Signal your body to prepare for repeated contractions
Get your muscles ready for usage and widen up
Sends more blood in your body everwhere to be used over and over again for respiration
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Cross over is the first way genes are shuffled to give rise to genetic diversity. Cross over takes place in sexual reproduction. The normal way that cross over occurs is chromosomes line up side by side and break off pieces of themselves, then trade those pieces with each other.
If they break the pieces at the same locus in the sequence of base pairs, the result is an exchange of genes called genetic recombination and it ensures that the daughter cells produced have a different genetic makeup from the parent cell and thus diversity occurs.
Stem cells are what allow planaria to grow and regenerate as the stem cells can change into any of the cells that make up the planaria.
Your answer would be $4 times $y.
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