instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: CHAPTER SUMMARY 37.1 Types of Hormones There are three basic types of hormones: lipid-derived, amino acid-derived, and peptide. Lipid-derived hormones are structurally similar to cholesterol and include steroid hormones such as estradiol and testosterone. Amino acid-derived hormones are relatively small molecules and include the adrenal hormones epinephrine and norepinephrine. Peptide hormones are polypeptide chains or proteins and include the pituitary hormones, antidiuretic hormone (vasopressin), and oxytocin. Answer: peptide
answer:
There are three basic types of hormones: lipid-derived, amino acid-derived, and what?

question:
Passage: The Universe contains about a hundred billion galaxies. Answer: about a hundred billion
answer:
Approximately how many galaxies are there in the universe?

question:
Passage: Atoms form covalent bonds by sharing valence electrons. The valence electrons are located in atomic orbitals. However, when a bond forms, the structure of the atomic orbitals changes. In this lesson, we will see how the atomic orbitals interact to share valence electrons and form different types of covalent bonds. Answer: covalent bonds
answer:
What do atoms form by sharing valence electrons?