if random chromosome alignment already shuffles chromosomes around so the eggs and sperm get a good mix of some “mom” alleles and some “dad” alleles, why do we even need to do crossing over

The correct answer is - to produce recombinant that leads to genetic variation.

Explanation:

Random shuffling or random alignment of the chromosome during gamete formation allows the formation of new allele combinations. In the crossing over the parts of the homologous chromosomes are switched between homologous and recombinants are formed that shows are genetic variation.

So, now they have different allele combinations and chromosome combinations as well. Random shuffling does not provide genetic variations as crossing over

amber has allowed scientists to study dna that has been preserved over millions of years.

oak trees? ? what was listed