How does mitosis and meiosis ensure that the chromosome number of a certain species remain the same across generations?

What is crossing over and where does it occur in meiosis? Why is crossing over important for creating genetic diversity?

What would happen to the chromosome number in gametes and offspring if ​gametes were formed by the mitotic process instead of the meiotic process?

Which of the following are differences between mitosis and meiosis I? CHOOSE ALL THAT APPLY. A) Crossing over occurs during meiosis I but not during mitosis B) DNA replication takes place prior to mitosis, but not before meiosis I C) Sister chromatids separate in mitosis, and homologs separate in meiosis I D) Only meiosis I results in daughter cells that contain identical genetic information E) Meiosis I results in two daughter cells, while mitosis results in four daughter cells