questions energy flow pyramids



Ecological Pyramids

Answer the following questions in the space provided.

1. a) What kind of ecological pyramid is depicted in the above diagram? a.

A pyramid of Numbers b.

A pyramid of Energy c.

A pyramid of Biomass b) Describe the shape of this ecological pyramid. Why doesn’t this pyramid collapse even though there are fewer organisms at the first trophic level than at the second trophic level?

It doesn’t collapse because 1 oak tree can sustain 2000 caterpillars. b) What happens to the energy stored in each trophic level as one moves up through the levels in the pyramid?

10% Heat energy is lost to the surroundings as one moves up through the levels


DATE: MAY 2014


CLASS: DIPLOMA BIOLOGY YEAR 12 NAME: a) What kind of ecological pyramid is depicted in the above diagram? Provide a definition explaining the nature of this pyramid.

A pyramid of biomass b) Describe two complications that can arise when biologists use a pyramid of biomass.

As a pyramid of biomass is measured by mass, the fresh mass is quite easy to access, however the presence of varying amounts of water makes it unreliable. The use of dry mass is an option, however it means the animal must be killed and this small sample is not representative. Also only the organisms present at a particular time are shown and not in different seasons during the whole year.



3. A grassland ecosystem in Alberta receives 1500 kJ of sunlight. One food chain in this community is depicted as follows: grass



hawks a) Draw an ecological pyramid that illustrates the transfer of energy in this community. Using the rule of 10, determine the amount of energy that is stored at each trophic level. Include all relevant labels. b) A farmer sets up a buffalo farm in this ecosystem. Over time, the buffalo greatly reduce the grass biomass in the community. Explain how the introduction of this new species could affect the amount of energy transferred within the food chain that is shown above.

There is not going to be sufficient energy from the first trophic level to pass on to the grasshoppers, blackbirds and hawks. Therefore due to the 10% rule, there can be no more energy to pass on to the last trophic level, therefore the hawks.

4. On the rest of this handout, discuss this statement: “Humans should all be vegetarians

In terms of energy and trophic levels, being plants our primary producers, humans can either be primary consumers or secondary consumers. Vegetarians are eating at the lowest trophic level and are only consuming primary producers, whilst non-vegans eat a large number of primary consumers.

These means that these animals we are eating such as Pigs, Cows and Chicken need a lot of energy for them to grow to the point where they can be eaten by the secondary consumers. Overall animals take huge amount of energy to be raised and in return we get a very small profit. This is one of the main causes why there are millions of people starving around the world, there is not enough meat for all humans to eat the necessary energy requirements to live. Most of the energy is lost and dissipated when it reaches humans. On the other hand, using plants used to feed animals could be possible


DATE: MAY 2014 CLASS: DIPLOMA BIOLOGY YEAR 12 NAME: nutrients for ourselves. We could and should be eating that food instead of wasting it. In addition, because our food needs a lot of processing and raising these farm animals take a huge amount of water, land, food and oil where plants could be easily be growing.

From the other side of the spectrum, humans do need protein source in their diets and this can be difficult especially for children going through their growth stage. However I think we should be more conscientious of what we eat.