### Theory:

Significance of meiosis:
1. Among the sexually reproducing organisms, each species' constant chromosome number is maintained by this division.
2. Due to crossing over, it increases the genetic variability in organisms' population from onegeneration to the next.
Note: Genetic variations are essential for the process of evolution.
Difference between mitosis and meiosis:
 Properties Mitosis Meiosis Type of cells It takes place in somatic cells. It takes place in reproductive cells. Number of division Single division Two divisions Growth and formation Involved in growth and the division and occurs continuously throughout life. Involved in gamete formation only during the reproductively active age. Synapsis of homologous chromosomes It does not occur In prophase I, crossing over occurs between the non-sister chromatids of chromosomes. Genetic composition Genetically identical daughter cells are formed. Daughter cells are genetically not similar to the parent cell and are randomly assorted. Number of daughter cells Two diploid daughter cells are formed. Four haploid daughter cells are formed. Chromosome number The chromosome number present  in the daughter cell is similar to the parent cell ($$2n$$). The chromosome number present in the daughter cell is just half ($$n$$) of the parent cell.

Difference between binary fission, mitosis and meiosis
Stem cell:
• They are special human cells, and they are undifferentiated cells that undergo unlimited divisions and give rise to many different types of cells.
• Embryonic stem cells differentiate into differenttissues and organs.
• Stem cells are used in the treatment of certain degenerative diseases such as parkinson's and Alzheimer's.
• In present days umbilical cord blood is collected at the time of childbirth and is being stored in stem cell banks to treat any diseases in the future.
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