4.2 Energy flow

Photoautotrophic

Use sunlight as a source of energy

chemoautotrophic

Derive energy from chemical processes

Trophic levels

The position an organism occupies within a feeding sequence

First trophic level is occupied by…

Producer

Food chains

Show the linear feeding relationships between species in a community

How is some energy lost in between trophic levels

* Respiration
* Heat
* Excretion

What is the chemical energy turned into and what kind of reactions are they

* Kinetic energy (e.g. during muscular contractions)
* Electrical energy (e.g. during the transmission of nerve impulses)
* Light energy (e.g. producing bioluminescence)

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All exothermic and therefore release heat

How efficient are energy transformations?

around 10%

Biomass

The total mass of a group of organisms - consisting of the carbon compounds contained in the cells and tissues.

Why are trophic levels limited?

Because energy and biomass is lost between each level of a food chain

Unit for energy at each trophic level

They are expressed in units of energy per area per time (e.g. kJ m–2 year–1)