Define the following : (i) Food chain, (ii) Trophic level,

 (i) Food chain: A succession of organisms in an ecological community that constitutes a continuation of food energy from one organism to another as each consumer is a lower member and in turn is preyed upon by a higher member is called a food chain.

(ii) Trophic level: Each step or level of the food chain is called trophic level.

(iii) Producers: Producers are organisms like plants and blue-green algae that produce complex organic compound from simple inorganic molecules using energy from sunlight in presence of chlorophyll.

(iv) Parasites: An organism that lives on or in another organism, obtain nourishment and protection while offering no benefit in return is called a parasite.

(v) Non-biodegradable substance are substances that cannot be broken down by biological processes.