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

Ex Input:
Passage: When heat is positive, the total energy of the system is increasing. Answer: it increases

Ex Output:
What happens to the total energy of the system when heat is positive?

Ex Input:
Passage: Like a blanket on a sleeping person, greenhouse gases act as insulation for the planet. The warming of the atmosphere is because of insulation by greenhouse gases. Greenhouse gases are the component of the atmosphere that moderate Earth's temperatures. Answer: insulation

Ex Output:
Like a blanket on a sleeping person, greenhouse gases act as what for the planet?

Ex Input:
Passage: Even though large life forms have been very successful on Earth, most of the life forms on Earth today are still prokaryotessmall, relatively simple single-celled organisms. As it is difficult to identify, observe and study such small forms of life, most of these organisms remain unknown to scientists. Advancing technologies, however, do allow for the identification and study of such organisms. Answer: prokaryote

Ex Output:
What is a small, relatively simple single-celled organism called?