Explain and provide and example of how energy flow is represented in food chains, food webs and pyramids. explain how changing a factor in an ecosystem (especially involving a keystone species) can impact this flow of energy and the ecosystem as a whole: provide an example of this in your answer.
heterotroph
autotroph
producer
food chain
consumer
energy pyramid
trophic level
food web
keystone species

Well all 3 it would start with a producer,

example:

African Iris- African Killer Bee- Anteater- Spotted Hyena-(when the hyena dies of natural causes since it is an apex predator)- Earthworm

I don't know if this is exactly what you mean, but this is the best example I can with.

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.

a- multicellular

b-eukaryotic

c-no cell wall

d-heterotrophic

e-autotrophic