Why is it important that egg and sperm only have on set of chromosomes?

Because when they combine the fertilized egg will have 46 chromosomes. The egg has 23 chromosomes and the sperm has 23 so adding them together is the 46 chromosomes the human body is supposed to have.

Explanation:

the  different  of  these  two  are  that  they  differently  handle  their  team.

an  expressive  leader  focuses  on  the  task  at  hand  and  make  sures  that  their  goal  is  achieved.  they  accurately  finish  the  task.  an  instrumental  leader  on  the  other  hand  works  on  the  unity  of  the  group,  they  care  more  about  their  employees.  all  the  while  creating  a  good  environment.