What does the Solar System revolve around and how long does it take for one revolution?

Bottom line: The planets in our solar system orbit (revolve) around the sun, and the sun orbits (revolves) around the center of the Milky Way galaxy. We take about 225-250 million years to revolve once around the galaxy's center. This length of time is called a cosmic year.

Explanation:

the answer would be 2, if crossing over doesn’t occur 2 out of 4 of the daughter cells will have that allele.

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