Question

The energy flows from the autotrophs to heterotrophs.
A. True
B. False

Answer 1

Hint: A food chain may be a sequence of living organisms that involves the transfer of energy from producers through many steps of different organisms with repeated eating and being eaten. Each level or step that helps to make a food chain where the transfer of energy takes place is called a trophic level.

Complete answer: All living organisms i.e., plants, animals and microorganisms that are present in the environment constitute the biotic components of the ecosystem. On the ability of their role in the ecosystem, these can be made to exist into three main groups:
(i) Producers: They are green photosynthetic plants that entrap solar energy through chlorophyll to synthesize organic food from inorganic raw materials. So, they are called autotrophs (self-nourishing).
In an aquatic ecosystem, chief producers are phytoplankton, algae and the floating, submerged and marginal plants found at the edges.
(ii) Consumers: They are animals that are not in the state of synthesizing food materials. They are dependent and reliable on producers directly or indirectly for their survival. Thus, they are called heterotrophs. Consumers are of the following types:
a) Primary Consumers (PC) or first-order consumers: These animals are directly dependent on producers for obtaining food. They are also called herbivores. In an aquatic ecosystem, common herbivores are molluscs, tadpole and mosquito larvae.
b) Secondary Consumers (SC) or primary carnivores: These are animals that feed on herbivores.
In an aquatic ecosystem Hydra, frog, and zooplanktons constitute the secondary consumers.
c) Tertiary Consumers (TC) or secondary carnivores: Carnivores are organisms that feed and eat upon secondary consumers, e.g., large fishes (aquatic ecosystem), snake (terrestrial ecosystem). There may be quaternary or fourth-order consumers that act as predators of secondary carnivores.
The energy transfer takes place from one trophic level to another, and only 10% of energy is transferred. The law was proposed by Lindeman in 1942.
Hence, the correct answer is option B.

Note: When the plants are eaten by the herbivore, 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.