(iv) \quad(i)$
  • C
    $(iii)\quad(ii) \quad(i) \quad(iv)$
  • D
    $(iv)\quad(iii) \quad(ii) \quad(i)$
Answer
Correct option: B.
$(ii)\quad(iii) \quad(iv) \quad(i)$
b
$(ii)\quad(iii) \quad(iv) \quad(i)$
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MCQ 91 Mark
Which of the following ecological pyramids is generally inverted ?
  • A
    Pyramid of numbers in grassland
  • B
    Pyramid of energy
  • C
    Pyramid of biomass in a forest
  • ✓
    Pyramid of biomass in a sea
Answer
Correct option: D.
Pyramid of biomass in a sea
d
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MCQ 101 Mark
What type of ecological pyramid would be obtained with the following data?
Secondary consumer: $120\,g$
Primary consumer: $60\,g$
Primary producer: $10\,g$
  • A
    Upright pyramid of biomass
  • ✓
    Inverted pyramid of biomass
  • C
    Upright pyramid of numbers
  • D
    Pyramid of energy
Answer
Correct option: B.
Inverted pyramid of biomass
b
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MCQ 111 Mark
The mass of living material at a trophic level at a particular time is called
  • A
    net primary productivity
  • ✓
    standing crop
  • C
    gross primary productivity
  • D
    standing state
Answer
Correct option: B.
standing crop
b
(b) :Standing crop is the total amount of living material in a specified population at a particular time, expressed as biomass (standing biomass) or its equivalent in terms of energy. The standing crop may vary at different times of the year; for example, in a population of deciduous trees between summer and winter.
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MCQ 121 Mark
Most animals that live in deep oceanic waters are
  • A
    tertiary consumers
  • ✓
    detritivores
  • C
    primary consumers
  • D
    secondary consumers.
Answer
Correct option: B.
detritivores
b
(b) :Benthos is the community of organisms which live on, in, or near the sea bed, also known as the benthic zone. As no light is available at this zone of sea, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column which drifts down to the depths. This dead and decaying matter sustains the benthic organisms, and therefore, most organisms in benthic zone $i.e.$, in deep oceanic waters, are scavengers or detritivores.
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MCQ 131 Mark
When man eats fish which feeds onzooplanktons which have eaten small plants,the producer in this chain is
  • ✓
    small plants
  • B
    fish
  • C
    man
  • D
    zooplankton
Answer
Correct option: A.
small plants
a
(a) :The transfer of food energy from producers to consumers through a series of organisms with repeated eating and being eaten is known as food chain. Green plants are always the first link of food chain because they alone are capable of synthesising organic food by using light energy by photosynthesis. The logical sequence of a food chain is : Producer Consumers Decomposer
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MCQ 141 Mark
Which of the following is a primary consumerin maize field ecosystem ?
  • ✓
    Grasshopper
  • B
    Wolf
  • C
    Phytoplankton
  • D
    Lion
Answer
Correct option: A.
Grasshopper
a
(a) : Primary consumers are herbivorous organisms that feed on producers. Carnivores are termed secondary, tertiary etc., consumers depending upon their position in food chain. In food chain on land, grasshopper is a herbivore (primary consumer) while wolf and lion are carnivores. Phytoplanktons are producers in aquatic food chains.
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MCQ 151 Mark
Secondary productivity is rate of formation ofnew organic matter by
  • ✓
    consumers
  • B
    decomposers
  • C
    producers
  • D
    parasites.
Answer
Correct option: A.
consumers
a
(a) :The rate of photosynthesis of organic matter by the consumers is known as secondary productivity. It depends upon the loss while transferring energy containing organic matter from the previous trophic level plus the consumption due to respiration and predation. Therefore, net productivity decreases with each trophic level.
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MCQ 161 Mark
Which one of the following processes during decomposition is correctly described ?
  • A
    Catabolism -Last step in thedecomposition under fully anaerobiccondition
  • B
    Leaching -Water soluble inorganicnutrients rise to the top layers of soil
  • ✓
    Fragmentation -Carried out by organismssuch as earthworm
  • D
    Humification -Leads to the accumulationof a dark coloured substance humuswhich undergoes microbial action at a veryfast rate.
Answer
Correct option: C.
Fragmentation -Carried out by organismssuch as earthworm
c
(c) :Decomposition is the process in which decomposers break down complex organic matter into inorganic substances like carbon dioxide, water and nutrients. The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralisation. Detritivores ($e.g.$, earthworm) break down detritus into smaller particles. This process is called fragmentation. By the process of leaching, water­ soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts. Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called as catabolism. Humification and mineralisation occur during decomposition in the soil. Humification leads to accumulation of a dark coloured amorphous substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralisation.
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MCQ 171 Mark
$A $ : Ecological pyramids cannot explain all the vital functions of any ecosystem.

$R$ : Pyramids actually does not explain the role of organisms working at more than one trophic levels.

  • ✓
    Assertion and Reason both are correct and also correct explanation.
  • B
    Assertion and Reason both are correct but not explanation of assertion.
  • C
    Assertion is correct, but Reason is incorrect.
  • D
    Both Assertion and Reason are incorrect.
Answer
Correct option: A.
Assertion and Reason both are correct and also correct explanation.
a
Ecological pyramids assume food chain but actually food web exists.
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MCQ 181 Mark
Pyramid of number in a cropland ecosystem is
  • ✓
    Upright
  • B
    Inverted
  • C
    Rhomboidal
  • D
    Spindle shaped
Answer
Correct option: A.
Upright
a
Pyramid of number in a cropland is upright.
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MCQ 191 Mark
What does the given ecological pyramid represent?
  • A
    Inverted pyramid of number in pond
  • B
    Role of decomposers
  • ✓
    Inverted pyramid of biomass in pond
  • D
    Pyramid of biomass in a forest ecosystem
Answer
Correct option: C.
Inverted pyramid of biomass in pond
c
Shows inverted pyramid of biomass in a pond.
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MCQ 201 Mark
If producer is a large tree that supports a number of herbivorous animals which are further attacked by ectoparasites, the pyramid of number shall be
  • ✓
    Inverted
  • B
    Upright
  • C
    Irregular
  • D
    Spindle shaped
Answer
Correct option: A.
Inverted
a

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MCQ 211 Mark
Which of the following ecological pyramids is most representative of functional characteristics of an ecosystem?
  • A
    Pyramid of number
  • B
    Pyramid of biomass
  • ✓
    Pyramid of energy
  • D
    All are equally representative
Answer
Correct option: C.
Pyramid of energy
c
Pyramid of energy.
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MCQ 221 Mark
The respiratory loss of producers, herbivores and carnivores are respectively
  • A
    $10\;\%, 20\;\%, 30\;\%$
  • ✓
    $20\;\%, 30\;\%, 60\;\%$
  • C
    $20\;\%, 40\;\%, 80\;\%$
  • D
    $Always\; 10\;\%$
Answer
Correct option: B.
$20\;\%, 30\;\%, 60\;\%$
b
Respiratory loss of producers, herbivores and carnivores are $20\;\%, 30\;\% $ and $60\;\%$ respectively.
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MCQ 231 Mark
Which of the following organisms were not given any place in ecological pyramids?
  • A
    Working at several trophic levels
  • B
    Decomposers
  • C
    Parasites
  • ✓
    More than one option is correct
Answer
Correct option: D.
More than one option is correct
d
Both parasites and decomposers.
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MCQ 241 Mark
In forest ecosystem, pyramid of number is
  • ✓
    Upright
  • B
    Inverted
  • C
    Any of the two
  • D
    None of the above
Answer
Correct option: A.
Upright
a
(a)The pyramid of number in forest is erect or upright as producers are maximum in number and top consumers are least in number.
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MCQ 251 Mark
In lake ecosystem, pyramid biomass is
  • A
    Upright
  • ✓
    Inverted
  • C
    Anything is possible
  • D
    None is correct
Answer
Correct option: B.
Inverted
b
(b)In pond or lake ecosystem pyramid of biomass are of inverted type as biomass of producers is minimum and of top consumers is maximum.
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MCQ 261 Mark
In a tree ecosystem, the pyramid of number is
  • A
    Upright
  • B
    Inverted
  • ✓
    Both of the above
  • D
    None of the above
Answer
Correct option: C.
Both of the above
c
(c)In tree ecosystem the pyramid of number is intermediate. Here the number of primary consumers is more than producers as well as top consumers.
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MCQ 271 Mark
The pyramid that cannot be inverted in a stable ecosystem, is pyramid of
  • A
    Number
  • ✓
    Energy
  • C
    Biomass
  • D
    All the above
Answer
Correct option: B.
Energy
b
(b)Because at each trophic level only $10\% $ energy is left. Thus the amount of energy decreases and pyramid will be straight and cannot be inverted in any condition.
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MCQ 281 Mark
The pyramid of number in a grassland ecosystem is
  • ✓
    Always erect
  • B
    Always inverted
  • C
    Either erect or inverted
  • D
    Irregular
Answer
Correct option: A.
Always erect
a
(a)In a grassland food chain the number of individuals decrease at the successive higher levels.
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MCQ 291 Mark
Organisms living in open sea are called
  • ✓
    Planktons
  • B
    Nektons
  • C
    Pelagic
  • D
    Benthos
Answer
Correct option: A.
Planktons
a
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MCQ 301 Mark
If phytoplankton are destroyed in the sea, then
  • A
    Algae will get more space to grow
  • B
    Primary consumers will grow luxuriently
  • ✓
    It will effect the food chain
  • D
    No effect will be seen
Answer
Correct option: C.
It will effect the food chain
c
(c)Because phytoplankton is the main producer in the sea.
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MCQ 311 Mark
With regard to ecological food chain, man is a
  • A
    Producer
  • ✓
    Consumer
  • C
    Both producer and consumer
  • D
    Producer and decomposer
Answer
Correct option: B.
Consumer
b
(b)Because man can not produce the food himself and he depends on plants (producer) for food.
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MCQ 321 Mark
The transfer of energy from organism to organism in a natural community establishes
  • ✓
    Food chains
  • B
    Biological control
  • C
    Natural barriers
  • D
    All the above
Answer
Correct option: A.
Food chains
a
(a)The transfer of food energy from the producers through a series of organisms (herbivores $→$ carnivores $→$ decomposers) with repeated eating and being eaten is known as a food chain.
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MCQ 331 Mark
Which of the following are called key industry animals?
  • A
    Autotrophs
  • B
    Decomposers
  • ✓
    Herbivores
  • D
    Top carnivores
Answer
Correct option: C.
Herbivores
c
Key industry animals are herbivores.
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MCQ 341 Mark
Pyramid of energy is
  • ✓
    Upright
  • B
    Inverted
  • C
    Oblique
  • D
    None of these
Answer
Correct option: A.
Upright
a
It’s obvious.
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MCQ 351 Mark
The aquatic organism that can actively swim at will against the water current is
  • A
    Neuston
  • B
    Plankton
  • ✓
    Nekton
  • D
    Benthos
Answer
Correct option: C.
Nekton
c
Nekton are aquatic organisms that can actively swim at will against the water current. They live in shallow and deep ocean waters. Most nekton eat zooplankton, other nekton or thy scavange for waste.
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MCQ 361 Mark
Choose correct food chain (GFC).
  • A
    Cow $\rightarrow$ grass - wolf $\rightarrow$ lion
  • ✓
    Grass $\rightarrow$ Cow $\rightarrow$ wolf $\rightarrow$ lion
  • C
    Grass $\rightarrow$ wolf Cow $\rightarrow$ lion
  • D
    Trees $\rightarrow$ wolf $\rightarrow$ Cow $\rightarrow$ lion
Answer
Correct option: B.
Grass $\rightarrow$ Cow $\rightarrow$ wolf $\rightarrow$ lion
b
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MCQ 371 Mark
In ecological crisis, whom interference play important role
  • A
    Green plants
  • ✓
    Human
  • C
    Biotic and abiotic components
  • D
    None of these
Answer
Correct option: B.
Human
b
It’s obvious.
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MCQ 381 Mark
$A$ : In secondary productivity, no new organic matter is formed.

$R$ : It is only utilisation of part of food manufactured by primary producers in building of consumer biomass.

  • ✓
    Assertion and Reason both are correct and also correct explanation.
  • B
    Assertion and Reason both are correct but not explanation of assertion.
  • C
    Assertion is correct, but Reason is incorrect.
  • D
    Both Assertion and Reason are incorrect.
Answer
Correct option: A.
Assertion and Reason both are correct and also correct explanation.
a
Secondary productivity Rate of biomass accumulation by consumers.
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MCQ 391 Mark
$A$ : Detritus food chain begins with detritus.

$R$ : Detrivores like fungi and bacteria are major decomposers in such food chains.

  • A
    Assertion and Reason both are correct and also correct explanation.
  • B
    Assertion and Reason both are correct but not explanation of assertion.
  • ✓
    Assertion is correct, but Reason is incorrect.
  • D
    Both Assertion and Reason are incorrect.
Answer
Correct option: C.
Assertion is correct, but Reason is incorrect.
c
Fungi and bacteria are decomposers.
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MCQ 401 Mark
Which of the following statement is not correct about energy flow in an ecosystem?
  • A
    Pyramid of energy is always straight
  • B
    Energy flow is unidirectional
  • ✓
    Energy flow is cyclic
  • D
    Ecological efficiency is generally $10\;\%$
Answer
Correct option: C.
Energy flow is cyclic
c
Energy flow is not cyclic in an ecosystem.
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MCQ 411 Mark
The gross primary productivity of ocean billion tone.
  • A
    $150$
  • ✓
    $55$
  • C
    $180$
  • D
    $210$
Answer
Correct option: B.
$55$
b
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MCQ 421 Mark
An inverted pyramid of $...A...$ may occasionally be observed in $...B...$ communities
  • A
    $A-$energy; $B-$grassland
  • B
    $A-$energy; $B-$forest
  • ✓
    $A-$biomass; $B-$marine
  • D
    $A-$biomass; $B-$grassland
Answer
Correct option: C.
$A-$biomass; $B-$marine
c
An inverted pyramid of biomass may occasionally be observed in marine communities
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MCQ 431 Mark
Abiotic components refers to
  • ✓
    Non-living physico-chemical factors
  • B
    Living physico-chemical factors
  • C
    Gases produced by industries
  • D
    Living organisms
Answer
Correct option: A.
Non-living physico-chemical factors
a
A biotic components includes the non-living physico-chemical factors of the environment. These components not only affect the distribution and structure of organisms but also their behavior and inter-relationships. Abiotic factors include inorganic substances, organic compounds, climatic factors and edaphic factors
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MCQ 441 Mark
The two components of an ecosystem are
  • A
    Plants and animals
  • B
    Weeds, trees, animals and man
  • C
    Energy flow and mineral cycling
  • ✓
    Biotic and abiotic
Answer
Correct option: D.
Biotic and abiotic
d
The components of an ecosystem may be divided into two main types, $i.e.$, Biotic component comprising the various kinds of living organisms and Abiotic component consisting of environmental factors
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MCQ 451 Mark
Vertical distribution of different species occupying different level is called..........
  • ✓
    Stratification
  • B
    Productivity
  • C
    $GPP$
  • D
    $NPP$
Answer
Correct option: A.
Stratification
a
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MCQ 461 Mark
Ecosystem involves
  • A
    Gain of energy and loss of minerals
  • B
    Loss of energy and gain of minerals
  • ✓
    Gain of energy and gain of minerals
  • D
    Loss of energy and loss of minerals
Answer
Correct option: C.
Gain of energy and gain of minerals
c
It’s obvious.
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MCQ 471 Mark
If decomposers are removed what will happen to the ecosystem?
  • A
    Energy cycle is stopped
  • ✓
    Mineral cycle is stopped
  • C
    Consumers cannot absorb solar energy
  • D
    Rate of decomposition of mineral increases
Answer
Correct option: B.
Mineral cycle is stopped
b
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MCQ 481 Mark
Which of the following is most important abiotic factor in pond ecosystem
  • ✓
    Water
  • B
    Phytoplankton
  • C
    Zooplankton
  • D
    Temperature
Answer
Correct option: A.
Water
a
It’s obvious.
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MCQ 491 Mark
Ecosystem is defined as
  • A
    Relation between plants and animals
  • ✓
    Relation between biotic and physical components
  • C
    Relation between producers and decomposers
  • D
    None of these
Answer
Correct option: B.
Relation between biotic and physical components
b
It’s obvious.
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MCQ 501 Mark
Ecosystem may be defined as
  • A
    Group of plants which act as the energy suppliers
  • B
    Group of organisms which form population
  • ✓
    Functional unit for ecological studies
  • D
    None of these
Answer
Correct option: C.
Functional unit for ecological studies
c
It’s obvious.
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