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Which one of the following is not a correct match?
(d) : Crop field is considered as man-made (anthropogenic or artificial) ecosystem. Natural ecosystem is developed in nature without human involvement, e.g., forest, ocean, etc.
Vertical distribution of different species occupying different levels in dense vegetation is called
(a) : Vertical distribution of different species occupying different levels is called stratification. For example, trees occupy top vertical strata or layer of a forest, shrubs the second layer and herbs and grasses occupy the bottom layer.
Term ‘ecosystem’ was coined by
(b) : The term ecosystem was introduced by Tansley in 1935.
Which of the following pairs is not correct?
(d)
Match column I with column II and choose the correct option from the given codes.
\(
\begin{array}{|l|l|l|l|}
\hline & \text { Column I } & & \text { Column II } \\
\hline \text { A. } & \text { Population } & \text { (i) } & \begin{array}{l}
\text { Part of the earth consisting of } \\
\text { all the ecosystems of the world }
\end{array} \\
\hline \text { B. } & \text { Community } & \text { (ii) } & \begin{array}{l}
\text { Assemblage of all the individuals } \\
\text { belonging to different species } \\
\text { occurring in an area }
\end{array} \\
\hline \text { C. } & \text { Ecosystem } & \text { (iii) } & \begin{array}{l}
\text { Group of similar individuals } \\
\text { belonging to the same species, } \\
\text { found in an area }
\end{array} \\
\hline \text { D. } & \text { Ecosphere } & \text { (iv) } & \begin{array}{l}
\text { Interaction between the living } \\
\text { organisms and their physical } \\
\text { environment }
\end{array} \\
\hline & & \text { (v) } & \begin{array}{l}
\text { Classification of organisms } \\
\text { based on the type of } \\
\text { environment }
\end{array} \\
\hline
\end{array}
\)
(d)
Which of the following is not a functional component of ecosystem?
(d) : Interaction of biotic and abiotic components result in a physical structure, that is characteristic of each type of ecosystem. Components of ecosystem function as one single unit. Four important functional aspects of the ecosystem are: (i) Productivity, (ii) Decomposition, (iii) Energy flow and (iv) Nutrient cycling. Ecological pyramids are graphical representation of number, biomass and energy flow in an ecosystem.
Which of the following is not an abiotic component of ecosystem?
(d)
Arrange the following ecosystems in an increasing order of their mean NPP (tons/ha/year).
A. Tropical deciduous forest
B. Temperate coniferous forest
C. Tropical rainforest
D. Temperate deciduous forest
(d) : Tropical rainforest shows the maximum diversity and also the maximum productivity. More solar energy and resources are available in tropics which promotes higher productivity. On land the maximum primary production rate is found in tropical rainforests followed by tropical deciduous forests, temperate forests, savannah, temperate grasslands and desert scrub.
The rate of conversion of light energy into chemical energy of organic molecules in an ecosystem is
(b)
Read the given statements and select the correct option.
Statement 1 : Net primary productivity is less than the gross primary productivity.
Statement 2: Net primary productivity is equal to the gross primary productivity minus the respiration losses.
(a) : Gross primary productivity (GPP) of an ecosystem is the rate of production of organic matter during photosynthesis. Net primary productivity (NPP) is the amount of organic matter stored by producers after respiration per unit area per unit time. Gross primary productivity minus respiration losses is the net primary productivity, i.e., NPP \(=\) GPP – R.
The biomass made available by producer for consumption by herbivores and the decomposers is called
(a) : The balance energy or biomass remaining after meeting the cost of respiration of producers, is called net primary productivity.
\(\qquad\)
is the rate of production of organic matter by consumers.
(b) : The rate at which food energy is assimilated at the trophic level of consumers is called secondary productivity. In other words, the rate of synthesis of organic matter by consumers is called as secondary productivity.
The rate of formation of new organic matter by rabbit in a grassland, is called
(b) : Since rabbit is a consumer therefore, the rate of formation of new organic matter by rabbit in a grassland is called secondary productivity.
Primary productivity depends upon
(d) : The primary productivity of an ecosystem is the rate at which biomass or organic matter is produced per unit area per unit time by plants (primary producers). Primary productivity depends upon plant species of the area, their photosynthetic capacity, availability of nutrients, solar radiations, precipitation, soil type and a number of other environmental factors.
The annual net primary productivity of the whole biosphere is approximately
(c) : The annual net primary productivity of the whole biosphere is approximately 170 billion tons. Out of this, oceans contribute 55 billion tons.
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The annual net primary productivity of the whole biosphere is approximately
(c): The annual net primary productivity of the whole biosphere is approximately 170 billion tons. Out of this, oceans contribute 55 billion tons.
Which one of the following exhibits least productivity?
(c) : In oceans, there are lots of nutrients but no sufficient sunlight is available in deep areas hence, oceans have least productivity. Grasslands are less productive ecosystem with annual productivity of \(200-1000 \mathrm{gm} / \mathrm{m}^2\). Maximum productivity can be seen in coral reefs followed by estuaries. Salty marshes are estuaries where brackish and salt water mix.
Which one of the following is the most productive ecosystem?
(d) :
Productivity at the second trophic level is always
(b) : Productivity at second trophic level is always less than productivity at first trophic level. This is because only \(10 \%\) of energy is transferred from one trophic level to another. Thus, decrease in energy would result in decrease in productivity.
Fragmentation, leaching and catabolism are some of the important steps of decomposition. Study the following statements [(i), (ii) and (iii)] regarding these and select the correct option.
(i) Detritivores (e.g., earthworm) breakdown detritus into smaller particles.
(ii) Water soluble inorganic nutrients go down into soil horizon and get precipitated as unavailable salts.
(iii) Decomposers (e.g., bacteria and fungi) secrete digestive enzymes and degrade detritus into simpler inorganic substances.
(c) : The process of decomposition can be categorised as fragmentation of detritus, leaching and catabolism. Fragmentation of detritus is the process that causes breakdown of detritus into smaller particles. It is primarily due to the action of detritus feeding invertebrates (detritivores, e.g., termites, earthworms, etc.). The detritus gets pulverised when passing through the digestive tracts of animals. Due to fragmentation, the surface area of detritus particles is greatly increased. The extracellular enzymes released by bacteria and fungi carry out catabolism, i.e., enzymatic conversion of the decomposing detritus to simpler and inorganic substances. Leaching is the process by which dissolved nutrients are moved into lower layers of soil or groundwater to form unavailable salts.
Read the given statements and select the correct option.
Statement 1 : Decomposition is the physical and chemical breakdown of complex organic matter into simple inorganic substances.
Statement 2 : Humification is the process of formation of humus from detritus or organic remains.
(a)
Match column I with column II and select the correct option from the given codes.
\(
\begin{array}{|l|l|l|l|}
\hline & \text { Column I } & & \text { Column II } \\
\hline \text { A. } & \begin{array}{l}
\text { Gross primary } \\
\text { productivity }
\end{array} & \text { (i) } & \text { Self-sustainable ecosystem } \\
\hline \text { B. } & \begin{array}{l}
\text { Net primary } \\
\text { productivity }
\end{array} & \text { (ii) } & \text { Terrestrial ecosystem } \\
\hline \text { C. } & \text { Pond } & \text { (iii) } & \text { O2 requiring process } \\
\hline \text { D. } & \text { Crop field } & \text { (iv) } & \text { Photosynthetic production } \\
\hline \text { E. } & \text { Decomposition } & \text { (v) } & \begin{array}{l}
\text { Available to secondary } \\
\text { consumers }
\end{array} \\
\hline
\end{array}
\)
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(b)
Which of the following is not a characteristic of humus?
(d) : Humus is dark brown amorphous gummy substance formed by partial decomposition of plant and animal matter. Process of formation of humus from raw organic remains is called humification. Nutrients are released slowly as the humus is decomposed slowly. Humus is further degraded by some microbes and release of inorganic nutrients occur by the process of mineralisation.
During the process of decomposition
(b) : Decomposition process is related to the breakdown of complex organic matter by decomposers to inorganic raw materials like carbon dioxide, water and various nutrients. Oxygen is required by aerobic bacteria for decomposition.
Rate of decomposition depends upon
(d) : Rate of decomposition of detritus depends upon chemical nature of detritus, temperature, soil moisture and soil pH . A soil temperature of \(25^{\circ} \mathrm{C}\) and more hastens decomposition. A low temperature of less than \(10^{\circ} \mathrm{C}\) reduces rate of decomposition. Moisture is essential for decomposition. Excessive moisture also impedes decomposition probably due to anaerobiosis. Neutral and slightly alkaline soils are rich in detritivores, earthworms and decomposer microbes.
Decomposers are also called as
(d) : Decomposers are also called as reducers because they are able to remove or degrade the dead bodies of organisms and due to their small size they are known as micro-consumers.
The ultimate energy source of all ecosystems is
(d)
Read the given statements and select the correct option.
Statement 1 : Herbivores are also called as first order consumers.
Statement 2 : Herbivores obtain their food directly from plants.
(a) : All animals depend on plants for their food needs directly or indirectly. Hence, they are called as consumer and also heterotrophs. If they feed on the producers i.e., the plants directly they are called as primary consumers or first order consumers. Primary consumers are herbivores.
Percentage of photosynthetically active radiation (PAR) in the incident solar radiation is
(a)
Percentage of photosynthetically active radiation (PAR) that is captured by plants in synthesis of organic matter is
(d)
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