Question

In the following food chain, grass provides 4000j of energy to the grasshopper. How much energy will be available to snakes and frogs?
Grass, Grasshopper, Frogs, Snakes

Answer 1

Hint: Food chain is defined as the sequence of organisms which depend on each other to obtain their food and nutrients. It is a series of organisms in which if one organism dies the whole chain will get disturbed as every organism is dependent on others to fulfil their nutrients.

Complete answer:
In a food chain The energy transfer takes place from one trophic level to another and only 10% energy is transferred. The law was proposed by Lindeman in 1942. The transfer of energy from one trophic level to another trophic level is accompanied by loss of energy at each level or step.
When the plants are eaten by herbivores, about 10% of energy in the food is fixed into animal flesh while 90% is consumed in ingestion, respiration, maintenance of body heat and other activities. Similarly, when a carnivore consumes that herbivore, again about 10% of energy is fixed. So, at each and adjacent trophic level the energy transfer only 10% of the total energy is actually available to the next trophic level. It is called 10% law.
So there are maximum 4-5 trophic levels in a food chain.
The trophic levels includes :-
(1) Producers : They are green photosynthetic plants that entrap solar energy through chlorophyll to synthesise organic food from inorganic raw materials. So, they are called autotrophs (self-nourishing).
Example- grass
(ii) Consumers : They are the animals that are not capable of synthesizing and preparing the food materials on their own. They are dependent on producers directly or indirectly for their survival by obtaining food from them. Thus, they are called heterotrophs.
Consumers are of following types:
> Primary Consumers (PC) or First Order Consumers : These animals directly feed on producers and obtain nutrition from them. They are also named as herbivores or main industry animals. (Convert plant matter into animal matter)
Example- grasshoppers
> Secondary Consumers (SC) or Second Order Consumers or Primary Carnivores : They are animals which feed on herbivores.
Example- frogs
> Tertiary Consumers (TC) or Third Order Consumers or Secondary Carnivores : Carnivores
which feed upon secondary consumers e.g., snake (terrestrial ecosystem). There may be quaternary or fourth order consumers which prey upon secondary carnivores.
As only 10% energy is transferred to the next trophic level so grass that has 4000 j of energy \[4000 \times 10\% \] will be transferred to grasshopper that is $400J$.
Now, \[400 \times 10\% \] energy will be transferred to the frog that is $40J$ and \[40 \times 10\% \] will be transferred to that of a snake that is $4J$.

The correct option is $4J$.

Note:
Food chain is the most defined system of living organisms. Ecology deals with and described with the study of interactions and interrelationships between organisms and their environment. It is a branch of science which includes the different areas of biological information and unites them in a single form thus, it gives the holistic perspective to biology.