What will happen if we kill all the organisms in one trophic level?

If we kill all the organisms in one trophic level, then transfer of energy as well as matter to next higher level will stop. It will lead to over- population at one particular level causing amongst the individuals. This would seriously disturb the food chain and can cause the collapse of an ecosystem even.

by killing 2 or more organisms, you will disrupt the chain and can lead to loss of other organisms higher in the levels and lower level organisms will increase in volume

Explanation:

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.