Biology: 4b Pyramids

What is pyramids of number

shows how many organisms are present at each level of a food chain

What indicates to the number of organisms at each level?

width of the box indicates the number of organisms at that trophic level

Pyramids of numbers aren’t always…

pyramid sized.

What is pyramids of biomass?

shows how much living matter is present at each trophic level of a food chain

Is is biomass a measure of?

Biomass is often a measure of the dry mass of an organism (without water)

Are pyramids of biomass always pyramid shaped and why?

always pyramid-shaped, available biomass always decreases at higher trophic levels.

Why is pyramids of biomass more useful?

take into account the size of organisms at each trophic level, so provide a more accurate representation of the living matter within an ecosystem

energy is stored in biomass, so biomass can be used as an approximate representation of the energy available

What is the pyramids of energy (transfer)?

shows the stored energy within the biomass at each trophic level

What pyramids of energy measured in ?

Joules/kilojoules

Are pyramids of energy always pyramid shaped and why?

Yes, because energy is lost at each trophic level

How much energy entering trophic level is passed on?

only 10%

Why is only 10% passed on?

organisms use same energy for movement, respiration, reproduction (MRS H GREN) meaning not all energy gained is available to pass on.

Some materials are also not absorbed and are egested/unable to digest.

What does this mean for the no of trophic levels in pyramid of energy?

Limits no. tophic levels possible.