(a) What is meant by the term Food chain?
(b) Draw a food chain involving four trophic levels which can be found in a terrestrial habitat.
(c) Explain
(i) the flow of energy through the food chain drawn in (b) above;
(ii) how energy in the chain is lost to the environment.
Explanation
Food chain: This is a linear feeding relationship; in which energy is transferred from producer/plants; through a series of organisms/trophic levels; in which each organism feeds on the preceding one; and provides food for the succeeding one in the habitat.
Terrestrial food chain: Terrestrial organism correctly named (TN) - Producer listed first correctly named primary consumer; secondary consumer; and tertiary consumer/decomposer; correct direction of arrows (CA)
(c)(i) Flow of energy: Energy flow is unidirectional/non-cyclic; it is either utilized; or stored. Light energy from the sun is absorbed by chlorophyll in green plants; and used in photosynthesis to produce carbohydrates; the chemical energy in the carbohydrate is passed down the food chain; when the primary consumers feed on the plants/producer; the chemical energy is passed along the food chain to the secondary consumer; and then to the tertiary consumer/decomposer.
(ii) Energy loss: - Energy is lost at each tropic level - when a herbivore/primary consumer feeds on a plant/producer; not all parts of the plant is eaten; as a result not all the energy in the plant/ producer is consumed; plants lose energy via respiration, do not utilize all the energy present in preceding members; energy is also lost in respiration; excretion, movement; and other metabolic activities.