Why does secondary succession occur faster than
primary succession?

Secondary succession usually occurs faster than primary succession because the substrate is already present.

In primary succession, there is no soil and it needs to form.

Explanation:

gametes or germ cells are haploid cells (example: sperm and ova) containing only one set (or n) number of chromosomes and autosomal or somatic cells are diploid cells containing 2n number of chromosomes.