a male and a female sex cell are required to perform sexual reproduction & each sex cell provides half the number of chromosomes in a fertilized egg through sexual reproduction ->  a male sex cell provide half the number of chromosomes and a female sex cell provides half the number of chromosomes in a fertilized egg through sexual reproduction  a male sex cell provide half the number of chromosomes and a female sex cell provides half the number of chromosomes in a fertilized egg through sexual reproduction & if two things provide half of something to something else, then that something else will recive a full amount of that something ->  a fertilized egg recives a full set of chromosomes through sexual reproduction  a fertilized egg recives a full set of chromosomes through sexual reproduction & fertilization is when an egg cell becomes fertilized -> new cells with a full set of chromosomes are formed by fertilization