what would happen to all the energy fixed by autotrophic organism if the community has no animals to eat the plants ? The animals would not survive also would they ? So the plants would also not survive or will they because of the microbes? I am confused please explain.

Your friend has answered correctly. However, I would like to add more points.
Animals are important for natural balance in the environment. Firstly, if there are no animals to eat the plants, the population of plants will increase enormously and this will result in instability of ecosystem.
Secondly, plants are dependent on animals like insects, birds, mammals for pollination and seed dispersal. When animals are not present, the pollination and seed dispersal will not occur, so plants also cannot survive in this ecosystem. The animals eat fruits and throw seeds at different places. Thus, helps in the dispersal of seeds. These seeds grow into new plants during favourable conditions. Thus, if there are no animals to eat fruits, seeds will not be moved to different places and they will not grow into new plants.  
Thus, it is not possible for this type of ecosystem to exist in reality.



 

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It's impossible for such ecosystem to exist. It would be impossible for plants also to survive in such a condition. Animals and insects are essential for plants, too. They help them in pollination and thus, tgey help them in reproduction. If there wouldn't be any animal or insect, how would they get pollinated? At first, the answer may seem that "Wind is always there to pollinate." But think about the plants which have heavy pollen grains,or, their pollen grains are just not compatible for wind pollination. Without it, they'd die. And, not only this, insects offer many other advantages. Also, think about the mutual relationship between the members of kingdom Fungi and Plants, for example, lichen, which is an obligatory relationship.
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