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

Input: Consider Input: Passage: When electrons are removed from an atom, that process requires energy to pull the electron away from the nucleus. Addition of an electron releases energy from the process. Answer: energy

Output: What is required when electrons are removed from an atom, and released from the process when an electron is added?

Input: Consider Input: Passage: Insects spread disease and destroy crops. However, they are essential for pollinating flowering plants. Answer: insects

Output: What are essential for pollination, but can spread disease and destroy crops?

Input: Consider Input: Passage: Both alpha and beta decay change the number of protons in an atom's nucleus, thereby changing the atom to a different element. In alpha decay, the nucleus loses two protons. In beta decay, the nucleus either loses a proton or gains a proton. In gamma decay, no change in proton number occurs, so the atom does not become a different element. Answer: protons
Output: Both alpha and beta decay change the number of what in an atom's nucleus?