– Male and female gametes fuse together during fertilization to form a zygote. The chromosome number is halved during the formation of gametes by the process of meiosis. This maintains the chromosome number generations after generations. Meiosis leads to genetic diversity which is very essential for evolution.

1. Cell Division – Meiosis Sexual reproduction in eukaryotes takes place by the fusion of gametes and they maintain their ploidy. How is this possible?

17. Meiosis I- Prophase I Image reference – http://www.pinkmonkey.com/studyguides/subjects/biology- edited/chap6/b0606302.asp

24. Image reference –http://www2.estrellamountain.edu/faculty/farabee/biobk/biobookmeiosis.html

28. Comparison between Mitosis and Meiosis Four daughter cells are formed. Two daughter cells are formed. Dividing cells are diploid. Dividing cells can be haploid or diploid. May take place only once (simultaneous type) or twice (successive type). Cytokinesis takes place only once. Consists of two nuclear divisions M-I and M-II. Consists of only one nuclear division. Occurs in reproductive cells. Occurs in somatic cells. Meiosis Mitosis

29. Comparison between Mitosis and Meiosis Meiosis Mitosis Chromosomal characters are altered due to "crossing over" causing recombination of genes. Original characters of the chromosomes are maintained in the daughter cells. It is a reduction division. It is an equational division. Pairing of homologous chromosomes and crossing over occur during Prophase-I. Does not involve either pairing of homologous chromosomes or crossing over.

30. Comparison between Mitosis and Meiosis Meiosis Mitosis Helps in the sexual reproduction and regulation of chromosome number in the life cycle of sexually reproducing organism. Helps in growth and body repairs. Daughter cells differ from each other as well as from the original mother cell. Daughter cells are similar to each other and also to the original mother cell.