instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
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
answer:
What is required when electrons are removed from an atom, and released from the process when an electron is added?

question:
Passage: Photography by Kat. Ferns are common in the understory of the tropical rainforest . CC BY 2.0. Answer: understory
answer:
In a tropical rainforest, where are ferns common?

question:
Passage: Cycle of Sexual Reproduction. Sexual reproduction involves the production of haploid gametes by meiosis. This is followed by fertilization and the formation of a diploid zygote. The number of chromosomes in a gamete is represented by the letter n. Why does the zygote have 2n, or twice as many, chromosomes?. Answer: meiosis
answer:
Sexual reproduction involves the production of haploid gametes by what?