Question

In an ecosystem, which of the following shows one-way passage?
(a) Free energy
(b) Carbon
(c) Nitrogen
(d) Potassium

Answer 1

Hint: This is the capacity associated with a chemical reaction that can be used to do work. The only natural source from which this is obtained is the sun.

Complete answer:
Free energy shows a one-way passage in an ecosystem that means the flow of energy is non-reversible. In an ecosystem, the amount of energy that flows from one trophic level to another trophic level is known as energy flow. The energy flows only in one direction i.e., from $Solar\quad radiation\rightarrow Producers\rightarrow Primary\quad consumers\rightarrow Secondary\quad consumers\rightarrow Tertiary\quad consumers\rightarrow Decomposers$. This energy cannot be passed back or passed in the reverse direction, thus it is said that energy flow is the unidirectional or one-way passage.
-The sunlight is the only natural source of energy on this Earth. In an ecosystem, the free energy flows through different trophic levels such as producers, primary consumers, secondary consumers, sometimes tertiary consumers, and decomposers.
-From the sun the energy is obtained by plants or producers through the process of photosynthesis. -By consuming producers or using them as a source of food this energy is obtained by the herbivores or primary consumers.
-Now, by using primary consumers or herbivores as a source of food the energy is obtained by the secondary consumers or carnivores. Similarly, the free energy is obtained by tertiary consumers as well as the decomposers from the members of the previous trophic level by using them as a source of energy.
-At each successive trophic level the energy present is ${ 10 }$ % of the previous trophic level. This shows a decrease in the content and flow of energy with rising in trophic level because some energy is lost at every trophic level in the form of heat.

So, the correct answer is, 'Free energy.'

Note:
-The free energy from the sun flows only in one direction i.e., from the sun it flows to producers then from producers it flows to the primary consumers to secondary consumers then to tertiary consumers, and finally to the decomposers.
-From the sun the energy is obtained by plants or producers through the process of photosynthesis.
-The energy that remains present at each successive trophic level is only ${ 10 }$% of the previous trophic level. This shows that with rising trophic levels, a decrease in the content and flow of energy occurs because of the loss of energy in the form of heat at every trophic level.