Read the following and answer any 4 questions from 20 (i) to 20 (v).
Define, state and draw the following
4
20 (i) Define Biomagnification
20 (ii) Define Food Web
20 (iii) What are Tropic levels?
20 (iv) Draw an Energy Pyramid showing different tropic levels.
Answers
Answer:
Explanation:
Biomagnification refers to the accumulation of toxic substances in the food chain. ... The pesticides and chemicals such as DDT, and mercury released into the lakes and rivers are ingested by the aquatic organisms. These get accumulated in their body tissues and are transferred to other organisms that feed on them.
Food web is a network of food chains where all the chains are naturally interconnected. ... Flow of energy in a food chain is unidirectional, once it reaches the next tropic level it does not come back again. For example- energy which passes to the herbivores does not come back again to autotrophs.
A trophic level is the group of organisms within an ecosystem which occupy the same level in a food chain. The second trophic level consists of herbivores, these organisms gain energy by eating primary producers and are called primary consumers. ...
A pyramid of energy represents how much energy, initially from the sun, is retained or stored in the form of new biomass at each trophic level in an ecosystem. Typically, about 10% of the energy is transferred from one trophic level to the next, thus preventing a large number of trophic levels.