Trophic relationshipsTrophic chains and webs

Lesson #28

Organic matter

• Living organisms are made up of organic matter.

• Organic compounds are made up of carbon. Methane is the simplest form CH4. 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.

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 thebeginning 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.

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 exceptthe 1st level.

Trophic/ Food chain

Trophic/food web

Cycle of matter

http://textbookofbacteriology.net/themicrobialworld/environmental.html

Food web: Excercise

1. Group the organisms in columns according to thetrophic level they belong to.

a) When do we say that anorganism can belong to more than one trophic level? Isthere an example in this foodweb?

b) Which trophic level do mushroom belong to?

Excercise

2. 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.

a) Make three different trophic chains in this crop field.

b) Make the food web.