Question

Which group of organisms are not constituents of a food chain?
(i) Grass, lion, rabbit, wolf
(ii) Plankton, man, fish, grasshopper
(iii) Wolf, grass, snake, tiger
(iv) Frog, snake, eagle, grass, grasshopper.
A. (i) and (ii)
B. (iii) and (iv)
C. (ii) and (iii)
D. (i) and (iv)

Answer 1

An ecosystem is the interaction between the biological communities with the abiotic physical environments. The biotic factors are the living organisms such as microorganisms, plants as well as the animals. The different components are connected with each other by different types of relations.

Complete step by step answer: In an ecosystem, the different factors or the components are related with one another which may be directly or indirectly. The plants are the organism that can manufacture food materials in the form of simple sugars. The plants produce the simple sugars from the raw materials such as carbon dioxide, water and minerals in the presence of light energy. The plants are the autotrophs or the producers.
The other animals cannot manufacture their own food but depends on other sources such as plants or animals, as their food and are known as the consumers. The animals that depend directly on the plants as food are known as herbivores and are first level consumers while some animals are dependent on the herbivores for food and are the carnivores or the second level consumers.
The different organisms are linked with one another in linear chains or sequences. Through these sequences, the energy and nutrients contained in the food is transferred from one organism to another and are known as food chains. In this process, the plants are eaten by the herbivores and in turn the herbivores are eaten by the carnivore animals.
In the first food chain, the grass is the producer and it is eaten by the rabbit which is herbivore or first level consumer. The rabbit is eaten by the wolf and the lion and both are carnivores or second level consumers. This type of food chain is found in the grassland ecosystem.
Similarly, in the fourth type of food chain, the grass is the producer and is eaten by the grasshoppers. The frogs feed on the grasshoppers and frogs are eaten by the snakes which are the second level of consumers. The snakes are fed on by the eagle which is an apex predator.
In the third type of food chain, the grass is produced but the snake, wolf and tiger are carnivore consumers and in this food chain, herbivores are not present and so it is not a suitable food chain.
The second food chain, the plankton are the producers and fishes are second level consumers but they do not exist in the terrestrial food chain. Whereas, the other organisms such as grasshoppers and man are of terrestrial food chain but the two cannot be linked in a food chain.
Therefore, the correct option is option C.

Note: The different organisms such as the plants and animals are related as well as dependent on one another. In a food chain, the organisms are related with one another in a linear sequence that reflects the feeding and food of the organism. In the grassland ecosystem, the grasses are producers and are eaten by grasshoppers and rabbits. Frogs eat the grasshoppers and rabbits and frogs are eaten by second level consumers.