B7.4 Trophic levels in an ecosystem Flashcards
What is a trophic level?
The position a species occupies in a food chain.
Name two organisms found in trophic level 1 (the lowest level).
Plants and algae.
What is the group name for organisms which are found in in trophic level 1?
Producers.
Name the group of organisms found in trophic level 2.
Herbivores or primary consumers
Name the group of organisms found in trophic level 3.
Carnivores that eat herbivores or secondary consumers.
What is the group name for carnivores with no predators?
Apex predators.
Which group of organisms break down dead plant and animal matter?
Decomposers (microorganisms).
How do they break down the plant & animal matter?
By secreting enzymes into the environment.
What do pyramids of biomass represent?
The relative amount of biomass in each level of a food chain.
In a pyramid of biomass, where would trophic level 1 be placed?
At the bottom.
Approximately how much light energy that falls on Earth is absorbed by plants and algae?
1%
Approximately how much energy is transferred between a trophic level and the level above it?
10%
State two reasons for the loss of biomass through a food web.
“1. Not all the ingested material is absorbed, some is egested as faeces
2. Some absorbed material is lost as waste, such as carbon dioxide and water in respiration and water and urea in urine”
In a hypothetical food chain, the producers contain 500kJ of biomass. The primary consumers contain 435kJ of biomass. What is the percentage of energy transferred from producers to primary consumers?
(500 – 435) / 500 *100 = 13%
In the same food chain, the secondary consumers contain 326.25kJ of biomass. What fraction of the biomass was lost between the two levels?
“435 – 326.25 = 108.75
108.75/435 = 0.25 = 1/4”
