How did earths atmosphere change during precambrian time?

Guinea pig coat color is determined by a single gene. the allele for black coat color is dominant to brown. in a cross between twoblack-haired guinea pigs, 20 offspring are born. if both parents were heterozygous, probability would predict that approximately howmany of the 20 offspring would have brown hair?

What is the period of cell life when it is conducting

True or false multiple lane changes must be done individually going through the same procedures for each lane change