Which human cells never have 23 pairs of chromosomes? a. blood cells b. nerve cells c. mature sex cells d. mutant cells

All the given cells in the human body that are found in the choices are composed of 23 pairs of chromosomes. However, one of them is not. The answer to this item is mature sex cells. That is letter C. The egg cell and sperm cell when combined will form 23 pair of chromosomes but not individually. The answer is letter C.

It is mature sex cells (sperm for male or egg for female) that never have 23 pairs of chromosomes. In this case, they instead contain 23 chromosomes (without the pairing). The full complement of chromosomes is regained when male and female sex cells fuse.

Air enters through the nose (and sometimes the mouth), moves through the nasal cavity, the  pharynx, the  larynx, enters the  trachea, moves through the  bronchi  andbronchioles  till the alveoli.