Given a scientific question, generate a correct answer to it.

Input: Consider Input: Which part of the nerve cell helps transmit nerve impulses?

Output: long, threadlike extensions

Input: Consider Input: Any sound with a frequency above the highest audible frequency is defined as what, a phenomenon useful in medical diagnosis and therapy?

Output: ultrasound

Input: Consider Input: What is the distinctive shape of the molecule that contains genetic information?
Output: spiral