Ecosystem Test

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Ecosystem Test - 81

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Weekly Quiz Competition

Question 1
1 / -0

Identify the incorrect statement for the following.

A
Pyramids of number and biomass may be either upright or inverted

B
Pyramid of biomass in sea is generally inverted as biomass of fish far exceeds that of phytoplankton

C
Food chains are generally short with few trophic levels as only 10% of the energy is transferred to higher trophic level from lower one

D
Pyramid of energy is mostly upright but sometimes it may be inverted

Solution

Ecological pyramid is a graphical representation indicating the relationship between organisms at different trophic levels. It is expressed in terms of number, biomass and energy. Based on this, it is of 3 types, pyramid of number, pyramid of biomass and pyramid of energy. Pyramids of number and biomass may be either upright or inverted. For example, the pyramid of biomass in sea is generally inverted as biomass of fish far exceeds that of phytoplankton. However, the pyramid of energy is always upright and never be inverted. Food chains are generally short with few trophic levels as only 10% of the energy is transferred to higher trophic level from lower one. The rest of the energy is lost during the process.
Thus, the correct answer is 'Pyramid of energy is mostly upright but sometimes it may be inverted.'
Question 2
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Gross primary productivity of an ecosystem is 170 tons of organic matted and amount used in respiration is 50 tons. Calculate the net primary productivity of the ecosystem.

A
120 tons

B
100 tons

C
70 tons

D
12 tons

E
17 tons

Solution

In a food chain, energy stored at the producer level is called as primary productivity. Energy stored at the consumer level is called as secondary productivity. Gross primary productivity is the rate of conversion of light energy into chemical energy of organic molecules in an ecosystem. Net primary productivity is the rate of storage of organic matter except which is utilized for the respiration by plants. In the given ecosystem, the gross primary productivity is 170 tons of organic matter. Out of these, 50 tons is used in respiration. Hence, the net primary productivity will be 170 - 50 = 120 tons.
Thus, the correct answer is '120 tons.'
Question 3
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All of the following statements are true for ecological pyramid except

A
Energy available at a lower trophic level is always more than that at a higher level

B
The pyramid of numbers in a parasitic food chain is inverted

C
Pyramid of biomass in sea is upright normally

D
In a tree ecosystem, squirrels are primary consumers and ticks are secondary consumers

Solution

An ecological pyramid is a graphical representation of the biomass or bio productivity at each trophic level in a given ecosystem.
Pyramid of the number shows graphically the population of each level in a food chain. It may be upright (e.g. Grassland ecosystem), inverted (parasitic ecosystem) or dumbbell-shaped (forest ecosystem).
An energy pyramid is a graphical model of energy flow in a system. Energy pyramids begin with producers on the bottom and proceed through the various trophic levels. The consumers at the top of a food pyramid have much less energy available to support them than those closer to the bottom.
Marine environments (sea, ocean) have inverted biomass pyramids. In particular, the biomass of consumers is larger than the biomass of primary producers.
So, the answer is C.
Question 4
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Number of individuals decreases from producer level to consumer level in

A
Pyramid of numbers

B
Pyramid of energy

C
Pyramid of biomass

D
All of the above

Solution

Ecological pyramid is a graphic representation indicating the relationship between organisms at each different trophic level. These are of 3 types, pyramid of numbers, pyramid of energy and pyramid of biomass. Pyramid of number indicates the number of organisms at each trophic level. In an ecological pyramid, the number of individuals usually decreases from producer level to consumer level. The number of individuals decreases significantly at each trophic level.
Thus, the correct answer is 'All of the above.'
Question 5
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In plant succession, the net productivity of climax community

A
Continuous to increase

B
Becomes stable

C
Becomes halved

D
Reduced to $$10\%$$

E
Becomes zero

Solution

An ecological community in which population of plant or animal remains "stable" and exist in balance with each other and their environment or in general we can say there is no changes at all.
So the correct option is "becomes stable".
Question 6
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Highest value in g C m$$^{−2}$$ yr$$^{−1}$$ of a grassland ecosystem would be

A
Gross primary production

B
Net primary production

C
Secondary production

D
Tertiary production

Solution

So the correct option is A.
Question 7
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Which of the following statements about productivity is true?

A
Primary productivity of all ecosystems is a constant

B
Annual net primary productivity of the whole of the biosphere is 17 billion tons (dry weight) of organic matter

C
Net primary productivity is the amount of biomass available for consumption by carnivores

D
Secondary productivity is defined as the rate of formation of new organic matter by decomposers

E
Primary productivity depends upon the plant species inhabiting a particular area

Solution

a) Primary productivity of all ecosystems varies depending upon the number of producers in an ecosystem.
b) Annual net primary productivity of the whole of the biosphere is 170 billion tons (dry weight) of organic matter.
c) Gross primary productivity is the rate of photosynthesis. Net primary productivity is the rate of storage of organic matter except which is utilized for the respiration by plants. It is the total biomass available for consumers.
d) The rate of formation of new organic matter by producer is called as secondary productivity. Consumer level includes herbivores, carnivores and decomposers. In other words, it is the rate of formation of new organic matter by consumers.
e) In a food chain, energy stored at the producer level is called as primary productivity. Primary productivity depends upon the plant species inhabiting a particular area.
Thus, the correct answer is 'Primary productivity depends upon the plant species inhabiting a particular area.'
Question 8
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Source of maximum sulphur is/reservoir of sulphur is

A
Ocean

B
Lakes

C
Land

D
Rocks

Solution

Source of maximum sulfur is/reservoir of sulfur is rocks. It is found in the form of iron pyrites, evaporite rocks in the form of anhydrite and baryte and calcium and magnesium carbonates.
Thus, the correct answer is 'Rocks.'
Question 9
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Read the following statements regarding ecological pyramids and choose the correct answer.
(a) Relationship between organisms at different trophic levels is expressed in terms of number, biomass and energy.
(b) Any calculations of energy content, biomass or number has to include one group of organisms at that trophic level.
(c) In most ecosystems, all the pyramids of number, biomass and energy are upright.
(d) The pyramid of biomass in sea is generally inverted.
(e) Pyramid of energy is always inverted and can never be upright.

A
a, c and d are wrong

B
a is wrong

C
b and e are wrong

D
a and e are wrong

E
d and e are wrong

Solution

Ecological pyramid is a graphical representation indicating the relationship between organisms at different trophic levels. It is expressed in terms of number, biomass and energy. Based on this, it is of 3 types, pyramid of number, pyramid of biomass and pyramid of energy.
Any calculations of energy content, biomass or number has to include all groups of organisms at that trophic level.
In most ecosystems, all the pyramids of number, biomass and energy are upright as the producers mainly have high numbers, maximum biomass and thus greater energy and it decreases as we move from producers to higher trophic level.
In some ecosystems, pyramid of number and pyramid of biomass is inverted. For example, the pyramid of biomass in sea is generally inverted.
However, the pyramid of energy is always upright and never be inverted.
Thus, the correct answer is 'b and e are wrong.'
Question 10
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Which of the following is the correct trend of succession in hydroseric succession?

A
Phytoplankton $$\rightarrow$$ Rooted submerged $$\rightarrow$$ Reed swamp $$\rightarrow$$ Sedge meadow.

B
Phytoplankton $$\rightarrow$$ Reed swamp $$\rightarrow$$ Rooted submerged $$\rightarrow$$ Sedge meadow.

C
Phytoplankton $$\rightarrow$$ Sedge medow $$\rightarrow$$ Reed swamp $$\rightarrow$$ Sedge meadow.

D
Rooted submerged $$\rightarrow$$ Phytoplankton $$\rightarrow$$ Reed swamp $$\rightarrow$$ Sedge meadow.

Solution

There are main eight stages of hydroseric succession in plants. These are Phytoplankton stage, rooted submerged stage, floating Stage, reed swamp stage, sedge meadow stage, alder or willow carr stage, wood land stage and climax woodland stage. Phytoplankton stage includes autotrophic diatoms, phytoflagellates, cyanobacteria. Rooted submerged stage includes species like Myriophyllum, Hydrilla, Ceratophyllum. Foating plants are rooted in the mud, however leaves float on the surface of the water. Example includes Water-lilies. Reed swamp stage is also called as amphibious stage. It includes typha, sagittaria. Sedge meadow plants include plants those are newly emerged from water and highly vulnerable to drying out. Willow carr plants include rushes, ferns and small flowering herbs. Woodland plants can tolerate sunlight and water logged condition. These include Cornus, Cephlanthus. Climax plants include Oak, Ash, Beech.
Thus, the correct answer is option A.

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Ecosystem Test - 81

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Ecosystem Test - 81

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Question 1

Pyramids of number and biomass may be either upright or inverted

Pyramid of biomass in sea is generally inverted as biomass of fish far exceeds that of phytoplankton

Food chains are generally short with few trophic levels as only 10% of the energy is transferred to higher trophic level from lower one

Pyramid of energy is mostly upright but sometimes it may be inverted

Solution

Question 2

120 tons

100 tons

70 tons

12 tons

17 tons

Solution

Question 3

Energy available at a lower trophic level is always more than that at a higher level

The pyramid of numbers in a parasitic food chain is inverted

Pyramid of biomass in sea is upright normally

In a tree ecosystem, squirrels are primary consumers and ticks are secondary consumers

Solution

Question 4

Pyramid of numbers

Pyramid of energy

Pyramid of biomass

All of the above

Solution

Question 5

Continuous to increase

Becomes stable

Becomes halved

Reduced to $$10\%$$

Becomes zero

Solution

Question 6

Gross primary production

Net primary production

Secondary production

Tertiary production

Solution

Question 7

Primary productivity of all ecosystems is a constant

Annual net primary productivity of the whole of the biosphere is 17 billion tons (dry weight) of organic matter

Net primary productivity is the amount of biomass available for consumption by carnivores

Secondary productivity is defined as the rate of formation of new organic matter by decomposers

Primary productivity depends upon the plant species inhabiting a particular area

Solution

Question 8

Ocean

Lakes

Land

Rocks

Solution

Question 9

a, c and d are wrong

a is wrong

b and e are wrong

a and e are wrong

d and e are wrong

Solution

Question 10

Phytoplankton $$\rightarrow$$ Rooted submerged $$\rightarrow$$ Reed swamp $$\rightarrow$$ Sedge meadow.

Phytoplankton $$\rightarrow$$ Reed swamp $$\rightarrow$$ Rooted submerged $$\rightarrow$$ Sedge meadow.

Phytoplankton $$\rightarrow$$ Sedge medow $$\rightarrow$$ Reed swamp $$\rightarrow$$ Sedge meadow.

Rooted submerged $$\rightarrow$$ Phytoplankton $$\rightarrow$$ Reed swamp $$\rightarrow$$ Sedge meadow.

Solution

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