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

[Q]: Passage: Alkenes are unsaturated hydrocarbons with at least one double bond between carbon atoms. Answer: alkenes
[A]: What are unsaturated hydrocarbons with at least one double bond between carbon atoms called?

[Q]: Passage: The menstrual cycle includes events that take place in the ovary, such as ovulation. Answer: ovary
[A]: Ovulation takes place in what organ and is part of the menstrual cycle?

[Q]: Passage: Physical activity is an important part of balanced eating. It helps you use up any extra Calories in the foods you eat. You should try to get at least an hour of exercise just about every day (see Figure below ). Exercise has many health benefits in addition to balancing the energy in food. For example, it strengthens the bones and muscles and may improve your mood. Answer: hour
[A]:
How much exercise should a person ideally get during a single day?