Energy Flow Questions in English

(A) The energy for the detritus food chain is derived from organic remains,also known as detritus. In terrestrial ecosystems,a much larger fraction of energy flows through the detritus food chain compared to the grazing food chain. Detritus consists of dead plant parts and animal remains,which serve as the primary energy source for decomposers and detritivores.

(C) The ultimate source of energy for all living organisms in an ecosystem is sunlight.
Solar energy is captured by producers (plants) through photosynthesis and converted into chemical energy.
This energy then flows through various trophic levels in the ecosystem.
Therefore,solar energy acts as the primary driving force for the functioning of any ecosystem.

(D) Tiger is the top consumer in a food chain.
It can feed upon lower carnivores as well as herbivores.
Herbivores are dependent upon producers ($i.e.$, green plants) for their food.
Thus, indirectly, the tiger is also linked with trees ($i.e.$, primary producers) because the energy flow originates from the producers and passes through the herbivores to the top carnivore.

(A) According to the ecological efficiency,green plants (producers) trap only about $1 \; \%$ of the solar energy incident on them.
Given solar energy = $2000 \; J$.
Energy trapped by producers $(A)$ = $1 \; \%$ of $2000 \; J = (1/100) \times 2000 = 20 \; J$.
According to Lindeman's $10 \; \%$ law,only $10 \; \%$ of the energy is transferred to the next trophic level.
Energy transferred to herbivores $(B)$ = $10 \; \%$ of $A = 10 \; \%$ of $20 \; J = 2 \; J$.
Energy transferred to carnivores $(C)$ = $10 \; \%$ of $B = 10 \; \%$ of $2 \; J = 0.2 \; J$.
Thus,$A = 20 \; J, B = 2 \; J, C = 0.2 \; J$.

(D) According to the $10 \%$ law of energy transfer,only about $10 \%$ of the energy available at one trophic level is transferred to the next trophic level. The majority of the energy (about $90 \%$) is consumed by the organism for its own metabolic activities such as respiration,movement,growth,and maintenance of body heat,and is lost as heat to the environment.

(B) According to the $10\%$ law of energy transfer,only $10\%$ of the energy is transferred from one trophic level to the next.
First,the producers $(T_1)$ capture about $1\%$ of the total solar energy falling on the land. Thus,energy at $T_1 = 1\% \text{ of } 10,000 \; J = 100 \; J$.
Next,the energy transferred to the primary consumers $(T_2)$ is $10\%$ of the energy at $T_1$.
Therefore,energy at $T_2 = 10\% \text{ of } 100 \; J = 10 \; J$.

(C) In terrestrial ecosystems,the major conduit for energy flow is the $DFC$ $(Detritus Food Chain)$,where a much larger fraction of energy flows through the detritus pathway compared to the grazing pathway.
In aquatic ecosystems,the major conduit for energy flow is the $GFC$ $(Grazing Food Chain)$,as the primary producers are mostly phytoplankton which are consumed by zooplankton and higher trophic levels.

(B) In a tropical rain forest ecosystem,the majority of the energy flow occurs through the detritus food chain. This is because a large amount of organic matter (litter) is produced,which is decomposed by microorganisms and detritivores,forming the basis of the energy pathway.

(B) Energy requirement for the maintenance of the body increases with successively higher trophic levels. As we move up the food chain,organisms at higher trophic levels require more energy to maintain their metabolic processes and body functions relative to the energy available to them.

(B) The grazing food chain $(GFC)$ begins with producers (green plants) that capture solar energy. Through the process of photosynthesis,these producers convert inorganic nutrients (like $CO_2$,$H_2O$,and minerals) into organic matter (biomass). This organic matter then serves as the energy source for consumers in the food chain.

(C) In an ecosystem,energy flow is unidirectional,meaning it moves from producers to consumers and cannot be recycled back to the producers. Therefore,the statement that energy flow is cyclic is incorrect. The pyramid of energy is always upright because energy is lost as heat at each trophic level. Ecological efficiency,which refers to the percentage of energy transferred from one trophic level to the next,is generally considered to be $10\%$ (Lindeman's $10\%$ Law).

(D) Energy transfer in an ecosystem occurs through the food chain,where organisms at one trophic level consume organisms from the lower trophic level.
This interaction,where one organism (the predator) kills and eats another organism (the prey) to obtain energy,is known as $Predation$.
$Predation$ acts as a conduit for energy transfer across trophic levels.

(B) In an ecosystem, energy flow is always $Unidirectional$.
$1$. Energy enters the ecosystem from the sun in the form of solar radiation.
$2$. Producers (plants) convert this solar energy into chemical energy through photosynthesis.
$3$. This energy is then transferred to consumers (herbivores, carnivores, etc.) through food chains.
$4$. At each trophic level, a significant portion of energy is lost as heat, according to the $10\%$ law of energy transfer.
$5$. Because energy cannot be recycled back to the sun or to previous trophic levels, the flow is strictly one-way or unidirectional.

(A) Photosynthetically active radiation $(PAR)$ is the portion of the light spectrum that plants can use for photosynthesis.
Plants are not able to capture all the available solar energy.
It is a well-established ecological fact that plants capture only about $2-10 \%$ of the $PAR$ to perform photosynthesis and produce organic matter.
Therefore,the correct option is $A$.

(B) The statement refers to the $2^{nd}$ law of thermodynamics.
According to the $2^{nd}$ law of thermodynamics, energy transfer is never $100\%$ efficient, and some energy is always dissipated as heat, leading to an increase in the entropy of the system.
In ecological systems, this is reflected in the $10\%$ law of energy transfer, where only about $10\%$ of the energy is transferred to the next trophic level, while the rest is lost as heat during metabolic processes.

(B) According to the $10\%$ Law of Lindeman,only $10\%$ of the energy available at one trophic level is transferred to the next higher trophic level.
$1$. Producers (Plants): $1000\,J$.
$2$. Primary Consumers (Herbivores): $10\%$ of $1000\,J = 100\,J$.
$3$. Secondary Consumers (Carnivores,e.g.,a lion eating a herbivore): $10\%$ of $100\,J = 10\,J$.
Therefore,the energy reaching the lion's trophic level is $10\,J$.

(D) According to the $10\%$ law of energy transfer in an ecosystem,only about $10\%$ of the energy available at one trophic level is transferred to the next higher trophic level.
As energy moves from producers $(P)$ to primary consumers $(Q)$,secondary consumers $(R)$,and finally to tertiary consumers $(S)$,a significant amount of energy is lost as heat at each step.
Therefore,the energy available decreases as we move up the food chain.
In the given food chain,$S$ represents the highest trophic level (tertiary consumer),and thus it will have the lowest amount of energy available.

(B) According to Lindeman's $10 \%$ law,only $10 \%$ of the energy is transferred from one trophic level to the next.
The $NPP$ of the first trophic level acts as the $GPP$ for the second trophic level.
Therefore,the $GPP$ of the second trophic level is $100x \text{ kcal } m^{-2} yr^{-1}$.
Assuming the energy transfer efficiency is $10 \%$,the $NPP$ of the second trophic level is $100x \times 10 \% = 10x \text{ kcal } m^{-2} yr^{-1}$.
This $NPP$ of the second trophic level acts as the $GPP$ for the third trophic level.
Thus,the $GPP$ of the third trophic level is $10x \text{ kcal } m^{-2} yr^{-1}$.

(A) According to the $10\%$ law of energy transfer in an ecosystem,energy decreases as it moves from one trophic level to the next higher trophic level.
Producers (Grass) occupy the first trophic level and possess the maximum amount of energy.
As energy flows from producers to primary consumers (Rabbit),then to secondary consumers (Wolf),and finally to tertiary consumers (Lion),a significant portion of energy is lost as heat at each step.
Therefore,the organism at the base of the food chain,which is the Grass,contains the maximum energy.

(A) In an aquatic ecosystem, the $Grazing$ $food$ $chain$ $(GFC)$ is the major conduit for energy flow.
This is because the primary producers in aquatic ecosystems are $phytoplankton$, which are consumed by $zooplankton$ and small fish.
In contrast, in a terrestrial ecosystem, the $Detritus$ $food$ $chain$ $(DFC)$ is the major conduit for energy flow because a much larger fraction of energy flows through the $detritus$ pathway compared to the $GFC$.

(D) food chain represents the sequence of transfer of energy from producers to consumers.
$1$. The producer is the organism that synthesizes its own food,which in this case is Grass.
$2$. The primary consumer feeds on the producer,which is the Grasshopper.
$3$. The secondary consumer feeds on the primary consumer,which is the Frog.
$4$. The tertiary consumer feeds on the secondary consumer,which is the Snake.
$5$. The apex predator or quaternary consumer is the Eagle.
Therefore,the correct sequence is: Grass $\longrightarrow$ Grasshopper $\longrightarrow$ Frog $\longrightarrow$ Snake $\longrightarrow$ Eagle.

(C) The second law of thermodynamics states that energy transfer is never $100\%$ efficient,as some energy is always lost as heat. Ecosystems follow this law because energy is lost at each trophic level during transfer.
Therefore,the Assertion is true.
In a food chain,energy flow is always unidirectional (from producers to consumers). It never flows in the reverse direction.
Therefore,the Reason is false.

(C) The Sun is the ultimate and primary source of energy for almost all ecosystems on Earth.
Photosynthesis,performed by producers (plants,algae,and cyanobacteria),converts solar energy into chemical energy,which then flows through the food chain.
Deep-sea hydrothermal ecosystems are the exception,as they rely on chemosynthesis,where organisms derive energy from chemical reactions involving inorganic substances like hydrogen sulfide,rather than sunlight.

(C) In an ecosystem,nutrients like water,carbon,and nitrogen undergo biogeochemical cycles,meaning they are continuously recycled between the biotic and abiotic components.
However,energy flow in an ecosystem is unidirectional (non-cyclic).
Energy enters the ecosystem from the sun,is converted into chemical energy by producers,and then flows through various trophic levels.
At each transfer,a significant portion of energy is lost as heat,which cannot be reused by organisms. Therefore,energy is not recycled.

(C) According to the $10\%$ law of energy transfer in an ecosystem,only $10\%$ of the energy available at one trophic level is transferred to the next trophic level.
$1$. The first trophic level (producers/plants) receives $10000 \ J$ of energy.
$2$. The second trophic level (primary consumers) receives $10\%$ of $10000 \ J$,which is $1000 \ J$.
$3$. The third trophic level (secondary consumers) receives $10\%$ of $1000 \ J$,which is $100 \ J$.
Therefore,the energy available at the third trophic level is $100 \ J$.

$(D)$ Statement $I$ is incorrect because the amount of energy available decreases at each successive trophic level due to energy loss as heat during metabolic processes and respiration.
Statement $II$ is correct because according to the $10\%$ law (Lindeman's law), only about $10\%$ of the energy is transferred from one trophic level to the next, while the rest is lost.
Therefore, Statement $I$ is incorrect and Statement $II$ is correct.

(B) According to the $10\%$ law of energy transfer proposed by Lindeman, only about $10\%$ of the energy available at one trophic level is transferred to the next trophic level. The remaining $90\%$ of the energy is lost as heat during metabolic processes or remains in the form of chemical energy in the biomass that is not consumed. Due to this significant loss of energy at each step, the number of trophic levels in a grazing food chain is typically limited to $4$ or $5$.

(C) According to the $10\%$ Law of energy transfer in an ecosystem,only about $10\%$ of the energy available at one trophic level is transferred to the next trophic level.
$1$. Primary Producers: $100 \ J$
$2$. Primary Consumers (First trophic level to second): $10\%$ of $100 \ J = 10 \ J$
$3$. Secondary Consumers (Second trophic level to third): $10\%$ of $10 \ J = 1 \ J$
Therefore,the secondary consumer receives $1 \ J$ of energy.

(D) The incorrect statement is $D$.
Green plants capture only about $1\%$ of the solar energy that falls on their leaves.
This energy is used in the process of photosynthesis to convert light energy into chemical energy,which is then stored as food.
The other statements $(A, B, C)$ are correct: energy is lost as heat at each trophic level,energy transfer follows the $10\%$ law,and energy flow in an ecosystem is always unidirectional.

(B) The correct answer is $B$.
Photosynthetically active radiation $(PAR)$ consists of light with wavelengths between $400 \ nm$ and $700 \ nm$,which is the specific portion of the light spectrum utilized by plants for photosynthesis.
Out of the total incident solar radiation reaching the Earth,less than $50\%$ constitutes $PAR$.
Plants are only able to capture and utilize approximately $2-10\%$ of this $PAR$ for the process of photosynthesis.

(B) The correct answer is $(B)$ $0.03 \ J$.
According to the $10 \%$ law proposed by Lindeman $(1942)$,only $10 \%$ of the energy available at one trophic level is transferred to the next trophic level.
In the given food chain: Plant $\rightarrow$ Mice $\rightarrow$ Snake $\rightarrow$ Peacock.
$1$. Energy at producer level (Plant) = $30 \ J$.
$2$. Energy available to primary consumer (Mice) = $10 \%$ of $30 \ J = 3 \ J$.
$3$. Energy available to secondary consumer (Snake) = $10 \%$ of $3 \ J = 0.3 \ J$.
$4$. Energy available to tertiary consumer (Peacock) = $10 \%$ of $0.3 \ J = 0.03 \ J$.
Therefore,the peacock receives $0.03 \ J$ of energy.

(A) According to the $10\%$ law of energy transfer in ecosystems,only about $10\%$ of the energy is transferred from one trophic level to the next.
Step $1$: Energy at the producer level = $1000 \ J$.
Step $2$: Energy at the primary consumer level = $10\%$ of $1000 \ J = 100 \ J$.
Step $3$: Energy at the secondary consumer level = $10\%$ of $100 \ J = 10 \ J$.
Therefore,the energy available at the secondary consumer level is $10 \ J$.