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In an ecosystem if the Net Primary Productivity (NPP) of first trophic level is \(100 x\left(\mathrm{kcal} \mathrm{m}^{-2}\right) \mathrm{yr}^{-1}\), what would be the GPP (Gross Primary Productivity) of the third trophic level of the same ecosystem? [NEET 2024]
Answer (3)
Sol. 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, \(100 \times\left(\mathrm{kcal} / \mathrm{m}^2 / \mathrm{yr}\right)\) would be GPP at second trophic level and \(100 x \times 10 \%\left(\mathrm{kcal} / \mathrm{m}^2 / \mathrm{yr}\right)\) i.e., \(10 x\left(\mathrm{kcal} / \mathrm{m}^2 / \mathrm{yr}\right)\) energy would be GPP at third trophic level.
Match List I with List II.
List I
A. Logistic growth
B. Exponential growth
C. Expanding age pyramid
D. Stable age pyramid
List II
I. Unlimited resource availability condition
II. Limited resource availability condition
III. The percent individuals of pre-reproductive age is largest followed by reproductive and post reproductive age groups
IV. The percent individuals of pre-reproductives and reproductive age group are same
Choose the correct answer from the options given below: [NEET 2023]
Answer (1)
Logistic growth occurs when there is limited resource availability condition.
Exponential growth occurs when there is unlimited resource availability condition.
Expanding age pyramid reflects growing population where the percent individuals of pre-reproductive age is largest followed by reproductive and post-reproductive age groups.
Stable age pyramid shows stable population where the percent individuals of pre-reproductive and reproductive age group are same.
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:[NEET 2022]
Answer (3)
Sol. Decomposition is the process by which decomposers breakdown complex organic matter into inorganic substances.
The rate of decomposition is controlled by chemical composition of detritus and climatic factors. Decomposition is slower if detritus is rich in lignin and chitin and quicker, if detritus is rich in nitrogen and water soluble substances like sugars.
The mass of living material at a trophic level at a particular time is called (2015 Cancelled)
(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.
Vertical distribution of different species occupying different levels in a biotic community is known as
(2015 Cancelled)
(d)
In an ecosystem the rate of production of organic matter during photosynthesis is termed as
(2015 Cancelled)
(d) :The amount of energy accumulation in green plants as biomass or organic matter per unit area over a time period is known as primary productivity. The rate of total capture of energy, or the rate of total production of organic material (biomass), is known as gross primary productivity..
Secondary productivity is rate of formation of new organic matter by (NEET 2013)
(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.
Identify the possible link “A” in the following food chain.
Plant \(\rightarrow\) Insect \(\rightarrow\) Frog \(\rightarrow\) “A” \(\rightarrow\) Eagle
(NEET 2012)
(c)
Which one of the following is not a functional unit of an ecosystem? (NEET 2012)
(d) :Four important functional aspects of the ecosystem are productivity, decomposition, energy flow and nutrient cycling.
The upright pyramid of number is absent in (NEET 2012)
(b) :In forests, a single tree can support a large number of birds thus base showing producers in a pyramid of number will be narrower than the next slab showing primary consumers. Hence an upright pyramid of number is not formed in a forest ecosystem.
The rate of formation of new organic matter by rabbit in a grassland, is called (NEET 2012)
(b) :The rate of resynthesis of organic matter by consumers or the rate at which food energy is assimilated at the trophic level of consumers is called secondary productivity. In a grassland ecosystem, the rate of formation of new organic matter by rabbit is referred as secondary productivity.
Mass of living matter at a trophic level in an area at any time is called (NEET 2011)
(a) : 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.
Of the total incident solar radiation the proportion of PAR is (NEET 2011)
(c) :The source of energy in all ecosystem is solar energy. About \(50 \%\) of the solar energy incident over earth is present in PAR (Photosynthetically active radiation). About \(1-5 \%\) of incident solar radiation or \(2-10 \%\) of PAR is captured by the photosynthetic organisms in the synthesis of organic matter (gross primary productivity). Roughly \(20 \%\) of it is consumed in respiration so that net capture of energy (net primary productivity) is \(0.8-4 \%\) of incident radiation or \(1.6-8 \%\) of PAR.
Which one of the following animals may occupy more than one trophic levels in the same ecosystem at the same time?
(Mains 2011)
(a) :Sparrow can be herbivorous (eating seeds and fruits) or carnivorous (eating insects).
The breakdown of detritus into smaller particles by earthworm is a process called (Mains 2011)
(b) : 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, watersoluble 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.
The biomass available for consumption by the herbivores and the decomposers is called (NEET 2010)
(a):The total organic matter synthesised by the producers in the process of photosynthesis per unit time and area is known as gross primary productivity. Net primary productivity is equal to the rate of organic matter created by photosynthesis minus the rate of respiration and other losses. It is actually the biomass available for consumption by the herbivores and the decomposers.
Consider the following statements concerning food chains.
A. Removal of \(80 \%\) tigers from an area resulted in greatly increased growth of vegetation.
B. Removal of most of the carnivores resulted in an increased population of deers.
C. The length of food chains is generally limited to 3-4 trophic levels due to energy loss.
D. The length of food chains may vary from 2 to 8 trophic levels.
Which two of the above statements are correct? (NEET 2008)
(c): Removal of \(80 \%\) tigers (i.e., tertiary consumer) from an area resulted in decreased growth of vegetation because there will be increased numbers of secondary or primary consumers which feeds on green plant. Removal of most of the carnivores resulted in an increased population of deers on which carnivores depends. The length of food chain is generally limited to 3-4 trophic level due to energy loss because all the food available at one level is neither eaten nor used by animals at the next level and a lot of the energy is lost in respiration to drive the organisms metabolism so less energy is left to support higher trophic level.
The slow rate of decomposition of fallen logs in nature is due to their (NEET 2008)
(d) : Decomposition is largely an oxygenrequiring process. The rate of decomposition is controlled by chemical composition of detritus and climatic factors. In a particular climatic condition, decomposition rate is slower if detritus is rich in lignin and chitin, and quicker, if detritus is rich in nitrogen and water-soluble substances like sugar. Temperature and soil moisture are the most important climatic factors that regulate decomposition through their effects on the activities of soil microbes. Warm and moist environment favour decomposition whereas low temperature and anaerobiosis inhibit decomposition resulting in build up of organic materials.
Which one of the following is not used for construction of ecological pyramids? (NEET 2006)
(a) : Ecological pyramids represents the trophic structure and trophic function of an ecosystem. In an ecological pyramid, the first trophic level forms the base and successive trophic levels the tiers which make up the apex. Ecological pyramids may be of three general types pyramid of number, pyramid of biomass and pyramid of energy. Pyramid of biomass i.e. the living weight of the organisms of the food chain present at any time in an ecosystem forms the pyramids of biomass. The pyramid of biomass indicates the decrease or the gradual reduction in biomass at each trophic levels from base to apex. Fresh weight is not used in ecological pyramids.
Which of the following is expected to have the highest value ( \(\mathrm{gm} / \mathrm{m}^2 / \mathrm{yr}\) ) in a grassland ecosystem?
(NEET 2004)
(c) : Productivity is rate of accumulation of energy containing organic matter by an ecosystem per unit area per unit time. It is of two types- primary and secondary.
Productivity at producers level is known as primary productivity. It is two types: Gross primary productivity is primary productivity including that amount which is utilized in respiration and other metabolic activities. Net primary productivity (NPP) is primary productivity in excess to that which is utilised in respiration and other metabolic activities.
Bamboo plant is growing in a fir forest then what will be the trophic level of it? (NEET 2002)
(a): Trophic structure of ecosystem is a type of producer-consumer arrangement, in which each food level is called trophic level and the graphical representation of trophic structure of ecosystem constitutes ecological pyramids. The green plants are producers and represent the first trophic level \(\left(\mathrm{T}_1\right)\). So bamboo plant is the first trophic level \(\left(\mathrm{T}_1\right)\).
Plant decomposers are (NEET 2001)
(a) : Microorganisms (bacteria and fungi) are decomposers of the ecosystem. They feed upon dead decaying living organisms (both plant and animals) and break them into simpler compounds. These are released free in the atmosphere and are utilized by producers for the synthesis of their food materials. They mainly belong to monera and fungi.
The \(10 \%\) energy transfer law of food chain was given by (AIPMT 1996)
(a) : Herbivores are eaten by primary carnivores. Only \(10 \%\) of the herbivores productivity is utilized for raising productivity of primary carnivores. The rest is consumed in ingestion, respiration, maintenance of body heat and other activities. Higher carnivores similarly are able to retain only \(10 \%\) of energy present in primary carnivores. It is called \(10 \%\) law which was proposed by Lindemann. Accordingly, if plant trapped \(20 \mathrm{~J}\) of energy, mice will have \(2 \mathrm{~J}\), snake will have \(0.2 \mathrm{~J}\) and hence, peacock will have \(0.02 \mathrm{~J}\) of energy.
If we completely remove the decomposers from an ecosystem, its functioning will be adversely affected, because
(AIPMT 1995)
(a) : Decomposers are saprotrophs which decompose the organic remains by secreting extracellular digestive enzymes. They are also known as mineralisers as they release minerals trapped in organic remains. So in the absence of microorganisms the flow of minerals will stop.
In a biotic community, the primary consumers are (AIPMT 1995)
(b)
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