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

[Q]: Passage: Some nonmetals are very reactive, whereas others are not reactive at all. It depends on the number of electrons in their outer energy level. Answer: reactivity
[A]: The number of electrons in the outer energy level determines what property of nonmetals?

[Q]: Passage: What does sunshine have to do with sleep (other than the sun shining in your eyes and waking you up)? For many people, sleeping problems have to do with an amine that the brain makes called melatonin. This compound affects the sleep-wake cycle and is affected by sunlight. During the winter, the daily cycle of melatonin production may be affected by less sunlight hours. If this cycle is changed, the person may have trouble sleeping. Melatonin supplements are available in pharmacies and health food stores and may be of help for those with sleeping problems. Answer: melatonin
[A]: During the winter, production of what amine involved in the sleep-wake cycle may be affected by less sunlight hours?

[Q]: Passage: 27.1 | Anatomy and Physiology of the Male Reproductive System By the end of this section, you will be able to: Describe the structure and function of the organs of the male reproductive system Describe the structure and function of the sperm cell Explain the events during spermatogenesis that produce haploid sperm from diploid cells Identify the importance of testosterone in male reproductive function Unique for its role in human reproduction, a gamete is a specialized sex cell carrying 23 chromosomesone half the number in body cells. At fertilization, the chromosomes in one male gamete, called a sperm (or spermatozoon), combine with the chromosomes in one female gamete, called an oocyte. The function of the male reproductive system (Figure 27.2) is to produce sperm and transfer them to the female reproductive tract. The paired testes are a crucial component in this process, as they produce both sperm and androgens, the hormones that support male reproductive physiology. In humans, the most important male androgen is testosterone. Several accessory organs and ducts aid the process of sperm maturation and transport the sperm and other seminal components to the penis, which delivers sperm to the female reproductive tract. In this section, we examine each of these different structures, and discuss the process of sperm production and transport. Answer: sperm
[A]:
What is the male gamete called in humans?