The discovery of DNA has allowed us to trace ancestors and find out how early humans lived, what they looked like, and who they were.
They are less likely to be separated during crossing over.
1. The cell wall has lignin (hard substance): to prevent the xylem vessel from collapsing and withstand high pressure.
2. The absence of protoplasm (nucleus + cytoplasm) and cross wall: to allow water to move through the lumen easily.
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Answer:
Cells and tissue
Explanation:
Cells are the most basic unit of life made up of several organelles that perform various functions which enables the cell to exist.
An aggregation of cells is called a tissue. The bone is composed of several interconnected cells and tissues.
A bone heals when bone cells and tissues are gradually repaired. Hence, the most basic levels of organization involved when a bone heals are cells and tissues.