BIOL116 Lecture #19 (11/17/25) *food webs*

Trophic levels describe feeding positions of ___

groups of organisms in ecosystems

Trophic efficiency

The amount of energy transferred from one trophic level to the next

Changes in the abundance of organisms at one trophic level can influence energy flow at __ levels

multiple

Food chains are __

unrealistic (not linear transfer of matter and energy)

Food webs are __

realistic

Food web

diagram showing multiple trophic connection among organisms

What is feeding position/trophic level based on?

The number of feeding steps by which an animal is separated from autotrophs

Herbivore is also known as __ consumer

primary

Primary carnivores are also known as ___ consumes

secondary consumers

Secondary carnivores are also known as ___

tertiary consumers

Trophic efficiency

The amount of energy transferred from one trophic level to the next one.

10% rule

amount of energy at one trophic level divided by amount of energy at the trophic level below it. (Typically 10% or 0.1)

Available energy ___ with each trophic level.

deceases (kilocalories, calories, kilojoules, or even biomass)

Q

E) Both C and D

If we follow the 10% rule, producing 1g of primary consumer biomass requires ___g of producers

10g

Trophic pyramid portrays __

relative amounts of energy or biomass in each trophic level

Consumption efficiency is

the proportion of the available biomass that is ingested by consumers

Detritus

biomass that is not ingested or assimilated enters the pool of detritus

Assimilating efficiency

the proportion of biomass that consumers assimilate by digestion.

Production efficiency

the proportion of assimilated biomass used to produce new consumer biomass.

Trophic cascade

• changes in the abundances of organisms or rate of consumption at one trophic level can influence factors at the lower trophic levels

the impact of the top predator on the lower trophic levels

What are the factors that can be effected in the trophic cascade?

• energy flow

• composition

• abundance

• (ALL AT LOWER TROPHIC LEVELS)