Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Are humans a new or old species on the earth?
Are humans a new or old species on the earth?

The discovery of ribozymes nullified the idea that all biological catalysts are proteins.
What nullified the idea that all biological catalysts are proteins?

Unlike ammonia, oxygen cannot be liquefied at room temperature because its critical temperature is below room temperature.
Unlike ammonia, oxygen cannot be liquefied at room temperature because its what is below room temperature?