Given a scientific question, generate a correct answer to it.

Ex Input:
What is the place called where the axon of one neuron meets the dendrite of another?

Ex Output:
synapse

Ex Input:
What can radioactive strontium replace in the human body making it dangerous?

Ex Output:
calcium

Ex Input:
Vertical layering is an important feature of the terrestrial type of what kind of community?

Ex Output:
biome