B5 -PYRAMIDS OF BIOMASS & EFFICIENCY OF BIOMASS TRANSFER

disadvantage of food chains

• don’t show the number of organisms involved

• size of biomass transferred

what is a pyramid of numbers ?

show population at each trophic with the producer at the base and the bar width showing the number of organisms present

why aren’t all pyramids of numbers pyramids shaped?

they don’t take into account the size of the organisms present

what is an advantage of pyramids of biomass?

• by plotting the amount of biomass at each trophic level , you take into account both the number and size of the organism present

what are pyramids of biomass ?

they show the relative mass of each trophic level

how to calculate biomass?

• Find the dry mass of the plant (when there is no more change in mass after heating)

• measure the average mass of each of these organisms and multiply by number of organisms present

state one disadvantage of collecting biomass data

difficult to obtain as the organism needs to be killed and heated in an oven to remove any water, until a constant dry mass is obtained.

why do producers only take in a small amount of energy from the sun?

most of the light is reflected from the leaf and the proportion of energy that is transferred to chemical stores by photosynthesis is limited by factors

when is biomass lost?

• not all of organism is eaten

• some of biomass used in respiration + respiration also causes thermal energy to transfer to environment

• some parts of an organism cannot be digested

• waste products produced by body are lost

• not all of the organisms at previous trophic level are eaten

what is egestion?

removal of undigested waste

what is excretion?

the process of removing waste from the body

where do plants obtain the nutrients they need for growth?

soil