In each of the following comparisons, indicate whether the molecular clock is expected to tick faster on average in the first (1) or the second (2) case. Your answer would be a four-digit number composed of digits 1 and 2 only, e.g. 2222. ( ) 1: The exons, or 2: the introns of a gene ( ) 1: The mitochondrial, or 2: the nuclear DNA of vertebrates ( ) 1: The first, or 2: the third position in synonymous codons ( ) 1: A gene, or 2: its pseudogene counterpart