Lesson 28 trophic relationships

Trophic relationships

1. Trophic relationships Trophic chains and webs Lesson #28

2. Organic matter Living organisms are made up of organic matter . Organic compounds are made up of carbon . Methane is the simplest form CH 4 . Living organisms are made up of larger organic molecules ( biomolecules ) such as: proteins , carbohydrates , nucleic acids , lipids …etc… They therefore need organic matter to grow and to obtain energy . Some living organism make organic matter out of inorganic matter .

3. Trophic relationships Living organisms relate to obtain the matter and energy necessary for their nutrition . Organisms in an ecosystem are organized according to how they obtain their matter and energy in: Producers : autotrophic organisms . They produce organic matter out of inorganic matter . Consumers : heterotrophic organisms which feed on living organic matter . Primary consumers ; Hervibores Secondary consumers Terciary or final consumers Scavengers : considered as a type of carnivore that consumes dead animals . They are the beginning of the decomposition of this non-living organic matter . Detritivores / Decomposers : heterotrophic organism which feed on detritus/ debris (non-living organic matter ) and break it down . Decomposition : when organic matter is broken down into smaller or simpler forms of matter .

4. Trophic chain and webs Organisms are chained together according “ eating and being eaten ” The arrow means “ eaten by ” The chain advances through TROPHIC LEVELS An organism can be part of different trophic levels at the same time. Producers are alway on the 1st level . Consumers can be part of any trophic level except the 1st level .

5. Trophic / Food chain

6. Trophic / food web

7. Cycle of matter http://textbookofbacteriology.net/themicrobialworld/environmental.html

8. Food web: Excercise Group the organisms in columns according to the trophic level they belong to. When do we say that an organism can belong to more than one trophic level ? Is there an example in this food web? Which trophic level do mushroom belong to?

9. Excercise In a crop field , the roots serve as food supply for the crickets , and the larvae of insects . The shrew eat larvae and crickets and are the prey of foxes and buzzards . Make three different trophic chains in this crop field . Make the food web.