Where did the extra chromosome in down syndrome come from?

Which of the following is not a characteristic of natural selection? 100 points pls more offspring are born than will survive to reproduce. mutations appear randomly breeding pairs are chosen by humans organisms that are better adapted are more likely to survive

How much time has elapsed from the very beginning of "the memior of the conquistador bernal diaz del castillo" to the end? a. castillo's whole life b. a quarter of an hour c. a few weeks d. a decade

One of the reasons that stars are so large is because