Witch atmospheric level is farthest from the lithosphere

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

What would be the result if crossing over did not happen during meiosis in humans? a. there would be less genetic variation in humans. b. parents would be more likely to look like their children. c. the human population could not reproduce. d. children would have more chromosomes.

In 1992, hurricane andrew left a wake of destruction through florida. one victim of the storm was a reptile-breeding facility. over 900 burmese pythons were set free, and today thousands of pythons live in florida. these pythons are an invasive species, or a harmful species not native to the region. 1. what impacts do you think the burmese pythons might have on local ecosystems