Answer:
1. Humans have 23 pairs of chromosomes--22 pairs of numbered chromosomes, called autosomes, and one pair of sex chromosomes, X and Y. Each cell in the human body contains 23 pairs of such chromosomes; hence our diploid number is 46, the number 'singularity' is 23.
2. This is because our chromosomes exist in matching pairs - with one chromosome of each being inherited from the biological parent.