Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

Q: Question: What are flightless birds that are strong swimmers and spend much of their time in the water? Answer: penguins

A: Penguins are flightless birds that are strong swimmers and spend much of their time in the water.
****
Q: Question: What are the highest clouds in the atmosphere? Answer: noctilucent clouds

A: Noctilucent clouds are the highest clouds in the atmosphere.
****
Q: Question: In humans, a zygote has how many chromosomes? Answer: 46

A:
Upon fertilization a diploid zygote is formed. In humans, a zygote has 46 chromosomes, 23 inherited from each parent. The gametes, sperm and eggs, are haploid cells, with 23 chromosomes each.
****