Given a scientific passage and an answer, generate a question for the given answer.

[Q]: Passage: Some chemical reactions can occur in only one direction. These reactions are called irreversible reactions. The reactants can change to the products, but the products cannot change back to the reactants. These reactions are like making a cake. The ingredients of a cakesuch as eggs and flourare the reactants. They are mixed together and baked to form the cake, which is the product (see Figure below ). The cake can't be "unbaked" and "unmixed" to change it back to the raw eggs, flour, and other ingredients. So making a cake is irreversible. Answer: irreversible
[A]: What are reactions that can occur only in one direction called?

[Q]: Passage: Coal is the source of most electricity. Answer: coal
[A]: What is the source of most electricity?

[Q]: Passage: In many species display behaviors, rather than actual physical attacks, are used to show aggression. This helps prevent injury and death. Male gorillas, for example, are more likely to put on a display of aggression than to attack another male. In fact, gorillas have a whole series of display behaviors that they use to show aggression. They beat on their chest, dash back and forth, and pound the ground with their hands. Answer: showing aggression
[A]:
How do the male gorillas show display behaviors?