In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

Question: What occurs when an unstable nucleus emits a beta particle and energy? Answer: beta decay
Beta decay occurs when an unstable nucleus emits a beta particle and energy.

Question: Which form of energy is produced when paper is burned? Answer: heat
Heat is produced when paper is burned.

Question: What can demonstrate the decrease in energy, biomass or numbers within an ecosystem? Answer: ecological pyramids

Ecological pyramids can demonstrate the decrease in energy, biomass or numbers within an ecosystem.