Blog # 11

The sexual reproduction in plants include two alternations between meiosis and fertilization. For the alternative part of meiosis the chromosomes reduce from diploids to haploids number. It is the opposite in fertilization where the haploids are increased to diploids after the two nuclei of gametes fuse together. Therefore these variation have to occur alternatively in order for sexual reproduction to run smoothly.
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Alternation.html
http://en.wikipedia.org/wiki/Alternation_of_generations