23.2 biomass transfer

What is biomass

The mass of living material in a particular place

What is a trophic level

Each step in a food chain

What is the first trophic level

producers

What are producers

Autotrophic Organisms that convert light energy into chemical energy through photosynthesis

What are consumers

Organisms that obtain their energy by consuming other organisms

What is the second trophic level

primary consumers (herbivores)

What are all the trophic levels

-producer
-primary consumer
-secondary consumer
-tertiary consumer
-Quaternary consumer

Why do food chains not usually have more than 5 trophic levels

There is not enough biomass/stored energy left to support any further organisms

What are decomposers

What are decomposers

Where are producers placed on a food chain pyramid

At the bottom, with all subsequent trophic levels added above

What can biomass be equated to

energy content

How to calculate biomass at each trophic level

biomass present in each organism x total number of organisms in that trophic level

Why is calculating biomass unreliable

Water content must be discounted and the presence of varying amounts of water in organisms makes the technique unreliable

What is biomass measured in on land and on water

landGrams per square metre (g/m²)

water grams per cube meter

Why is the biomass in each trophic level less than the previous level (3)

-Not all parts of the organism are eaten e.g. bones left behind
-Not all ingested material is absorbed, some is egested as faeces

-some energy is given off as metabolic heat from respiration (radiation)

What is energy available at each trophic level measured in

kilojoules per metre squared per year (KJ/m²/yr)

What is ecological efficiency

he efficiency with which biomass or energy is transferred from one trophic level to the next

Why do producers convert so little sunlight energy into chemical energy (3)

-not all of the solar energy available is used for photosynthesis (lots reflected)
-other factors may limit photosynthesis (e.g. temperature)
-a proportion of energy is 'lost' as it is used for photosynthetic reactions

What is gross production

total solar energy that plants convert to organic matter

What is net production

Energy available to the next trophic level

Net production formula

gross production- respiratory losses

Ecological efficiency formula

(energy or biomass available after the transfer / energy or biomass available before the transfer) x 100

why can animals within the same trophic level have different biomasses?

eat more digestible

ora mainly protein and fat ;

contains no cellulose

-depends on the metabolism of the animal, more active animals respire more

-animals that survive harsher conditions may have more storage molecules, as environment may not provide them with the opportunity to gain nutrients through food or water