9.7: energy transformations

What do pyramids of biomass show?

The relative biomass of each trophic level

What is a trophic level?

Each stage in a food chain or web

What do the arrows on a food chain show?

The transfer of biomass from one trophic level to another

What percentage of biomass is transferred to each higher trophic level?

10% on average, which is why each trophic level gets smaller

What percentage of the sun’s energy is converted into biomass?

1% through photosynthesis

Why is only 10% biomass transferred?

Not all of the biomass is eaten (since some organisms die naturally, or certain parts of an organism aren’t eaten, such as bones, hooves, claws and teeth), and not all of the biomass eaten is converted into the biomass of the animal eating it (lots of glucose is used in respiration, biomass consumed can be lost as faeces etc)

What is the shape of a pyramid of biomass?

A pyramid - the tertiary consumers are much smaller than the producers since there are fewer organisms that are tertiary consumers than producers

What is a decomposer?

An organism (bacteria and fungi) which breaks down dead animal and plant matter

How do decomposers work?

They secrete enzymes on the surface of the dead organisms which breaks it down, then they absorb the digested food molecules since they are smaller

Why is wood considered biomass?

It was recently a plant

Why are fossil fuels not biomass?

Biomass is living or recently dead tissues - fossil fuels were remains of organisms which died millions of years ago

How to draw pyramids of biomass

Bars equally spaced around the midpoint, bars touching, producer at the bottom (and tertiary consumer at the top), the length of each bar is proportional to the amount of biomass available at each trophic level

What is the largest food chain?

Around 6 trophic levels long, since only 10% is transferred the the next trophic level