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

Ex Input:
Passage: Amines are weak bases due to the presence of a lone pair of electrons on the nitrogen atom. This lone pair can attract the hydrogen atom from a water molecule, causing the bond between it and the oxygen atom to break. The resultant products are the conjugate acid of the amine and the hydroxide ion. Answer: electrons

Ex Output:
Amines are weak bases due to the presence of a lone pair of what on the nitrogen atom?

Ex Input:
Passage: If a solute is a solid or liquid, increasing the temperature increases its solubility. For example, more sugar can dissolve in hot water than in cold water. Answer: increases its solubility

Ex Output:
What does increasing a solute's temperature do?

Ex Input:
Passage: Vertebrates evolved from primitive chordates. This occurred about 550 million years ago. The earliest vertebrates may have been jawless fish, like the hagfish in Figure below . Vertebrates evolved a backbone to replace the notochord after the embryo stage. They also evolved a cranium , or bony skull, to enclose and protect the brain. Answer: chordates

Ex Output:
Vertebrates evolved from primitive forms of which creature?