The stem supports the plant and because of the stem the plant is able to grow taller if needed
Sister chromosome exchanges are recombination events that occur between homologous chromosomes and are often the result of exposure of the cell to DNA damaging agents.
Cross over, or recombination, is the exchange of chromosome segments between non sister chromatids in meiosis. Crossing over creates new combinations of genes in the gametes that are not found in either parent, contributing to genetic diversity.
Is there a phrase choice??
Graphs that are clearly labeled are much less likely to be misread or misinterpreted.